Radiant Efficacy Enhancement for Vertical-Cavity Surface-Emitting Laser Devices Using Enhanced Specular Reflection Structures

Vertical-cavity surface-emitting laser (VCSEL) devices operate using a variety of viewing angles to satisfy the demands of different applications. One simple and universal approach to accomplish this is by using scattering elements in the packaging process for VCSEL chips. However, inevitable backward scattering loss is introduced, which suppresses the radiant efficacy of VCSEL devices. Therefore, we have proposed an enhanced specular reflection (ESR) structure with an opening circle window (OCW) to recycle the backward scattered light. The ray-tracing method is used to optimize the diameter of the OCW, as well as the thickness of the ESR structure. Furthermore, the light extraction mechanism is discussed. According to theoretical results, VCSEL devices with optimized ESR structures are fabricated and compared with traditional VCSEL devices. The experiment results demonstrate that ESR structures can significantly enhance the radiant efficacy of VCSEL devices using scattering elements. This shows great potential for applications involving illumination and 3-D imaging.