Micro-led design for chief ray walk-off compensation

Abstract

Techniques disclosed herein relate to micro light emitting diodes (micro-LEDs) for a display system. A display system includes an array of micro light emitting diodes (micro-LEDs), an array of output couplers optically coupled to the array of micro-LEDs and configured to extract light emitted by respective micro-LEDs in the array of micro-LEDs, a waveguide display, and display optics configured to couple the light emitted by the array of micro-LEDs and extracted by the array of output couplers into the waveguide display. Each output coupler in the array of output couplers is configured to direct a chief ray of the light emitted by a respective micro-LED in the array of micro-LEDs to a different respective direction.

1 . A display system comprising:
 an array of micro light emitting diodes (micro-LEDs);   an array of output couplers optically coupled to the array of micro-LEDs, wherein each output coupler in the array of output couplers is configured to:
 extract light emitted by a respective micro-LED in the array of micro-LEDs; and 
 direct a chief ray of the light emitted by the respective micro-LED in the array of micro-LEDs to a different respective direction; 
   display optics; and   a waveguide display,   wherein the display optics are configured to couple the light emitted by the array of micro-LEDs and extracted by the array of output couplers into the waveguide display.   
     
     
         2 . The display system of  claim 1 , further comprising an electrical integrated circuit bonded to the array of micro-LEDs. 
     
     
         3 . The display system of  claim 1 , wherein each micro-LED in the array of micro-LEDs is characterized by a half-width half-magnitude light emission angle less than 60°. 
     
     
         4 . The display system of  claim 1 , wherein each output coupler in the array of output couplers is offset from a respective micro-LED in the array of micro-LEDs by at least one of a vertical or horizontal displacement that is equal to or greater than zero. 
     
     
         5 . The display system of  claim 1 , wherein each micro-LED in the array of micro-LEDs includes a mesa structure that has an inward tilted, vertical, or outward tilted shape. 
     
     
         6 . The display system of  claim 5 , wherein the mesa structure includes:
 a mesa reflector including a dielectric layer or a metal; and   a back reflector including a semiconductor layer and a metal electrode.   
     
     
         7 . The display system of  claim 1 , wherein each output coupler in the array of output couplers includes at least one of a micro-lens, a wedge, a prism, a roughened surface, an antireflective coating, a diffractive optical element, or a photonic crystal. 
     
     
         8 . The display system of  claim 1 , wherein each output coupler in the array of output couplers includes:
 a first micro-lens, a first diffractive optical element, or a first photonic crystal; and   at least one of a second micro-lens, a second diffractive optical element, a second photonic crystal, a wedge, a prism, a roughened surface, or an antireflective coating.   
     
     
         9 . The display system of  claim 1 , wherein the array of output couplers includes a dielectric material, an organic material, or a semiconductor material. 
     
     
         10 . The display system of  claim 1 , wherein:
 each output coupler of the array of output couplers includes a micro-lens on top of the respective micro-LED,   a lateral size of the micro-lens is equal to or greater than 80% of a lateral size of a mesa structure of the respective micro-LED, wherein sidewalls of the mesa structure are vertical or inwardly tilted in a light emitting direction, and   a distance between a focal point of the micro-lens and a top surface of the mesa structure is between 0.8 and 1.25 times of a thickness of semiconductor materials in the mesa structure.   
     
     
         11 . The display system of  claim 10 , wherein the micro-lens includes a spherical micro-lens, an aspherical micro-lens, or a toroidal micro-lens. 
     
     
         12 . The display system of  claim 10 , wherein each micro-lens in the array of output couplers is characterized by a different respective horizontal displacement from the respective micro-LED. 
     
     
         13 . The display system of  claim 10 , wherein a pitch of the array of output couplers is different from a pitch of the array of micro-LEDs. 
     
     
         14 . The display system of  claim 10 , wherein the mesa structure is characterized by a parabolic or conic shape. 
     
     
         15 . The display system of  claim 1 , wherein:
 each output coupler of the array of output couplers includes a micro-lens on top of the respective micro-LED,   a lateral size of the micro-lens is equal to or greater than 80% of a lateral size of a mesa structure of the respective micro-LED, wherein sidewalls of the mesa structure are outwardly tilted in a light emitting direction; and   a distance between a focal point of the micro-lens and a top surface of the mesa structure is between 1.2 and 4 times of a thickness of semiconductor materials in the mesa structure.   
     
     
         16 . The display system of  claim 15 , wherein the mesa structure is characterized by a conic shape and a mesa facet angle between 30° and 40°. 
     
     
         17 . The display system of  claim 15 , wherein the mesa structure is characterized by a parabolic or conic shape. 
     
     
         18 . The display system of  claim 15 , wherein the micro-lens includes a spherical micro-lens, an aspherical micro-lens, or a toroidal micro-lens. 
     
     
         19 . The display system of  claim 15 , wherein each micro-lens in the array of output couplers is characterized by a different respective horizontal displacement from the respective micro-LED. 
     
     
         20 . The display system of  claim 15 , wherein a pitch of the array of output couplers is different from a pitch of the array of micro-LEDs.