SEMICONDUCTOR LASER DRIVER DEVICE

PURPOSE: To positively record data by making flat the frequency characteristics within the frequency band of a write data pattern. CONSTITUTION: At the time of reproduction the control voltage from a CPU 1 is applied to a high-frequency oscillation circuit 8 and a high frequency is superposed on current for recording and the current is supplied to a semiconductor laser LD1. At the time of recording, no control voltage is applied from the CPU l to the high-frequency oscillation circuit 8 and the circuit 8 is turned off. Then, by setting series resonance frequency outside the frequency band of write data pattern on recording, current for recording can be supplied to the semiconductor laser LD1 without being affected by the series resonance frequency of the LC (a coil 13 and capacitors C2, C4-C6, and C8) of the high-frequency oscillation circuit 8 and the series resonance frequency due to an LC filter at a reproduction side, thus positively recording data.