Optical semiconductor apparatus

Abstract

The optical semiconductor apparatus includes, on an n-GaAs substrate, a surface-emitting semiconductor laser device and a photodiode integrated on the periphery of the laser device with an isolation region interposed there between. The laser device is composed of an n-DBR mirror, an active region, and a p-DBR mirror and includes a columnar layered structure with its sidewall covered with an insulating film. The photodiode is formed on the substrate and has a circular layered structure wherein an i-GaAs layer and a p-GaAs layer surrounds the laser device with an isolating region interposed between the i-GaAs and p-GaAs layers and the laser device. The diameter of the photodiode is smaller than the diameter of the optical fiber core optically coupled with the optical semiconductor apparatus. Since the laser device and the photodiode are monolithically integrated, the devices do not require optical alignment, and thus, facilitate optical coupling with an optical fiber.

What is claimed is: 
     
         1 . An optical semiconductor apparatus in the form of an optical signal transmitter-receiver of a bidirectional communication system employing a single-core optical fiber, comprising:
 a light-receiving device; and   a surface-emitting semiconductor laser device;   wherein the light-receiving device functions as a light signal receiving device and a circular layered structure on a semiconductor substrate;   wherein   the surface-emitting semiconductor laser device functions as a light-transmitting device, is disposed on the central region of the layered structure of the light-receiving device, and has a columnar layered structure with a diameter smaller than the diameter of the light-receiving device;   the region on the layered structure of the light-receiving device excluding the region of the surface-emitting semiconductor laser device functions as a light-receiving surface; and   the diameter of the light-receiving device is smaller than the optical fiber core optically coupled with the optical semiconductor apparatus.   
     
     
         2 . The optical semiconductor apparatus according to  claim 1 , wherein:
 a first electrode of the light-receiving device is disposed on the backside of the semiconductor substrate and a second electrode is disposed on the periphery of the light-receiving surface on the layered structure of the light-receiving device, and   a first electrode of the surface-emitting semiconductor laser device is circularly disposed on the layered structure of the surface-emitting semiconductor laser device and a second electrode is disposed on the lowermost layer of the layered structure of the surface-emitting semiconductor laser device extending outwards from the layered structure of the surface-emitting semiconductor laser device on the layered structure of the light-receiving device.   
     
     
         3 . The optical semiconductor apparatus according to  claim 1 , wherein the light-receiving device is capable of receiving a laser beam with an oscillation wave length of the surface-emitting semiconductor laser device.