Laser driving apparatus and method

Abstract

A device for driving a semiconductor laser in which, when a high frequency signal is superposed on a driving signal for the semiconductor laser for suppressing the scoop noise in the semiconductor laser, the amplitude of the high frequency signal can be controlled reliably and satisfactorily without dependency on temperature characteristics or chronological changes in the semiconductor laser. To this end, the device for driving the semiconductor laser includes a voltage controlled oscillator for superposing a high frequency signal on the driving signal for the semiconductor laser LD, a photodetector for receiving at least a portion of the light radiated from the semiconductor laser, an amplitude information extraction unit for extracting the amplitude information based on an output signal of the photodetector, input through a narrow band-pass filter or high-pass filter configured for extracting high frequency, and a comparator for comparing the amplitude information obtained from the amplitude information extraction unit to a reference value to control the voltage controlled oscillator based on the results of comparison.

Dependencies are inferred from the claim text.