Tilted cavity semiconductor device and method of making same

Abstract

A novel class of semiconductor lasers, or “tilted cavity lasers” includes at least one active element with an active region generating an optical gain by injection of a current and mirrors. The active element is placed into a cavity. The cavity is designed such that the optical path of the resonant optical mode is tilted with respect to both the vertical direction and the lateral plane. Thus, the feedback both in the vertical and in the lateral direction is provided for the resonant optical mode. Depending on the particular embodiment, the laser operates as both a surface emitting laser and an edge-emitting laser. Employing a tilted optical mode allows the use of substantially fewer layers in the bottom and the top interference reflectors than in conventional lasers. This preserves the necessary high reflection coefficients. Also, a wavelength-stabilized laser is realized for edge-emitters. The wavelength stabilization is due to the difference in the dispersion laws for the tilted optical modes in layers having different refractive indices.

1 - 73 . (canceled)  
     
     
         74 . A photodetector comprising: 
 a) a bottom reflector;    b) a top reflector;    c) a cavity located between the bottom reflector and the top reflector; and    d) a light absorbing region that absorbs light generating a photocurrent;    wherein the photodetector is operated in at least one resonant optical mode such that: 
 i) light is absorbed by the light absorbing region;  
 ii) light in the resonant optical mode propagates in the cavity in a direction tilted with respect to both a direction normal to a lateral plane and the lateral plane itself;  
 iii) the resonant optical mode has minimum optical losses compared with optical losses of the other optical modes; and  
 iv) a wavelength and a tilt angle of propagation of the light is stabilized.  
   
     
     
         75 . The photodetector of  claim 74 , further comprising a substrate below the bottom reflector.  
     
     
         76 . The photodetector of  claim 75 , wherein: 
 a) the light absorbing region generates electron-hole pairs when absorbing light; and    b) the cavity further comprises: 
 i) a first confinement region below the light absorbing region;  
 ii) a second confinement region above the light absorbing region;  
 iii) a first n-doped current spreading region above the substrate and below the first confinement region;  
 iv) a first p-doped current spreading region above the second confinement region and below the top reflector;  
 v) a current aperture placed between each neighboring region; and  
 vi) a bias control device between the first n-doped current spreading region and the first p-doped current spreading region such that electrons and holes created by the absorption of light in the light absorbing-layer generate photocurrent in an external circuit.  
   
     
     
         77 . The photodetector of  claim 76 , wherein the photodetector detects light coming from the vertical direction.  
     
     
         78 . The photodetector of  claim 76 , wherein the photodetector detects light coming from the lateral direction.  
     
     
         79 . An amplifier comprising: 
 a) a bottom reflector;    b) a top reflector;    c) a cavity located between the bottom reflector and the top reflector; and    d) an active region that amplifies light;    wherein the amplifier is operated in at least one resonant optical mode such that: 
 i) light is amplified at the active region;  
 ii) light in the resonant optical mode propagates in the cavity in a direction tilted with respect to both a direction normal to a lateral plane and the lateral plane itself;  
 iii) the resonant optical mode has minimum optical losses compared with optical losses of the other optical modes; and  
 iv) a wavelength and a tilt angle of propagation of the light is stabilized.  
   
     
     
         80 . The amplifier of  claim 79 , further comprising a substrate below the bottom reflector.  
     
     
         81 . The amplifier of  claim 80 , wherein: 
 a) the active region amplifies light when exposed to an injection current when a forward bias is applied; and    b) the cavity further comprises: 
 i) a first confinement region below the active region;  
 ii) a second confinement region above the active region;  
 iii) a first n-doped region above the substrate and below the first confinement region;  
 iv) a first p-doped region above the second confinement region and below the top reflector; and  
 v) a bias control device between the first n-doped current spreading region and the first p-doped current spreading region such that current can be injected into the light generating layer to amplify light.  
   
     
     
         82 . The amplifier of  claim 80 , wherein the substrate is n-doped, the bottom reflector is n-doped, and the top reflector is p-doped.  
     
     
         83 . The amplifier of  claim 82 , further comprising: 
 d) an n-contact located below the substrate; and    e) a p-contact located above the top reflector.    
     
     
         84 . The amplifier of  claim 83 , wherein the p-contact is rotated in the lateral plane with respect to a lateral direction of propagation of the tilted optical mode, such that the amplifier does not operate as a laser.  
     
     
         85 - 89 . (canceled)  
     
     
         90 . An optical fiber comprising: 
 a) a core; and    b) a multilayered coating designed such that only light in a certain interval of wavelengths can propagate, thus providing a wavelength-stabilized system.    
     
     
         91 - 97 . (canceled)  
     
     
         98 . An optoelectronic device comprising: 
 a) a bottom reflector;    b) a top reflector;    c) a cavity located between the bottom reflector and the top reflector; and    d) an active element comprising an active region;    wherein the semiconductor device is operated in at least one resonant optical mode such that: 
 i) applying a forward bias to the active element amplifies light and applying a reverse bias to the active element generates a photocurrent when the device is exposed to an external light;  
 ii) light in the resonant optical mode propagates in the cavity in a direction tilted with respect to both a direction normal to a lateral plane and the lateral plane itself;  
 iii) the resonant optical mode has minimum optical losses compared with optical losses of the other optical modes; and  
 iv) a wavelength and a tilt angle of propagation of the light is stabilized.  
   
     
     
         99 . The optoelectronic device of  claim 98 , wherein the optoelectronic device is a photodetector and the active region comprises a light absorbing region that absorbs light when the reverse bias is applied.  
     
     
         100 . The optoelectronic device of  claim 98 , wherein the optoelectronic device is an optical amplifier that amplifies light when the forward bias is applied.