TEMPERATURE CONTROLLING SYSTEM FOR SEMICONDUCTOR LASER

摘要

PURPOSE:To reduce the amount of heating of a circuit, which drives a Peltier element, by controlling a current conducting time for the temperature controlling Peltier element in correspondence with the temperature of a semiconductor laser. CONSTITUTION:A heat sensitive element comprising a thermistor 11 detects the temperature of a laser and inputs the detected signal to a temperature control part A. The temperature control part A controls a temperature controlling Peltier element 21 in correspondence with the detected value of the temperature sensitive element 11. The control part A is composed of a ramp-waveform generating part 13, comparators 14 and 15, AND gates 16 and 18 and switching circuits 19 and 22. The outputs the temperature control part A are obtained from the switching circuits 19 and 22. Currents I1 and I2 in two directions, which depend on the detected temperatures, are made to flow to the Peltier element 21. The currents are selected in correspondence with the difference between the detected temperatures and the reference value. The currents are made to flow during the time corresponding to the change from the reference value.