Light-receiving device and photodetector comprising light-receiving device

Abstract

A light-receiving element is provided, which may easily detect the barycenter of a light intensity of light having a long-wavelength band in an optical communication. An InGaAs layer (i-type layer) and a p-type InP layer are stacked on an n-type InP substrate. Electrodes are formed on both sides of the top surface of the p-type layer, and an electrode is formed on the bottom surface of the n-type substrate. An incident light impinged upon the light-receiving element is photoelectric-converged into a photocurrent, and the photocurrent flows in the p-type layer to the electrodes. As a result, a current is derived from each of the electrodes, the magnitude thereof being dependent on the distances from the light impinging position to respective electrodes. The barycenter of a light intensity may be calculated from the currents derived from the electrodes and a light intensity may be obtained from the summation of the currents.

1 . A light-receiving element for detecting a light intensity and a barycenter thereof for an incident light of a long-wavelength, comprising: 
 a semiconductor layer of III-V group compound semiconductor;    a first conductivity-type of resistor layer provided on the top surface of the semiconductor layer;    a second conductivity-type, opposite to the first conductivity-type, of substrate provided on the bottom surface of the semiconductor layer; and    at least one pair of opposing electrodes provided on the resistor layer.    
     
     
         2 . The light-receiving element of  claim 1 , wherein the III-V group compound semiconductor is selected from the group consisting of InGaAs, GaAs, AlGaAs, InAs, and InGaAsP.  
     
     
         3 . The light-receiving element of  claim 2 , wherein the III-V group compound semiconductor is InGaAs.  
     
     
         4 . The light-receiving element of  claim 3 , wherein when the first conductivity-type is p-type and the second conductivity-type is n-type, the first conductivity-type of resistor layer is a p-type InP layer, and the second conductivity-type of substrate is a n-type InP substrate.  
     
     
         5 . A photodetector for detecting a light intensity and a barycenter thereof for each of lights demultiplexed from an incident light, the incident light including N (N is an integer equal to or larger than 2) time-divisioned wavelengths, comprising; 
 one light-receiving element of any one of claims  1 - 4 ,    wherein the one light-receiving element is operated in N time-divisioned timing matched to the impinging timing of respective demultiplexed lights.    
     
     
         6 . A photodetector for detecting a light intensity and a barycenter thereof for each of lights demultiplexed from an incident light, the incident light including N (N is an integer equal to or larger than 2) wavelengths, comprising; 
 N light-receiving elements of any one of claim  1 - 4 , these light-receiving elements being arrayed in one dimension.    
     
     
         7 . A photodetector for detecting a light intensity and a barycenter thereof for each of lights demultiplexed from an incident light, the incident light including N (N is an integer equal to or larger than 2) wavelengths, comprising 
 a first photodetecting means for detecting a barycenter of a light-intensity of each of the demultiplexed lights, the first photodetecting means including N light-receiving elements of any one of claims  1 - 4  arrayed in one dimension; and    a second photodetecting means for detecting a light intensity of each of the demultiplexed lights, the second photodetecting means including N light-receiving elements arrayed in one dimension.    
     
     
         8 . The photodetector of  claim 7 , wherein the light-receiving elements of the second photodetecting means are photodiodes.  
     
     
         9 . A photodetector for detecting a light intensity and a barycenter thereof for each of lights demultiplexed from an incident light, the incident light consisting of multiplexed bands each including a plurality of wavelengths, comprising; 
 a plurality of light-receiving elements of any one of claims  1 - 4  for every band, the plurality of light-receiving elements being arrayed in one dimension.    
     
     
         10 . An optical demultiplexer for demultiplexing an incident light including multiplexed wavelengths, comprising: 
 an optical means for demultiplexing the incident light into a plurality of lights; and    a photodetector of  claim 5  for receiving the plurality of light demultiplexed by the optical means.    
     
     
         11 . An optical demultiplexer for demultiplexing an incident light including multiplexed wavelengths, comprising: 
 an optical means for demultiplexing the incident light into a plurality of lights; and    a photodetector of  claim 6  for receiving the plurality of light demultiplexed by the optical means.    
     
     
         12 . An optical demultiplexer for demultiplexing an incident light including multiplexed wavelengths, comprising: 
 an optical means for splitting the incident light into two lights; and    a first optical means for demultiplexing one of the two lights;    a second optical means for demultiplexing the other of the two lights;    a photodetector of  claim 6  for receiving the lights demultiplexed by the first optical means and for detecting a barycenter of a light intensity for each of the demultiplexed light; and    a light-receiving element array for receiving the lights demultiplexed by the second optical means and for detecting a light intensity for each of the demultiplexed lights.    
     
     
         13 . The optical demultiplexer of  claim 12 , wherein the light-receiving element array is a photodiode array.  
     
     
         14 . An optical demultiplexer for demultiplexing an incident light consisting of multiplexed bands each including a plurality of wavelengths, comprising: 
 an optical means for demultiplexing the incident light into a plurality of lights for every band; and    a light-receiving means for receiving the demultiplexed lights for every band, the light-receiving means including a plurality of photodetectors of claim  6 .