Kabushiki Kaisha Toshiba

Masahide Miyachi

Hiroyuki Ibe

Taro Shibagaki

Shigeru Ohshima

Fuminori Kishino

An optical modulator includes a phase modulator configured to drive light with an NRZI-coded drive signal for phase modulation and an intensity modulator to modulate the intensity of a phase-modulated NRZI-coded optical signal received from the phase modulator. The operating point of the intensity modulator is set such that the output of the intensity-modulated optical signal is eliminated when the NRZI-coded optical signal is not varied.

Apparatus and method for optical modulation

A wavelength division multiplexing optical transmission apparatus comprises an optical wavelength demultiplexer which demultiplexes, for each wavelength, the wavelength division multiplex optical signal transmitted via an optical fiber, receivers which receive the output beams from the optical wavelength demultiplexer, a wavelength detector that detects the difference between the wavelength of a transmitter and a wavelength minimizing the loss in the optical wavelength demultiplexer, and an alarm generator that determines an abnormality when the wavelength difference has exceeded an allowable value and raises the alarm.

Growing community of inventors

Kanagawa, Japan

Masahide Miyachi