Vertical-cavity surface-emitting laser for near-field illumination of an eye

Abstract

A vertical-cavity surface-emitting laser (VCSEL) includes a semiconductor substrate, a first reflector, a second reflector, a first electrical contact, a second electrical contact, and a through-hole via. The first reflector is disposed on a first side of the semiconductor substrate and the second reflector is disposed between the first reflector and an emission side of the VCSEL. The first and second electrical contacts are disposed on a second side of the semiconductor substrate, opposite the first side, for mounting the VCSEL to a transparent substrate. The through-hole via electrically connects the second electrical contact to the second reflector.

What is claimed is: 
     
         1 . A vertical-cavity surface-emitting laser (VCSEL), comprising:
 a semiconductor substrate;   a first reflector disposed on a first side of the semiconductor substrate;   a second reflector disposed between the first reflector and an emission side of the VCSEL for emitting a diverging infrared beam;   a first electrical contact disposed on a second side of the semiconductor substrate, opposite the first side, for mounting the VCSEL to a transparent substrate, wherein the first electrical contact is electrically coupled to the first reflector;   a second electrical contact disposed on the second side of the semiconductor substrate, for mounting the VCSEL to the transparent substrate; and   a through-hole via for electrically connecting the second electrical contact to the second reflector.   
     
     
         2 . The VCSEL of  claim 1 , further comprising an active region disposed between the first reflector and the second reflector, and wherein the through-hole via extends through the semiconductor substrate and the active region. 
     
     
         3 . The VCSEL of  claim 1 , further comprising an isolation layer disposed between the semiconductor substrate and the second electrical contact for electrically insulating the second electrical contact from the first reflector, wherein the through-hole via also extends through the isolation layer. 
     
     
         4 . The VCSEL of  claim 1 , wherein the VCSEL has a footprint of less than 125 microns by 125 microns. 
     
     
         5 . The VCSEL of  claim 1 , wherein the VCSEL is configured to generate infrared light for illuminating an eye at distance of less than 25 mm from the eye. 
     
     
         6 . The VCSEL of  claim 1 , wherein the semiconductor substrate is a thinned semiconductor substrate such that the VCSEL has a total thickness of less than 100 microns. 
     
     
         7 . The VCSEL of  claim 1 , wherein the VCSEL is configured as a single-mode emitter or a multi-mode emitter. 
     
     
         8 . The VCSEL of  claim 1 , further comprising an aperture definition layer disposed between the first reflector and the second reflector, the aperture definition layer configured to beam shape infrared light into the diverging infrared beam. 
     
     
         9 . The VCSEL of  claim 1 , wherein
 the first reflector comprises a first distributed Bragg reflector (DBR); and   the second reflector comprises a second DBR.   
     
     
         10 . The VCSEL of  claim 9 , wherein
 the first DBR comprises an N doped DBR; and   the second DBR comprises a P doped DBR.   
     
     
         11 . The VCSEL of  claim 1 , further comprising a wafer level optic disposed on the emission side of the VCSEL to direct the diverging infrared beam to illuminate an eye of a user. 
     
     
         12 . The VCSEL of  claim 11 , wherein the wafer level optic is formed from a high index Gallium arsenide (GaAs). 
     
     
         13 . The VCSEL of  claim 1 , further comprising a polarization layer disposed on the second reflector. 
     
     
         14 . A near-eye optical element, comprising:
 a transparent substrate; and   an array of vertical-cavity surface-emitting lasers (VCSELs) disposed on the transparent substrate within a field of view of a user of the near-eye optical element, wherein at least one VCSEL of the array comprises:
 a semiconductor substrate; 
 a first reflector disposed on a first side of the semiconductor substrate; 
 a mesa region disposed on the first reflector to generate a diverging infrared beam, wherein the mesa region includes a second reflector; 
 a first electrical contact disposed on a second side of the semiconductor substrate, opposite the first side, for mounting the VCSEL to the transparent substrate, wherein the first electrical contact is electrically coupled to the first reflector; 
 a second electrical contact disposed on the second side of the semiconductor substrate, for mounting the VCSEL to the transparent substrate; and 
 a through-hole via for electrically connecting the second electrical contact to the second reflector, wherein the through-hole via extends through the semiconductor substrate. 
   
     
     
         15 . The near-eye optical element of  claim 14 , wherein the mesa region further includes an active region disposed between the first reflector and the second reflector, and wherein the through-hole via extends through the semiconductor substrate and the active region. 
     
     
         16 . The near-eye optical element of  claim 14 , wherein the at least one VCSEL further comprises an isolation layer disposed between the semiconductor substrate and the second electrical contact for electrically insulating the second electrical contact from the first reflector, wherein the through-hole via also extends through the isolation layer. 
     
     
         17 . The near-eye optical element of  claim 14 , wherein the at least one VCSEL has a footprint of less than 125 microns by 125 microns. 
     
     
         18 . A head mounted device, comprising:
 an eye-tracking camera configured to capture images of an eye in response to infrared light; and   a near-eye optical element configured to illuminate the eye with the infrared light, the near-eye optical element comprising:
 a transparent substrate; and 
 an array of vertical-cavity surface-emitting lasers (VCSELs) disposed on the transparent substrate, wherein at least one VCSEL of the array comprises: 
 a semiconductor substrate; 
 a first reflector disposed on a first side of the semiconductor substrate; 
 a mesa region disposed on the first reflector to generate a diverging infrared beam, wherein the mesa region includes a second reflector; 
 a first electrical contact disposed on a second side of the semiconductor substrate, opposite the first side, for mounting the VCSEL to the transparent substrate, wherein the first electrical contact is electrically coupled to the first reflector; 
 a second electrical contact disposed on the second side of the semiconductor substrate, for mounting the VCSEL to the transparent substrate; and 
 a through-hole via for electrically connecting the second electrical contact to the second reflector, wherein the through-hole via extends through the semiconductor substrate. 
   
     
     
         19 . The head mounted device of  claim 18 , wherein the at least one VCSEL has a total thickness of less than 100 microns. 
     
     
         20 . The head mounted device of  claim 18 , wherein the at least one VCSEL has a footprint of less than 125 microns by 125 microns.