Optical wavelength stability control apparatus, optical transmitter and multiple wavelength transmitter

An optical transmitter including a plurality of laser diode modules, each having a laser diode, a photo diode, and a thermoelectric cooler, the optical transmitter comprising:

• an auto power control circuit for controlling stability of an optical power output by varying a laser diode drive current driving said laser diode;
• a laser diode drive current detector for detecting a laser diode drive current value;
• a laser diode drive current increase/decrease normalization unit for outputting a variation of said laser diode drive current value through normalization based upon a detected laser diode drive current value;
• a compensated reference voltage generator for generating a laser diode temperature control target value in response to the normalized variation of the laser diode drive current value;
• a temperature monitor circuit for detecting a laser diode temperature value;
• a comparator for detecting a difference between said laser diode temperature value and said laser diode temperature control target value;
• and
• a current controller for determining a current value to be applied to said thermoelectric cooler to reduce a temperature difference detected by said comparator.

An optical multiple wavelength transmitter for transmitting light having a plurality of different wavelengths, said optical multiple wavelength transmitter comprising:

• a plurality of laser diodes;
• means for detecting respective drive current driving said plurality of laser diodes;
• and
• means for controlling respective temperatures of said plurality of laser diodes,
• wherein said means for controlling includes a temperature detection means for detecting respective temperatures of said plurality of laser diodes, a cooling means for cooling said respective laser diode and a control means for setting a control target temperature for said respective laser diode using a conversion coefficient predetermined for said respective laser diode in response to the variation of the detected drive current and controlling said cooling means to regulate the respective detected temperatures of said laser diodes to a set control target value.