Akito Chiba

Gunma University

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Document Type

Co-Authors

Takahide Sakamoto

Tokyo Metropolitan University

Tetsuya Kawanishi

Waseda University

Kaoru Higuma

Sumitomo Osaka Cement (Japan)

Junichiro Ichikawa

Sumitomo Osaka Cement (Japan)

Masaaki Sudo

Sumitomo Osaka Cement (Japan)

Masayuki Izutsu

Waseda University

Atsushi Kanno

Jichi Medical University

K. Takada

Gunma University

Guo-Wei Lu

University of Aizu

Kawanishi Tetsuya

Cooperative Institutions

National Institute of Information and Communications Technology

Japan Science and Technology Agency

The University of Tokyo

Osaka University

Gunma University

Shizuoka University

Tohoku University

NTT (Japan)

National Center for University Entrance Examinations

National Institute of Advanced Industrial Science and Technology

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Advances and challenges in vector modulation technologies

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2008)

Tetsuya Kawanishi Takahide Sakamoto Akito Chiba

This paper describes recent progress of high-speed vector optical modulation technologies based on Mach- Zehnder interferometer devices. Multi-level quadrature amplitude modulation signal can be synthesized by using parallel Mach-Zehnder modulators. We can generate complicated multi-level optical signals from binary data streams, where binary modulated signals are vectorially summed in optical circuits. Modulation speed can be higher than 80 Gbaud by using a dual parallel Mach-Zehnder modulator with thin lithium niobate substrate.

Modulation (music)

Electro-optic modulator

SIGNAL (programming language)

10.1117/12.816361

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Citations (1)

Optical trellis-coded modulation with multi-parallel MZM

European Conference on Optical Communication (2009)

Takahide Sakamoto Akito Chiba Isao Morohashi Tetsuya Kawanishi

We demonstrated trellis-coded modulation onto 10-Gbaud 16QAM by electro-optic vector digital-to-analogue converter employing multi-parallel MZM and trellis encoder. The signal was demodulated with a digital homodyne employing Viterbi decoder.

Trellis (graph)

Trellis modulation

Modulation (music)

Source

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Citations (3)

Ultra high extinction-ratio and ultra low chirp optical intensity modulation for pure two-tone lightwave signal generation

Conference on Lasers and Electro-Optics (2008)

Tetsuya Kawanishi Takahide Sakamoto Akito Chiba Masahiro Tsuchiya Hiroyuki Toda

Pure two-tone signal generation with spurious suppression ratio of 47 dB was demonstrated by using an optical Mach-Zehnder modulator with precisely balanced operation, where extinction ratio and chirp parameter were respectively 64 dB and 0.0099.

Extinction ratio

Chirp

Tone (literature)

Modulation (music)

SIGNAL (programming language)

Spurious relationship

Extinction (optical mineralogy)

10.1109/cleo.2008.4550935

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Citations (17)

Demonstration of optical quadrature amplitude modulation by using a high-speed optical DQPSK modulator and precise voltage-control technique

Akito Chiba

Quadrature (astronomy)

Electro-optic modulator

Modulation (music)

Source

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Citations (2)

Agile Wideband Light Source forOptical Coherence Tomography UsingOptical SSBFrequency SweepTechnique

Takehiro Yamamoto Ryuji Kohno Akito Chiba Takahide Sakamoto Tetsuya Kawanishi

per, weusedtwotypes ofmulti-wavelength sources: 1)a Wepropose anagile wideband light source, whichtargeted laser array and2)anoptical combgenerator based onEO onoptical coherence tomography (OCT), consists ofanop- modulation [3]. Generation ofa1.6nm wideband signal tical single-sideband modulation (SSB) frequency sweeper with2MHzrepetition rate (500 nssweeptime) wasdemoncascaded withanoptical frequency combgenerator anda strated bytheSSBmodulation withcombgeneration techmulti-wavelength light source. nique.

Wideband

Modulation (music)

Source

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Citations (0)

Digital Optical Phase Locked Loop for Real-Time Coherent Demodulation of Multilevel PSK/QAM

Optical Fiber Communication Conference (2010)

Takahide Sakamoto Guo-Wei Lu Akito Chiba Tetsuya Kawanishi

We propose a digital optical phase locked loop (DOPLL) for real-time demodulation of high-speed multilevel PSK/QAM. It was simply implemented using low-speed digital signal processor after electrical sampling to demodulate high-speed BPSK, QPSK and 16QAM.

QAM

Carrier recovery

Modulation (music)

10.1364/ofc.2010.oms5

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Citations (6)

RF Signal Estimation Utilizing Low-Frequency Beat Signal Due to Harmonics of Phase-Modulation Lightwave

Akito Chiba Yusuke Sunaga

We propose a method for estimating parameters of an RF-signal within high-frequency region, by adopting a low-frequency reference RF signal source to generate harmonics of the modulation lightwave.

SIGNAL (programming language)

Beat (acoustics)

Signal transition

Modulation (music)

10.1109/cleo-pr62338.2022.10432081

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Citations (0)

Ultra Wideband Light Source Using 136-Wavelengths SSB Frequency Sweep Technique for Optical Coherence Tomography

Takehiro Yamamoto Ryuji Kohno Akito Chiba Takahide Sakamoto Tetsuya Kawanishi

We demonstrate an ultra-wideband light source using multi-wavelength single-sideband modulation (SSB) frequency sweep technique, aiming at optical coherence tomography (OCT). The light source consists of an optical SSB frequency sweeper with an optical frequency comb generator cascaded with a multi-wavelength laser. Ultra-wideband signal was generated by sweeping frequency of each components of an optical multi-wavelength light source. The proposed system can achieve much faster and more precise spectrum measurement than the conventional OCT system.

Wideband

Optical Tomography

Modulation (music)

Superluminescent diode

10.1109/mwp.2007.4378175

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Citations (0)

Performance Improvement of High-Extinction-Ratio LiNbO3 Optical Intensity Modulator by Means of Polarization Crosstalk Reduction

IEICE Technical Report; IEICE Tech. Rep. (2007)

Toda Hiroyuki Fukuta Katsuya Daisuke Arai Akito Chiba Kiyotaka Sasagawa

Extinction ratio

Crosstalk