Chihiro Ohshima

Novel 1500 nm-band EDFA with discrete Raman amplifier

We first demonstrate amplification in EDFA at wavelengths of 1489-1519 nm using a multi-stage configuration of silica-based EDF (erbium doped fiber) and ASE (amplified spontaneous emission) suppressing filters. The Raman/EDFA hybrid amplifier realizes a useful S-band optical amplifier with dispersion compensation and low non-linearity.

Interplay between local oscillator phase noise and electrical chromatic dispersion compensation in digital coherent transmission system

We demonstrate that the interplay between local oscillator phase noise and electrical chromatic dispersion compensation induces timing jitter as well as intensity noise. The interplay is investigated in 3000 km-long transmission (accumulated dispersion of 47,000 ps/nm) without optical dispersion compensation.

Interplay between PMD and nonlinearity in 112 Gb/s DP-QPSK transmission with co-propagating 10.7 Gb/s NRZ channels

We experimentally demonstrate interplay between PMD and nonlinearity in 112 Gb/s DP-QPSK signal transmission with 10.7 Gb/s NRZ neighbors can have both positive and negative impact depending on channel spacing and fiber launched power.

Nonlinear mitigation technique using subcarrier power pre-emphasis and digital nonlinear compensation in superchannel transmission

We propose combined nonlinear mitigation technique for superchannel transmission. We experimentally demonstrate 3.1 dB performance improvement by optimizing subcarrier power pre-emphasis and applying digital nonlinear compensator with perturbation back-propagation algorithm for four-subcarrier DP-QPSK superchannel in 900 km dispersion-uncompensated transmission.

Techniques and algorithms in coherent detection

Complex interaction among optical signal distortions, analog component characteristics, and digital signal processing algorithms can give rise to significant performance degradation in the coherent system performance. Two topics are introduced as examples of such phenomena.