A laser control circuit comprises a temperature control circuit and a data processing
circuit. The temperature control circuit adjusts the temperature of a laser diode
by controlling a temperature regulator. The data processing circuit receives the
output of a wavelength monitor. The data processing circuit first adjusts the,
temperature of the laser diode to a temperature value previously associated with
the target wavelength. Then the data processing circuit finely adjusts the temperature
of the laser diode according to the output of the wavelength monitor. Because rough
adjustment has been carried out, it is not necessary to change the wavelength significantly
according to the output of the wavelength monitor. Therefore, the periodic wavelength
dependence of the output of the wavelength monitor does not decrease the accuracy
of the control.
