| 摘要 |
PURPOSE:To stabilize a laser and to reduce the noise in a signal band higher than the DC component by separating a part of the front exit light of a semiconductor laser into a low-frequency component and a high-frequency component and feeding back the result of comparison with a reference voltage changing in accordance with each mode to the semiconductor laser. CONSTITUTION:When the front exit light of a semiconductor laser 1 passes a beam splitter 3, partial reflected light is detected by a photodetector 12 and is amplified and separated to the low-frequency component from the DC to the servo band and the high-frequency component by a DC amplifier 13 and an AC amplifier 15 respectively. Both signals are added by an adder 16, and the output is compared with the output of a reference voltage generator 19 by a comparing circuit 20, and the result of this comparison is fed back to a laser driving circuit 21 to not only stabilize the laser but also reduce the noise. The output of the reference voltage generator 19 is changed by a reproducing, erasing, or recording mode signal 16. |
