Riu Hirai

Intensity-modulated / direct-detection (IM/DD) Nyquist pulse-amplitude modulation (PAM) signaling for 100-Gbit/s/λ optical short-reach transmission

We propose a new high-speed optical IM/DD transmission scheme employing Nyquist-shaped PAM4 and PAM6 signaling with digital signal processing for short-reach applications and experimentally demonstrate its 100-Gbit/s operation over 2-km singe mode fiber at 1.5 μm band.

High-speed optical 64QAM signal generation using InP-based semiconductor IQ modulator

The use of InP-based IQ modulator for ultra-high speed precise 28-GBaud 64QAM signal generation (336 Gbit/s with polarization multiplexing) is experimentally demonstrated using digital modulator non-linearity compensation techniques, for the first time to our knowledge.

FPGA prototyping of single-polarization 112-Gbit/s optical transceiver for optical multilevel signaling with delay detection

We develop full-rate / fully-functional FPGA-based high-speed optical 16-APSK/QAM transceiver prototype using optical delay-detection for single-polarization 100-Gbit/s/channel short- to mid-range fiber transmission. Four channel WDM (448-Gbit/s) field trial over 18.2-km SMF is also performed.

FPGA Prototyping of Single-Polarization 112-Gb/s Transceiver for Optical Multilevel Signaling With Intensity and Delay Detection

As the proof-of-concept of a next-generation 100-Gb/s/channel high-speed optical transceiver for short- to mid-range applications, we develop a first full-rate and fully-functional FPGA-based single-polarization 16APSK/16QAM transceiver prototype using optical delay- and intensity-detection. Almost all the major transceiver functions, such as multilevel modulation/demodulation, timing recovery, framing functions with FEC, and linear equalizers are implemented into eight FPGAs, and the feasibility of the proposed transceiver with small circuit size and low power consumption is confirmed. Various compensation functions previously reported for the performance improvement of the delay-detection-based multilevel signaling, such as Rx-side phase noise, chromatic dispersion canceling circuits, compensation of unbalance of balanced photodetectors, symbol decision with non-Euclidian metric, etc., are also implemented in the real-time transceiver for the first time. In this paper, its basic concept, FPGA implementation, real-time signal demodulation, and BER performances are shown and four-channel WDM (448 Gb/s) field trial over 18.2-km SMF is also demonstrated.