| 摘要 |
PURPOSE:To dispense with a temperature detection element and to prevent the variation of oscillating wavelength by maintaining the temperature of semiconductor at constant level by driving heating and cooling element utilizing the characteristics of optical output which is dependent on the temperature. CONSTITUTION:The output of a semiconductor laser LD is detected by a photodetecting element PD, and its output is supplied to a optical power control circuit PC. The output of the circuit LD is supplied to the laser LD as a drive current. This drive current is picked up at a converter circuit CC, and then amplified and linearized. The output of the circuit CC is matched with a temperature setting voltage Vs at an arithmetic circuit OP, and the difference of them is amplified at a drive circuit DR and activates Peltier effect element (heating an cooling element) PE. Here, when the output of the circuit CC is higher than the voltage Vs, the temperature of the laser LD is lowered by the element PE though an aluminum block AB. Contrarily, if the output of the circuit CC is lower than the voltage Vs, the temperature of the laser LD is increased by the element PE. Thus the laser LD is maintained at the constant temperature. |
