Oclaro Japan, Inc.

Opnext Japan, Inc.

Shigehiro Takashima

Taichi Kogure

Mitsuo Akashi

Kazuyoshi Yamaki

Hirofumi Nakagawa

Kouji Takeguchi

Takayoshi Fukui

Yoshikuni Uchida

Yoshikazu Era

Youichi Honzawa

Atsushi Takai

Saki Narisawa

In pattern synchronization for correctly regenerating received data, which is performed in an optical receiver for receiving an optical signal that has been subjected to quadrature phase modulation, signal conduction is quickly established without using duplicate combinations of bit shifting and pattern changing. A control method that does not involve verifying the duplicate combinations generated in modulation formats and pattern synchronization search orders. Specifically, a signal check circuit () performs data verification of data multiplexed by a MUX circuit () for multiplexing two data strings, and a bit shift pattern change control circuit () controls a bit shift circuit () and a pattern changing circuit () based on a result of the data verification and detects a correct combination of correct regenerated data to establish the signal conduction. At this time, for the bit shift circuit () and the pattern changing circuit (), the duplicate combinations are not verified.

Optical receiver

The I phase modulator modulates a phase based on the bias voltage in which a first modulation signal and a first pilot signal are inherent and the Q phase modulator modulates a phase based on the bias voltage in which a second pilot signal different from the first pilot signal and a second modulation signal are inherent. A time-average power synchronous detection unit detects an optical power at a timing at which the positivity and negativity of the voltages of both pilot signals become the same, and an optical power when the positivity and negativity of the voltages of both pilot signals are opposite. The bias voltage control unit controls the bias voltage so that the difference between both the optical powers becomes small based on the detection result of the time-average power synchronous detection unit.

Optical output module, optical transceiver, and optical transmission system

A technology to automatically control the biasing of an optical duobinary transmitter using a single-drive LN-MZ modulator is provided. A low-frequency signal is amplitude modulated onto a voltage signal input into a Mach-Zehnder optical modulator. The optical output from the optical modulatoris detected by an optical detection subsystem. In a bias control subsystem, the low-frequency signal component amplitude modulated onto the electrical signal is detected from the optical output, and a DC bias voltage applied to the optical modulator is controlled such that the low-frequency signal component is either minimized or maximized.

Optical transmitter

Growing community of inventors

Tokorozawa, Japan

Shigehiro Takashima