Patent ID: 6111901
Filing Date: 2000-08-29
Classification: G11B,H01S

Abstract:
A semiconductor laser device comprising:a semiconductor laser for outputting a laser beam in accordance with a supplied driving current;a photodetector for detecting the laser beam output from said semiconductor laser and outputting a detection signal;a control amplifier for receiving the detection signal output from said photodetector and a control signal for instructing a light-emission period of said semiconductor laser, and generating and outputting complementary control error signals;a differential amplifier for receiving the control error signals, and outputting a first driving signal and an inverted first driving signal, which are complementary signals, on the basis of the control error signals;a driving signal generation circuit for receiving the first driving signal output from said amplifier and the control signal, and outputting a second driving signal which has a level substantially equal to a level of the first driving signal during the light-emission period instructed by the control signal, and has a level obtained by decreasing the level of the first driving signal during an extinction period;a driving circuit for receiving the second driving signal output from said driving signal generation circuit, and generating and outputting a driving current to be supplied to said semiconductor laser on the basis of the second driving signal;a control circuit for receiving the control error signal or the inverted first driving signal output from said amplifier, and controlling the level of the first driving signal to be decreased by said driving signal generation circuit during the extinction period on the basis of the control error signal or the inverted first driving signal;a sample-hold circuit for receiving the control error signal or the inverted first driving signal, and the control signal, holding a level of the control error signal or the inverted first driving signal during the light-emission period, and outputting the held level during the extinction period; anda comparator for receiving and comparing the control error signal or the inverted first driving signal, and the level output from said sample-hold circuit, and supplying a comparison result to said control amplifier during the extinction period so as to adjust the level of the control error signal output from said control amplifier during the extinction period on the basis of the level of the control error signal or the inverted first driving signal during the light-emission period.