Light Emitting Devices with Improved Light Extraction Efficiency

Abstract

A device includes a light emitting semiconductor device bonded to an optical element. In some embodiments, the optical element may be elongated or shaped to direct a portion of light emitted by the active region in a direction substantially perpendicular to a central axis of the semiconductor light emitting device and the optical element. In some embodiments, the semiconductor light emitting device and optical element are positioned in a reflector or adjacent to a light guide. The optical element may be bonded to the first semiconductor light emitting device by a bond at an interface disposed between the optical element and the semiconductor light emitting device. In some embodiments, the bond is substantially free of organic-based adhesives.

1 . A device comprising: 
 a first semiconductor light emitting device comprising a stack of semiconductor layers including an active region; and    an optical element bonded to the first semiconductor light emitting device;    wherein the optical element is elongated in a first direction.    
   
   
       2 . The device of  claim 1  wherein the first semiconductor light emitting device is elongated in the first direction.  
   
   
       3 . The device of  claim 1  further comprising a second semiconductor light emitting device comprising a stack of layers including an active region bonded to the optical element next to the first semiconductor light emitting device.  
   
   
       4 . The device of  claim 3  wherein the active region of the first semiconductor light emitting device and the active region of the second semiconductor light emitting device emit light of different colors.  
   
   
       5 . The device of  claim 1  wherein the optical element is bonded to the first semiconductor light emitting device by a bond at an interface disposed between said optical element and said first semiconductor light emitting device, wherein said bond is substantially free of organic-based adhesives.  
   
   
       6 . The device of  claim 1  wherein the optical element is an optical concentrator.  
   
   
       7 . The device of  claim 1  wherein: 
 the optical element has a first surface adjacent to the bond connecting the optical element to the first semiconductor light emitting device, a second surface substantially parallel to the first surface, and a substantially parabolic cross section; and    an area of the first surface is smaller than an area of the second surface.    
   
   
       8 . The device of  claim 7  wherein the optical element has a side surface.  
   
   
       9 . The device of  claim 8  wherein the side surface connects the first surface to the second surface.  
   
   
       10 . The device of  claim 8  further comprising a mirror on at least a portion of the side surface.  
   
   
       11 . The device of  claim 1  further comprising a light guide adjacent to the optical element.  
   
   
       12 . The device of  claim 11  wherein the light guide is in contact with the optical element.  
   
   
       13 . The device of  claim 11  wherein the light guide is spaced apart from the optical element.  
   
   
       14 . A device comprising: 
 a semiconductor light emitting device comprising a stack of semiconductor layers including an active region; and    an optical element bonded to the semiconductor light emitting device;    wherein the semiconductor light emitting device and the optical element are positioned in a reflector.    
   
   
       15 . The device of  claim 14  further comprising a heat sink attached to the semiconductor light emitting device.  
   
   
       16 . The device of  claim 14  wherein the optical element is shaped to direct a portion of light emitted by the active region in a direction substantially perpendicular to a central axis of the semiconductor light emitting device and the optical element.  
   
   
       17 . The device of  claim 16  wherein the reflector is shaped to direct a portion of the light exiting the optical element in a direction substantially parallel to the central axis.  
   
   
       18 . The device of  claim 14  wherein the optical element is bonded to the semiconductor light emitting device by a bond at an interface disposed between said optical element and said semiconductor light emitting device, wherein said bond is substantially free of organic-based adhesives.  
   
   
       19 . The device of  claim 14  further comprising a light guide adjacent to the reflector.  
   
   
       20 . The device of  claim 19  wherein the light guide is in contact with the reflector.  
   
   
       21 . The device of  claim 19  wherein the light guide is spaced apart from the reflector.  
   
   
       22 . A device comprising: 
 a first semiconductor light emitting device comprising a stack of semiconductor layers including an active region;    an optical element bonded to the semiconductor light emitting device; and    a light guide adjacent to the optical element.    
   
   
       23 . The device of  claim 22  wherein the light guide is in contact with the optical element.  
   
   
       24 . The device of  claim 22  wherein the light guide does not touch the optical element.  
   
   
       25 . The device of  claim 22  wherein the light guide comprises: 
 a first surface adjacent to the optical element; and    a second angled surface, wherein and angle between the first and second is greater than 90 degrees.    
   
   
       26 . A device comprising: 
 a semiconductor light emitting device comprising a stack of semiconductor layers including an active region; and    an optical element bonded to the first semiconductor light emitting device;    wherein the optical element comprises a material selected from the group of an oxide of tellurium, aluminum oxynitride, cubic zirconia, transparent alumina, and spinel.    
   
   
       27 . The device of  claim 26  wherein the optical element is bonded to the semiconductor light emitting device by a bond at an interface disposed between said optical element and said semiconductor light emitting device, wherein said bond is substantially free of organic-based adhesives.