Nippon Telegraph and Telephone Corporation

Toshihiro Ito

Ken Tsuzuki

Kiyofumi Kikuchi

Masayuki Takahashi

Kotaro Takeda

A optical modulator with reduced with a reduced amount of ripple is provided. A Mach-Zehnder optical modulator includes a phase modulation unit including optical waveguides having a PN junction structure and traveling wave electrodes, and a dummy phase modulation unit including portions of the traveling wave electrodes, the portions being obtained by forming the respective traveling wave electrodes longer than the phase modulation unit in the light propagation direction of the phase modulation unit, and optical waveguides having the same PN junction structure as that of the optical waveguides of the phase modulation unit and not connected to the optical waveguides of the phase modulation unit.

Optical modulator

There is provided an optical communication device capable of minimum suppressing inter-signal interference of inductors mounted to enable a transmission signal to be transmitted and received with a high frequency. The optical communication device comprises a sub-package as a subassembly in each of a plurality of signal channels. The sub-package includes a substrate on which an optical semiconductor and an IC are flip-chip connected. The optical semiconductor includes a pair of photodiodes receiving a differential optical signal and outputting a differential current signal. The IC includes a transimpedance amplifier converting the differential current signal from the optical semiconductor to a voltage signal. The optical semiconductor has a pair of inductors formed for each of the pair of photodiodes and a ground wiring formed so as to surround the formed pair of inductors.

Optical communication apparatus

Provided is an optical transmitter having improved frequency characteristics by controlling the band by using components constituting the optical transmitter. An optical transmitter including an optical modulator that includes a traveling-wave electrode and a terminating resistor, and an optical modulator driver configured to drive the optical modulator, in which a characteristic impedance of a transmission line connecting the optical modulator driver and the optical modulator is 20% or more higher than a characteristic impedance of the optical modulator, and an electrical length of the transmission line is 1/20 or more and &#xbd; or less of a wavelength corresponding to a 3 dB band frequency of an electrical signal driving the optical modulator.

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Musashino, Japan

Toshihiro Ito