COMPOSITE PHOTOSEMICONDUCTOR ELEMENT

PURPOSE:To enable to perform the effective wide-band lighgt and electricity negative feed-back by preventing the leakage of the current from the light emitting element into the light-detecting element by separating a drive current path of the light emitting element from a light-detecting current path of the light- detecting element. CONSTITUTION:A light-detecting element consisting of PD20 is formed in annular shape and monolithicly on one surface of a light emitting element consisting of LED10. The light output from an active region 14 is detected partly in the PD20 as well as is outputted to the outside partly through a light penetrating part 30 or the outside of an electrode 17 and enters into the optical fibers 1-40. In this constitution, one electrode 17 of the LED10 is formed inside a light-detecting part 25a of the PD20 and one electrode 24 of the PD20 is arranged outside the light-emitting part 25, so that the electrode path 30 of the LED10 is present inside the current path 40 and these are independent of each other. Accordingly, leakage of the current from the LED10 side into the PD20 side can be prevented and the genuine monitor current of the LED10 can be obtained by the PD20.