Semiconductor light source

摘要

A semiconductor light source for transmitting light signals of digital or analog data having a laser diode and a photodiode for monitoring the output power of the laser diode. The driving current of the laser diode is adjusted by the photocurrent of the monitoring photodiode. The photodiode has a light receiving region at a center enclosed by an annular electrode and a light non-receiving region outside the annular electrode. If leak light beams entered the non-receiving region, delayed photocurrent is produced. The delayed photocurrent misleads the control of the laser diode. This invention provides a non-receiving region of the photodiode with a dielectric layer for reflecting or absorbing light beams in order to preventing the light beams from producing the delayed photocurrent.