LASER DRIVE DEVICE, OPTICAL HEAD, AND OPTICAL INFORMATION PROCESSOR

摘要

A low-cost reliable laser drive is provided which uses a plurality of light sources required to treat different types of optical discs, such as CD and DVD. A two-wavelength (LD) device includes a semiconductor laser (1a), a semiconductor laser (1b) and a photodetector (2). Based on the respective voltages across variable resistors (4a, 4b) connected in series to the photodetector (2), APC circuits (6a, 6b) control the optical output of the semiconductor lasers (1a, 1b). An alternative two-wavelength (LD) device includes a semiconductor laser (1a), a semiconductor laser (1b) and a photodetector (2). Based on the respective intermediate potentials of the variable resistors (4a, 4b) connected in parallel with the photodetector (2), APC circuits (6a, 6b) control the optical output of the semiconductor lasers (1a, 1b).