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Access Inquiries Sitemap JP AboutIntroduction to IRIDeSGreetings from the DirectorOrganizational structureCOVID-19 preventive measuresCurrent updatesActivitiesPress releasesQuick reponse disaster surveyOpeningsOrganizationResearch organizationFaculty membersRisk Evaluation and Disaster Mitigation Research Division Disaster Humanities and Social Science Division Disaster Medical Science Division Practical Research and Collaboration Division Endowed Research Division Joint Research Division Co-creation Center for Disaster Resilience Global Centre for Disaster Statistics Kesennuma Satellite Office Public Relations Office Administration OfficeResearch and PracticeGreat East Japan EarthquakeDisaster investigationsDisaster Resilience Co-Creation Research ProjectApplication Guidelines 2024Collaboration in JapanMoUs with local governmentsMoUs with educational institutionsRadiation Emergency Medicine Promotion CenterInternational collaborationInternational research collaboration and partnershipsInternational MoUsAPRU-IRIDeS Multi-Hazards ProgramTU/UCL Collaborative Research and Education Centre for a Resilient SocietyInternational Collaborating Center of Disaster Education Research and ImplementationWorld Tsunami Awareness DayG7 Science and Technology Ministers&＃039; 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IRIDeS VisitOrganizations and projects collaborating with IRIDeSDesignated National University Core Research Cluster of Disaster ScienceWorld BOSAI ForumInstitute for Disaster Reconstruction and Regeneration Research -IDRRRWISE Program for Sustainability in the Dynamic Earth(SyDE)International Joint Graduate Program in Resilience and Safety StudiesTOHOKU FORUM for CREATIVITY -Thematic ProgramsArcDR³ Initiative(Architecture and Urban Design for Disaster Risk Reduction and Resilience)Japan Hub of Disaster Resilience Partners(JHoP)EventsUpcoming eventsRegular events in JapaneseInternational regular eventsWorld Bosai Forum - IRIDeSAIWESTIRIDeS tourPrint & Digital ResourcesPublicationsIRIDeS ChannelDatabaseTsunami Trace Database in JapanStatistical Database on the Great East Japan EarthquakeDatabase in JapaneseMedia coverageFor visitorsMedia/PressVisitorsInquiries about studying at IRIDeSFor IRIDeS Faculty and Staff Organization HOME Organization NAKAZAWA Masataka Research Division Risk Evaluation and Disaster Mitigation Research Division Disaster Humanities and Social Science Division Disaster Medical Science Division Practical Research and Collaboration Division Endowed Research Division Joint Research Division Co-creation Center for Disaster Resilience Global Centre for Disaster Statistics Kesennuma Satellite Office Public Relations Office Administration Office Practical Research and Collaboration Division Resilient EICT Research Promotion Office Research Fellow (Specially Appointed) Ph.D. (Engineering) NAKAZAWA Masataka +81-22-217-5522 @ Nakazawa Group Earthquake Research Institute, University of Tokyo, Araya Laboratory Researcher Database Research Subject(s) I have been engaging in research on disaster-resistant optical communication technology. During disasters, the transmission signal level tends to become lower due to obstructions. I aim to develop an optical communication system that can be connected even during disasters by adaptively controlling the multiplicity of optical communication and maintaining a high signal level. In addition, as 5G/6G technology, I introduce digital coherent transmission technology into mobile fronthaul which enables high-capacity optical communication with a higher multiplicity through an injection-locking technique. Key Words Optical Communication Technology / Lasers and Quantum Electronics / Optical Fiber Measurement Website Nakazawa Group Earthquake Research Institute, University of Tokyo, Araya Laboratory Research Activities I proposed a new optical pulse called the Nyquist pulse, which enables ultrahigh-speed coherent transmission with high spectral efficiency. This research was adopted as a Grant-in-Aid for Specially Promoted Research (KAKENHI) and has made significant progress worldwide. I also proposed a laser that generates a Nyquist pulse and later demonstrated that arbitrary optical pulses can be generated from a mode-locked laser by generalizing the Nyquist laser . I also succeefully demonstrated long-distance, high-speed and large-capacity QAM/QNSC cipher transmission which has been difficult to achieve with other previous schemes by taking advantage of the quantum noise. I am working on application of digital coherent transmission and our proposed full-coherent transmission to mobile fronthaul. In particular, full-coherent transmission has been attracting attention as a promising technology for 6G because it enables high-speed system with high reliability and low cost. I also demonstrate the importance of Guided Acoustic-Wave Brillouin Scattering (GAWBS) noise as a new problem in coherent transmission, and show that compensation for this noise is important for long-distance transmission. I have developed a frequency-stabilized fiber laser whose frequency is locked to the absorption line of acetylene molecules at a wavelength of 1.5 μm. As an application of this laser, I have developed a new gravity accelerometer with the Earthquake Research Institute of the University of Tokyo, and have been collaborating with JAMSTIC on crustal strain and tsunami measurements using optical fiber interferometry. Selected Works M. Nakazawa, T. Hirooka, P. Ruan, and P. Guan, "Ultrahigh-speed “orthogonal” TDM transmission with an optical Nyquist pulse train," Opt. Express vol. 20, no. 2. pp. 1129-1140, Jan. (2012). M. Nakazawa, M. Yoshida, T. Hirooka, and K. Kasai, "QAM quantum stream cipher using digital coherent optical transmission," Opt. Express vol. 22, no. 4, pp. 4098-4107, February (2014). M. Yoshida, T. Kan, K. Kasai, T. Hirooka, K. Iwatsuki, and M. Nakazawa, “10 channel WDM 80 Gbit/s/ch, 256 QAM bi-directional coherent transmission for a high capacity next-generation mobile fronthaul,” J. Lightwave Technol., vol. 39, no. 5, pp. 1289-1295, March (2021). M. Nakazawa, M. Yoshida, M. Terayama, S. Okamoto, K. Kasai, and T. Hirooka, "Observation of guided acoustic-wave Brillouin scattering noise and its compensation in digital coherent optical fiber transmission," Opt. Express vol. 26, no. 7, pp. 9165-9181, April (2018). M. Nakazawa, M. Yoshida, and K. Kasai, "Diastrophism and tsunami measurement using optical fiber network," Optical and Electro-Optical Engineering Contact, vol. 54, no. 12, pp. 22-31 (2016). Selected Memberships IEEE ＯPTICA (Formaly OSA) IEICE Japan Society of Applied Physics Laser Society of Japan Selected Awards Medal with Purple Ribbon Japan Academy Prize Charles Hard Townes Award Others On April 1, 2023, Dr. Masataka Nakazawa was awarded the prominent title of "Distinguished Professor Emeritus of Tohoku University. ページの先頭に戻る Inquiries Site Policy For IRIDeS Faculty and Staff 関係部局リンク--> About Introduction to IRIDeSGreetings from the DirectorOrganizational structureCOVID-19 preventive measuresCurrent updatesActivitiesPress releasesQuick reponse disaster surveyOpenings Organization Research organizationFaculty membersRisk Evaluation and Disaster Mitigation Research Division Disaster Humanities and Social Science Division Disaster Medical Science Division Practical Research and Collaboration Division Endowed Research Division Joint Research Division Co-creation Center for Disaster Resilience Global Centre for Disaster Statistics Kesennuma Satellite Office Public Relations Office Administration Office Research and Practice Great East Japan EarthquakeDisaster investigationsDisaster Resilience Co-Creation Research ProjectCollaboration in JapanInternational collaborationOrganizations and projects collaborating with IRIDeS Events Upcoming eventsRegular events in JapaneseInternational regular eventsIRIDeS tour Print & Digital Resources PublicationsIRIDeS ChannelDatabaseTsunami Trace Database in JapanStatistical Database on the Great East Japan EarthquakeDatabase in JapaneseMedia coverage For visitors Media/PressVisitorsInquiries about studying at IRIDeSFor IRIDeS Faculty and Staff Great East Japan Earthquake Access Inquiries Site map Site policy (Japanese) International Research Institute of Disaster Science (IRIDeS), Tohoku University 468-1 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, Japan 980-8572 Phone: +81-22-752-2011 (switchboard), +81-22-752-2049 (PR Office) 2011-2019 © International Research Institute of Disaster Science no cache