| 摘要 |
PURPOSE:To directly control peak power and bias power at the time of recording by a method wherein the peak current and the bias current are controlled by sampling the output of a photo detector on the basis of code values changing into the peak power and the bias power in modulation signals. CONSTITUTION:By means of the reproduction mode, a terminal alpha led out of a semiconductor laser 1 is connected to a terminal beta on the basis of a mode signal (a), and a transistor 15 is controlled by comparing the monitor current from the photo detector 2 with the voltage value from a reproducing reference voltage source 13, thus controlling the photo output of the laser 1 to a constant reproduction power. By means of the recording mode, the terminal alpha is connected to a modulation circuit 20, which circuit is changed over on the basis of a modulation signal (b). When the signal (b) is of the bias power, a transistor 24 is controlled by comparing a monitor current Im with a bias reference voltage source 23, thus controlling the photo output of the laser 1 to the bias power. When the signal (b) is of the peak power, this output is controlled to the peak power by comparison with a reference voltage source 27. |
