KINDAI UNIVERSITY


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SASAKI Ai-ichiro

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FacultyDepartment of Electronic Engineering and Computer Science / Graduate School of System Enginnering
PositionAssociate Professor
DegreePh.D. in Electrical Engineering
Commentator Guidehttps://www.kindai.ac.jp/meikan/2147-sasaki-aiichiro.html
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Last Updated :2020/09/04

Education and Career

Education

  •   1992 04  - 1996 03 , Tokyo University of Science, Faculty of Science
  •   1996 04  - 1998 03 , University of Tokyo, Graduate School of Arts and Sciences

Academic & Professional Experience

  •   2018 04 ,  - 現在, Associate Professor, Dept. of Electronic Engineering and Computer Science, Faculty of Engineering, Kindai University
  •   1998 04 ,  - 2018 03 , Science & Core Technology Labs., NTT Corporation

Research Activities

Research Areas

  • Manufacturing technology (mechanical, electrical/electronic, chemical engineering), Communication and network engineering
  • Manufacturing technology (mechanical, electrical/electronic, chemical engineering), Measurement engineering

Research Interests

  • Machine learning, Position estimation, Electromagnetic field, Wireless communication, Body area network, Optical measurement

Published Papers

  • Magnetic-field-based position sensing using machine learning, Ai-ichiro Sasaki, Eisuke Ohta, IEEE Sensors J., IEEE Sensors J., 20(13), 7292 - 7302, Jul. 2020 , Refereed
  • Double-solenoid ferrite coils for magnetic-field amplification in LF and MF bands, Ai-ichiro Sasaki, IEEE Trans. Magn., IEEE Trans. Magn., 55(12), 4004209, Dec. 2019 , Refereed
  • Method for systematically designing polarization optics to maximize sensitivity of electrooptic sensors, Ai-ichiro Sasaki, Akinori Furuya, Akihiko Hirata, Hiroki Morimura, Junichi Kodate, Jpn. J. Appl. Phys., Jpn. J. Appl. Phys., 56(9), 09NB01.1 - 09NB01.6, Sep. 2017 , Refereed
    Summary:A systematic design method is considered for maximizing the sensitivity of electrooptic sensors used for electric-field detection. The design method can be reduced to a routine procedure that includes matrix manipulation and differentiation. By applying the design method, the maximum sensitivity is realized with fewer optical components than in conventional electrooptic sensing systems. Since the proposed method shows a wide generality, it can be applied to designing sensors including various optical crystals. (C) 2017 The Japan Society of Applied Physics
  • Analysis and experimental study of magnetic-field amplification by a double coil, Ai-ichiro Sasaki, Olivier Ouellette, Maxime Beaudry-Marchand, Akihiko Hirata, Hiroki Morimura, IEEE Trans. Ind. Electron., IEEE Trans. Ind. Electron., 64(4), 3216 - 3226, Apr. 2017 , Refereed
    Summary:We investigated the amplification of the magnetic field generated by a floating coil placed in resonance with a driving coil connected to a signal source. With this method, the magnetic field can be amplified without increasing power consumption of the signal source. From an equivalent-circuit model composed of the floating and driving coils, we derived useful formulae for maximizing the magnetic-field amplitude at an arbitrary target frequency. The validity of the formulae was experimentally demonstrated. It was found that under specific conditions, the current induced in the floating coil can be increased by more than one order of magnitude compared to the current in the driving coil, leading to amplification of the magnetic field that reaches 22 dB at the target frequency of 10 MHz without increasing power consumption. We also found that the floating coil is effective in suppressing undesirable magnetic field components originating from common-mode currents. These results pave the way to further reduction of the power consumption in wireless communication schemes such as near field communication.
  • Alignment of graded-index lens on silica-based PLC for sensor platform, Kei Watanabe, Yu Kurata, Ai-ichiro Sasaki, Mikitaka Itoh, Proc. 21st Microoptics Conf., Proc. 21st Microoptics Conf., Oct. 2016 , Refereed
  • Design of polarization optics for electrooptic sensors, Ai-ichiro Sasaki, Akinori Furuya, Akihiko Hirata, Hiroki Morimura, Proc. Int. Symp. Opt. Memory 2016, Proc. Int. Symp. Opt. Memory 2016, 38 - 39, Oct. 2016 , Refereed
  • Magnetooptical and crystalline properties of sputtered garnet ferrite film on spinel ferrite buffer layer, Akinori Furuya, Ai-ichiro Sasaki, Hiroki Morimura, Osamu Kagami, Takaya Tanabe, Jpn. J. Appl. Phys., Jpn. J. Appl. Phys., 55(9), 09SD01.1 - 09SD01.7, Sep. 2016 , Refereed
    Summary:The purpose of this study is to provide garnet films for volumetric magnetic holography. Volumetric magnetic holography usually employs an easily obtainable short-wavelength laser (visible light, not infrared light) with a large diffraction intensity. Bi-substituted garnet ferrite with a large Faraday rotation is promising for volumetric magnetic holography applications in the visible light region. However, a garnet film without a deteriorated layer must be obtained because a deteriorated layer (minute polycrystalline grains containing an amorphous phase) is formed during the initial deposition on a glass substrate. In particular, the required magnetooptical properties have not been obtained in a thin garnet film (100 nm or less) after annealing (1 h, 700 degrees C, oxygen atmosphere). Therefore, there is a need for excellent garnet films with the required magnetooptical (MO) properties even if the films are thin. By using a spinel ferrite buffer layer for garnet film deposition, we could obtain a thin garnet film with excellent MO properties. We determined the effect of the initial buffer layer on the crystallinity of the deposited garnet films by observing the film cross section. In addition, we undertook a qualitative estimation of the influence of the crystallinity and optical properties of the garnet film on a glass substrate with a spinel ferrite buffer layer. (C) 2016 The Japan Society of Applied Physics
  • Magnetic-field amplification by a double coil, Ai-ichiro Sasaki, Akihiko Hirata, Hiroki Morimura, 2016 IEEE Antennas Propag. Soc. Int. Symp., 2016 IEEE Antennas Propag. Soc. Int. Symp., 2016(APSURSI), 409 - 410, 2016 , Refereed
    Summary:In magnetic-resonance wireless power transfer systems, a transmitter is equipped with a floating coil. We investigated the functions of the floating coil by analyzing an equivalent-circuit model of the transmitter. It is derived from the model that currents of the floating coil can be amplified without increasing the power consumption of the transmitter. As a result, strong magnetic fields can efficiently be generated with the floating coil. By solving the model, we obtain formulas for maximizing magnetic-field amplitude at an arbitrary frequency. The validity of our analysis is experimentally demonstrated.
  • Magneto-optical and crystalline properties of sputtered garnet ferrite film on spinel ferrite buffer layer, Akinori Furuya, Ai-ichiro Sasaki, Hiroki Morimura, Osamu Kagamk, Takaya Tanabe, Proc. Int. Symp. Opt. Memory 2015, Proc. Int. Symp. Opt. Memory 2015, Oct. 2015 , Refereed
  • Magnetooptical and crystalline properties of sputtered garnet ferrite film using a stress relaxation buffer layer, Akinori Furuya, Ai-ichiro Sasaki, Hiroki Morimura, Osamu Kagami, Takaya Tanabe, Jpn. J. Appl. Phys., Jpn. J. Appl. Phys., 54(9), 09MF02.1 - 09MF02.9, Sep. 2015 , Refereed
    Summary:The purpose of this study was to improve the optical characteristics of garnet ferrite films sputter-deposited on a glass substrate. The magnetooptical properties of the garnet ferrite film are strongly influenced by the thermal stress imposed on the substrate during crystallization. The condition of the interface between the garnet film and the substrate during the initial film deposition affects the magnetooptical characteristics of the entire film. In particular, we revealed the effect of stress generated at the interface on the crystallinity of the deposited garnet films with a stress relaxation buffer layer by observing the film cross section and the film surface. In addition, we qualitatively estimated of the effect of cracking in the garnet film on a glass substrate. (C) 2015 The Japan Society of Applied Physics
  • An isotropic receiver for area discrimination with magnetoquasistatic fields, Ai-ichiro Sasaki, Ryoichi Okuizumi, Tsutomu Mizota, Hiroki Morimura, Osamu Kagami, Proc. 2014 Asia-Pacific Microw. Conf. (APMC), Proc. 2014 Asia-Pacific Microw. Conf. (APMC), 967 - 970, Nov. 2014 , Refereed
    Summary:We propose the concept of area discrimination with magnetoquasistatic (MQS) fields. Unlike radio waves, MQS fields are valid for forming a clearly defined area whose radius is below about 1 meter. Such an area can be utilized for identification of persons with mobile terminals. Since an important characteristic required for the terminals is isotropy in receiving magnetic fields, we made an isotropic receiver equipped with a 3-axis loop antenna. It is experimentally demonstrated that the receiver possesses sufficient isotropy. With the isotropic receiver, we measured areas formed by MQS fields at 10 MHz and demonstrated that MQS fields are useful for forming a clearly defined area for identification of mobile terminals.
  • Magneto-optical property dependence of sputtered garnet ferrite film on initial deposition condition of substrate, Akinori Furuya, Ai-ichiro Sasaki, Hiroki Morimura, Osamu Kagami, Takaya Tanabe, Proc. Int. Symp. Opt. Memory 2014, Proc. Int. Symp. Opt. Memory 2014, Oct. 2014 , Refereed
  • Extended noisy-channel models for capacitively coupled personal area network under influence of a wall, Ai-ichiro Sasaki, Tsutomu Mizota, Hiroki Morimura, Seiji Yabe, Ryoji Kikuchi, Satoshi Suzuki, Ryouichi Matsumoto, IEEE Trans. Antennas Propag., IEEE Trans. Antennas Propag., 62(5), 2802 - 2812, May 2014 , Refereed
    Summary:Many application systems of capacitively coupled personal area networks (CC-PANs) are installed in the vicinity of walls. We therefore investigated noisy-channel models of a CC-PAN in consideration of a wall and a noise-reduction mechanism (NRM). Equivalent circuits representing the proposed channel models can be reduced to a Wheatstone bridge. It is found from the model that the noise is suppressed when the Wheatstone bridge is balanced. In practical CC-PAN systems, such a balanced condition can be realized by tuning a variable capacitor introduced as the NRM. The validity of the noisy-channel models and NRM is experimentally demonstrated.
  • Human body communication based on magnetic coupling, Takayuki Ogasawara, Ai-ichiro Sasaki, Koji Fujii, Hiroki Morimura, IEEE Trans. Antennas Propag., IEEE Trans. Antennas Propag., 62(2), 804 - 813, Feb. 2014 , Refereed
    Summary:This paper presents a method of human body communication that employs magnetic coupling. Since a human body acts as one component of a loop for creating the magnetic coupling, strong coupling occurs only when a person closes the loop. Thus, a person's natural bodily movement forms a communication channel. Here, the validation of the mechanism of channel formation and the robustness against surrounding environment were presented. First, the validity of the circuit model was demonstrated through measurement of the transfer function of the channel (channel loss) at frequencies up to 20 MHz. Second, the validity of the mechanism of channel formation was demonstrated. Comparing to opening the loop, closing was found to increase the transfer function by more than 30 dB at frequencies below 10 MHz. This strong channel formation verifies its mechanism. Finally, to investigate the influence of a nearby metal object on the transfer function, a metal object was placed on or near the experimental setup; but no significant degradation of the transfer function was observed. This demonstrates robustness against surrounding environment. These results suggest the possibility of communication by magnetic coupling with a human body as part of the communication channel.
  • Electro-optical sensor fabricated using a bulk cleavage technique and Its characteristics for near-field intra-body communication, Akinori Furuya, Ai-ichiro Sasaki, Hiroki Morimura, Kimihisa Aihara, Mitsuru Shinagawa, Jpn. J. Appl. Phys., Jpn. J. Appl. Phys., 52(9), 09LA04.1 - 09LA04.6, Sep. 2013 , Refereed
    Summary:This paper describes how to obtain a low cost electro-optical (EO) sensor module for the mass production of near-field intra-body communication devices. In this study, we used a bulk cleavage technique to fabricate EO modulators without the need for any optical polishing or washing processes, and clarified the feasibility of assembling optical components using only a passive alignment technique with a compact housing. (c) 2013 The Japan Society of Applied Physics
  • EO sensor module fabrication for near-field intra-body communication, Akinori Furuya, Ai-ichiro Sasaki, Hiroki Morimura, Osamu Kagami, Mitsuru Shinagawa, Proc. Int. Symp. Opt. Memory 2013, Proc. Int. Symp. Opt. Memory 2013, Aug. 2013 , Refereed
  • Shaping magnetic-field patterns with multiple current loops for short-range wireless link, Ai-ichiro Sasaki, Takayuki Ogasawara, Koji Fujii, Hiroki Morimura, Osamu Kagami, Proc. 6th Global Symp. Millimeter-Waves 2013, Proc. 6th Global Symp. Millimeter-Waves 2013, Apr. 2013 , Refereed
  • Signal-to-noise ratio analysis of a noisy-channel model for a capacitively coupled personal area network, Ai-ichiro Sasaki, Takako Ishihara, Nobutaro Shibata, Ryusuke Kawano, Hiroki Morimura, Mitsuru Shinagawa, IEEE Trans. Antennas Propag., IEEE Trans. Antennas Propag., 61(1), 390 - 402, Jan. 2013 , Refereed
    Summary:We investigated a noisy-channel model for a capacitively coupled personal area network (CC-PAN) with megahertz-frequency signals. The new channel model describes the influence of a power line connected to transceivers. Using the model, we analyzed characteristics of a CC-PAN channel in detail. The signal-to-noise ratio (SNR) for the CC-PAN channel can be calculated from the model. It is also shown that the SNR can be enhanced by using a common-mode choke. We also give a physical interpretation of the mechanism of the SNR enhancement. Furthermore, we propose design guidelines to obtain a large-SNR CC-PAN system. The validity of our model and analyses are confirmed by experimental results.
  • EO sensor fabricated using a bulk cleavage technique and its characteristics for near-field intra-body communication, Akinori Furuya, Ai-ichiro Sasaki, Hiroki Mofimura, Kimihisa Aihara, Mitsuru Shinagawa, Proc. Int. Symp. Opt. Memory 2012, Proc. Int. Symp. Opt. Memory 2012, Oct. 2012 , Refereed
  • Cost-effective electro-optic sensor module for intra-body communication using optical pickup technology, Mirsuru Shinagawa, Ai-ichiro Sasaki, Akinori Furuya, Hiroki Morimura, Kimihisa Aihara, Proc. Int. Symp. Opt. Memory 2012, Proc. Int. Symp. Opt. Memory 2012, Oct. 2012 , Refereed
  • A Circuit parameter identification of personal area networks under the magnetic coupling, Takayuki Ogasawara, Ai-ichiro Sasaki, Koji Fujii, Makoto Yaita, Hiroki Morimura, Yousuke Fujino, Takafumi Fujita, Masashi Shimizu, 2012 IEEE Antennas Propag. Soc. Int. Symp. (APSURSI), 2012 IEEE Antennas Propag. Soc. Int. Symp. (APSURSI), 2012, 8 - 14, 2012 , Refereed
    Summary:This paper presents a circuit model of the communication channel via magneto quasi-static field for personal area network. To demonstrate the validity of the circuit model, we measured the frequency characteristics of the channel in the range from 100 kHz to 20 MHz. The measured data agree well with the calculated characteristics derived from the circuit model. We also extracted parameters of the model from measured data. The typical loss of the circuit is -62 dB at 10 MHz.
  • 10-Mbps short-range baseband wireless communications via quasi-static electric fields, Ai-ichiro Sasaki, Akinori Furuya, Mitsuru Shinagawa, IEICE Trans. Commun., IEICE Trans. Commun., E93-B(1), 144 - 153, 2010 , Refereed
    Summary:We propose a novel short-range wireless communications technology that uses quasi-static electric fields it enables data communication between devices separated by up to 10 cm via dielectric media at a speed of 10 Mbps. It is considered to be a secure wireless technology since communication area is restricted to below about 10 cm. To suppress electromagnetic radiation, we adopted a baseband transmission scheme in which the quasi-static electric field is directly modulated by 10BASE-T data signals. Since the spectra of the data signals are concentrated to below 20MHz, the amplitude of the electric field rapidly decreases outside the communication area. This contributes to enhancing security of the communications system. In this paper, we explain a basic principle of the short-range wireless communications technology. Since baseband data signals are carried by the quasi-static electric field, the quality of the communication is easily degraded by the existence of the earth ground. To isolate the communications system from the earth ground, we introduce a novel electro-optic sensor to receive the quasi-static electric field. With the electro-optic sensor, stable data communication is possible at 10Mbps via dielectric materials, such as a wooden table. Copyright © 2010 The Institute of Electronics, Information and Communication Engineers.
  • Study of semiconductor electro-optic modulators for sensing extremely-low-frequency electrical signals, Ai-ichiro Sasaki, Akinori Furuya, Mitsuru Shinagawa, Sens. Actuator A Phys., Sens. Actuator A Phys., 151(1), 1 - 8, Apr. 2009 , Refereed
    Summary:We investigated the characteristics of electro-optic modulators composed of ZnTe and CdTe. Their modulation depths below 100 kHz depend both on wavelength and input light power. The characteristics are explained by considering both the photoconduction effect and the Schottky effect. To keep the modulation depth constant below 100 kHz, the wavelength of the light should be long enough to suppress the photoconcluction effect. Using the ZnTe electro-optic modulator, we developed a sensitive voltage sensor that has constant sensitivity from DC to 30 MHz. Clear electrocardiograms can be obtained with the sensor. (C) 2009 Elsevier B.V. All rights reserved,
  • Principles and demonstration of intrabody communication with a sensitive electroooptic sensor, Ai-ichiro Sasaki, Mitsuru Shinagawa, Katsuyuki Ochiai, IEEE Trans. Instrum. Meas., IEEE Trans. Instrum. Meas., 58(2), 457 - 466, Feb. 2009 , Refereed
    Summary:We have investigated the basic principles of intrabody communication with a newly developed ridge-type electrooptic (EO) sensor. To intuitively understand the essence of intrabody communication, we introduced a simple model based on the fact that human body can approximately he considered as a conductor wrapped in an insulator. To demonstrate the propriety of the model., we measured the characteristics of communication systems including a human body using the EO sensor. The experimental results well agree with the predictions from the model. The new ridge-type EO sensor is shown to be superior to our previous EO sensor, both in sensitivity and in stability. With the ridge-type EO sensor, we succeeded in 10-Mb/s data transmission through the human body. Furthermore, we discussed the advantages of using the EO sensor for intrabody communication.
  • Principle and application of a sensitive handy electrooptic probe for sub-100-MHz frequency range signal measurements, Ai-ichiro Sasaki, Mitsuru Shinagawa, IEEE Trans. Instrum. Meas., IEEE Trans. Instrum. Meas., 57(5), 1005 - 1013, May 2008 , Refereed
    Summary:We have developed a new handy electrooptic (EO) probe to measure signals whose frequency is lower than 100 MHz. A distinct feature of the new EO probe is a long metal rod attached to an EO modulator. Measurement sensitivity does not depend on geometrical structures of devices under test (DUTs) with our new EO probe, whereas it does depend on geometrical structures of DUTs with a conventional handy EO probe. The sensitivity is at least 18 dB higher than that of the conventional one. In this paper, we qualitatively explain the effects of the rod on sensitivity and show experimental results, which agree well with the explanation. The advantages of signal measurements with an EO probe are also discussed, and two applications, where an EO probe plays important and essential roles, are proposed.
  • Polarization analysis of light propagating in electro-optic crystals with static birefringence and its application to sensor design, Ai-ichiro Sasaki, Mitsuru Shinagawa, Jpn. J. Appl. Phys., Jpn. J. Appl. Phys., 47(2), 918 - 924, Feb. 2008 , Refereed
    Summary:We analyzed the polarization states of light propagating in an electro-optic (EO) crystal with static birefringence. The analysis is based on a model in which the crystal consists of thin layers with the electro-optic effect and thin layers with static birefringence in an alternating sequence. The Jones matrix that represents the crystal was derived from the model. We also calculated the Jones matrix representing an EO crystal with optical activity because optical activity is considered to be a kind of static birefringence. Using the Jones matrices, we analyzed the polarization states of light modulated through an EO crystal with residual static birefringence and that with optical activity. It was shown that the modulation depth is decreased both by residual static birefringence and by optical activity. We obtained conditions to minimize the drop of the modulation depth. We also experimentally investigated the modulation depth using CdTe and Bi12SiO20, which are EO crystals possessing residual static birefringence and optical activity, respectively. The experimental results agreed well with the calculated results. The obtained conditions which minimize the drop of the modulation depth are valid for designing sensitive sensors using various EO crystals.
  • Electro-optic sensor for intrabody communication and its application to MICT, Ai-ichiro Sasaki, Katsuyuki Ochiai, Akinori Furuya, Mitsuru Shinagawa, Proc. 2006 Int. Symp. Medical Inform. Commun. Technol. (ISMICT), Proc. 2006 Int. Symp. Medical Inform. Commun. Technol. (ISMICT), B1-1, Dec. 2006 , Refereed
  • 光学的電界センサを用いたミリ波イメージングおよび人体通信に関する研究, Ai-ichiro Sasaki, Tokyo University of Science, Tokyo University of Science, Sep. 2006 , Refereed
  • Characterization of millimeter-wave antenna using photonic measurement techniques, Hiroyoshi Togo, Ai-ichiro Sasaki, Akihiko Hirata, Tadao Nagatsuma, Int. J. RF Microw. Computer-Aided Eng., Int. J. RF Microw. Computer-Aided Eng., 14(3), 290 - 297, Apr. 2004 , Refereed
    Summary:This article describes an electric-field measurement system that is based on electro-optic sampling (EOS). This system is able to map near- and far-field patterns of millimeter waves radiated from antennas by scanning the electric-field sensor probe. With the bandwidth set to more than 150 GHz, it can detect an electric field of less than 1.0 V/m at 60 GHz. This electric field is about one-tenth the field limit detectable by conventional microwave EOS systems. A comparison of measured and calculated electric fields in both the frequency and time-domains demonstrates the accuracy and usefulness of the system. (C) 2004 Wiley Periodicals. Inc.
  • Recent progress in optical measurement of radio-wave signals from gigahertz to terahertz, Tadao Nagatsuma, Hiroyoshi Togo, Koichi Narahara, Naofumi Shimizu, Ai-ichiro Sasaki, 2004 IEEE Int. Topical Meeting Microw. Photon., Tech. Dig., 2004 IEEE Int. Topical Meeting Microw. Photon., Tech. Dig., 20 - 23, 2004 , Refereed
    Summary:We review recent progress in optical techniques for radio-wave signal measurement in the frequency region from gigahertz to terahertz. This paper highlights a highly-sensitive electro-optic sensor material such as DAST, circuit diagnosis, antenna characterization, millimeter-wave and terahertz-wave imaging of objects.
  • Sensitive and stable electro-optic sensor for intrabody communication, Ai-ichiro Sasaki, Mitsuru Shinagawa, Katsuyuki Ochiai, 2004 IEEE LEOS Annu. Meet. Conf. Proc., vols. 1 & 2, 2004 IEEE LEOS Annu. Meet. Conf. Proc., vols. 1 & 2, 122 - 123, 2004 , Refereed
    Summary:We developed highly sensitive and stable electro-optic sensors for intrabody communication among mobile computers. We explain the principle of the communication and the advantage of detecting signals on human bodies with such sensors.
  • High-quality organic 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) crystal for electro-optic measurement, H. Adachi, K. Nagaoka, F. Tsunesada, M. Yoshimura, Y. Mori, T. Sasaki, A. Sasaki, T. Nagatsuma, Y. Ochiai, N. Fukasaku, IEICE Trans. Electron., IEICE Trans. Electron., E86-C(7), 1352 - 1358, Jul. 2003 , Refereed
  • Electric-field scanning system using electro-optic sensor, Ai-ichiro Sasaki, Tadao Nagatsuma, IEICE Trans. Electron., IEICE Trans. Electron., E86-C(7), 1345 - 1351, Jul. 2003 , Refereed
  • Electro-optic measurement using 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) crystal, H. Adachi, K. Nagaoka, F. Tsunesada, T. Higo, M. Yoshimura, Y. Mori, T. Sasaki, A. Sasaki, T. Nagatsuma, Y. Ochiai, N. Fukasaku, Proc. 7th Int. Conf. Organic Nonlinear Optics, Proc. 7th Int. Conf. Organic Nonlinear Optics, May 2003 , Refereed
  • High-power photonic millimetre wave generation at 100GHz using matching-circuit-integrated uni-travelling-carrier photodiodes, H Ito, T Nagatsuma, A Hirata, T Minotani, A Sasaki, Y Hirota, T Ishibashi, IEE Proc. Optoelectron., IEE Proc. Optoelectron., 150(2), 138 - 142, Apr. 2003 , Refereed
    Summary:The design and characterisation of a millimetre wave uni-travelling-carrier photodiode with a monolithically integrated matching (impedance transform) circuit utilising a coplanar-waveguide short stub are presented. The device with the matching circuit shows about 50% higher efficiency at 100 GHz than the one without it. The frequency response was characterised through time-domain measurement by means of an electro-optic sampling technique. The I dB down bandwidth of the device is as wide as 40 GHz, and the frequency response characteristics are in good agreement with circuit model calculations. The maximum saturation output power is 20.8 mW at 100 GHz for a bias voltage of -3 V, which is the highest output power ever generated directly from a photodiode in the W-band.
  • Electric-field imaging system using two- dimensional electro-optic sensor, Ai-ichiro Sasaki, Nicholas Meisl, Tadao Nagatsuma, Tech. Dig. 4th Korea-Japan Joint Workshop Microwave and Millimeter-Wave Photonics, Tech. Dig. 4th Korea-Japan Joint Workshop Microwave and Millimeter-Wave Photonics, 77 - 80, Jan. 2003 , Refereed
  • Electro-optic measurement using high-quality 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) crystal, H Adachi, K Nagaoka, F Tsunesada, M Yoshimura, Y Mori, T Sasaki, A Sasaki, T Nagatsuma, Y Ochiai, N Fukasaku, Jpn. J. Appl. Phys., pt. 2, Jpn. J. Appl. Phys., pt. 2, 41(10A), L1028 - L1030, Oct. 2002 , Refereed
    Summary:We evaluated the electro-optic (EO) properties of 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) crystals by external EO probing. The EO signal power obtained from the DAST crystal increased by 8 dB compared to that obtained from the KTiOPO4 (KTP) crystal at 90kHz. The larger EO signal power obtained from the DAST crystal was almost constant at low frequencies (30 Hz to 90 kHz), whereas the KTP crystal could not respond below 180 Hz. We also observed excellent signals at all measured points due to the high crystallinity of the crystal grown by the,lope nucleation method (SNM).
  • Millimeter-wave network analyzers based on photonic techniques, Tadao Nagatsuma, Nabil Sahri, Akihiko Hirata, Yakov Royter, Ai-ichiro Sasaki, 2002 IEEE MTT-S Int. Microw. Symp. Dig., vol1. 1-3, 2002 IEEE MTT-S Int. Microw. Symp. Dig., vol1. 1-3, 1497 - 1500, 2002 , Refereed
    Summary:We report the active photonic probes which enable on-wafer measurements of electrical scattering parameters with a bandwidth exceeding 300 GHz. The probes employ a high-speed uni-traveling-carrier photodiode to optically generate the electrical stimulus and the electro-optic sampling technique to measure the electrical response signals. The probe modules are packaged using micro-optic technology and exhibit excellent optical characteristics. They are easy to use and enable reliable and reproducible measurements and should help to overcome the bandwidth-limitation of present all-electronic systems.
  • Reflection-type CW-millimeter-wave imaging with a high-sensitivity waveguide-mounted electro-optic sensor, Ai-ichiro Sasaki, Tadao Nagatsuma, Jpn. J. Appl. Phys., Jpn. J. Appl. Phys., 41(1AB), L83 - L86, Jan. 2002 , Refereed
    Summary:We present a novel reflection-type imaging system that uses 100-GHz cw millimeter waves (MMWs). In the system, MMWs reflected by objects are separated from an incident MMW path by a circulator. The separated MMWs are detected by a high-sensitivity electro-optic (EO) sensor mounted in a rectangular waveguide. With the EO sensor, minimum detectable MMW power is less than -60 dBm. Using cw-MMWs, we can obtain both amplitude and phase images of objects directly. The system also features high-speed mechanical stages, which reduce image acquisition time. The acquisition time for 20,000-pixel amplitude and phase images is less than 10 min. We demonstrate that reflection-type imaging is effective in providing important information that cannot be obtained by conventional transmission-type imaging.
  • Reflection-type 100-GHz millimeter-wave imaging using a photonic mixer, Ai-ichiro Sasaki, Tadao Nagatsuma, Tech Dig. 3rd Japan-Korea Joint Workshop Microwave and Millimeter-Wave Photonics, Tech Dig. 3rd Japan-Korea Joint Workshop Microwave and Millimeter-Wave Photonics, 71 - 74, Jan. 2002 , Refereed
  • 1.55-um photonic systems for microwave and millimeter-wave measurement, T. Nagatsuma, M. Shinagawa, N. Sahri, A. Sasaki, Y. Royter, A.Hirata, IEEE Trans. Microw. Theory Techn., IEEE Trans. Microw. Theory Techn., 49(10), 1831 - 1839, Oct. 2001 , Refereed
    Summary:This paper reviews recent advances in 1.55-mum photonic systems for measurement and sensors covering the frequency range from microwaves to millimeter waves. We first deal with the basic technologies for photonic measurement, i.e., generation, transmission, and detection of high-frequency signals, and then discuss recent practical applications, including high-speed integrated-circuit probers, sampling oscilloscopes, network analyzers, and some free-space sensing systems.
  • Characterisation of uni-travelling-carrier photodiode monolithically integrated with matching circuit, T. Nagatsuma, T. Ishibashi, A. Hirata, Y. Hirota, T. Minotani, A. Sasaki, H. Ito, Electron. Lett., Electron. Lett., 37(20), 1246 - 1247, Sep. 27 2001 , Refereed
    Summary:A 100 GHz high-output power uni-travelling-carrier photodiode with a monolithically integrated matching circuit was designed and tested. The circuit consisted of a uni-travelling-carrier photodiode (UTC-PD). Two short planar waveguides and a metal-insulator, metal capacitor. The time domain and frequency domain characterstics of the device were measured by the EOS technique. The device exhibited a band operation with 3dB bandwidth of 50 GHz with output power at 100 GHz output power mW at 100 GHz.
  • Reflection-type millimeter-wave imaging with a waveguide-mounted electro-optic sensor, Ai-ichiro Sasaki, Tadao Nagatsuma, CLEO(R)/Pacific Rim 2001, vol. II, Tech. Dig., CLEO(R)/Pacific Rim 2001, vol. II, Tech. Dig., 2, 740 - 741, Jul. 2001 , Refereed
    Summary:We present a novel reflection-type millimeter-wave (MMW) imaging system that uses photonic techniques. In the system, we use a MMW circulator and a highly sensitive waveguide-mounted electro-optic (EO) sensor to detect MMWs reflected by objects.
  • Three-dimensional millimeter-wave photonic integrated circuits on Si, T. Minotani, Y. Royter, H. Ishii, A. Hirata, K. Machida, A. Sasaki, T. Nagatsuma, 2001 IEEE MTT-S Int. Microw. Symp. Dig., 2001 IEEE MTT-S Int. Microw. Symp. Dig., 57 - 60, May 2001 , Refereed
  • Observing radio waves by light - New measurement technology integrating radio and light waves, Tadao Nagatsuma, Mitsuru Shinagawa, Ai-ichiro Sasaki, NTT Rev., NTT Rev., 12(6), 55 - 58, Nov. 2000 , Refereed
    Summary:We are now living in an amazing "age of radio waves" and enjoying its many benefits. While a human being cannot feel the presence of radio waves with the five senses, radio waves can still be observed by a variety of measurement methods. Among these, technology for observing radio waves using light has recently become the focus of much attention. This article introduces this measurement technology and presents some examples of its application.
  • Millimeter-wave imaging using an electrooptic detector as a harmonic mixer, Ai-ichiro Sasaki, Tadao Nagatsuma, IEEE J. Sel. Topics Quantum Electron., IEEE J. Sel. Topics Quantum Electron., 6(5), 735 - 740, Sep. 2000 , Refereed
  • 1.55-um photonic systems for measurement and sensors up to the submillimeter-wave region, Nabil Sahri, Mitsuru Shinagawa, Ai-ichiro Sasaki, Tadao Nagatsuma, Proc. Int. Topical Workshop Contemporary Photon. Technol. 2000 (CPT2000), Proc. Int. Topical Workshop Contemporary Photon. Technol. 2000 (CPT2000), Jan. 2000 , Refereed
  • Ultrahigh-speed 1.55-mu m photodiodes on Si with low-loss multimeter-wave waveguides, Y. Royter, T. Minotani, H. Ishii, A. Hirata, S. Yagi, K. Machida, T. Furuta, T. Ishibashi, A. Sasaki, T. Nagatsuma, LEOS 2000 IEEE Annu. Meeting Conf. Proc., vols. 1 & 2, LEOS 2000 IEEE Annu. Meeting Conf. Proc., vols. 1 & 2, 283 - 284, 2000 , Refereed
  • TAMA300における300m Fabry-Perot共振器の開発, Ai-ichiro Sasaki, University of Tokyo, University of Tokyo, Jan. 1998 , Refereed
  • Analysis and measurement of rapidly attenuating fields around magnetic multipoles in low-frequency band, Ai-ichiro Sasaki, Junichi Kodate, 2017 IEEE Conference on Antenna Measurements and Applications, CAMA 2017, 2017 IEEE Conference on Antenna Measurements and Applications, CAMA 2017, 2018-(CAMA), 72 - 75, Jan. 29 2018 , Refereed
    Summary:It is known that the attenuation rate of fields around multipoles becomes larger as the order of the multipoles increases. We experimentally confirmed that a magnetic quadru-pole and octapole composed of coil antennas can create low-frequency magnetic fields attenuating at the rate of 80 and 100 dB/decade, respectively. We also obtained approximate equations that represent the fields around the quadrupole and octapole in simple forms. The rapid attenuation of the low-frequency magnetic fields can provide identification areas with well-defined boundaries, which will be needed in order to build reliable radio-frequency identification systems for communication with things and mobile/wearable devices.
  • Electrooptic sensor module fabrication for near-field intrabody communication, Akinori Furuya, Ai-ichiro Sasaki, Hiroki Morimura, Osamu Kagami, Mitsuru Shinagawa, Opt. Rev., Opt. Rev., 21(5), 605 - 613, Oct. 03 2014 , Refereed
    Summary:In this paper, we describe how to obtain a low cost electrooptic (EO) sensor module for the mass production of near-field intrabody communication devices. In our previous study, we used a bulk cleavage technique to fabricate EO modulators without the need for any optical polishing or washing processes. In this study, we fabricated EO modulators as a miniaturized chip sensor without a base portion, and clarified the feasibility of assembling optical components by only a passive alignment technique with a compact housing.
  • Compact electro-optic sensor module for intra-body communication using optical pickup technology, Mitsuru Shinagawa, Ai-ichiro Sasaki, Akinori Furuya, Hiroki Morimura, Kimihisa Aihara, Jpn. J. Appl. Phys., Jpn. J. Appl. Phys., 52(9), 09LA03.1 - 09LA03.8, Sep. 2013 , Refereed
    Summary:We developed a compact and low-cost electro-optic (EO) sensor module for intra-body communication using optical pickup technology. An EO crystal of zinc telluride (ZnTe) mainly contributes to use of the cost-effective optical pickup technology. ZnTe has the shortest wavelength for optical transmission, about 570 nm therefore it can use a low-cost 790-nm wavelength laser diode widely used in compact disc players. The measured modulation depth of the new EO sensor module was about 1.56 times deeper than our old one. The measured value agreed with the calculated value therefore, there is no performance deterioration by downsizing the sensor module. The sensor module was successfully applied to 10-Mbps half-duplex intra-body communication. © 2013 The Japan Society of Applied Physics.
  • SNR analysis of a noisy-channel model for a capacitively-coupled personal-area network, A. Sasaki, T. Ishihara, N. Shibata, R. Kawano, H. Morimura, M. Shinagawa, Proc. 2011 IEEE-APS Topical Conf. Antennas Propag. Wireless Commun. (APWC'11), Proc. 2011 IEEE-APS Topical Conf. Antennas Propag. Wireless Commun. (APWC'11), 351 - 354, 2011 , Refereed
    Summary:We propose a noisy-channel model for a capacitively-coupled personal-area network (PAN) with megahertz-frequency signals. The model describes the influence of power lines connected to transceivers. We analyzed the signal-to-noise ratio (SNR) for the PAN channel. It is derived from the model that the SNR can be enhanced by using a common-mode choke. We also found conditions for enhancing the SNR. The validity of the model and analysis are confirmed by experimental results. © 2011 IEEE.
  • High-quality organic 4-dimethylamino-n-methyl-4-stilbazolium tosylate (DAST) crystal for electro-optic measurement applications, H. Adachi, K. Nagaoka, F. Tsunesada, M. Yoshimura, Y. Mori, T. Sasaki, A. Sasaki, T. Nagatsuma, Y. Ochiai, N. Fukasaku, 2002 International Topical Meeting on Microwave Photonics, MWP 2002 - Technical Digest, 2002 International Topical Meeting on Microwave Photonics, MWP 2002 - Technical Digest, 85 - 88, 2002 , Refereed
    Summary:We present a new method called the slope nucleation method (SNM) for the growth of high-quality DAST crystals. Electro-optic (EO) measurement shows DAST crystals exhibits five-times sensitivity enhancement as compared to KTiOPO4 (KTP) crystals.
  • Two-dimensional electric-field scanner using photonic techniques, Ai-ichiro Sasaki, Tadao Nagatsuma, 2002 International Topical Meeting on Microwave Photonics, MWP 2002 - Technical Digest, 2002 International Topical Meeting on Microwave Photonics, MWP 2002 - Technical Digest, 81 - 84, 2002 , Refereed
    Summary:A novel electric-field scanner (E-Scan) allows us to obtain two-dimensional electric-field images in a short time by scanning with a laser beam. Measurement time with E-Scan is decreased by more than one order compared to previous electric-field mapping systems. We have demonstrated measurement of antenna radiation patterns and millimeter-wave imaging with E-Scan.

Misc

  • 磁界式端末位置推定におけるニューラルネットワークの有用性検証, Eisuke Ohta, Ai-ichiro Sasaki, B-15-15,   2020 09
  • Study of learning method for magnetic-field-based positioning of mobile devices, Ken Fukushima, Eisuke Ohta, Ai-ichiro Sasaki, 2020年電子情報通信学会総合大会論文集, B-15-35,   2020 03
  • Magnetic-field-based positioning of mobile devices using machine learning, Eisuke Ohta, Ken Fukushima, Ai-ichiro Sasaki, 2020年電子情報通信学会総合大会論文集, B-15-34,   2020 03
  • Short-range communications using electric and magnetic fields, Ai-ichiro Sasaki, Hiroki Morimura, 電子情報通信学会大会講演論文集(CD-ROM), 2019, ROMBUNNO.BI‐5‐2,   2019 03 , 招待有り, http://jglobal.jst.go.jp/public/201902254537313817
  • Ferrite bar antennas for magnetic-field amplification in MF and LF bands, Ai-ichiro Sasaki, 電子情報通信学会大会講演論文集(CD-ROM), 2018, ROMBUNNO.B‐21‐22,   2018 08 28 , http://jglobal.jst.go.jp/public/201802243678285597
  • Photonics-applied electromagnetic measurement, Ai-ichiro Sasaki, Hiroyoshi Togo, J. IEICE, 101, 2, 166, 173,   2018 02 , 招待有り, https://app.journal.ieice.org/trial/101_2/k101_2_166/index.html
  • Study of Magnetic-field Amplification by a Strongly-Coupled Double Coil, Ai-ichiro Sasaki, Hiroki Morimura, Junichi Kodate, 電子情報通信学会大会講演論文集(CD-ROM), 2017, ROMBUNNO.B‐21‐13,   2017 03 07 , http://jglobal.jst.go.jp/public/201702236160856763
  • Design and sensitivity stabilization of electric-field sensors utilizing electrooptic crystals, Ai-ichiro Sasaki, Akinori Furuya, Akihiko Hirata, Hiroki Morimura, 電子情報通信学会大会講演論文集(CD-ROM), 2016, ROMBUNNO.BCI‐1‐3,   2016 09 06 , 招待有り, http://jglobal.jst.go.jp/public/201602232648961552
  • On advantages and applications of sensors using electrooptic crystals, Ai-ichiro Sasaki, Hiroki Morimura, Osamu Kagami, IEICE Technical Report, PEM2015-02, 7, 12,   2015 05
  • An isotropic receiver for area discrimination with magnetic fields, Ai-ichiro Sasaki, Ryoichi Okuizumi, Takayuki Ogasawara, HIroki Morimura, Osamu Kagami, 電子情報通信学会大会講演論文集(CD-ROM), 2014, ROMBUNNO.B-1-42,   2014 03 04 , http://jglobal.jst.go.jp/public/201402215971780337
  • Shaping magnetic-field patterns with multiple current loops-toward short-range wireless identification-, Ai-ichiro Sasaki, Takayuki Ogasawara, Koji Fujii, Hiroki Morimura, Osamu Kagami, 電子情報通信学会技術研究報告, 113, 85(SRW2013 12-19), 7, 12,   2013 06 , http://jglobal.jst.go.jp/public/201302247740600354
  • SNR analysis of a noisy channel model for a capacitively coupled personal area network, Ai-ichiro Sasaki, Takako Ishihara, Nobutaro Shibata, Ryusuke Kawano, Hiroki Morimura, Mitsuru Shinagawa, 電子情報通信学会大会講演論文集, 2012, 19,   2012 08 28 , http://jglobal.jst.go.jp/public/201202280339906459
  • Modeling of human-body near-field communication and evaluation of communication quality, Ai-ichiro Sasaki, Ryusuke Kawano, Takako Ishihara, Mitsuru Shinagawa, NTT Tech. Rev., 8, 3,   2010 03 , 招待有り, https://www.ntt-review.jp/archive/ntttechnical.php?contents=ntr201003sf3.html
  • 人体近傍電界通信のモデル化と通信品質評価, Ai-ichiro Sasaki, Ryusuke Kawano, Takako Ishihara, Mitsuru Shinagawa, NTT技術ジャーナル, 22, 1, 23, 27,   2010 01 , http://www.ntt.co.jp/journal/1001/files/jn201001023.pdf
  • 10BASE-T Ethernet via the electric near field, Ai-ichiro Sasaki, Akinori Furuya, MItsuru Shinagawa, 電子情報通信学会大会講演論文集, 2008, 561,   2008 03 05 , http://jglobal.jst.go.jp/public/200902298912872379
  • Electro-optic sensor for intrabody communication, Ai-ichiro Sasaki, Mitsuru Shinagawa, Katsuyuki Ochiai, 電子情報通信学会大会講演論文集, 2005, 626,   2005 03 07 , http://jglobal.jst.go.jp/public/200902254361240891
  • Millimeter-wave imaging using photonic technologies, Ai-ichiro Sasaki, Tadao Nagatsuma, NTT R&D, 51, 6, 493, 501,   2002 06 , 招待有り, http://jglobal.jst.go.jp/public/200902128629577716
  • Millimeter-wave imaging using photonic techniques, Ai-ichiro Sasaki, Tadao Nagatsuma, NTT Rev., 14, 6, 32, 41,   2002 06 , 招待有り
  • All-photonic millimeter-wave imaging at 120-GHz band, Ai-ichiro Sasaki, Akihiko Hirata, Tadao Nagatsuma, 電子情報通信学会大会講演論文集, 2002, C-14-1, 354,   2002 03 07 , http://jglobal.jst.go.jp/public/200902114236515998
  • Electric-field measurement inside of a horn antenna using a micro-optic EO probe, Ai-ichiro Sasaki, Shigeki Ishibashi, Tadao Nagatsuma, 電子情報通信学会大会講演論文集, 2002, C-14-4, 357,   2002 03 07 , http://jglobal.jst.go.jp/public/200902182459137400
  • Reflection-type millimeter-wave imaging with a highly-sensitive EO sensor, Ai-ichiro Sasaki, Tadao Nagatsuma, 電子情報通信学会大会講演論文集, 2001, C-2-86, 110,   2001 08 29 , http://jglobal.jst.go.jp/public/200902175565066095
  • 光で電波を観測する 電波と光のハーモニーが創り出す新しい計測技術, Tadao Nagatsuma, Mitsuru Shinagawa, Ai-ichiro Sasaki, NTT技術ジャーナル, 12, 5, 56, 58,   2000 05 01 , http://jglobal.jst.go.jp/public/200902112569574778
  • Millimeterwave imaging using electro-optic sampling (2), Ai-ichiro Sasaki, Tadao Nagatsuma, Mitsuru Shinagawa, 電子情報通信学会大会講演論文集, 2000, C-2-128, 179,   2000 03 07 , http://jglobal.jst.go.jp/public/200902111533860760
  • Millimeter-wave imaging using electro-optic sampling, Ai-ichiro Sasaki, Takamitsu Takizawa, Tadao Nagatsuma, Mitsuru Shinagawa, 電子情報通信学会大会講演論文集, 1999, C-2-65, 94,   1999 08 16 , http://jglobal.jst.go.jp/public/200902199020981507
  • Highly sensitive measurement of millimeter-waves in free space using electro-optic sampling, Ai-ichiro Sasaki, Tadao Nagatsuma, Mitsuru Shinagawa, 電子情報通信学会大会講演論文集, 1999, C-2-109, 147,   1999 03 08 , http://jglobal.jst.go.jp/public/200902169461761972
  • Automatic alignment of laser interferometric gravitational wave detectors. VI., 佐々木 愛一郎, 栃久保 邦治, 坪野 公夫, 藤本 真克, 大橋 正健, 河辺 径太, 寺田 聡一, 日本物理学会講演概要集(分科会), 1997, 74,   1997 09 , http://jglobal.jst.go.jp/public/200902132832618050
  • Automatic alignment of laser interferometric gravitational wave detector. IV., 佐々木 愛一郎, とち久保 邦治, 河辺 径太, 坪野 公夫, 日本物理学会講演概要集(年会), 52, 1 Pt 1, 95,   1997 03 , http://jglobal.jst.go.jp/public/200902123494690566
  • Automatic alignment of laser interferometric gravitational wave detector. II., 佐々木 愛一郎, とち久保 邦治, 河辺 径太, 坪野 公夫, 日本物理学会講演概要集(分科会), 1996, Autumn Pt 1, 178,   1996 09 , http://jglobal.jst.go.jp/public/200902163897582234

Educational Activities

Teaching Experience

  • Communications engineering, Kindai University
  • Signal processing, Kindai University
  • Logic circuits, Kindai University
  • Vector analysis, Kindai University
  • Electromagnetic waves and their applications, Kanagawa Institute of Technology
  • Sensor technologies, Saitama University