Simulation study of a low-threshold, high-efficiency 1.55 µm InP PCSEL enabled by a bottom metal-capped DBR, peripheral DBRs, and a shifted triple-hole photonic crystal

Photonic-crystal surface-emitting lasers (PCSELs) at 1.55 µm are highly attractive for optical communication and LiDAR applications owing to eye safety and low fiber loss. However, their performance is limited by the trade-off between threshold gain and slope efficiency, as well as by the reflectivity and phase control of conventional distributed Bragg reflector (DBR) structures. In this work, we present a theoretical and numerical investigation of a novel InP-based PCSEL design, to our knowledge. Specifically, the metal-capped DBR is composed of three pairs of SiO 2 /TiO 2 layers and an Au layer, providing high reflectivity while substantially reducing fabrication complexity. In addition, DBRs surrounding the photonic crystal (PC) region are introduced to suppress in-plane loss and enhance the feedback of the lasing mode. Furthermore, a shifted triple-hole photonic crystal enables flexible control of the in-plane and vertical coupling strengths, achieving an optimized balance between threshold gain and slope efficiency. The device performance is evaluated using the transfer-matrix method and three-dimensional coupled-wave theory (3D-CWT). As a result, the optimized structure exhibits a low threshold gain for lasing oscillation of 16cm −1 and a corresponding threshold material gain of 76cm −1 , together with a high slope efficiency of 0.18 W/A, providing a promising theoretical design strategy for high-performance InP-based PCSELs operating at 1.55 µm.