Intensity-modulated / direct-detection (IM/DD) Nyquist pulse-amplitude modulation (PAM) signaling for 100-Gbit/s/λ optical short-reach transmission. - Nobuhiko Kikuchi; Riu Hirai (ECOC, 2014)

High-speed optical 64QAM signal generation using InP-based semiconductor IQ modulator. - Nobuhiko Kikuchi; Riu Hirai; Yuki Wakayama (OFC, 2014)

FPGA prototyping of single-polarization 112-Gbit/s optical transceiver for optical multilevel signaling with delay detection. - Nobuhiko Kikuchi; Takashi Yano; Riu Hirai (ECOC, 2015)

Experimental demonstration of 100G/lambda Nyquist-PAM4 transmission with digital pre-equalization of chromatic dispersion for extended-reach 400GbE. - Riu Hirai; Nobuhiko Kikuchi (OFC, 2015)

Practical implementation of 100-Gbit/s/lambda optical short-reach transceiver with Nyquist PAM4 signaling using electroabsorptive modulated laser (EML). - Nobuhiko Kikuchi; Riu Hirai; Takayoshi Fukui (OFC, 2015)

Quasi single-sideband (SSB) IM/DD Nyquist PAM signaling for high-spectral efficiency DWDM transmission. - Nobuhiko Kikuchi; Riu Hirai; Takayoshi Fukui (OFC, 2016)

High-spectral efficiency DWDM transmission of 100-Gbit/s/lambda IM/DD single sideband-baseband-Nyquist-PAM8 signals. - Riu Hirai; Nobuhiko Kikuchi; Takayoshi Fukui (OFC, 2017)

Modulator Non-Linearity Compensation in Tomlinson-Harashima Precoding (THP) for Short-Reach Nyquist- and Faster-than-Nyquist (FTN) IM/DD PAM Signaling. - Nobuhiko Kikuchi; Riu Hirai; Takayoshi Fukui; Shigehiro Takashima (ECOC, 2018)

Application of Tomlinson-Harashima Precoding (THP) for Short-Reach Band-Limited Nyquist PAM and Faster-Than-Nyquist PAM Signaling. - Nobuhiko Kikuchi; Riu Hirai; Takayoshi Fukui (OFC, 2018)

Superior BER Transmission of 106-Gb/s/lane Skewless PAM4 over 10 km by Utilizing 1.3-μm Directly Modulated InGaAlAs-MQW BH Lasers and Incoherent Multiplexing of Two NRZ Signals. - Kouji Nakahara; Riu Hirai; Takeshi Kitatani; Nobuhiko Kikuchi; Takayoshi Fukui; Kaoru Okamoto; Yasushi Sakuma; Kohichi Robert Tamura; Shigehisa Tanaka (OFC, 2018)

BER Improvement of IM/DD Higher-Order Optical PAM Signal with Precise Non-Linearity Compensation. - Nobuhiko Kikuchi; Riu Hirai; Takayoshi Fukui (OFC, 2019)

Proposal of LUT-based transmitter nonlinearity compensator with precursor compensation for Short-Reach IM/DD PAM Signalling with Tomlinson-Harashima Precoding (THP). - Nobuhiko Kikuchi; Riu Hirai (ECOC, 2020)

Application of Generalized THP for Arbitrary PAM Level Design in Short-Reach IM/DD Signalling. - Nobuhiko Kikuchi; Riu Hirai (ECOC, 2021)

Faster-Than-Nyquist IM/DD THP-PAM4 Signaling Using Directly-Modulated Laser with Laser Non-Linear Skew Compensation. - Nobuhiko Kikuchi; Riu Hirai; Takahito Tanimura (OECC/PSC, 2022)

Optical Status Representation by Collaborative and Unsupervised Learning. - Takahito Tanimura; Riu Hirai; Nobuhiko Kikuchi (OECC/PSC, 2022)

Physical Status Representation in Multiple Administrative Optical Networks by Federated Unsupervised Learning. - Takahito Tanimura; Riu Hirai; Nobuhiko Kikuchi (IEICE Trans. Commun., 2023)

Optical Single-Sideband (SSB) Conversion Technique Using Phase Modulator for High-Speed Short-Reach IM/DD PAM Signaling. - Nobuhiko Kikucih; Riu Hirai; Takahito Tanimura (OFC, 2024)