Fukutaro Hamaoka
Harvard University
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Publication
Featured researches published by Fukutaro Hamaoka.
european conference on optical communication | 2014
Fukutaro Hamaoka; Kohei Saito; Toshiya Matsuda; Akira Naka
We propose a super high density multi-carrier transmission system with MIMO processing by estimating the precise subcarrier spacing. We experimentally and numerically demonstrate that the proposed system enables the sub-carrier spacing to be reduced to half the baud rate.
optical fiber communication conference | 2016
Hideki Maeda; Takashi Kotanigawa; Kohei Saito; Masahiro Yokota; Shuto Yamamoto; Fukutaro Hamaoka; Mitsuteru Yoshida; Masahiro Suzuki; Takeshi Seki
We achieve double the performance in 400-Gbps optical transmission employing advanced digital coherent technologies based on field trials. Additionally, we show stable transmission of 400-Gbps channels that does not affect the existing 100-Gbps channels.
Journal of Lightwave Technology | 2017
Masanori Nakamura; Fukutaro Hamaoka; Asuka Matsushita; Kengo Horikoshi; Hiroshi Yamazaki; Munehiko Nagatani; Akihide Sano; Akira Hirano; Yutaka Miyamoto
We proposed coded eight-dimensional (8-D) quadrature amplitude modulation (QAM) and experimentally demonstrated in high baud-rate transmission. Both high baud rate and multilevel modulation techniques are necessary for large capacity long haul transmission without increasing the number of transponders. However, optical signal-to-noise ratio (OSNR) tolerance of higher order modulation is low due to the short minimum Euclidean distance. Therefore, to relax OSNR tolerance by enlarging minimum Euclidean distance, we proposed 8-D modulation formats. The spectral efficiency of the proposed coded 8-D-16QAM, 8-D-32QAM, and 8-D-64QAM is equivalent to polarization division multiplexed (PDM)-8QAM, PDM-16QAM, and PDM-32QAM, respectively. To confirm the applicability of the proposed 8-D modulation to high baud rate transmission, we experimentally demonstrated 96-GBaud 8-D-16QAM wavelength division multiplexed transmission over 5,-252 km using iterative soft output decoding. The line data rate is 576-Gbps and a net rate 478-Gbps. At the same spectral efficiency, 8-D-16QAM using iterative soft output decoding can expand the transmission reach by 1212 km compared to conventional PDM-8QAM.
Journal of Lightwave Technology | 2016
Shuto Yamamoto; Kohei Saito; Fukutaro Hamaoka; Toshiya Matsuda; Akira Naka; Hideki Maeda
We experimentally investigate the characteristics of a multi-carrier optical transmission system with neighboring-crosstalk compensation using multiple-input multiple-output processing as an integrated part of a polarization-demultiplexing stage in a homodyne detection scheme for high-speed optical signals. We show that the crosstalk compensation yields adequate performance in the presence of high polarization mode dispersion and high-speed changes in the state of polarization. We also clarify the performance required of local oscillators in the receivers for adequate crosstalk compensation in this scheme. Furthermore, we show the applicability of the system equipped with delay compensation to long-haul transmission through 480-km WDM transmission experiments employing 256-Gb/s optical multi-carrier signals with the subcarrier spacing of 25 GHz, which corresponds to 78% of the signal baud rate.
opto electronics and communications conference | 2015
M. Nakamura; Mitsuteru Yoshida; Fukutaro Hamaoka; Kazushige Yonenaga
We propose optical 8D time-polarization modulation using square-QAM-constellation and a simple decoding algorithm. Experiments show that the proposed modulation format can achieve significant gain and the decoding algorithm has the same performance as conventional maximum-likelihood-detection.
Optics Express | 2016
Seiji Okamoto; Fukutaro Hamaoka; Yoshiaki Kisaka
We present a feasible distance-adaptive optical transmission system that selects the optimum modulation format by referencing the estimated optical signal to noise ratio (OSNR) information transmitted from an opposing transceiver via a feedback channel. A modulation format free time-domain-multiplexed pilot sequence enables OSNR estimation and feedback channel transmission. Thanks to a feedback channel transmission, this system does not need to pass through a control plane in optimizing scheme. Using this system, we demonstrated 106.6 Gb/s QPSK and 213.3 Gb/s 16 QAM distance-adaptive optical transmission in a fully automatic manner in a field-installed fiber of 70.4 to 211.2 km.
opto electronics and communications conference | 2017
Asuka Matsushita; K. Horikoshi; Seiji Okamoto; Masanori Nakamura; Fukutaro Hamaoka; Yoshiaki Kisaka; Akira Hirano
We propose the use of differential code shift keying (DCSK) for a symbol rate adaptive low-complexity DSP algorithm by eliminating adaptive-equalizer (AEQ) with limited influence on circuit size. As a proof of concept, a 300km transmission using DCSK format was demonstrated without using AEQ.
european conference on optical communication | 2015
Kohei Saito; Masahiro Yokota; Fukutaro Hamaoka; Shuto Yamamoto; Takashi Kotanigawa; Hideki Maeda; Akira Naka
Hitless optical path switching using maximum ratio combining in route diversity transmission is successfully achieved under the condition of a field environment even if there are large polarization mode dispersion and fibre nonlinearities.
optical fiber communication conference | 2017
Takayuki Kobayashi; Masanori Nakamura; Fukutaro Hamaoka; Kohki Shibahara; Takayuki Mizuno; Akihide Sano; Hiroto Kawakami; Akira Isoda; Munehiko Nagatani; Hiroshi Yamazaki; Yutaka Miyamoto; Yoshimichi Amma; Yusuke Sasaki; Katsuhiro Takenaga; Kazuhiko Aikawa; Kunimasa Saitoh; Yongmin Jung; David J. Richardson; Klaus Pulverer; Marc Bohn; Md. Nooruzzaman; Toshio Morioka
IEICE Communications Express | 2014
Fukutaro Hamaoka; Toshiya Matsuda; Akira Naka