Lasing Characteristics of a Metal-Coated GaN Shallow Grating Structure at Room Temperature

This study demonstrated a metal-coated GaN laser from a defect cavity with shallow grating structure. With a structure optimization for surface plasmon waves, the shallow grating can support a high quality factor (Q) resonant mode, which leads to a lasing action in the metal-coated GaN cavity. The defect lasing mode was observed at a wavelength of approximately 365 nm at room temperature. The defect grating structure was 840 nm in period, 220 nm in width, and 200 nm in height, and the cavity length of the defect region was 300 nm. The quality factor was 480 and the threshold power density was 4.6 W/cm². Lasing modes were also characterized with FEM simulation. Furthermore, the optical image and far-field angle of the metal-coated defect mode GaN grating structure were analyzed, and the lasing behavior of the defect grating structure was attributed to the defect mode.