Mitsubishi Electric Corporation

Mitsubishi Denki Kabushiki Kaisha

Yasuhisa Shimakura

Eiji Yagyu

Sadayuki Matsumoto

Masakazu Takabayashi

Kentaro Enoki

Kiichi Yoshiara

Tsuyoshi Yoshida

Tateki Mitani

Shusaku Hayashi

Shigeki Kanamaru

Kazushige Sawada

Hiroaki Shintaku

Kazushi Ishii

A superposition circuitry superposes a dither signal on a reference DC bias voltage and outputs a resultant voltage as a bias voltage to an MZ modulator, during control of a driving voltage amplitude. During the control of the driving voltage amplitude to the MZ modulator, an amplitude setter determines, by varying the amplitude of an output voltage from an amplifier, a plurality of amplitudes of output curves from a synchronous detector, each of which is obtained by varying the reference DC bias voltage output from a bias controller, and the amplitude setter sets the amplification factor of the amplifier, based on an amplitude of the output voltage from the amplifier that corresponds to an amplitude satisfying a predetermined condition, out of the plurality of the amplitudes of the output curves from the synchronous detector.

Optical modulation device and method for controlling optical modulation device

An optical modulation unit included in an optical transmitter includes two optical modulators that modulate each of two light beams based on applied bias voltages and input modulation signals, and an optical phase regulator that is connected to either of the two optical modulators, and regulates a phase of the light beam incident on the optical modulator. In a state where no modulation signal is input to the two optical modulators, while keeping bias voltages to be applied to one optical modulator and the optical phase regulator constant, the controller determines a first initial bias voltage such that an output light beam from the other optical modulator becomes zero. Thereafter, the controller determines a second initial bias voltage such that an output light beam from the one optical modulator becomes zero, while applying the first initial bias voltage to the other optical modulator.

Optical transmitter and control method of optical transmitter

An optical fiber sensor that can detect a liquid level or detect a property of liquid with high reliability even under a frequently vibrational environment. The optical fiber sensor includes an optical fiber that includes a core having an area where a grating is formed and a clad, the optical fiber being disposed so that at least a part of the area with the grating is immersed in liquid, a light source for making light incident to the optical fiber so that a cladding mode light having a wavelength band is generated by the grating, and a light receiving unit for detecting the intensity of light which is incident from the light source to the optical fiber and transmitted through the grating.

Optical fiber sensor

A tunable dispersion compensator in which a heater portion can be easily constructed to reduce cost. A tunable dispersion compensator includes: an optical fiber having a grating portion; a heating unit for heating the grating portion to apply a temperature distribution to the grating portion; and a control unit for controlling the temperature distribution applied by the heating unit to control the group delay time characteristic of the grating portion. The heating unit includes: a heater including a single conductor having electrical resistors and which extends in a longitudinal direction of the grating portion over at least the entire length of the grating portion; and wirings electrically connected with the heater in respective positions along the longitudinal direction. The control unit supplies a voltage to each of the wirings.

Tunable dispersion compensator and method of manufacturing the same

Growing community of inventors

Tokyo, Japan

Yasuhisa Shimakura