PHOTOSEMICONDUCTOR COMPOSITE ELEMENT

PURPOSE:To enable to negatively feedback effective wide band light and electricity by preventing a current from a light emitting element to a photodetector from leaking, and increasing a true monitoring current of the light emitting element at the photodetector. CONSTITUTION:A semiconductor photodetector which is made of photodiodes (PD) 2-21-2-25 is integrated through a high resistance semiconductor layer 2-50 on a region which includes the oblique surface of mesa of a semiconductor light emitting element made of light emitting diodes (LED) 2-11-2-17. A light from the layer 2-14 is partly received by the PD, externally output through a light passage 2-30 inside the upper electrode 2-17 of the LED, and is incident to an optical fiber 1-40. The output of the PD is led to an external electronic circuit to form a wide band light and electricity negative feedback. The currents flows to the LED and the PD can be separated to prevent the currents flows from the LED side to the PD side from leaking.