Opnext Japan, Inc.

Yoichi Honzawa

Shigeru Tokita

Mitsuo Akashi

Naohiko Baba

Tadashi Hatano

Fumihide Maeda

Sunil Sharma

Hideki Satoh

Katsumi Saito

An optical transmission system includes a current source for outputting a drive current, a semiconductor laser for converting the drive current into a stimulated emission light and producing the same, a drive circuit for converting a transmission data signal into a modulation control signal and outputting the same, an optical modulator for receiving the stimulated emission light and a shading control signal for interrupting light emission and producing and outputting transmission signal light by changing an amount of transmission of the stimulated emission light according to the shading control signal, and a shading element for receiving the transmission signal light and a shading control signal for interrupting light emission and interrupting the transmission of the transmission signal light according to the shading control signal whereby an optical signal having wrong optical wavelength is rapidly prevented.

Optical transmission device and optical transmission system using the same

An optical transmitter receiver module and an apparatus incorporating the same module are provided, which realizes the reduction of power consumption and the enlargement of the operating temperature range. As an example, an optical transmitter module is provided which comprises a light emitting element to generate a light signal, a signal processing circuit to transmit an electrical signal to the light emitting element and a voltage regulating circuit to lower a power voltage so as to supply the signal processing circuit with a constant voltage, wherein the module is further provided with a current regulating circuit to shunt a part of a current to be supplied into the voltage regulating circuit from a power source so as to generate a control current and a temperature controller to receive the control current so as to control a temperature of the light emitting element, wherein the module is further provided with a temperature detector to detect the temperature of the light emitting element and a temperature controlling circuit to control the control current according to an electrical signal output by the temperature detector.

Optical transmission module with light element temperature control

In the initial state, any wavelength variation of the output signal light with a change of the current injected into the laser is monitored with a wavelength meter, the quantity of wavelength variation is fed back to the wavelength compensation circuit, a compensation voltage for maintaining the wavelength in the initial stage is figured out, and that voltage is recorded into a memory element or the like. A configuration to add this compensation voltage to a comparator makes it possible to compensate for fluctuations of the characteristics of the optical splitter, wavelength filter and light receiving elements and thereby to obtain a stable optical wavelength. By constantly monitoring the injected current applied to the laser when the optical transmitter is in operation and giving a compensation voltage matching the current variation to the comparator, stabilization of the optical wavelength can be realized. By simulating in the initial state the operation of the laser after deterioration and providing in advance a compensation voltage for suppressing wavelength fluctuations, wavelength fluctuations after deterioration can be restrained.

Optical wavelength stabilization circuit, optical transmitter and optical transmission system

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Yokohama, Japan

Yoichi Honzawa