Enhancement of angular flux utilization based on implanted micro pyramid array and lens encapsulation in GaN LEDs

In the application of projection display, the effective flux utilization is an important factor to the optical system with more optical efficiency of the system with utilization of the light source such as LEDs. In this paper, based on Monte Carlo ray tracing we simulate light extraction efficiency as well as directionality of the light pattern of sapphire-based and Thin-GaN LEDs implanted with micro-pyramid structure with or without lens encapsulation. We have shown that micro-pyramid structures at some specific slanted angles in the LEDs are useful to increase effective flux utilization through enhancement of light extraction efficiency. In the case of the sapphire-based GaN LEDs, the slanted angle in a range of 45° to 55° , with lens encapsulation, the enhancement ratio of angular flux utilization is as high as 390%. In the case of Thin-GaN LEDs, both the slanted angle of 25° without lens encapsulation and 45 ° with lens encapsulation (LEC) are effective ways to obtain high angular flux utilization. The enhancement ratio of angular flux utilization is as high as 500% or more and the light extraction efficiency in 30° light cone reaches more than 18%.