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T. Ohteki, S. Sakai, N. Tate, Nano-Photonic Metrics: Fundamentals and Experimental Demonstration, Photonics, 10.3390/photonics9080551, 9(8), 551, 1-7, 2022.08, As the popularity of Internet of Things (IoT) increases, there is a considerable demand for the improvement of physical security, owing to the increase in edge devices. However, fabrication and measurement techniques used by attackers are also improving continuously, and hence, it is becoming increasingly difficult to ensure the security of each device using conventional approaches. To counter variable attacks in this context, the concept of nano-photonic metrics has been proposed, which is based on a functional collaboration between existing physical security and near-field optical techniques. In this approach, the optical signals obtained from optical near-field interactions, which are induced between the target with nano-scale structures and the tip of the scanning probe as the reader, are defined as the unique features of each device to be authenticated. When attackers attempt spoofing, they must fabricate not only clones of original nano-scale structures but also the scanning probe; otherwise, they cannot impersonate regular users. Moreover, the estimation of the nano-scale structures of the target and the characteristics of the probe is typically a complex, inverse problem. Therefore, a novel authentication is expected to be performed. In this paper, we report the results of the quantitative evaluations of the performance from the viewpoint of physical security and the experimental verification of the practicality of the proposed approach.. |
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Naoya Tate, Yuki Miyata, Sun-ichi Sakai, Akihiro Nakamura, Suguru Shimomura, Takahiro Nishimura, Jun Kozuka, Yusuke Ogura, Jun Tanida, Quantitative analysis of nonlinear optical input/output of a quantum-dot network based on the echo state property, Optics Express, 10.1364/OE.450132, 30, 9, 14669-14676, 2022.04, The echo state property, which is related to the dynamics of a neural network excited by input driving signals, is one of the well-known fundamental properties of recurrent neural
networks. During the echo state, the neural network reveals an internal memory function that enables it to remember past inputs. Due to the echo state property, the neural network will asymptotically update its condition from the initial condition and is expected to exhibit temporally nonlinear input/output. As a physical neural network, we fabricated a quantum-dot network that is driven by sequential optical-pulse inputs and reveals corresponding outputs, by random dispersion of quantum-dots as its components. In the network, the localized optical energy of excited quantum-dots is allowed to transfer to neighboring quantum-dots, and its stagnation time due to multi-step transfers corresponds to the hold time of the echo state of the network. From the experimental results of photon counting of the fluorescence outputs, we observed nonlinear optical input/output of the quantum-dot network due to its echo state property. Its nonlinearity was quantitatively verified by a correlation analysis. As a result, the relation between the nonlinear input/outputs and the individual compositions of the quantum-dot network was clarified.. |
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Suguru Shimomura, Takahiro Nishimura, Yuki Miyata, Naoya Tate, Yusuke Ogura, Jun Tanida, Spectral and temporal optical signal generation using randomly distributed quantum dots, OPTICAL REVIEW, 10.1007/s10043-020-00588-7, 27, 2, 264-269, 2020.04, Quantum dots (QDs) have a great potential for realizing information processing because of their signal-modulation capability based on energy transfer. We present a method for generating diverse temporal and spectral signals based on the energy transfer between multiple QDs. The method uses randomly distributed QDs, so it is not necessary to precisely arrange a QD network. With multiple energy transfers between QDs, a variety of signals within the QD network can be generated by optical inputs. Experimental results revealed that fluorescence decays of dense QDs were faster when the density of QDs or the irradiation intensity decreased. Furthermore, depending on the positions, stacked QDs showed different spectral responses. The randomly distributed QDs can generate diverse signals, which is essential for signal processing to handle temporal information.. |
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Naoya Tate, Takashi Yatsui, Visible light-induced thymine dimerisation based on large localised field gradient by non-uniform optical near-field, SCIENTIFIC REPORTS, 10.1038/s41598-019-54661-6, 9, 2019.12, The localised excitations of several molecular reactions utilising optical irradiation have been studied in the field of molecular physics. In particular, deoxyribonucleic acid (DNA) strands organise the genetic information of all living matter. Therefore, artificial methods for freely controlling reactions using only light irradiation are highly desirable for reactions of these strands; this in regard with artificial protein synthesis, regional genetic curing, and stochastic analysis of several genetic expressions. Generally, DNA strands have strong absorption features in the deep ultra-violet (DUV) region, which are related to the degradation and reconstruction of the strand bonding structures. However, irradiation by DUV light unavoidably induces unintended molecular reactions which can damage and break the DNA strands. In this paper, we report a photo-induced molecular reaction initiated by the irradiation of DNA strands with visible light. We utilised photo-dissociation from the vibrational levels induced by non-uniform optical near-fields surrounding nanometric Au particles to which DNA strands were attached. The results were experimentally observed by a reduction in the DUV absorbance of the DNA strands during irradiation. There was a much higher yield of molecular reactions than expected due to the absorbance of visible light, and no defects were caused in the DNA strands.. |
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Naoya Tate, Makoto Naruse, Nanoscale hierarchical optical interactions for secure information, NANOPHOTONICS, 10.1515/nanoph-2016-0134, 6, 3, 613-622, 2017.05, There is increasing demand for novel physical security that can differentiate between real and false specific artifact that have been added to bank bills, certifications, and other vouchers. The most simple and effective method for improving the security level is to scale down the elemental structures so that they cannot be duplicated by attackers. While there is a paradox that the achieved fabrication resolution by a defender can also be realized by an attacker, further improvement in security is possible by the functional fusion of artifact metrics and nano-photonics. The fundamental advantages of this concept are the high-level clone resistance and individuality of nanoscale artifacts, which are based on the super-resolution fabrication and nanoscale hierarchical structure of optical near-field interactions, respectively. In this paper, the basis for the fabrication of nanoscale artifacts by utilizing random phenomena is described, and a quantitative evaluation of the security level is presented. An experimental demonstration using a nano-/macro-hierarchical hologram is presented to demonstrate the fundamental procedure for retrieving nanoscale features as hidden information. Finally, the concept and a simple demonstration of non-scanning probe microscopy are described as a practical application of the retrieval and authentication of nanoscale artifact metrics.. |
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Naoya Tate, Tadashi Kawazoe, Wataru Nomura, Motoichi Ohtsu, Shunsuke Nakashima, Development of Zinc Oxide Spatial Light Modulator for High-Yield Speckle Modulation, IEICE Transactions on Electronics, 10.1587/transele.E99.C.1264, E99-C, 11, 1264-1270, 2016.11, In order to realize high-yield speckle modulation, we developed a novel spatial light modulator using zinc oxide single crystal doped with nitrogen ions. The distribution of dopants was optimized to induce characteristic optical functions by applying an annealing method developed by us. The device is driven by a current in the in-plane direction, which induces magnetic fields. These fields strongly interact with the doped material, and the spatial distribution of the refractive index is correspondingly modulated via external control. Using this device, we experimentally demonstrated speckle modulation, and we discuss the quantitative superiority of our approach.. |
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Optical nano artifact metrics using silicon random nanostructures. |
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Eigenanalysis of morphological diversity in silicon random nanostructures formed via resist collapse. |
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Naoya Tate, Makoto Naruse, Tsutomu Matsumoto, Morihisa Hoga, Yasuyuki Ohyagi, Shumpei Nishio, Wataru Nomura, Motoichi Ohtsu, Non-scanning optical near-field microscopy for nanophotonic security, Applied Physics A: Materials Science & Processing, 121, 4, 1383-1387, 2015.07, We propose a novel method for observing and utilizing nanometrically fluctuating signals due to optical near-field interactions between a probe and target in near-field optical microscopy. Based on a hierarchical structure of the interactions, it is possible to obtain signals that represent two-dimensional spatial patterns without requiring any scanning process. Such signals reveal individual features of each target, and these features, when appropriately extracted and defined, can be used in security applications—an approach that we call nanophotonic security. As an experimental demonstration, output signals due to interactions between a SiO2 probe and Al nanorods were observed by using near-field optical microscopy at a single readout point, and these signals were quantitatively evaluated using an algorithm that we developed for extracting and defining features that can be used for security applications.. |
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Wataru Nomura, Takashi Yatsui, Tadashi Kawazoe, Naoya Tate, Motoichi Ohtsu, High-speed flattening of crystallized glass substrates by dressed-photon-phonon etching, Applied Physics A, 10.1007/s00339-015-9466-8, 121, 4, 1403-1407, 2015.12. |
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Naoya Tate, Tadashi Kawazoe, Wataru Nomura, Motoichi Ohtsu, Current-induced giant polarization rotation using a ZnO single crystal doped with nitrogen ions, SCIENTIFIC REPORTS, 10.1038/srep12762, 5, 2015.08, Giant polarization rotation in a ZnO single crystal was experimentally demonstrated based on a novel phenomenon occurring at the nanometric scale. The ZnO crystal was doped with N+ and N2+ ions serving as p-type dopants. By applying an in-plane current using a unique arrangement of electrodes on the device, current-induced polarization rotation of the incident light was observed. From the results of experimental demonstrations and discussions, it was verified that this novel behavior originates from a specific distribution of dopants and the corresponding light-matter interactions in a nanometric space, which are allowed by the existence of such a dopant distribution.. |
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Ryuji Hirayama, Makoto Naruse, Hirotaka Nakayama, Naoya Tate, Atsushi Shiraki, Takashi Kakue, Tomoyoshi Shimobaba, Motoichi Ohtsu, Tomoyoshi Ito, Design, implementation and characterization of a quantum-dot-based volumetric display, Scientific Reports, 10.1038/srep08472, 5, 8472-8472, 2014.01, In this study, we propose and experimentally demonstrate a volumetric display system based on quantum dots (QDs) embedded in a polymer substrate. Unlike conventional volumetric displays, our system does not require electrical wiring; thus, the heretofore unavoidable issue of occlusion is resolved because irradiation by external light supplies the energy to the light-emitting voxels formed by the QDs. By exploiting the intrinsic attributes of the QDs, the system offers ultrahigh definition and a wide range of colours for volumetric displays. In this paper, we discuss the design, implementation and characterization of the proposed volumetric display's first prototype. We developed an 8 × 8 × 8 display comprising two types of QDs. This display provides multicolour three-type two-dimensional patterns when viewed from different angles. The QD-based volumetric display provides a new way to represent images and could be applied in leisure and advertising industries, among others.. |
