Kyushu University Academic Staff Educational and Research Activities Database
List of Presentations
Kazutoshi Kato Last modified date:2019.07.03

Professor / Integrated Electronics / Department of Electronics / Faculty of Information Science and Electrical Engineering


Presentations
1. Ming Che, Takeshi Kuboki, and Kazutoshi Kato, Mitigating nonlinearity for VLC with CAP modulation, ICEVLC2019, 2019.03.
2. Hao CHEN, Kazutoshi KATO, Nonlinear Modeling and Measurement for Tens of Gigahertz Electrical Amplifier in High-baud Multi-level Modulated Coherent Optical System, Research Reports on Information Science and Electrical Engineering of Kyushu University, 2019.01.
3. Takeshi Kuboki, Ryo Takigawa, and Kazutoshi Kato, Analysis of Adhesive Layer for Lithium Niobate-on-insulator Waveguides on Silicon Wafer with Room-temperature Bonding Method, MOC2018, 2018.10.
4. Ken Mitsueda, Muhammad Imran, and Kazutoshi Kato, 300-GHz-Repetition Optical Pulse Generation and Measurement for Terahertz Pulse Wave Communication, MOC2018, 2018.10.
5. Yang Zhou, Nanami Nishiyama, Hiroshi Ito, Tadao Ishibashi and Kazutoshi Kato, 700-GHz Terahertz Wave Beam Combination by Optical Phase Control, MOC2018, 2018.10.
6. Younjin Kim, Takeshi Kuboki and Kazutoshi Kato, Monolithically Integrated Photonics Device for Terahertz Wave Generation, MOC2018, 2018.10.
7. Hiroki Fukuda, Shunta Kono, Takeshi Kuboki and Kazutoshi Kato, Wavelength Switching Method Accounting for Nonlinearity of Tunable Distributed Amplification DFB laser , MOC2018, 2018.10.
8. Ming Che, Takeshi Kuboki, and Kazutoshi Kato, Adaptive Equalizer Based on Sign-Data LMS for Carrierless Amplitude and Phase Modulation in Multipath Visible Light Communication, MOC2018, 2018.10.
9. Ming Che, Takeshi Kuboki, and Kazutoshi Kato, Opportunities and Challenges for Smart LED Light Bulbs: Illumination, Communication, Indoor Positioning and Energy Harvesting, PIERS2018, 2018.08.
10. Kazutoshi Kato, Photonics Integrated Circuit for High-power Coherent THz Generation, PIERS2018, 2018.08.
11. Yuta Naito, Yusuke Yamanaka, Nanami Nishiyama, Kazutoshi Kato, THz-wave Beam Steering by Utilizing Photomixing and Chromatic Dispersion of Two Lightwaves, PIERS2018, 2018.08.
12. Nanami Nishiyama, Zhou Yang, Gouki Sakano, Hiroshi Ito, Tadao Ishibashi, Kazutoshi Kato, 600 GHz Wave Combiner Using Arrayed Photomixer, PIERS2018, 2018.08.
13. Ming Che, Takeshi Kuboki, and Kazutoshi Kato, Dimmable Optical OFDM Based on Discrete Hartley Transform for Indoor Visible Light Illumination and Communication, OECC2018, 2018.07.
14. Yang Zhou, Goki Sakano, Yusuke Yamanaka, Hiroshi Ito, Tadao Ishibashi, Kazutoshi Kato, 600-GHz-wave beam steering by terahertz-wave combiner, Optical Fiber Communication Conference, OFC 2018, 2018.01, We achieved 600-GHz-wave power combination with directional gain by optically phase tuning of arrayed photomixers. Using this phase control technique for phase shift, we also demonstrated the beam steering within an angle of 35 degrees..
15. Hiroki Fukuda, Kenta Yamaguchi, Takeshi Kuboki, Kazutoshi Kato, Fast wavelength stabilization of tunable laser after starting laser oscillation, 22nd Microoptics Conference, MOC 2017, 2017.11, For fast wavelength switching within the full available wavelength range of the tunable laser array, we investigated a wavelength stabilizing method after switching on the injection current to the laser's active layer. Experimental results demonstrated that our feedback controller dramatically reduced wavelength switching time from 800 μs to 2.0 μs..
16. Masataka Gohara, Ryoga Kimura, Kenta Yamaguchi, Takeshi Kuboki, Kazutoshi Kato, Linearizer for wavelength sweep at tunable DBR-LD and linearity evaluation of sweep, 22nd Microoptics Conference, MOC 2017, 2017.11, We constructed the linear wavelength sweeping system with 2-μm-band distributed Bragg reflector laser for the second-harmonic-detection wavelength modulation spectroscopy. Using our devised linearity evaluation method with a germanium etalon filter, we experimentally confirmed that the nonlinearity of the laser can be efficiently compensated..
17. Ken Mitsueda, Yusuke Yamanaka, Kazutoshi Kato, Novel measurement method for optical pulse width at high-repetition frequency, 22nd Microoptics Conference, MOC 2017, 2017.11, We propose a measurement method of the optical pulse width at high-repetition frequencies. It consists of simple components such as a self-delayed interferometer and an optical power meter. We generated 50-GHz repetition pulses by superposing several lightwaves with 50-GHz spacing, and measured their pulse width with this measurement system..
18. Yusuke Yamanaka, Younjin Kim, Takeshi Kuboki, Kazutoshi Kato, Optical-to-wireless media conversion by utilizing cross gain modulation at semiconductor optical amplifier, 22nd Microoptics Conference, MOC 2017, 2017.11, We devise an optical-to-wireless media conversion method by XGM at the SOA aiming for a future use at a THz-wave access. We investigate the XGM characteristics and the performance of our proposed media conversion method. We configure the media-converted data transmission system and demonstrate an error free transmission..
19. Ming Che, Takeshi Kuboki, Kazutoshi Kato, Proposal of cost-efficient and low-complexity platform for software defined visible light communication, 22nd Microoptics Conference, MOC 2017, 2017.11, With the increasing popularity of LED lighting and a growing demand for bandwidth in wireless communication, the visible light communication (VLC) is one of the promising scheme for addressing the bottleneck in the emerging broadband access networks. For research in the field of VLC focused on solutions of contradiction between massive available bandwidth and limited modulation bandwidth of LED, the purpose of this paper is to design an VLC experiment platform with characteristics of high flexibility and rapid productization. As a result, this platform not only expand the concept of software defined communication, but has the advantage of simple structure and low cost..
20. Yang Zhou, Goki Sakano, Kota Tsugami, Haruichi Kanaya, Kazutoshi Kato, Terahertz wave beam steering by optical phase control, 22nd Microoptics Conference, MOC 2017, 2017.11, We investigated the ability to tilt the terahertz wave beam at arrayed photomixers. Experimental demonstration showed that optical phase control enabled us to make a beam steering of a 300-GHz terahertz wave in a range of 25 degrees..
21. Goki Sakano, Jun Haruki, Kota Tsugami, Haruichi Kanaya, Kazutoshi Kato, 4 × 4 Arrayed THz-wave combiner composed of UTC-PDs and slot antennas, 2017 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2017, 2017.07, 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..
22. Younjin Kim, Yusuke Yamanaka, Kazutoshi Kato, Demonstration of novel media conversion method from optical to THz-wave networks, 2017 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2017, 2017.07, We propose optical-to-THz-wave conversion method using the cross-gain modulation and photomixing. In this method, signals on one wavelength are converted to those on two wavelengths which result in signals on THz wave after photomixing. We experimentally demonstrate the feasibility of seamless media conversion from a lightwave for optical communication into a 300-GHz carrier for wireless..
23. Yusuke Yamanaka, Takeshi Kuboki, Kazutoshi Kato, Proposal of THz Phase Control System Utilizing Chromatic Dispersion at Optical Device and Its Feasibility Demonstration, 2017 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2017, 2017.07.
24. Abdulaziz E. El-Fiqi, Hossam M H Shalaby, Kazutoshi Kato, Impact of linear mode-coupling on nonlinear performance of long-haul strong-coupled multicore fibers transmission, 29th IEEE Photonics Conference, IPC 2016, 2017.01, We adapt Gaussian-noise (GN) model to evaluate the nonlinear performance of strong-coupled multicore fibers (MCFs) transmission. An expression for the nonlinear interference is obtained taking into account the linear mode-coupling. Our results show that linear mode-coupling can mitigate the nonlinearity effect in MCFs..
25. Haruichi Kanaya, Masahiko Koga, Kota Tsugami, Guan Chai Eu, Kazutoshi Kato, 4x4 planar array antenna on indium phosphide substrate for 0.3-THz band application, 2017 Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications VII Conference, 2017.01, This paper presents a design and fabrication of 4 × 4 one-sided directional slot array antenna on indium phosphide (InP) substrate for 0.3 THz (300 GHz) wireless link. The antenna has top antenna metal layer and bottom floating metal layer. Polyimide dielectric layer is stacked between each metal layer. The antenna is placed on the deep etched InP substrate. By optimizing the length of the bottom floating metal layer, one-sided directional radiation can be realized. The branched coplanar wave guide (CPW) transmission line is connected to each antenna element with the same electrical length. The size of the 4 × 4 array antenna is 2,730 μm x 3,000 μm with uni-traveling-carrier photodiodes, DC bias and ground lines. Simulated realized gain in peak direction of the proposed antenna is 11.7 dBi. The transmission measurement is carried and measured received power..
26. Abdulaziz E. El-Fiqi, Ahmed E. Morra, Hossam M.H. Shalaby, Salah S.A. Obayya, Kazutoshi Kato, Performance evaluation of hybrid DBPSK-MPPM technique in long-haul optical transmission, 2016 Conference on Lasers and Electro-Optics, CLEO 2016, 2016.12, The performance of DBPSK-MPPM technique is evaluated in long-haul transmission using GN-model. The BER expression is extended to address fiber nonlinearity. Results show that fiber nonlinearity effects are more significant in DBPSK-MPPM than traditional ones..
27. Kenta Yamaguchi, Yudai Tatsumoto, Ryoga Kimura, Takeshi Kuboki, Kazutoshi Kato, Sub-millisecond wavelength switching of tunable DFB laser array (TLA) with injection current control, 2016 International Semiconductor Laser Conference, ISLC 2016, 2016.12, For the purpose of sub-millisecond wavelength switching, the feedforward current control technique was applied to the DFB laser. At the switching from 191.2 THz to 191.0 THz, our designed controller successfully reduced the wavelength switching time of the tunable DFB laser array down to 800 μs..
28. 春木 隼, 坂野 豪紀, 佐熊 一輝, 加藤 和利, 犬伏 祐樹, 藤田 悠介, 久武 信太郎, 永妻 忠夫, First demonstration of 300-GHz band wireless transmission with arrayed photomixer, 2016年電子情報通信学会ソサイエティ大会, 2016.10.
29. 坪井 淳, Takeshi Kuboki, Kazutoshi Kato, Optical frequency stabilization within ±20MHz of distributed feedback laser controlled by novel feedback
algorithm, 21st Microoptics Conference, 2016.10.
30. 春木 隼, 坂野 豪紀, 佐熊 一輝, 加藤 和利, 犬伏 祐樹, 藤田 悠介, 久武 信太郎, 永妻 忠夫, First demonstration of 300-GHz band wireless transmission with arrayed photomixer, 21st Microoptics Conference, 2016.10.
31. 木村 凌河, 立本 雄大, 恩地 裕和, Takeshi Kuboki, Kazutoshi Kato, Internal-wavelength-locker based feedforward/feedback co-operative wavelength control for 100 ns wavelength switching, 21st Microoptics Conference, 2016.10.
32. 藤村 勇起, 中村 諒平, Takeshi Kuboki, Kazutoshi Kato, Wavelength Selective Filter Based Mach-Zernder Interferometric Phase Stabilization for High-Frequency Carrier Generation, 21st Microoptics Conference, 2016.10.
33. Goki Sakano, Jun Haruki, Kazuki Sakuma, Kazutoshi Kato, 4-channel synchronous THz-wave generatorcomposed of arrayed UTC-PDs and antennas, 21st OptoElectronics and Communications Conference, OECC 2016 - Held Jointly with 2016 International Conference on Photonics in Switching, PS 2016, 2016.10, We configured THz wave generator consistiong of four-channel arrayed photomixers/antennas. We demonstrated that the powers are combined with the directional gain of 5.9 dB and proportional to the square of the number of photomixers..
34. Yusuke Yamanaka, Yuki Fujimura, Kazutoshi Kato, Demonstration of controlling chromatic dispersion at SOA with Mach-Zehnder interferometric measurement system, 21st OptoElectronics and Communications Conference, OECC 2016 - Held Jointly with 2016 International Conference on Photonics in Switching, PS 2016, 2016.10, We proposed the Mach-Zehnder interferometric system to measure the chromatic dispersion at an optical device. We demonstrated that the phase difference between two lightwaves can be controlled at the SOA with our system..
35. キム ヨンジン, 加藤 和利, Optical Design of Evanescently Coupled Photodiode for Terahertz Wave Generation, 平成28年度電機・情報関係学会九州支部連合大会国際セッション, 2016.09.
36. 坂野 豪紀, 春木 隼, 佐熊 一輝, 加藤 和利, 4-Channel Synchronous THz-wave Generator Compoased of Arrayed UTC-PDs and Antennas, OECC/PS 2016, 2016.07.
37. 山中 友輔, 藤村 勇起, 加藤 和利, Demonstration of Controlling Chromatic Dispersion at SOA with Mach-Zehnder Interferometric Measurement System, OECC/PS 2016, 2016.07.
38. Haruichi Kanaya, Tomoki Oda, Naoto Iizasa, Kazutoshi Kato, 300 GHz one-sided directional slot array antenna on indium phosphide substrate, International Symposium on Antennas and Propagation, ISAP 2015, 2016.04, This paper presents a novel design of 300 GHz band 1 × 4 one-sided directional slot dipole array antenna fed by coplanar waveguide (CPW) on indium phosphide (InP). The proposed antenna has four antenna elements and branched CPW structure to achieve a high antenna gain and a sharp beam. We fabricated and measured the array antenna. In the EM simulation, forward directional peak gain is 7.35 dBi. The measured reflection coefficient is agreed with the simulation results..
39. Kazuki Sakuma, Yuki Fjimura, Shota Takeuchi, Kazutoshi Kato, Shintaro Hisatake, Tadao Nagatsuma, Coherent THz Power Combiner Consisting of Arrayed Uni-Traveling Carrier Photodiodes  and Planar Lightwave Circuit, SPIE Photonics West 2016, 2016.02.
40. Yuki Fujimura, Kazuki Sakuma, Shota Takeuchi, Kazutoshi Kato, Shintaro Hisatake, Tadao Nagatsuma, Compact and robust phase stabilization system for high-frequency carrier generation using an integrated lightwave circuit, 20th Microoptics Conference, MOC 2015, 2016.02, We devise an integrated lightwave circuit for the Mach-Zehnder Interferometric phase stabilization in a high-frequency carrier generation. With this integrated-circuit-based system, we demonstrate a data transmission with 1-Gbit/s binary phase-shift keying at the carrier frequency of 12.5 GHz..
41. Ryoga Kimura, Yudai Tatsumoto, Kazuki Sakuma, Hirokazu Onji, Makoto Shimokozono, Hiroyuki Ishii, Kazutoshi Kato, Fast wavelength stabilization of tunable lasers with the internal wavelength locker, 20th Microoptics Conference, MOC 2015, 2016.02, The wavelength control system with the internal wavelength locker of the tunable lasers is configured so as to accelerate the wavelength detection speed. With this control system the wavelength is stabilized within 3.8 μs after wavelength switching which is even faster than that with the conventional control system..
42. Jun Haruki, Kazuki Sakuma, Kazutoshi Kato, Synchronous THz wave combiner consisting of arrayed photomixers, 20th Microoptics Conference, MOC 2015, 2016.02, We propose a power combiner of the synchronous terahertz waves for generating a higher coherent terahertz output power. The combiner consists of arrayed photomixers with bowtie-antennas. The experimental results show terahertz waves synchronized by the combiner results sum of the powers from photomixers and the directional gain of about 2 dB..
43. Jun Tsuboi, Takeshi Kuboki, Kazutoshi Kato, Wavelength stabilization within 0.05 GHz with photo-mixing technique and laser current controlling, 20th Microoptics Conference, MOC 2015, 2016.02, The lasers for the WDM system with the flexible grid need to have highly accurate wavelength tuning and stability. Instead of using optical filters, we propose the microwave photonics approach with photo-mixing technique and the laser current controlling. Experimental results show that the optical frequency is stabilized with the accuracy of 0.05GHz..
44. Haruichi Kanaya, Tomoki Oda, Naoto Iizasa, Kazutoshi Kato, Planar array antenna with director on indium phosphide infstrate for 300GHz wireless link, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications IX, 2016.01, This paper presents a design and fabrication of 1 x 4 one-sided directional slot array antenna with director metal layer on indium phosphide (InP) infstrate for 300 GHz wireless link. The floating metal and polyimide dielectric layer are stacked on InP. Antenna is designed on the top metal layer. By optimizing the length of the bottom floating metal layer, one-sided directional radiation can be realized. The branched coplanar wave guide (CPW) transmission line is connected to each antenna element with the same electrical length. The size of the 1 x 4 array antenna is 2,550 μm x 1,217 μm x 18 μm. In order to enhance the gain of forward direction, director metal layer is placed over 83 μm from top metal layer. Simulated realized gain in peak direction of our antenna is 9.23 dBi. The measured center frequency is almost the same as that of the simulation results..
45. K. Sakuma, J. Haruki, G. Sakano, Kazutoshi Kato, S. Hisatake, T. Nagatsuma, Coherent THz wave combiner composed of arrayed uni-traveling carrier photodiodes and planar lightwave circuit, Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications IX, 2016, For high-power THz wave generation by photomixing of two lightwaves, we proposed the synchronous power combiner which consists of eight-arrayed photomixers/antennas and the THz phase control system. We experimentally confirmed the effectiveness of the power combination by synchronizing the phases of the THz wave by the mechanical optical delay lines and also demonstrated the same functionality at the lightwave-circuit-based optical phase control system. We found that the directional gain is increasing with increasing the number of photomixers from two to three and it reached up to 4.5 dB..
46. Ryoga Kimura, Yudai Tatsumoto, Takeshi Kuboki, Kazutoshi Kato, Internal-wavelength-locker based feedforward/feedback co-operative wavelength control for 100 ns wavelength switching, 2016.
47. K. Sakuma, S. Takeuchi, Y. Fujimura, J. Haruki, Kazutoshi Kato, S. Hisatake, T. Nagatsuma, First demonstration of Mach-Zehnder-interferometric phase-stabilization at optoelectronic carrier generation for phase-shift keying signal, Opto-Electronics and Communications Conference, OECC 2015, 2015.11, We devised a phase stabilization technique at optoelectronic carrier generation applicable for the future THz wireless coherent transmission. Based on a 1-Gbit/s data transmission with a 12.5-GHz carrier signal, we demonstrate for the first time that our technique using a Mach-Zehnder interferometric configuration is effective not only for on-off keying signals, but also for phase-shift keying signals..
48. Y. Tatsumoto, H. Onji, R. Kimura, Kazutoshi Kato, H. Ishi, M. Simokozono, High-speed, high-accuracy 400-GHz wavelength switching at tunable distributed amplification (TDA-) DFB laser using feedforward control, Opto-Electronics and Communications Conference, OECC 2015, 2015.11, We present the method of the high-speed wavelength switching of the tunable distributed amplification (TDA-) DFB laser by feedforward control. We designed and simulated the feedforward controller to accelerate the wavelength switching. A switching time of less than 100 ns with a frequency deviation of less than 1 GHz was achieved at switching toward 400-GHz spaced channels. The results indicate the feasibility of the TDA-DFB laser for future wavelength routing systems..
49. Ryoga Kimura, Yudai Tatsumoto, Kazuki Sakuma, Hitrokazu Onji, Makoto Shimokozono, Hiroyuki Ishii, Fast Wavelength Stabilization of Tunable Lasers with the Internal Wavelength Locker, 20th Microoptics Conference (MOC’15), 2015.10, [URL], The wavelength control system with the internal wavelength locker of the tunable lasers is configured so as to accelerate the wavelength detection speed. With this control system the wavelength is stabilized within 3.8 µs after wavelength switching which is even faster than that with the conventional control system..
50. Jun Haruki, Kazuki Sakuma, Kazutoshi Kato, SYNCHRONOUS THZ WAVE COMBINER CONSISTING OF ARRAYED PHOTOMIXERS, 20th Microoptics Conference (MOC’15), 2015.10, [URL], We propose a power combiner of the synchronous terahertz waves for generating a higher coherent terahertz output power. The combiner consists of arrayed photomixers with bowtie-antennas. The experimental results show terahertz waves synchronized by the combiner results sum of the powers from photomixers and the directional gain of about 2 dB..
51. Jun Tsuboi, Takeshi Kuboki, Kazutoshi Kato, WAVELENGTH STABILIZATION WITHIN 0.05 GHz WITH PHOTOMIXING TECHNIQUE AND LASER CURRENT CONTROLLING, 20th Microoptics Conference (MOC’15), 2015.10, The lasers for the WDM system with the flexible grid need to have highly accurate wavelength tuning and stability. Insteadof using optical filters, we propose the microwave photonics approach with photo-mixing technique and the laser current controlling. Experimental results show that the optical frequency is stabilized with the accuracy of 0.05GHz.
52. Tadao Nagatsuma, Kazutoshi Kato, Jeffrey Hesler, Enabling technologies for real-time 50-Gbit/s wireless transmission at 300 GHz, 2nd ACM International Conference on Nanoscale Computing and Communication, ACM NANOCOM 2015, 2015.09, There has been a growing interest in the application of terahertz (THz) waves to broadband wireless communications. Particularly, use of THz waves at frequencies above 275 GHz is one of the big concerns among researchers, because these frequency bands have not yet been allocated for specific active services, and there is a possible opportunity to utilize extremely large bandwidths for ultra-broadband wireless communications. In this paper, we describe photonics-based approaches to realizing most practical and robust 300-GHz-band wireless links to meet and explore realworld applications at the earliest opportunity as a technology driver. We present enabling technologies for a real-time 50-Gbit/s transmission at over 20-m distance..
53. Yudai Tatsumoto, Ryoga Kimura, Hirokazu Onji, Kazutoshi Kato, Hiroyuki Ishii, Makoto Shimokozono, High-speed, High-Accuracy 400-GHz Wavelength Switching at Tunable Distributed Amplification (TDA-) DFB Laser using Feedforward Control, 20th Optoelectronics and Communications Conference, 2015.07, [URL], We present the method of the high-speed wavelength switching of the tunable distributed amplification (TDA-) DFB laser by feedforward control. We designed and simulated the feedforward controller to accelerate the wavelength switching. A switching time of less than 100 ns with a frequency deviation of less than 1 GHz was achieved at switching toward 400-GHz spaced channels. The results indicate the feasibility of the TDA-DFB laser for future wavelength routing systems..
54. Kazuki Sakuma, Shota Takeuchi, Yuki Fujimura, Jun Haruki, Kazutoshi Kato, Shintaro Hisatake, Tadao Nagatsuma, First Demonstraion of Mach-Zehnder-Interferometric Phase-Stabilizaion at Optoelectronic Carrier Generation for Phase-Shift Keying Signal, 20th Optoelectronics and Communications Conference, 2015.06, [URL], We devised a phase stabilization technique at optoelectronic carrier generation applicable for the future THz wireless transmission. In this presentation we demonstrate at the first time that our technique using a Mach-Zehnder interferometric configuration is effective for the optoelectronic carrier for phase-shift keying signals as well as that for on-off keying signals by using an 1-Gbit/s binary-phase-shift keying transmission on a 12.5-GHz optoelectronic carrier..
55. Atsushi Saeki, Kazutoshi Kato, Fine wavelength stabilization of the DFB laser by photo-mixing with reference wavelengths, The Third International Japan-Egypt Conference on Electronics, Communications and Computers, March 17, 2015, 2015.03, The lasers for the future WDM system such as the flexible grid need to have highly accurate wavelength tuning which corresponds to the optical frequency stability within ±0.1 GHz. Instead of the use of the conventional wavelength locker which detects the optical frequency with optical filters, we propose the microwave photonics approach in which the beat signals are generated by photo-mixing with reference lights and filtered by the microwave filter. In this method the frequency accuracy depends on the accuracy of the microwave filter. Experimental results show that the optical frequency is stabilized at the grid with the accuracy of ±0.1 GHz by using the microwave filter..
56. Kazuki Sakuma, Shota Takeuchi, Yuki Fujimura, Jun Haruki, Kazutoshi Kato, Shintaro Hisatake, Tadao Nagatsuma, Mach-Zehnder Interferometric Phase Stabilization for Optoelectronic Carrier Generation, The Third International Japan-Egypt Conference on Electronics, Communications and Computers, March 17, 2015, 2015.03, We present a phase stabilization system of optoelectronic carrier generation for the future THz wireless transmission. The system has a Mach-Zehnder interferometric configuration and we transmitted 1-Gbit/s data at a 12.5-GHz carrier to confirm the effectiveness of the concept. We found that the noise floor which had been observed at the BER characteristics in our previous work disappeared with an optimized control and attained an error free performance..
57. Atsushi Saeki, Kazutoshi Kato, Fine wavelength stabilization of the DFB laser at the flexible grid by photo-mixing with reference wavelengths, 2014 Asia-Pacific Microwave Conference (APMC) 2014, FG1G-43, Sendai, 2014, 2014.11, The lasers for the flexible grid need to have highly accurate wavelength tuning which corresponds to the optical frequency stability within ±0.1 GHz. Instead of the use of the conventional wavelength locker which detects the optical frequency with optical filters, we propose the microwave photonics approach in which the beat signals are generated by photo-mixing with reference lights and filtered by the microwave filter. In this method the frequency accuracy depends on the accuracy of the microwave filter. Experimental results show that the optical frequency is stabilized at the grid with the accuracy of ±0.1 GHz by using the band elimination filter which has the 3-dB bandwidth of 0.1 GHz..
58. Shota Takeuchi, Kazutoshi Kato, Y.Yoshimizu, Y. Yasuda, Shintaro Hisatake, Tadao Nagatsuma, Coherent Sub-THz Carrier Frequency Transmission with Novel Pseudo-Mach-Zehnder Interferometric Phase Stabilization, 2014 International Topical Meeting on Microwave Photonics (MWP) 2014, TuEF-1, Sapporo, 2014, 2014.10.
59. Hirokazu Onji, Yudai Tatsumoto, Kazutoshi Kato, Nobuhiro Nunoya, Makoto Shimokozono, Hiroyuki Ishii, Stable Wavelength Switching within 50 ns using Tunable Distributed Amplification (TDA-) DFB Lasers
, 2014.08, Aiming fast wavelength switching for the tunable distributed amplification (TDA-) DFB lasers, the transfer function is deduced from the transient response and then the feedforward controller is designed. Experimental results show that the wavelength can be accurately stabilized within 35 ns and 30 ns when the optical frequency changes from 192.8 THz to 193 THz and vice versa, respectively..
60. Hirolazu Onji, Shota Takeuchi, Yudai Tatsumoto, Nobuhiro Nunoya, Makoto Shimokozono, Hiroyuki Ishii, Kazutoshi Kato, 35 ns Wavelength Switching with +/- 1 GHz Wavelength Accuracy using Tunable Distributed Amplification(TDA-) DFB Lasers, Photonics in Switching, Advanced Photonics for Communications, WPW4B.3, San Diego, USA, 2014 , 2014.07, For fast wavelength switching of TDA-DFB lasers, the feedforward controller is designed. Experimental results show switching times of 35 ns and 30 ns when the optical frequency changes from 192.8 THz to 193.0 THz and vice versa.
61. Shota Takeuchi, Kazutoshi Kato, Shintaro Hisatake, Tadao Nagatsuma, Sub-THz Carrier Frequency Generation Stabilized by Mach-Zehnder Interferometric Phase Detection Scheme, 19th Microoptics Conference, 2014.06, We propose a Mach-Zehnder interferometric phase detection for low phase noise subterahertz(THz) carrier frequency generation. In this scheme, phase fluctuation between two optical signals can be detected as the interference between their optical sidebands. Experimental result shows that, by controlling the interference to be constant, the phase noise is successfully reduced, which indicates effectiveness of the proposed method..
62. Optimization of Feedback Control Parameters for Tunable Lasers.
63. Atsushi Saeki, Kazutoshi Kato, Fine wavelength stabilization of the DFB laser at the flexible grid by photo-mixing with reference wavelengths, 2014 Asia-Pacific Microwave Conference, APMC 2014, 2014.03, The lasers for the flexible grid need to have highly accurate wavelength tuning which corresponds to the optical frequency stability within ±0.1 GHz. Instead of the use of the conventional wavelength locker which detects the optical frequency with optical filters, we propose the microwave photonics approach in which the beat signals are generated by photo-mixing with reference lights and filtered by the microwave filter. In this method the frequency accuracy depends on the accuracy of the microwave filter. Experimental results show that the optical frequency is stabilized at the grid with the accuracy of ±0.1 GHz by using the band elimination filter which has the 3-dB bandwidth of 0.1 GHz..
64. S. Takeuchi, Kazutoshi Kato, Y. Yoshimizu, Y. Yasuda, S. Hisatake, T. Nagatsuma, Coherent sub-THz carrier frequency transmission with novel pseudo-Mach-Zehnder interferometric phase stabilization, 2014 International Topical Meeting on Microwave Photonics, MWP 2014 and the 9th Asia-Pacific Microwave Photonics Conference, APMP 2014, 2014.01, We present a novel carrier-phase stabilization scheme for sub-THz communications. The scheme has a pseudo-Mach-Zehnder interferometric configuration in which two optical sidebands from an optical frequency comb travel along two different optical paths and then are coupled with each other. The interference between the optical frequencies generated from two sidebands are monitored and controlled to be constant, so that the phase noise of the generated sub-THz carrier is stabilized. Experimental results show an error-free (BER <) data transmission and better BER performance than that of the conventional method with 11-Gbit/s on-off keying modulation at 100-GHz carrier frequency..
65. H. Onji, S. Takeuchi, Y. Tatsumoto, Kazutoshi Kato, N. Nunoya, M. Shimokozono, H. Ishii, Stable wavelength switching within 50 ns using tunable distributed amplification (TDA-) DFB lasers, 12th International Conference on Optical Internet, COIN 2014, 2014.01, Aiming fast wavelength switching for the tunable distributed amplification (TDA-) DFB lasers, the transfer function is deduced from the transient response and then the feedforward controller is designed. Experimental results show that the wavelength can be accurately stabilized within 35 ns and 30 ns when the optical frequency changes from 192.8 THz to 193 THz and vice versa, respectively..
66. H. Onji, S. Takeuchi, Y. Tatsumoto, N. Nunoya, M. Shimokozono, H. Ishii, Kazutoshi Kato, 35 ns wavelength switching with +/-1 GHz wavelength accuracy using tunable distributed amplification (TDA-) DFB lasers, Photonics in Switching, PS 2014, 2014, For fast wavelength switching of TDA-DFB lasers, the feedforward controller is designed. Experimental results show switching times of 35 ns and 30 ns when the optical frequency changes from 192.8 THz to 193.0 THz and vice versa..
67. Tadao Nagatsuma, Kazutoshi Kato, Photonically-assisted 300-GHz wireless link for real-time 100-Gbit/s transmission, 2014 IEEE MTT-S International Microwave Symposium, IMS 2014, 2014, Previously reported 100-Gbit/s wireless links have been based on an off-line digital signal processing and/or have assumed a use of forward-error correction (FEC) technique. In this paper, we discuss a strategy for real-time/error-free 100-Gbit/s transmission using photonically-assisted signal generation and modulation techniques at 300 GHz, and demonstrate some of our recent results towards 100-Gbit/s transmission..
68. Mohammad Nasir Uddin, T. Kizu, Y. Hinokuma, K. Tanabe, A. Tajima, Kazutoshi Kato, Kiichi Hamamoto, First demonstration of high intrinsic modulation bandwidth (26.5 GHz) in active multimode interferometer laser diode by using split pumping configuration, 18th Microoptocs Conference (MOC'13), 2013.10.
69. Shota Takeuchi, Hirokazu Onji, Nobuhiro Nunoya, Makoto Shimokozono, Hiroyuki Ishii, Kazutoshi Kato, WAVELENGTH STABILIZATION OF TUNABLE LASERS BASED ON THERMAL-DRIFT CANCELER, 18th Microoptics Conference (MOC'13), 2013.10, The wavelength stabilization based on the digitally controlled thermal-drift canceler is proposed and experimentally demonstrated. The tunable distributed amplification (TDA-) DFB laser controlled by this canceler reaches the targeted wavelength within a microsecond and keeps it stably..
70. Hirokazu Onji, Shota Takeuchi, Nobuhiro Nunoya, Makoto Shimokozono, Hiroyuki Ishii, Kazutoshi Kato, ACCELERATION OF WAVELENGTH SWITCHING FOR TUNABLE DISTRIBUTED AMPLIFICATION (TDA-) DFB LASERS
, 18th Microoptics Conference (MOC'13), 2013.10, The feedforward controller is designed and demonstrated to accelerate the wavelength switching for the tunable distributed (TDA) DFB lasers. The controller has an impulse overshoot waveform so as to induce prompt transition of short time phenomena. The controlled laser shows a wavelength switching time of 150 ns which shows effectiveness of the proposed technique..
71. Hirokazu Onji, Shota Takeuchi, Nobuhiro Nunoya, Makoto Shimokozono, Hiroyuki Ishii, Kazutoshi Kato, Acceleration of wavelength switching for tunable distributed amplification (TDA-) DFB lasers, 2013 18th Microoptics Conference, MOC 2013, 2013, The feedforward controller is designed and demonstrated to accelerate the wavelength switching for the tunable distributed amplification (TDA) DFB lasers. The controller has an impulse overshoot waveform so as to induce prompt transition of short time phenomena. The controlled laser shows a wavelength switching time of 150 ns which shows effectiveness of the proposed technique..
72. Mohammad Nasir Uddin, Takaaki Kizu, Yasuhiro Hinokuma, Akio Tajima, Kazutoshi Kato, Kiichi Hamamoto, Demonstration of resonance frequency enhancement effect by using split pumping region in active multi-mode interferometer laser diode, 2013 18th OptoElectronics and Communications Conference Held Jointly with 2013 International Conference on Photonics in Switching, OECC/PS 2013, 2013, We demonstrate for the first time, the resonance frequency enhancement effect by using split pumping region in active multi-mode interferometer laser diode (active MMI LD). Significant enhancement of 3 dB bandwidth up to 6.2 GHz from 2.3 GHz due to the enhancement of resonance frequency has been successfully confirmed by using this scheme..
73. Mohammad Nasir Uddin, Takaaki Kizu, Yasuhiro Hinokuma, Kazuhiro Tanabe, Akio Tajima, Kazutoshi Kato, Kiichi Hamamoto, First demonstration of high intrinsic modulation bandwidth (26.4 GHz) in active multimode interferometer laser diode by using split pumping configuration, 2013 18th Microoptics Conference, MOC 2013, 2013, High intrinsic 3dB modulation bandwidth in asymmetric active multimode interferometer laser diode is demonstrated by using split pumping configuration. Significant enhancement of 3 dB intrinsic bandwidth up to 24.6 GHz has been confirmed successfully by using this scheme..
74. Shota Takeuchi, Hirokazu Onji, Nobuhiro Nunoya, Makoto Shimokozono, Hiroyuki Ishii, Kazutoshi Kato, Wavelength stabilization of tunable lasers based on thermal-drift canceler, 2013 18th Microoptics Conference, MOC 2013, 2013, The wavelength stabilization based on the digitally controlled thermal-drift canceler is proposed and experimentally demonstrated. The tunable distributed amplification (TDA-) DFB laser controlled by this canceler reaches the targeted wavelength within a microsecond and keeps it stably..
75. Shogo Yagi, Kazunori Naganuma, Tadayuki Imai, Yasuo Shibata, Jun Miyazu, Masahiro Ueno, Yuuichi Okabe, Yuzo Sasaki, Kazuo Fujiura, Masahiro Sasaura, Kazutoshi Kato, Masato Ohmi, Masamitsu Haruna, Improvement of coherence length in a 200-kHz swept light source equipped with a KTN deflector, Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XVI, 2012, We are developing a new light source for swept-source OCT, namely, an external-cavity LD equipped with a KTN electro-optic deflector. Being free from mechanical resonance, our 1.3-μm laser exhibits scanning range of almost 100 nm up to 200-kHz under a ±300 V deflector driving voltage. Using a semi-empirically derived equation, we find that KTN's convex lens power degrades the coherence length, and this can be compensated with a cylindrical concave lens. Such compensation was experimentally confirmed by observing reduction of elliptical beam divergence. OCT images of a human fingernail are obtained using the swept source..
76. Shogo Yagi, Kazunori Naganuma, Tadayuki Imai, Yasuo Shibata, Shigeo Ishibashi, Yuzo Sasaki, Masahiro Sasaura, Kazuo Fujiura, Kazutoshi Kato, A mechanical-free 150-kHz repetition swept light source incorporated a KTN electro-optic deflector, Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XV, 2011.04, We present a new light source for the swept-source OCT, that is, an external-cavity LD incorporating an electro-optic deflector. We use a KTN deflector that is unique in being very fast and simultaneously providing an appreciable deflection caused by injected carriers. Particularly, high-speed and nearly linear to the applied voltage operation is attained when KTN crystal is pre-charged. Our 1.3-μm Littman-Metcalf external-cavity laser exhibits static linewidth < 0.1 nm, and a 110-nm scanning range up to 150-kHz under a ±200 V sinusoidal driving voltage to the deflector. Being free of mechanical resonance, the laser would hopefully realize a faster (in a separate study, deflector itself worked up to 400 kHz) and wavenumber-linear scan that is ideal for the swept-source OCT by designing the waveform of driving voltage. And as for the resolving power of deflector, while our KTN deflector has only 35 spatial resolvable points, the number of wavelength points for the swept source clearly exceeds to this limit, which we attribute to line narrowing effect accompanied by the laser operation. Preliminary OCT images taken using the swept source are also presented..
77. K. Kitayama, T. Kubo, R. Takahashi, S. Matsuo, S. Arakawa, M. Murata, M. Notomi, K. Nozaki, Kazutoshi Kato, All-optical RAM buffer subsystem demonstrator, 2011 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2011, 2011.03, A comprehensive R&D program aiming at all-optical RAM buffer subsystem for optical packet switching will be presented, featuring nano-cavity based optical bit memory, a unique beam addressing optics, and optical SP and PS converters..
78. N. Fujiwara, R. Yoshimura, Kazutoshi Kato, H. Ishii, F. Kano, Y. Kawaguchi, Y. Kondo, K. Ohbayashi, H. Oohashi, Single-mode 140 nm swept light source realized by using SSG-DBR lasers, Coherence Domain Optical Methods and Optical Coherence Tomography in Biomedicine XII, 2008.04, We demonstrate a single-mode and fast wavelength swept light source by using Superestrucuture grating distributed Bragg reflector (SSG-DBR) lasers for use in optical frequency-domain reflectometry optical coherence tomography. The SSG-DBR lasers provide single-mode operation resulting in high coherency. Response of the wavelength tuning is very fast; several nanoseconds, but there was an unintentional wavelength drift resulting from a thermal drift due to injecting tuning current. The dri1ft unfortunately requires long time to converge; more than a few milliseconds. For suppressing the wavelength drift, we introduced Thermal Drift Compensation mesa (TDC) parallel to the laser mesa with the spacing of 20 μm. By controlling TDC current to satisfy the total electric power injected into both the laser mesa and the TDC mesa, the thermal drift can be suppressed. In the present work, we fabricated 4 wavelength's kinds of SSG-DBR laser, which covers respective wavelength band; S-band (1496-1529 nm), C-band (1529-1564 nm), L--band (1564-1601 nm), and L+-band (1601-1639). We set the frequency channel of each laser with the spacing 6.25 GHz and 700 channels. The total frequency channel number is 2800 channels (700 ch × 4 lasers). We simultaneously operated the 4 lasers with a time interval of 500 ns/channel. A wavelength tuning range of more than 140 nm was achieved within 350 μs. The output power was controlled to be 10 mW for all channels. A single-mode, accurate, wide, and fast wavelength sweep was demonstrated with the SSG-DBR lasers having TDC mesa structure for the first time..
79. N. Fujiwara, R. Yoshimura, Kazutoshi Kato, H. Ishii, Y. Kawaguchi, Y. Kondo, H. Oohashi, 70 nm fast wavelength sweep using SSG-DBR lasers, 2007 Conference on Lasers and Electro-Optics - Pacific Rim, CLEO/PACIFIC RIM, 2007.12, A quasi-continuous wavelength sweep range of 70 nm is achieved by utilizing thermal compensation in SSG-DBR lasers. The frequency spacing is set at 6.25 GHz, and the output power is 10 mW for the whole tuning range. Thermal drift compensation enhances wavelength accuracy, and realizes fast and stable tuning..
80. Makoto Nakamura, Susumu Nishihara, Kazuyoshi Nishimura, Keiji Kishine, Shunji Kimura, Tomoaki Yoshida, Yusuke Ohtomo, Naoto Yoshimoto, Kazutoshi Kato, A 10G burst-mode PIN-TIA module with 10-nsec response for PON systems, 20th Annual Meeting of the IEEE Lasers and Electro-Optics Society, LEOS, 2007.12, A 10G burst-mode PIN-TIA module has been developed using a fast two-stage AOC technique. It exhibits a quick response of 10 nsec, high sensitivity of-19.5 dBm, and a wide dynamic range of 20.5 dB..
81. Akira Ohki, Seiji Fukushima, Mitsuru Sugo, Kazutoshi Kato, Yuji Akatsu, Novel TO-BOSA for FTTH using new optical path alignment technology, OFC/NFOEC 2007 - Optical Fiber Communication and the National Fiber Optic Engineers Conference 2007, 2007.12, We propose a new assembly technique that provides cost-effective way to integrate Tx and Rx in one TO-pakage. The TO-BOSA developed using this technique performed sufficientyly well for FTTH service applicatons..
82. Takashi Nakanishi, Youichi Fukada, Ken Ichi Suzuki, Naoto Yoshimoto, Makoto Nakamura, Kazutoshi Kato, Kazuyoshi Nishimura, Yusuke Ohtomo, Makoto Tsubokawa, Wide dynamic range and high sensitivity APD burst receiver configuration based on m-switching technique for 10GEPON system, 20th Annual Meeting of the IEEE Lasers and Electro-Optics Society, LEOS, 2007.10, We propose the M-switching technique to realize a high sensitivity and wide dynamic range 10Gbit/s APD burst receiver. Experiments show that the combination of M-switching and FEC realizes high sensitivity (-31.4dBm) and wide dynamic range (24.4dB)..
83. Takeshi Kurosaki, Yasuo Shibata, Nobuhiro Kikuchi, Ken Tsuzuki, Wataru Kobayashi, Hiroshi Yasaka, Kazutoshi Kato, 200-km 10-gbit/s optical duobinary transmission using an n-i-n InP mach-zehnder modulator, IPRM'07: IEEE 19th International Conference on Indium Phosphide and Related Materials, 2007.05, We have demonstrated 10-Gbit/s optical duobinary transmission using an n-i-n InP Mach-Zehnder modulator. A 200-km single-mode fiber transmission with no bit-error-rate floor and small sensitivity penalty was achieved under push-pull operation with low-driving voltage (<3 V)..
84. Susumu Nishihara, Shunji Kimura, Tomoaki Yoshida, Makoto Nakamura, Jun Terada, Kazuyoshi Nishimura, Keiji Kishine, Kazutoshi Kato, Yusuke Ohtomo, Takamasa Imai, A 10.3125-Gbit/s SiGe BiCMOS burst-mode 3R receiver for 10G-EPON systems, National Fiber Optic Engineers Conference, NFOEC 2007, 2007.03, The first burst-mode 3R receiver operating at 10.3125 Gbit/s using monolithic ICs is reported. We achieved sensitivity of -18.0 dBm with a PIN-PD, dynamic range of over 16.5 dB, and instantaneous responsivity of 75 ns. These are the highest sensitivity and the widest dynamic-range among all reported 10-Gbit/s-class burst-mode receivers for NRZ data format..
85. N. Fujiwara, R. Yoshimura, Kazutoshi Kato, H. Ishii, Y. Kawaguchi, Y. Kondo, H. Oohashi, 70 nm fast wavelength sweep using SSG-DBR lasers, Conference on Lasers and Electro-Optics/Pacific Rim, CLEOPR 2007, 2007.01, A quasi-continuous wavelength sweep range of 70 nm is achieved by utilizing thermal compensation in SSG-DBR lasers. The frequency spacing is set at 6.25 GHz, and the output power is 10 mW for the whole tuning range. Thermal drift compensation enhances wavelength accuracy, and realizes fast and stable tuning..
86. Susumu Nishihara, Makoto Nakamura, Kazuyoshi Nishimura, Keiji Kishine, Shunji Kimura, Kazutoshi Kato, A fast-response and high-sensitivity PIN-TIA module with wide dynamic range for 10G burst-mode transmissions, 2007 33rd European Conference and Exhibition of Optical Communication, ECOC 2007, 2007.01, A 10G burst-mode PIN-TIA module has been developed with a new function of automatic offset compensation. An instantaneous response of 10 ns, high sensitivity of-19.5 dBm, and a wide dynamic range of 20.5 dB were obtained..
87. Nobuhiro Nunoya, Yasuo Shibata, Hiroyuki Ishii, Hiroshi Okamoto, Yoshihiro Kawaguchi, Yasuhiro Kondo, Hiromi Oohashi, Kazutoshi Kato, Novel tunable DFB laser with separated high coupling coefficient gratings, 2006 International Conference on Indium Phosphide and Related Materials Conference Proceedings, 2006.12, A novel continuously tunable DFB laser is proposed that has separated high coupling coefficient gratings with simple current tuning. Deep corrugations designed to realize a high coupling coefficient are fabricated by using dry etching followed by shallow wet chemical etching and slow speed re-growth. A large stop-band width achieved by using a grating with a coupling coefficient as high as 200 cm-1 provides a continuous tuning wavelength range of 2.1 nm..
88. Ken Tsuzuki, Nobuhiro Kikuchi, Hiroaki Sanjoh, Yasuo Shibata, Kazuo Kasaya, Hiromi Oohashi, Hiroyuki Ishii, Kazutoshi Kato, Yuichi Tohmori, Hiroshi Yasaka, Compact wavelength tunable laser module integrated with n-i-n structure Mach-Zehnder modulator, 2006 European Conference on Optical Communications, ECOC 2006, 2006.09, A compact wavelength tunable laser module is fabricated by integrating a wavelength tunable laser array and an n-i-n structure Mach-Zehnder modulator. Without the need to change the driving condition of the Mach-Zehnder modulator, the module can operate at 10 Gb/s in the 32 nm C-band range..
89. Kazutoshi Kato, Hiroki Itoh, Yoshio Itaya, Photonic integrated devices for WDM application, Integrated Photonics Research and Applications, IPRA 2006, 2006.04, The integration of optical semiconductor devices such as lasers, photodetectors, wavelength multiplexers/demultiplexers and optical amplifiers/gates realizes the wavelength tunable function required for WDM systems. We describe several monolithic integrated devices being developed for WDM applications..
90. H. Masuda, A. Mori, K. Shikano, K. Oikawa, Kazutoshi Kato, M. Shimizu, Ultra-wide-band hybrid tellurite/silica fiber Raman amplifier, Optical Fiber Communication Conference and Exhibit, 2002.03, A novel hybrid tellurite/silica fiber Raman amplifier was reported. This amplifier yielded a flattened gain spectrum and a gain bandwidth of 135 nm with a minimum gain of 22.8 dB. The maximum and minimum gains in the gain-band of the amplifier were 34.6 and 22.8 dB respectively. It was used as a pre-amplifier in an eight-channel×10-Gb/s transmission experiment..
91. T. Kurosaki, T. Hashimoto, N. Ishihara, Y. Suzuki, M. Yanagisawa, H. Kimura, M. Nakamura, Y. Tohmori, Kazutoshi Kato, Y. Kawaguchi, Y. Akahori, Y. Yamada, Ku Kato, H. Toba, J. Yoshida, Full duplex 1300/1550-nm-WDM optical transceiver modules for ATM-PON systems using PLC-hybrid-integration and CMOS IC technologies, Proceedings of the 1998 24th European Conference on Optical Communication, ECOC. Part 1 (of 3), 1998.12, The optical transceivers using a PLC -optical-hybrid-integrated module and CMOS front-end ICs for ATM-PON systems are realized. Under full duplex operation at 156 Mb/s, receiver sensitivity of less than -34 dBm and dynamic range of over 28 dB are achieved, which satisfies FSAN-class B/C specification..
92. I. Ogawa, F. Ebisawa, N. Yoshimoto, K. Takiguchi, F. Hanawa, T. Hashimoto, A. Sugita, M. Yanagisawa, Y. Inoue, Y. Yamada, Y. Tohmori, S. Mino, T. Ito, K. Magari, Y. Kawaguchi, A. Himeno, Kazutoshi Kato, Lossless hybrid integrated 8-ch optical wavelength selector module using PLC platform and PLC-PLC direct attachment techniques, 1998 Optical Fiber Communication Conference, OFC 1998, 1998.01.
93. Hiroyasu Mawatari, Mitsuo Fukuda, Kazutoshi Kato, Atsuo Kozen, Masahiro Yuda, Tatsuya Takeshita, Naoto Uchida, Hiromu Toba, Reliability and degradation behavior of a InGaAsP/InP waveguide photodiode for subscriber systems, Proceedings of the 1997 Pacific Rim Conference on Lasers and Electro-Optics, CLEO/Pacific Rim, 1997.07, A selective-area impurity-doped planar edge-coupled waveguide photodiode (SIMPLE-WGPD) has a long lifetime for subscriber system use and the device life is determined by the perimeter of the pn-junction. The thickness of the absorption layer is 3 μm. The pn-junction is formed at the absorption layer by means of Zn diffusion from the surface. The facet at which the input light received is formed by cleavage and coated with SiN, filmed formed by plasma enhanced chemical vapor deposition. The responsivity is about 0.8 A/W at bias of -2 V. On these SIMPLE-WGPDs, several kinds of reliability tests were performed..
94. T. Kominato, A. Himeno, M. Ishii, T. Goh, K. Hattori, F. Hanawa, Kazutoshi Kato, Silica-based optical switch with a single-facet fiber array connection, Proceedings of the 1997 Pacific Rim Conference on Lasers and Electro-Optics, CLEO/Pacific Rim, 1997.07, To reduce the optical fiber interconnection area needed when mounting on a printed circuit board, a silica-based 4×4 thermo-optic matrix switch makes use of a single fiber array connection, with the input and output waveguides of the switch chip located on one side of the chip. The logical arrangement of the switch is based on the path independent insertion loss (PI-LOSS) arrangement whose switch elements are composed of double Mach-Zehnder interferometers. This configuration enables a low insertion loss and high extinction ratio to be achieved. The cost of the module is also reduced as a result of the reduction in the number of fiber connection components..
95. Makoto Yaita, Tadao Nagatsuma, Kazuto Noguchi, Hiroshi Miyazawa, Kazutoshi Kato, Taiichi Otsuji, Kazuyoshi Matsuhiro, Osamu Mitomi, Ultrafast optical eye diagram measurement using optoelectronic techniques, Proceedings of the 1997 Pacific Rim Conference on Lasers and Electro-Optics, CLEO/Pacific Rim, 1997.07, A fast waveguide p-i-n photodiode (WGPD) and a traveling-wave electro-optic (EO) modulator are used to achieve an optical eye diagram measurement. The optical sampling head consists of a traveling-wave LiNbO3 intensity modulator, an optical-to-electrical conversion probe head with the WGPD, and a bias/termination probe head. Optical sampling pulses of 0.7-ps full width at half maximum (FWHM) are generated using a fiber laser at 40-MHz repetition rate. The bandwidth of the system is limited by the chip-to-chip interconnection using the probe heads since the 3-dB bandwidths of the WGPD and the LiNbO3 modulator are beyond 100 GHz..
96. N. Uchida, Y. Yamada, Y. Hibino, Y. Suzuki, T. Kurosaki, N. Ishihara, M. Nakamura, T. Hashimoto, Y. Akahori, Y. Inoue, K. Moriwaki, Kazutoshi Kato, Y. Tohmori, M. Wada, T. Sugie, Low-cost and high-performance hybrid WDM module integrated on a PLC platform for fiber-to-the-home, Proceedings of the 1996 22nd European Conference on Optical Communication, ECOC. Part 5 (of 6), 1996.12, Recent progress on a low-cost and high-performance hybrid WDM module for fiber-to-the-home is presented. The low-cost module is achieved by employing a flip-chip bonding method with passive alignment using a spot-size converter integrated laser diode (SS-LD) and waveguide photodiodes (WGPDs) on a planar lightwave circuit (PLC) platform. It is clarified that the SS-LD and the WGPD provide high coupling efficiency and a tolerance large enough for passive alignment. To achieve receiver hightsensitivity, the module is designed to employ an asymmetric PLC Y-splitter that prefers the PD responsivity and to reduce the parasitic capacitance. Dynamic properties for a 50-Mb/s burst signal, such as instantaneous AGC response and a small APC deviation of the transceiver, are also demonstrated..
97. Osamu Mitomi, Kohichi Wakita, Kazutoshi Kato, Millimeter-wave region optical devices, Proceedings of the 1996 International Topical Meeting on Microwave Photonics, MWP'96, 1996.12, This paper describes ultra-high-speed optical-device structures and characteristics of Mach-Zehnder waveguide LiNbO3 modulators, electroabsorption MQW semiconductor modulators, and edge-coupled photodetectors..
98. Noboru Iwasaki, Fuminori Ishitsuka, Kazutoshi Kato, High performance flip-chip technique for wide-band modules, Proceedings of the 1996 5th Topical Meeting on Electrical Performance of Electronic Packaging, 1996.10, A novel wide-band flip-chip technique is proposed, where optimized wide-gap coplanar waveguides are used to reduce the discontinuity. The flip-chip technique made it possible to achieve the return loss of over 28 dB up to 60 GHz..
99. Akihide Sano, Tomoyoshi Kataoka, Masahito Tomizawa, Kazuo Hagimoto, Kenji Sato, Koichi Wakita, Kazutoshi Kato, Automatic dispersion equalization by monitoring extracted-clock power level in a 40-Gbit/s, 200-km transmission line, Proceedings of the 1996 22nd European Conference on Optical Communication, ECOC. Part 5 (of 6), 1996.09, A novel receiver configuration enabling automatic dispersion equalization is proposed. An equalizer is configured with variable-dispersion, and it is shown that the optimum dispersion can be detected by monitoring the clock component of the transmitted signal after square law detection. Using this equalizer, a 40-Gbit/s transmission experiment over 200 km of DSF was successfully carried out..
100. N. Uchida, Y. Hibino, Y. Suzuki, T. Kurosaki, N. Ishihara, M. Nakamura, T. Hashimoto, Y. Akahori, Y. Inoue, K. Moriwaki, Y. Yamada, Kazutoshi Kato, Y. Tohmori, M. Wada, T. Sugie, Passively aligned hybrid WDM module integrated with a spot-size converted laser diode and waveguide photodiode on a PLC platform for fiber-to-the-home, 19th Optical Fiber Communication Conference, OFC 1996, 1996.01.
101. Y. Akatsu, Y. Muramoto, M. Ikeda, M. Ueki, A. Kozen, T. Kurosaki, K. Kawano, Kazutoshi Kato, J. Yoshida, 1.3-μm multimode waveguide photodiodes suitable for optical hybrid integration with a planar lightwave circuit, Proceedings of the 1995 21st European Conference on Optical Communication, ECOC'95. Part 1 (of 4), 1995.09, We propose a multimode waveguide photodiode utilizing asymmetric waveguide structure which is suitable for optical hybrid integration without coupling lenses, and has a high responsivity of 0.95 A/W at a wavelength of 1.31 μm. Its 1-dB coupling tolerance to a planar lightwave circuit is ±2 μm in the vertical direction..
102. R. Nagase, Kazutoshi Kato, S. Iwano, Simplified SC-type receptacles for optical subscriber systems, Proceedings of the 1995 21st European Conference on Optical Communication, ECOC'95. Part 1 (of 4), 1995.09, We have developed novel, low-cost simplified SC-type receptacles. They are fully compatible with normal SC plugs, and have the same optical characteristics as SC connectors..
103. Taiichi Otsuji, Kazutoshi Kato, Tadao Nagatsuma, Mikio Yoneyama, 10 to 72-Gb/s, optoelectronic RZ pulse-pattern generation and its application to on-wafer large-signal characterization for ultrahigh-speed electronic devices, Proceedings of the 1994 IEEE LEOS Annual Meeting. Part 1 (of 2), 1994.08, A pulse-rate tunable, fully electrically controllable optoelectronic random pulse generator operating at 10 to 72 Gb/s in return-to-zero (RZ) mode and an on-wafer optical-to-electrical conversion stimulus probe head with 0.6-A/W responsivity, 200-mVpp saturation output, and a near 100-GHz bandwidth is addressed. Its application, in combination with electrooptic sampling (EOS), to characterizing an ultrawide band amplifier is also demonstrated..