High dynamic range optical sensing device employing broadband optical filters integrated with light intensity detectors

Abstract

A high dynamic range image sensors enabled by integrating broadband optical filters with individual sensor pixels of a pixel array. The broadband optical filters are formed of engineered micro or nanostructures that exhibit large differences in transmittance, e.g. up to 5 to 7 orders of magnitude. Such high transmittance difference can be achieved by using a single layer of individually designed filters, which show varied transmittance as a result of the distinct absorption of various material and structures. The high transmittance difference can also be achieved by controlling the polarization of light and using polarization-sensitive structures as filters. With the presence of properly designed integrated nanostructures, broadband transmission spectrum with transmittance spanning several orders of magnitude can be achieved. This enables design and manufacturing of image sensors with high dynamic range which is crucial for applications including autonomous driving and surveillance.

1 . A high dynamic range image sensor comprising:
 a plurality of spatial pixels forming an array,   wherein each spatial pixel includes a plurality of detector pixels disposed adjacent to each other, each detector pixel including a light intensity detector,   wherein in each spatial pixel, at least some of the detector pixels each have a broadband optical filter disposed above the respective light intensity detector, and wherein each spatial pixel either includes at least one detector pixel without any broadband optical filter and at least one detector pixel with a broadband optical filter, or includes at least two detector pixels with respective broadband optical filters that have different transmittances,   wherein each broadband optical filter includes a nanostructure formed of one or more layers of semiconductor, metal, and/or dielectric material and is integrated with the corresponding light intensity detector.   
     
     
         2 . The high dynamic range image sensor of  claim 1 , wherein the light intensity detector is a CMOS (complementary metal-oxide-semiconductor) sensor. 
     
     
         3 .- 5 . (canceled) 
     
     
         6 . The high dynamic range image sensor of  claim 1 , wherein each broadband optical filter includes a patterned layer of metal or semiconductor forming a two-dimensional wire grid, the two-dimensional wire grid including a first set of straight wires disposed parallel to each other and extending in a first orientation and a second set of straight wires disposed parallel to each other and extending in a second orientation, where the first and second orientations are at a predefined angle relative to each other. 
     
     
         7 . The high dynamic range image sensor of  claim 6 , wherein the first and second sets of wires each form a periodic structure, wherein a pitch of the periodic structures and a width of the wires are less than 400 nm. 
     
     
         8 . The high dynamic range image sensor of  claim 6 , wherein each spatial pixel includes at least two detector pixels each having the broadband optical filter, and wherein the broadband optical filters for the two detector pixels have different relative angles. 
     
     
         9 . The high dynamic range image sensor of  claim 1 , wherein each broadband optical filter includes a nanostructure selected from:
 one or more patterned layers of metal or semiconductor nanostructures, the nanostructures having sizes smaller than 400 nm and random shapes;   one or more layers of nanocone structures; and   one or more layers of metamaterial structures.   
     
     
         10 . The high dynamic range image sensor of  claim 9 , wherein each spatial pixel includes at least two detector pixels each having the broadband optical filter, and wherein the broadband optical filters for the two detector pixels have different geometries of their nano structures. 
     
     
         11 . The high dynamic range image sensor of  claim 1 , wherein each broadband optical filter includes a uniform layer of metal or semiconductor. 
     
     
         12 . The high dynamic range image sensor of  claim 11 , wherein each spatial pixel includes at least two detector pixels each having the broadband optical filter, and wherein the broadband optical filters for the two detector pixels have different layer thicknesses. 
     
     
         13 . The high dynamic range image sensor of  claim 11 , wherein each spatial pixel includes at least two detector pixels each having the broadband optical filter, and wherein the broadband optical filters for the two detector pixels are formed of different materials and have identical layer thickness. 
     
     
         14 . The high dynamic range image sensor of  claim 1 , wherein each detector pixel further includes a resonant nanostructure integrated above the light intensity detector. 
     
     
         15 . The high dynamic range image sensor of  claim 14 , wherein the resonant nanostructure is a 2D photonic crystal, a 3D photonic crystal, a Fabry-Perot structure formed of alternating layers of dielectric films, a plasmonic nanostructure, or a nano-cones array. 
     
     
         16 . The high dynamic range image sensor of  claim 1 , wherein each spatial pixel includes a 2×2 array of detector pixels, including two detector pixels without any broadband optical filter located at diagonal positions of the 2×2 array, and two detector pixels having broadband optical filters with different transmittances located at remaining diagonal positions of the 2×2 array. 
     
     
         17 .- 20 . (canceled)