Practical Research and Collaboration Division
Resilient EICT Research Promotion Office
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
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)
  • Japan Society of Applied Physics
  • Laser Society of Japan
Selected Awards
  • Medal with Purple Ribbon
  • Japan Academy Prize
  • Charles Hard Townes Award