MODULATING CIRCUIT FOR SEMICONDUCTOR OPTICAL MODULATOR

摘要

A modulating circuit for a semiconductor optical modulator comprises a driver DC-coupled to an optical modulator, a load resistor connected in parallel to the modulator, and a constant current source connected in parallel to the optical modulator for drawing out the photo-current generated in the optical modulator by absorption of light emitted from a semiconductor laser. The modulating circuit can perform light intensity modulation with low wavelength chirping using a driver DC-coupled to the optical modulator. The drawing out current is approximately equal to or greater than the average photo-current which is generated in the optical modulator by light absorption at the time of modulation.