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April 3, 2025
Information
Masanori Nakamura received The Tingye Li Innovation Prize at OFC2025, the world's largest international conference in the field of optical communications technology, and two Postdeadline Papers from NTT were accepted.
At OFC (Optical Fiber Communications Conference and Exhibition) 2025, the world's largest international conference in the optical communications technology, held in San Francisco, USA from March 30 to April 3, 2025, Distinguished Researcher Masanori Nakamura received The Tingye Li Innovation Prize, which is awarded annually to 1 young researcher under the age of 39 for his innovative research. In addition, two NTT papers were accepted for the Postdeadline Paper, was the most challenging presentation session of the conference.
The affiliation of each author is indicated by the following symbols.
*1: Network Innovation Laboratories
*2: Device Technology Laboratories
*3: NTT Innovative Devices Corporation
[The Tingye Li Innovation Prize]
Winner: Masanori Nakamura (*1)
Paper title:
628 Gb/s Net Bitrate IMDD Transmission Using Ultra-Broadband InP-DHBT-Based Electrical Mixer With Upper-Sideband Gain-Enhanced Mode- This paper proposes a new frequency-domain multiplexing technique to overcome the bandwidth limitations of analog-to-analog converters (DACs) in ultra-high-speed optical signal transmission within data centers. In the proposed method, a newly developed indium phosphide double heterojunction bipolar transistor (InP DHBT) electrical mixer integrated circuit with an upper sideband gain enhancement mode is used to expand the DAC bandwidth, and accurate linear and nonlinear digital pre-distortion signal processing is realized to correct the imperfections of this device and generate high symbol rate signals with symbol rates※1 of 216 to 232 GBaud, making it possible to generate high symbol rate signals while maintaining the signal-to-noise ratio. As a result, the world's fastest 628 Gb/s IMDD※2 optical signal transmission was demonstrated over 11 km, using an advanced optical modulation format (probabilistically shaped 14-level pulse amplitude modulation: PS-PAM14) with a symbol rate of 224 GBaud. This is expected to lead to even greater capacity increases in short-reach application within data centers in the future.
[Postdeadline paper]
27-THz ISRS-Supported Transmission Over 1040 km in S+C+L+U and Extreme Longer-Wavelength Band
- Shimizu Shinpei (*1), Kimura Kosuke (*1), Kawai Akira (*1), Abe Masashi (*2), Konno Toshiya (*2), Kazama Takushi (*2), Nakamura Masanori (*1), Hamaoka Fukutaro (*1), Enbutsu Koji (*2), Kashiwazaki Takahiro (*2), Hase Munehiko (*2), Wakita Hitoshi (*2), Shiratori Yuta (*2), Yushi Yamazaki (*2), Takahashi Hiroyuki (*2), Umeki Takami (*2), Kobayashi Takayuki (*1), MIYAMOTO Yutaka (*1)
- In backbone optical fiber transmission systems, an inline optical amplified transmission system is used in which optical signals are multiplexed on the wavelength axis and are simultaneously amplified by optical amplifiers. Optical signal wavelength bands are standardized from shorter wavelength band to longer wavelengh band as O, E, S, C, L, and U band, and ultra-wideband multiband transmission systems using three or more wavelength bands have been studied. This paper successfully demonstrated potential new wavelength band of an extreme long-wavelength band (X band) as a longer wavelength band in addition to the S+C+L+U band. By utilizing the interband stimulated Raman scattering (ISRS) effect, we dramatically improved the signal quality in the X band and succeeded in wavelength division multiplexing (WDM) transmission experiment with a transmission bandwidth of 27 THz, which is approximately six times larger than that of conventional bands. Using an all-optical wavelength band conversion with a periodically poled lithium niobate (PPLN) waveguide optical parametric amplifier (OPA) being developed by NTT, we achieved ultra-wideband WDM inline amplified transmission experiment with the record capacity of 160.2 Tb/s, over 1000 km using a single-mode fiber.
Uncooled O-band InP MZ Modulator PIC for 3.2 Tb/s (400 Gb/s/lane) Pluggable Transceiver
- Ogiso Yoshihiro (*3), Ozaki Tsunesuke (*3), Sugiura Kenta (*3), Yamazaki Hiroshi (*2), Taniguchi Hiroki (*1), Kanazawa Shigeru (*3), Nakamura Masanori (*1), Miyamoto Hiroshi (*1), Ishikawa Koei (*3), Kaneko Akimasa (*3)
- To cope with the rapid increase in communication traffic in data centers, technology development for high-capacity next-generation Ethernet systems such as 1.6 Tb/s and 3.2 Tb/s is being actively pursued. In particular, optical modulator technology that achieves 400 Gb/s per lane is attracting attention, but the technologies reported so far have had problems in terms of bandwidth characteristics, size, and manufacturing technology. We fabricated an O-band 8 lane integrated Mach-Zehnder modulator chip using mature InP modulator technology and demonstrated 100 GHz-class optical modulation bandwidth at 20~80°C and 500 m PAM-6 transmission at 400 Gb/s/lane (total 3.2 Tb/s). The chip, which is only 5 mm square and capable of non-cooling operation, will be used in the next generation of 3.2 Tb/s small form-factor pluggable (SFP) transceivers.
NTT is engaged in research on cutting-edge technologies with the aim of expanding its business domains, creating new ideas and concepts that transform society, and providing environmentally and human-friendly technologies. These results will contribute to expanding communication capacity to provide innovative information and communications networks and to device technology that will open up the next generation of information and communications fields.
[Glossary of Terms]
※1Symbol rate
The number of times the optical waveform switches per second where Baud is the unit of measurement. The 224 GBaud optical signal shown in the paper's information by switching the optical waveform 224 billion times per second.
※2IMDD (Intensity Modulation and Direct Detection)
Method for encoding information in optical intensity with respect to transmission wavelength. It can be configured using only a semiconductor laser, external optical modulator, driver amplifier, and optical detector thereby facilitating the development of simple and low-cost optical transmitters and receivers.
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Please be advised that information may be outdated after that point.
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