DISTRIBUTED BRAGG REFLECTOR FOR REFLECTING LIGHT OF MULTIPLE WAVELENGTHS FROM AN LED

摘要

A blue LED device has a transparent substrate and a reflector structure disposed on the backside of the substrate. The reflector structure includes a Distributed Bragg Reflector (DBR) structure having layers configured to reflect yellow light as well as blue light. In one example, the DBR structure includes a first portion where the thicknesses of the layers are larger, and also includes a second portion where the thicknesses of the layers are smaller. In addition to having a reflectance of more than 97.5 percent for light of a wavelength in a 440 nm-470 nm range, the overall reflector structure has a reflectance of more than 90 percent for light of a wavelength in a 500 nm-700 nm range.