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超高速フォトダイオードとその通信技術への応用

電子情報通信学会和文論文誌Cに優れたレター論文を発表した

電子情報通信学会和文論文誌Cに優れたレター論文を発表した

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1109/LPT.2020.3007415

Language：English   Publishing type：Research paper (scientific journal)  

Nonlinear compensation for indoor visible light communication systems with carrierless amplitude and phase modulation
Although there are enormous available bandwidths for license-free visible light communication (VLC), a relatively narrow modulation bandwidth of LED is still an obstacle for further application. The carrierless amplitude and phase (CAP) modulation is a high spectral efficiency modulation technology which has begun to draw more attention in recent years. However, to meet the illumination of indoor VLC, the nonlinear interference is quite serious because of multipath fading channels. Thus, the spectrum efficiency of VLC with CAP modulation is greatly limited by these nonlinear effects. In this paper, the nonlinear distortion of indoor VLC systems, which was introduced by the nonlinearity of analog device and multipath fading channel, has been analyzed. Therefore, the problem we are trying to solve is to study an adaptive digital equalizer at CAP modulation which can efficiently mitigate nonlinearity of indoor VLC. The simulation result shows that the adaptive digital decision-feedback equalizer is an effective solution that can mitigate inter-symbol interference and improve the receiver performance efficiently.

DOI： 10.7567/1347-4065/ab1fd8

Language：English  

700 GHz terahertz wave beam combination by optical phase control

DOI： 10.7567/1347-4065/ab26aa

Language：Japanese  

Language：Japanese  

半導体光増幅器(SOA)における注入電流変化に対する光位相変化を測定するためにマッハ・ツェンダ干渉計型強度変調器を模した測定系を光ファイバで構成し、かつ光ファイバ長の揺らぎの影響を受けない測定法を提案している。本測定により、SOAの注入電流に対する光位相変化を高精度で測定でき、本測定法が有効である事を確認した

Language：English  

DOI： 10.1587/transele.e99.c.1048, 10.7567/1347-4065/ab26aa_references_DOI_5YmyZzbRIm9Zdn1o04YvQNbqpIi

Language：English   Publishing type：Research paper (international conference proceedings)  

The lasers for the flexible-grid wavelength division multiplexing (WDM) system are required to have high precision of wavelength stability. Previously, we proposed the wavelength-controlling system of the Distributed FeedBack Laser Diode (DFB-LD) with the photomixing technique and a microwave filter to precisely measure the optical frequency error from the target value. To enlarge the wavelength-capture range, we improve the system to detect the wavelength error with two different microwave filters in parallel. Experimental results show that the wavelength-capture range is extended up to 4 GHz while the wavelength error is still kept within ±50 MHz.

DOI： 10.7567/JJAP.55.08RB10

Language：English  

Sub-microsecond wavelength stabilization of tunable lasers with the internal wavelength locker
We proposed a method of accelerating the wavelength stabilization after wavelength switching of the Tunable Distributed Amplification (TDA-) DFB laser using the internal wavelength locker to reduce the size and the cost of wavelength control system. The configuration of the wavelength stabilization system based on this locker was as follows. At the wavelength locker, the light intensity after an optical filter is detected as a current by the photodiodes (PDs). Then, for estimating the wavelength, the current is processed by the current/voltage-converting circuit (IVC), logarithm amplifier (Log Amp) and Field Programmable Gate Array (FPGA). Finally, the laser current is controlled to tune to the desired wavelength with reference to the estimated wavelength. With this control system the wavelength is stabilized within 800 ns after wavelength switching which is even faster than that with the conventional control system.

DOI： 10.7567/JJAP.55.08RB07

Language：English  

Fast wavelength switching with tunable distributed amplification distributed feedback laser by feedforward control technique
We proposed the way to accelerate the wavelength switching at the TDA-DFB laser based on the feedforward control. From experimental lasers’ responses, we designed and simulated the feedforward controllers using MATLAB/Simulink so as to reduce the time for wavelength stabilization. We applied this technique to two different situations; one is for the laser drive circuit with a large output current and 50-ns rise time, and the other is for that with a moderate output current and 5-ns rise time. In both situations, we showed the improvement of the wavelength switching times which were from 450 ns to 150 ns and 75 ns to 35 ns, respectively. From these results, it is confirmed that the proposed control technique is efficient for possible practical applications.

DOI： 10.7567/JJAP.53.08MB11

Language：Japanese  

高周波キャリアを二光波のビート信号で生成する光学系をマッハ・ツェンダ干渉計として構成し，干渉光強度の安定化制御で高周波キャリアの位相安定化を行う方法を提案している．実験により10 Hz以下の位相ゆらぎが低減され本提案の有効性が確認された．

Publisher：Optics Communications  

We propose a cost-effective THz wireless communication scheme for future femtocell networks that leverages either direct gain modulation (DGM) or cross gain modulation (XGM) of a semiconductor optical amplifier (SOA) to convert coaxially or optically carried data into intensity-modulated THz waves, respectively. This architecture, based on an SOA and a uni-traveling-carrier photodiode (UTC-PD), has advantages over typical THz modulation schemes involving a resonant tunneling diode or an electro-optic modulator combined with a UTC-PD. Consequently, it facilitates the seamless convergence of hybrid fiber-coaxial networks to THz radio access networks with low cost, straightforward monolithic integration, and a more compact footprint. Furthermore, we experimentally verified the possibility of non-return-to-zero on–off keying wireless communication over 0.5 m in the 300 GHz band, achieving real-time transmission of 4 Gbit/s for coaxial access via an SOA's DGM and 10 Gbit/s for fiber access via the SOA's XGM. Notably, these data rates were attained by simple non-coherent THz intensity demodulation based on a Fermi-level managed barrier diode while meeting the 7% hard-decision forward error correction (HD-FEC) threshold (3.4×10−3). Finally, we conducted an analysis of the merits and drawbacks of the proposed THz communication scheme based on the combination of an SOA and a UTC-PD, discussed bottlenecks that hinder further rate improvement, and explored possibilities for optimization. In conclusion, this scheme is crucial for realizing future ultra-high-speed wireless networks that seamlessly connect to fiber-coaxial networks.

DOI： 10.1016/j.optcom.2024.130724

Scopus

Language：Japanese  

This article presents research trends in terahertz-wave wireless communications as well as our research results on terahertz wave phase management in an optical domain at photomixing technology, such as power combining, beam steering and phase stabilization for multi-level phase modulation.

DOI： 10.14923/transelej.2023jci0017

CiNii Research

Publisher：Electronics (Switzerland)  

Advancements in semiconductor devices, such as Uni-travelling-carrier photodiodes (UTC-PDs), have played a significant role in the development of Terahertz communication technology. However, the persistent challenge is the limited output power from a single UTC-PD required for practical transmission distances. To enhance the output power, we propose and demonstrate a novel Terahertz wave power combining technique using a photomixer device comprising two arrayed UTC-PDs monolithically integrated with a microstrip line-based 2 × 1 Wilkinson power combiner and a patch antenna on a Silicon Carbide (SiC) substrate at 300 GHz. When the two UTC-PDs are activated at photocurrents of 8 mA and 10 mA, the device exhibits a 7.3 dB increase in power relative to the power obtained when only the 8 mA UTC-PD is activated, and a 4.4 dB increase in power relative to the power obtained with the 10 mA UTC-PD. This implies that power can be enhanced by a factor of N2 if the photocurrent is multiplied by N. Additionally, we demonstrate that the UTC-PD output saturation depends on the space charge effect, which modulates the electric field in the depletion region and results from critical charge density of about 80 kA/cm2 for the device in this work.

DOI： 10.3390/electronics13132661

Scopus

Publisher：Optics Communications  

Reconfigurable Intelligent Surfaces (RISs), proposed as innovative units, possess the potential to establish reliable connections in Underwater Optical Wireless Communication (UOWC) systems, where direct transmission (DT) experiences significant weakening due to dynamic channel conditions. In this paper, we examine the performance of a UOWC system consisting of an RIS and a modulating retroreflector (MRR), referred to as the RIS-assisted MRR-UOWC system. The channel is affected by a combination of path loss, gamma–gamma (G–G) turbulence, and pointing error (PE). The considered system employs the spectral-power-efficient L-ary Quadrature Amplitude Modulation Multi-Pulse Pulse-Position Modulation (LQAM-MPPM) technique. For our system performance measures, we present upper-bound (UB) and approximate UB expressions for the average bit-error rate (BER) of LQAM-MPPM signals. These expressions are used to analyze the system's performance. Performance metrics are established by deriving the Probability Density Function (PDF), Cumulative Distribution Function (CDF), and Moment-Generating Function (MGF) for the end-to-end signal-to-noise ratio (SNR), resulting from the sum of products of independent but not identically distributed (i.ni.d) channel coefficients. The results of our study indicate that the LQAM-MPPM scheme surpasses traditional schemes.

DOI： 10.1016/j.optcom.2024.130444

Scopus

Publisher：Japanese Journal of Applied Physics  

Photomixing is one of the promising THz-wave generation methods. A conventional photomixing system with two lasers results in increasing the volume and power consumption of the system. For downsizing the system and reducing its power consumption, we have previously proposed a method to generate a THz-wave by a single wavelength-tunable laser. This technique can generate a quasi-continuous THz wave as well as a pulsed THz wave, based on which we are studying toward pulse frequency-amplitude modulation as a multi-level modulation method. In this paper, we have successfully generated a THz wave with frequency modulation between 286 GHz and 322 GHz by a single wavelength-tunable laser.

DOI： 10.35848/1347-4065/ad37c3

Scopus

Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

We explored the potential of an optoelectronic frequency hopping system within the 300 GHz band, leveraging a tunable distributed feedback laser array and uni-traveling carrier photodiode. Our experiments successfully achieved a 10-channel terahertz (THz) frequency hopping, marking a significant advancement in THz secure communication technologies. Notably, the system exhibited a rapid frequency-hopping capability with a short transition time of 0.8 ms between channels, ranging from 288 to 331 GHz. Further, we conducted data transmission tests at a rate of 5 Gbit s⁻¹ across several channels. The results were promising, showing each channel maintained a clear eye pattern and a low bit error rate, crucial factors for reliable and secure data transmission. These findings not only demonstrate the efficacy of our system but also open new avenues for high-speed, secure THz communication.

DOI： 10.35848/1347-4065/ad3926

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Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/ad3926/pdf

Publisher：2024 International Conference on Electronics Packaging, ICEP 2024  

We designed a terahertz wave power combiner which combines high-frequency currents from each photomixer in a micro strip line and investigated the feasibility of terahertz wave power combining. The designed terahertz power combiner was fabricated on silicon carbide (SiC) substrate because of its high thermal conductivity, which prevents thermal damage to the UTC-PD at high photocurrent. The UTC-PDs was activated with a bias voltage of -1.0 V and a photo current of 8 mA. Experimental results show that the output power of four photo mixers is multiplied by 11 dB (approximately 13 times) compared to that of a single photomixer, which confirms a great advantage of arrayed photomixers as a current source. In addition, the THz waves was higher without narrowing the beam width, compared to using the method of arrayed antennas with UTC-PDs.

DOI： 10.23919/ICEP61562.2024.10535617

Scopus

Publisher：2024 Optical Fiber Communications Conference and Exhibition, OFC 2024 - Proceedings  

We proposed a photonic frequency-hopping physical-secure Terahertz-wave communication system driven by a high-speed wavelength tunable laser and a photomixer, and experimentally demonstrated a frequency-hopping time of less than 25 ns at 300-GHz band.

Scopus

Publishing type：Research paper (scientific journal)  

THz technology has the potential to revolutionize various fields, including high-speed wireless communication, medical imaging, and spectroscopy. One challenge facing THz technology, however, is the limited output power (on the order of microwatts) of photonic THz sources (e.g., uni-traveling-carrier photodiode). Researchers are therefore exploring THz beam steering techniques to maximize their power effectiveness. To this end, we propose a photonic THz beam steering method that utilizes fiber chromatic dispersion, eliminating the need for energy-consuming active electronics. This paper explains its basic operating principle, fabrication and performance analysis of the associated THz array antenna, and demonstrates the feasibility of achieving a 300 GHz beam steering within 10∘ by means of dispersion-varied polarization-maintaining fibers. In conclusion, the present scheme can greatly enhance the power efficiency of photonic THz sources, and enable the potential advantages of seamless integration with fiber-optic networks, including reduced complexity, simplified operation, low power consumption, and cost-effectiveness.

DOI： 10.1007/s10762-024-00975-0

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Publisher：International Journal of High Speed Electronics and Systems  

A terahertz (THz) wave generator for multiplying the output power from arrayed photomixers is developed. The generator is composed of two uni-traveling carrier photodiodes (UTC-PDs) as the photomixers, a 2 × 1 T-junction power combiner and a microstrip rectangular patch antenna on a silicon carbide (SiC) substrate in which photocurrents of 300 GHz from the UTC-PDs are combined to be fed to the antenna. Experimental results show that the output power is multiplied by 5.8 dB (approximately fourfold) compared to that of a single UTC-PD. This advancement has the potential for further multiplication of THz power by cascaded combining of a larger number of UTC-PDs.

DOI： 10.1142/S0129156424400251

Scopus

Language：Others   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

As a high-frequency carrier, the terahertz (THz) wave is essential for achieving high-data-rate wireless transmission due to its ultra-wide bandwidth. Phase stabilization becomes crucial to enable phase-shift-based multilevel modulation for high-speed data transmission. We developed a Mach–Zehnder interferometric phase stabilization technique for photomixing, which has proved a promising method for phase-stable continuous THz-wave generation. However, this method faced inefficiencies in generating phase-modulated THz waves due to the impact of the phase modulator on the phase stabilization system. By photomixing, which is one of the promising methods for generating THz waves, the phase of the generated THz waves can be controlled in the optical domain so that the stability of the generated THz wave can be controlled by photonics technologies. Thus, we devised a new phase stabilization approach using backward-directional lightwave, which is overlapped with the THz wave generation system. This study presented a conceptual and experimental framework for stabilizing the phase differences of optical carrier signals. We compared the optical domain and transmission performances between forward-directional and backward-directional phase stabilization methods. Remarkably, our results demonstrated error-free transmission at a modulation frequency of 3 Gbit/s and higher.

DOI： 10.3390/electronics12153366

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

Future wireless communications require higher security as well as a higher data rate. We have been studying physically secured wireless transmission systems and previously proposed encryption/decryption techniques based on the AND operation caused by coherent detection between two encrypted data sequences on two different terahertz carriers. Furthermore, we suggested that by employing the XOR operation as the decryption, the proposed system can be made more secure because XOR increases the computational complexity for eavesdroppers to recover the plaintext. In this paper, we propose the XOR operation between two data sequences on FSK-modulated terahertz waves. By constructing the XOR encryption transmitters/receivers, which consisted of high-speed wavelength tunable lasers and arrayed uni-traveling-carrier photodiodes (UTC-PDs), we successfully demonstrated the XOR operation between two data sequences on 200 GHz waves from the two transmitters.

DOI： 10.3390/electronics12122629

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

DOI： 10.1109/tthz.2023.3251736

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Authorship：Last author,　Corresponding author  

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Language：Others  

Publisher：Photonics  

The photomixing of two lightwaves is one of the promising methods of generating a terahertz (THz) wave. The conventional photomixing system consisting of two lasers and a modulator results in large transmitter volumes and high power consumption. To solve this issue, we devised a novel THz wave generation and modulation system based on photomixing using a single wavelength-tunable laser in combination with delayed self-multiplexing. We successfully demonstrated the feasibility of 300-GHz wave generation and modulation.

DOI： 10.3390/photonics10040369

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Language：Japanese  

We have previously demonstrated beam steering of terahertz waves generated from arrayed photomixers by mechanically adjusting the optical phase. This time, we succeeded in electronically controlling the beam steering angle with an accuracy of less than 10° using an optical phased array that can adjust the optical phase electrically.

DOI： 10.14923/transelej.2022jcl0007

CiNii Research

Publishing type：Research paper (international conference proceedings)  

We designed and assessed a power combiner-radiator complex for integration with 300-GHz-band arrayed photomixers. The device consists of a microstrip-line based combiner (Wilkinson combiner or a T-junction combiner) and a patch antenna. Simulation results show an increase of the radiated power by 2.54 dB with a Wilkinson combiner and 2.94 dB with a T-junction combiner in comparison to a conventional single port-fed device. The results further show realized directional gains of 4.85 dBi and 5.04 dBi for the complex based on a Wilkinson combiner and a T-junction combiner, respectively. Additionally, the Wilkinson combiner gives better return loss and isolation between the input ports than the T-junction combiner, while the T-junction combiner has a better radiation efficiency of 85% compared to 77% of the Wilkinson combiner.

DOI： 10.23919/URSIGASS57860.2023.10265384

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Publisher：International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz  

We developed a fiber-coupled uni-traveling-carrier photodiode (UTC-PD) array chip for the purpose of combining the generated THz waves, and the feasibility of 300 GHz beam steering with the aid of a genetic algorithm is demonstrated in this work. Not only is this algorithm capable of automatically compensating for the optical path difference arising from the inconsistent lengths of coupled fibers, but it can also calculate the optimal phase shift in each channel for deflecting the THz beam to a predetermined angle. The implementation of this optimization algorithm in THz beam steering provides an attractive solution for efficient THz wireless communication or imaging applications in a large-scale UTC-PD array.

DOI： 10.1109/IRMMW-THz57677.2023.10299236

Scopus

Publisher：2023 Opto-Electronics and Communications Conference, OECC 2023  

We designed and analyzed the performance of a 2 by 1 coupled line Wilkinson combiner-antenna device for arrayed photomixers at 300 GHz. Simulation results showed that there is a 2.59 dB increase in total radiated THz-wave power when the coupled line Wilkinson combiner is used to integrate two identical UTC-PDs and feed their output power into an antenna, compared to a single-port feed for a single UTC-PD. Additionally, there is a -21.5 dB isolation between the feed ports and a realized gain of 4.8 dBi in the +z (theta = 0) direction. Furthermore, the quarter wavelength lines for the designed combiner covers a half area of 0.1 × 0.055 mm2 compared to the conventional Wilkinson combiner.

DOI： 10.1109/OECC56963.2023.10209621

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Publishing type：Research paper (international conference proceedings)  

We demonstrated an optoelectronic frequency hopping system in the 300-GHz band using a tunable DFB laser array and an antennas-integrated UTC-PD chip. The experimental result exhibited a fast-hopping speed of 4.4 GHz/ms in the 300-330 GHz range, which shows great potential for THz secure communication.

DOI： 10.23919/MOC58607.2023.10302896

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DOI： 10.1364/OFC.2023.M3D.4

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Publishing type：Research paper (international conference proceedings)  

We developed a THz-wave power-combination and beam-steering system driven by an optoelectronic phased array. The 300-GHz waves from an antenna-coupled InP/InGaAs UTC-PD array are combined with 16-dB gain and steered continuously over a 30° range.

DOI： 10.23919/OFC49934.2023.10116084

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Publisher：28th Microoptics Conference, MOC 2023  

We designed a novel terahertz wave power combiner which combines high-frequency currents from each photomixer in a micro strip line. The experimental result showed that the combined power increases super-linearly with the number of the photomixers, which for the first time confirms a great advantage of photomixing as a current source.

DOI： 10.23919/MOC58607.2023.10302740

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Publishing type：Research paper (international conference proceedings)  

To exploit the extremely wide bandwidth in the THz region for ultra-high-speed wireless communication, UTC-PD-based THz emitters enjoy a wide bandwidth and high linearity, but face challenges in increasing power due to saturation effects and thermal effects. We designed a 16-way WR3 power combiner for 12 dB gain using the Y-branch structure in the 300 GHz band. Additionally, a 37.7 dBi gain reflector-integrated diagonal horn antenna was developed for a pencil beam at 300 GHz. Furthermore, ongoing efforts are dedicated to manufacturing them with 3D printing technique.

DOI： 10.1117/12.2647226

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Publisher：2023 35th General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2023  

Higher-frequency carriers are inevitable for higher-speed wireless communication. To maximize their advantage, phase stabilization is an essential technology for phaseshift-based multi-level modulation. At photomixing, which has been a promising way for continuous THz-wave generation, we have devised a Mach-Zehnder interferometric phase stabilization method. However, the serious drawback of the method is the ineffectiveness for a phase-modulated THz wave. This time, we invent a phase stabilization system with a backward-direction lightwave overlapping on the THz-wave generation system. A conceptual and experimental setup of phase detection and phase stabilization is presented in this paper. The stabilization system is revealed to be effective at above a couple of Gbit/s.

DOI： 10.23919/URSIGASS57860.2023.10265667

Scopus

Publisher：ICECOM 2023 - 24th International Conference on Applied Electromagnetics and Communications  

This paper presents our strategic approaches for increasing data rates of terahertz (THz) wireless communications using photonics-based transmitters and receivers and shows recent results in the 300-GHz-band.

DOI： 10.1109/ICECOM58258.2023.10367950

Scopus

Publisher：28th Microoptics Conference, MOC 2023  

Based on our devising THz-wave-generation method by photomixing using single wavelength-Tunable laser, we design a pulse frequency modulation system. Experimental results show the feasibility of pulsed THz wave generation with different frequencies. Together with the use of a wavelength selective switch, the system can be developed into pulse frequency-Amplitude modulation.

DOI： 10.23919/MOC58607.2023.10302887

Scopus

Language：Japanese  

The photomixing technique is a promising method of terahertz-wave generation. However, the conventional method uses two lasers, which results in a large space and high-power consumption. We devised a photomixing system using a single wavelength-tunable laser. We successfully demonstrated the system at 300 GHz using a reflection-type transversal filter laser.

DOI： 10.14923/transelej.2022jcl0003

CiNii Research

Language：Others  

Authorship：Last author,　Corresponding author  

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Language：Others   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

DOI： 10.1109/jlt.2022.3204113

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Language：Japanese  

Evaluation of High-Security Wireless Communication System Utilizing AND Operation Between Two Data
We have proposed a method to improve physical layer security of wireless communication by radiating two data from different locations. In this system, a receiver can decode original data by implementing AND operation between two data. This time, we confirmed feasibility of proposed system by implementing AND operation between two light waves.

DOI： 10.14923/transelej.2022jcl0001

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1109/LPT.2021.3137808

Language：Others   Publishing type：Research paper (scientific journal)  

DOI： 10.1109/LPT.2021.3137808

Publisher：OECC/PSC 2022 - 27th OptoElectronics and Communications Conference/International Conference on Photonics in Switching and Computing 2022  

We proposed a physical layer secure wireless communication system using AND operation. In this paper, we demonstrate data transmission based on AND operation between two 300-GHz-band signals from two transmitters.

DOI： 10.23919/OECC/PSC53152.2022.9850185

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Publisher：Asia-Pacific Microwave Conference Proceedings, APMC  

Terahertz-wave has been attracting attention for high-speed wireless communication and photomixing is considered to be a promising method for generating terahertz-waves. Since the output power of the conventional InGaAsP-based photomixer saturates due to its lower voltage resistance, an InGaN-based photomixer with higher voltage resistance is under investigating. One of the essential technologies of InGaN-based photomixing is two-tone single-mode lightwave. In this paper, we devised a method to make a two-tone lightwave using a 405-nm laser and a periodic optical filter. We successfully demonstrated the two-tone lightwaves for four different terahertz bands.

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Publisher：Asia-Pacific Microwave Conference Proceedings, APMC  

We had previously proposed a physically encrypted Terahertz (THz) communication system based on AND operation between two signals and confirmed the effectiveness of the decryption. In this paper, by utilizing uni-traveling carrier photodiodes (UTC-PDs) arrays with 4 × 4 slot antennas as transmitters and coherent detection at the receiver, we experimentally demonstrated the feasibility of the proposed system with 500 Mbit/s data transmission on 300-GHz band.

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Publisher：Proceedings of SPIE - The International Society for Optical Engineering  

6G/beyond 5G technologies should meet the requirement for both high speed and high security. We have focused on terahertz (THz) waves for high-speed transmission, and by photomixing, we have demonstrated power enhancement and beam steering. In terms of the security of wireless transmission, physical-layer security becomes an important issue. We have proposed a novel wireless communication system based on beam steering and coherent detection. In this system, two different data encoded from original data on two THz beams are radiated from two different locations and are overlapped at a target area by beam steering. Then, a receiver at the area implements logical AND operation between the two data as a result of coherent detection, which deduces the original data. This time, as a feasibility confirmation, we performed logical AND operation between two data on different lightwaves and measured the bit error rate of the deduced original data. Experimental results showed that the original data is deduced exactly from the two encoded data when the amplitude ratio between the two data is smaller than 5. This indicates that the acceptable ratio between the distances from two different transmitters would be up to 5. Experimental results also showed that the bit error rate suddenly deteriorates when the time slots of the two data are shifted by 0.7 bits This indicates that the receivable area is limited in several centimeters square for a 1-Gbit/s data.

DOI： 10.1117/12.2606717

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Publishing type：Research paper (international conference proceedings)  

To realize a high-speed high-reliability wavelength switching at future WDM networks, we proposed the injection-current/temperature cooperative control method of the tunable-distributed-feedback (DFB) laser array (TLA) for avoiding a large injection current, which is the primary cause of laser degradation. We successfully demonstrated a full-C-band wavelength switching within 124 ms by rapid increase of the injection current and following gradual decrease of the injection current to avoid laser aging. Compared to the conventional control method, the meantime to failure of the TLA in the proposed method is estimated to be extended by 44 times.

DOI： 10.1117/12.2604422

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Publishing type：Research paper (international conference proceedings)  

Taking advantage of photomixing technique, we successfully demonstrated the generation of pulsed THz waves with a repetition rate of 5, 10, and 25 GHz, as well as their enhancement by 10 dB using 4-arrayed UTC-PDs.

DOI： 10.23919/OECC/PSC53152.2022.9849992

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Publisher：OECC/PSC 2022 - 27th OptoElectronics and Communications Conference/International Conference on Photonics in Switching and Computing 2022  

TLA have succeeded in improving reliability through current/temperature cooperative control. We aim to obtain the equation relating temperature, current, and wavelength required for feed-forward control to improve the wavelength switching speed.

DOI： 10.23919/OECC/PSC53152.2022.9850042

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Publisher：Proceedings of the 10th International Japan-Africa Conference on Electronics, Communications, and Computations, JAC-ECC 2022  

In this letter, outage probability of terahertz (THz) link between two unmanned aerial vehicles (UAVs) is analytically and numerically investigated. Composite fading statistical model is developed considering joint effects of multipath fading, angle of arrival (AoA), and pointing-errors. The derived expression for outage probability is used to illustrate the misleading results in case of neglecting UAV antenna orientation fluctuations. In addition, effect of antenna half power beam width (HPBW) on maximum achievable link length under constraint of threshold outage probability is numerically investigated. Derived expression is validated by comparing analytical results with Monte Carlo (MC) simulation and they show high degree of agreement.

DOI： 10.1109/JAC-ECC56395.2022.10044033

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Publishing type：Research paper (international conference proceedings)  

We analyzed the performance of a microstrip patch antenna fed by a 2 by 1 Wilkinson power combiner at 300 GHz. Simulation results show that a 2.54 dB gain in total radiated power can be achieved when the Wilkinson power combiner is used to feed the antenna compared to a single-port power feed. Results further show that the combiner provides a good isolation of -21.5 dB between the input ports. Additionally, the peak power in the +z (theta =0) direction for both xz and yz planes increases by 4.8 dB.

DOI： 10.1109/JAC-ECC56395.2022.10043902

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Publisher：Asia Communications and Photonics Conference, ACP  

The performance of modulating retro-reflector underwater optical wireless communication systems with the spectral-power-efficient L-ary quadrature amplitude modulation multi-pulse pulse-position modulation (LQAM-MPPM) technique is investigated. Our results reveal that the LQAM-MPPM technique outperforms conventional ones.

DOI： 10.1109/ACP55869.2022.10089065

Web of Science

Scopus

Publisher：OECC/PSC 2022 - 27th OptoElectronics and Communications Conference/International Conference on Photonics in Switching and Computing 2022  

A photonics-based control system to stabilize the phases of the optical signal for terahertz wave phase modulation is introduced. The analysis of the phase modulator with inverse direction lightwave is successfully presented.

DOI： 10.23919/OECC/PSC53152.2022.9850107

Scopus

Publisher：Asia-Pacific Microwave Conference Proceedings, APMC  

High-frequency carriers have been widely used in recent wireless communication. To comply with this situation, a phase-stable wave carrier generation is an essential technology. We devised a phase stabilization system for photomixing-based THz wave phase modulation with an inverse pilot lightwave. A stable 300-GHz phase modulated wave was successfully generated and transmitted, testifying to the effectiveness of the proposed system.

Scopus

Web of Science

Publisher：Asia-Pacific Microwave Conference Proceedings, APMC  

We proposed a high speed intensity modulation system of THz waves with a low voltage signal by combining a wavelength-tunable laser and photomixing technology. We demonstrated 150 Mbit/s intensity modulation of THz waves at 2 Vpp by using an RTF laser as a wavelength tunable laser.

Scopus

Web of Science

Language：Others   Publishing type：Research paper (scientific journal)  

DOI： 10.1109/LPT.2021.3124826

Language：Japanese  

二つのRF信号のコヒーレント検波により，それらのアンド信号が得られることを利用し，無線の物理レイヤでの新たな暗号化手法を考案した．二つの300GHz帯無線キャリアのヘテロダイン検波によるアンド演算を確認し，考案した手法の受信原理を実証した．

DOI： 10.14923/transelej.2021JCL0002

Language：English  

DOI： 10.1016/j.ijleo.2021.167203

Language：English  

DOI： 10.1364/OE.423308

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English  

DOI： 10.1049/ell2.12122

Language：English  

DOI： 10.1587/elex.18.20210008

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1049/ell2.12122

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese  

波長可変分布活性DFBレーザの最大波長可変幅800 GHzでの高速波長切替を目指して，レーザの非線形性を考慮したモデルを開発した．フィードフォワード制御の高精度化により30 nsの高速波長切替を達成し，更にフィードバック制御の併用で長期波長安定化を実現した．

DOI： 10.14923/transelej.2020jcl0009

Language：English   Publishing type：Research paper (scientific journal)  

High-Speed Wavelength Switching at TDA-DFB Laser Based on a Nonlinear Model
In order to realize a high-speed optical switch for optical packet switching (OPS), we have been focused on a wavelength routing optical switch consisting of tunable lasers and an arrayed waveguide grating (AWG), and have studied high-speed wavelength switching of a tunable distributed amplification (TDA)-distributed feedback (DFB) laser. Previously, we achieved high-speed wavelength switching by feedforward control based on linear control theory. In this article, to realize higher-speed wavelength switching, we proposed a more accurate control model based on the nonlinearity of the TDA-DFB laser. We applied our nonlinear model to 400-GHz-wide and 600-GHz-wide wavelength switching and realized high-speed wavelength switching times of 33 ns and 39 ns, respectively.

DOI： 10.1109/LPT.2020.3026739

Language：Others   Publishing type：Research paper (other academic)  

DOI： 10.1109/OECC48412.2020.9273595

Language：Others   Publishing type：Research paper (other academic)  

DOI： 10.1109/OECC48412.2020.9273522

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1109/LPT.2020.3007415

Language：English  

Language：Others   Publishing type：Research paper (other academic)  

DOI： 10.23919/MOC46630.2019.8982899

Language：Others   Publishing type：Research paper (other academic)  

DOI： 10.23919/MOC46630.2019.8982905

Language：Others   Publishing type：Research paper (other academic)  

Language：Others   Publishing type：Research paper (other academic)  

DOI： 10.23919/PS.2019.8818137

Language：Japanese  

Language：English  

DOI： 10.15017/2195853

Language：Others  

DOI： 10.7567/jjap.57.08pd04

Language：Japanese  

Language：Others   Publishing type：Research paper (other academic)  

DOI： 10.1117/12.2287326

Language：Others   Publishing type：Research paper (other academic)  

DOI： 10.23919/MOC.2017.8244620

Language：Others   Publishing type：Research paper (other academic)  

DOI： 10.1109/OECC.2017.8114812

Language：Others   Publishing type：Research paper (other academic)  

DOI： 10.23919/MOC.2017.8244486

Language：Others   Publishing type：Research paper (other academic)  

DOI： 10.23919/MOC.2017.8244604

Language：Others   Publishing type：Research paper (other academic)  

DOI： 10.23919/MOC.2017.8244600

Language：English   Publishing type：Research paper (other academic)  

Language：English  

Language：Others   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (other academic)  

DOI： 10.1117/12.2248859

Language：Others   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1109/TCOMM.2015.2512922

Language：Others   Publishing type：Research paper (other academic)  

DOI： 10.1109/MOC.2015.7416475

Language：English   Publishing type：Research paper (other academic)  

DOI： 10.1117/12.2212017

Language：English  

DOI： 10.34385/proc.37.s2.1.1

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1109/TCOMM.2015.2467372

Language：English   Publishing type：Research paper (other academic)  

DOI： 10.1145/2800795.2800824

Language：Others  

DOI： 10.7567/jjap.53.08mb09, 10.7567/jjap.55.08rd04_references_DOI_Tdkkh8ulZvCb0YVD8qOC3zLOGvM

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Ultrafast optical signal measureent using optoelectronic techniques

DOI： 10.1023/A:1006964727065

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1109/68.481134

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢   Country：Japan  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢   Country：Japan  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢   Country：Japan  

Event date： 2017.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名城大学   Country：Japan  

Event date： 2017.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名城大学   Country：Japan  

Event date： 2017.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名城大学   Country：Japan  

Event date： 2017.3

Language：English  

Country：United States  

Event date： 2016.11

Language：Japanese  

Venue：東京 機械振興会館   Country：Japan  

Event date： 2016.10

Language：English  

Country：United States  

Event date： 2016.10

Language：English  

Country：United States  

Event date： 2016.10

Language：English  

Country：United States  

Event date： 2016.10

Language：English  

Country：United States  

Event date： 2016.10

Language：English  

Venue：UC Berkeley   Country：United States  

Event date： 2016.9

Language：English  

Country：Japan  

Event date： 2016.9

Language：Japanese  

Venue：宮崎大学   Country：Japan  

Event date： 2016.9

Language：Japanese  

Venue：北海道大学   Country：Japan  

Event date： 2016.9

Language：Japanese  

Venue：北海道大学   Country：Japan  

Event date： 2016.9

Language：Japanese  

Venue：北海道大学   Country：Japan  

Event date： 2016.9

Language：Japanese  

Venue：北海道大学   Country：Japan  

Event date： 2016.9

Language：Japanese  

Venue：北海道大学   Country：Japan  

Event date： 2016.7

Language：English  

Country：Japan  

Event date： 2016.7

Language：English  

Country：Japan  

Event date： 2016.4

Language：Japanese  

Venue：リゾーピア熱海   Country：Japan  

Event date： 2016.4

Language：Japanese  

Venue：リゾーピア熱海   Country：Japan  

Event date： 2016.4

Language：Japanese  

Venue：リゾーピア熱海   Country：Japan  

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Event date： 2016.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Event date： 2016.2

Language：English   Presentation type：Oral presentation (general)  

Country：United States  

Event date： 2016.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：名城大学   Country：Japan  

Event date： 2015.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢しいのき迎賓館   Country：Japan  

Event date： 2015.10

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Other Link： http://www.moc2015.com/

Event date： 2015.10

Language：English   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

Country：Japan  

Event date： 2015.10

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Other Link： http://www.moc2015.com/

Event date： 2015.6 - 2015.7

Language：English   Presentation type：Oral presentation (general)  

Country：China  

Other Link： http://www.oecc2015.sjtu.edu.cn/

Event date： 2015.6 - 2015.7

Language：English   Presentation type：Oral presentation (general)  

Country：China  

Other Link： http://www.oecc2015.sjtu.edu.cn/

Event date： 2015.3

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2015.3

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2015.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：立命館大学、草津市   Country：Japan  

UTC-PDアレイと光位相調整器によるコヒーレントテラヘルツ波発生デバイスの試作

Event date： 2015.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：立命館大学、草津市   Country：Japan  

モジュール内蔵波長ロッカを用いたフィードバック制御による TDA-DFBレーザの高速波長切替

Event date： 2015.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：立命館大学、草津市   Country：Japan  

マッハ・ツェンダ干渉計型二光波間位相安定化法によるPSK変調キャリアの位相雑音低減

Event date： 2015.3

Language：Japanese  

Venue：立命館大学、草津市   Country：Japan  

マッハ・ツェンダ干渉計型二光波間位相安定化法によるPSK変調キャリアの位相雑音低減

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Event date： 2014.11

Language：English  

Country：Japan  

Event date： 2014.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：長崎市   Country：Japan  

Event date： 2014.10

Language：English  

Country：Japan  

Event date： 2014.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：徳島大学   Country：Japan  

光バースト、光パケットシステムなどの波長ルーティングシステム発展のためには、より高速に波長切替可能な光源が必要となってくる。我々はこれまでに、制御層への電流変化により波長が変化するTDA(Tunable Distributed Amplifier) DFBレーザについて、フィードフォワード(FF)制御を導入することによってより、長波長ある波長安定状態から制御層電流を増加し短波長側(光周波数の増大方向制御層電流増加)への波長切替において応答高の速化を実現してきた[2]。本稿では短波長側への切替に加えて制御層電流を減少した長波長側(光周波数の増大方向) (制御層電流減少)への波長切替応答高速化を目指しについても、FF制御を導入することでそれぞれ波長切替時間35 ns、30 nsを実現したことと、切替応答について考察を行ったのでが高速化されたことについて報告する。

Event date： 2014.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：徳島大学、徳島市   Country：Japan  

基準光との光差周波を用いた半導体レーザの高精度波長安定化

Event date： 2014.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：徳島大学、徳島市   Country：Japan  

フィードフォワード/フィードバック切替型制御による波長可変レーザの高速波長安定化

Event date： 2014.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：徳島大学、徳島市   Country：Japan  

TDA-DFBレーザの波長切替応答高速化の検討

Event date： 2014.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

フィードフォワード制御によるTDA-DFBレーザの波長切替高速化と光スイッチ動作

Event date： 2014.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：徳島大学、徳島市   Country：Japan  

Event date： 2014.8

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2014.7

Language：English   Presentation type：Oral presentation (general)  

Country：United States  

Event date： 2014.6

Language：English   Presentation type：Oral presentation (general)  

Country：France  

Event date： 2014.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟大学   Country：Japan  

光バースト/パケットスイッチングの実現に向けて高速かつ高精度に波長切替可能な波長可変レーザ(TDA-DFBレーザ)の研究が行われている。我々はデジタル制御による複雑な系の安定化の実現可能性に注目し、フィードフォワード(FF)制御とフィードバック(FB)制御を組み合わせることでFBループ周期よりも高速に波長安定化できることを報告した。本稿では、波長可変レーザおよびその周辺回路を含むシステム全体の特性に基づいた最適なFB制御パラメータの設計とその検証を行ったので報告する。

Event date： 2014.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：北九州国際会議場   Country：Japan  

光通信の大容量化に向けてフレキシブルグリッドが注目されている。フレキシブルグリッドでは6.25GHz間隔で配置された光周波数を中心に帯域粒度12.5GHzの任意の幅のスロットを配置できるため高密度な波長多重伝送が可能となるが、グリッド間隔が6.25GHzと狭いためレーザーには±0.1GHz以内の精度での波長安定化が必要となる。本研究では、フレキシブルグリッドから半周期ずらした基準光群と被測定光の差周波を波長誤差検出信号として用い、高精度にレーザーの波長を安定化する方法を検討した。

Event date： 2014.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：新潟大学   Country：Japan  

光バーストシステムや光パケットシステムには波長可変範囲が広く高速波長切替が可能な光源が求められる。その候補の一つとしてTDA (Tunable Distributed Amplification）-DFBレーザが開発されている。熱ドリフト補償器を集積したTDA-DFBレーザでは波長切替時の熱ドリフトを抑制し0.31 usまでの高速波長切替が実現できている。我々はフィードフォワード制御により駆動回路の立ち上がり時間を高速化し、波長切替時間150 nsを実現した。本稿ではさらに高速な回路を設計し、それに適合したフィードフォワード制御によって波長切替時間50 ns以下を実現したので報告する。

Event date： 2013.10

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2013.10

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2013.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡工業大学   Country：Japan  

FF制御とFB制御を組み合わせた制御法を考案し、これをTDA-DFBレーザに適用した。実験により、熱ドリフトを補償することで320nsの高速な波長安定化を確認した。

Event date： 2013.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡工業大学   Country：Japan  

波長切替高速化を目的にTDA-DFBレーザの波長切替特性のモデル化とフィードフォワード制御の設計を行った。実際に制御系を作製し波長切替150 nsを実現した。

Event date： 2024.3

Language：Others  

Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島   Country：Japan  

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島   Country：Japan  

Event date： 2023.12

Language：Japanese  

Venue：仙台   Country：Japan  

Event date： 2023.12

Language：Japanese  

Venue：仙台   Country：Japan  

Event date： 2023.12

Language：Japanese  

Country：Japan  

Event date： 2023.12

Language：Japanese  

Country：Japan  

Event date： 2023.12

Language：Japanese  

Country：Japan  

Event date： 2023.12

Language：Japanese  

Country：Japan  

Event date： 2023.9

Language：Others  

Country：Other  

Event date： 2023.9

Language：Others  

Country：Other  

Event date： 2023.9

Language：Others  

Country：Other  

Event date： 2023.9

Language：Others  

Country：Other  

Event date： 2023.9

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Event date： 2023.9

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Event date： 2023.9

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Event date： 2023.9

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Event date： 2023.9

Language：Others  

Country：Other  

Event date： 2023.9

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Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本   Country：Japan  

Event date： 2023.9

Language：Others  

Country：Other  

Event date： 2023.9

Presentation type：Oral presentation (invited, special)  

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Event date： 2023.9

Language：Others  

Country：Other  

Event date： 2023.6

Language：Japanese  

Venue：渋川   Country：Japan  

Event date： 2023.6

Language：Japanese  

Venue：渋川   Country：Japan  

Event date： 2023.6

Language：Japanese  

Venue：渋川   Country：Japan  

Event date： 2023.6

Language：Japanese  

Venue：渋川   Country：Japan  

Event date： 2023.6

Language：Japanese  

Venue：渋川   Country：Japan  

Event date： 2022.9

Language：Others  

Country：Other  

Event date： 2022.9

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Event date： 2022.9

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Event date： 2022.9

Language：Others  

Country：Other  

Event date： 2022.9

Language：Others  

Country：Other  

Event date： 2022.9

Language：Others  

Country：Other  

Event date： 2022.9

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Event date： 2022.9

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Event date： 2022.9

Language：Others  

Country：Other  

Event date： 2022.9

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Event date： 2022.6

Language：Others  

Country：Other  

Event date： 2022.6

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Event date： 2022.6

Language：Others  

Country：Other  

Event date： 2022.6

Language：Others  

Country：Other  

Event date： 2022.6

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Event date： 2022.6

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Event date： 2022.3

Language：English   Presentation type：Oral presentation (general)  

Event date： 2022.3

Language：English   Presentation type：Oral presentation (general)  

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Italy  

Event date： 2022.3

Language：English   Presentation type：Oral presentation (general)  

Event date： 2022.3

Language：English   Presentation type：Oral presentation (general)  

Event date： 2022.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2022.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2022.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2022.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.11

Language：English   Presentation type：Oral presentation (general)  

Event date： 2021.11

Language：English   Presentation type：Oral presentation (general)  

Event date： 2021.11

Language：English   Presentation type：Oral presentation (general)  

Event date： 2021.11

Language：English   Presentation type：Oral presentation (general)  

Event date： 2021.11

Language：English   Presentation type：Oral presentation (general)  

Event date： 2021.11

Language：English   Presentation type：Oral presentation (general)  

Event date： 2021.11

Language：English   Presentation type：Oral presentation (general)  

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

Event date： 2021.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.11

Language：English   Presentation type：Oral presentation (general)  

Event date： 2021.9

Language：English   Presentation type：Oral presentation (general)  

Event date： 2021.9

Language：English   Presentation type：Oral presentation (general)  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.8

Language：English   Presentation type：Oral presentation (general)  

Event date： 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン  

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.12

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.12

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.12

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：横浜   Country：Japan  

Event date： 2020.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：徳島 (online)   Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：徳島 (online)   Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：徳島 (online)   Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.10

Language：English   Presentation type：Oral presentation (general)  

Country：Taiwan, Province of China  

Event date： 2020.10

Language：English   Presentation type：Oral presentation (general)  

Country：Taiwan, Province of China  

Event date： 2020.10

Language：English   Presentation type：Oral presentation (general)  

Country：Taiwan, Province of China  

Event date： 2020.10

Language：English   Presentation type：Oral presentation (general)  

Country：Taiwan, Province of China  

Event date： 2020.10

Language：English   Presentation type：Oral presentation (general)  

Country：Taiwan, Province of China  

Event date： 2020.10

Language：English   Presentation type：Oral presentation (general)  

Country：Taiwan, Province of China  

Event date： 2020.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡 (online)   Country：Japan  

Event date： 2020.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡 (online)   Country：Japan  

Event date： 2020.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡 (online)   Country：Japan  

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：佐賀   Country：Japan  

Event date： 2020.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：佐賀   Country：Japan  

Event date： 2020.9

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.8

Language：English   Presentation type：Oral presentation (general)  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島   Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島   Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島   Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：広島   Country：Japan  

Event date： 2019.12

Language：English   Presentation type：Oral presentation (general)  

Country：Singapore  

Event date： 2019.12

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.12

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.12

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2019.9 - 2019.10

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2019.9 - 2019.10

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪府豊中市   Country：Japan  

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪府豊中市   Country：Japan  

Event date： 2019.9 - 2019.8

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.7

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.4 - 2020.4

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：群馬県   Country：Japan  

Event date： 2019.4

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：群馬県   Country：Japan  

Event date： 2019.4

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：群馬県   Country：Japan  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.3

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.1

Language：English  

Country：Japan  

Event date： 2018.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2018.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2018.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Event date： 2018.11

Language：Japanese  

Venue：福岡   Country：Japan  

Event date： 2018.10

Language：English   Presentation type：Oral presentation (general)  

Country：Taiwan, Province of China  

Event date： 2018.10

Language：English   Presentation type：Oral presentation (general)  

Country：Taiwan, Province of China  

Event date： 2018.10

Language：English   Presentation type：Oral presentation (general)  

Country：Taiwan, Province of China  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢   Country：Japan  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢   Country：Japan  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：金沢   Country：Japan  

Event date： 2018.8

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.8

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.8

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.8

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.7

Language：English   Presentation type：Oral presentation (general)  

Country：Korea, Republic of  

Event date： 2018.4

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：湯河原   Country：Japan  

Event date： 2018.4

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：湯河原   Country：Japan  

Event date： 2018.4

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：湯河原   Country：Japan  

Event date： 2017.11

Language：English  

Country：Japan  

Event date： 2017.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.11

Language：English   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.7 - 2017.8

Language：English  

Venue：Singapore   Country：Singapore  

We have previously proposed a synchronous THzwave combiner with linearly arrayed power sources. With four arrayed photomixers we experimentally confirmed directional gain of 5.9 dB. In this paper, for exerting full performance of the array effect, we configured for the first time two-dimensionally arrayed THz-wave combiner and demonstrated a power gain of 4.8 dB compared to the linear array.

Event date： 2017.7 - 2017.8

Language：English   Presentation type：Oral presentation (general)  

Country：Singapore  

Event date： 2017.1 - 2017.2

Language：English  

Country：United States  

Event date： 2016.10

Language：English  

Country：United States  

Event date： 2016.9

Language：English  

Country：Japan  

Event date： 2016.7

Language：English  

Country：Japan  

Event date： 2016.7

Language：English  

Country：Japan  

Event date： 2016.6

Language：English  

Country：United States