Grading waveguide to improve the performance of ultraviolet laser diodes

AlGaN laser diode (LD), in the ultraviolet (UV) wavelength range of 260 nm–270 nm, with enhanced optical and electrical properties is proposed numerically in this work. A laser diode with a graded upper waveguide (WG) is introduced which greatly increases the output power while lowering the lasing threshold. Optical field is confined in the active region due to the enhancement of refractive index contrast between the WG and the cladding layer (CL). Less electron leakage and a high hole injection efficiency result in higher slope efficiency (SE), and internal quantum efficiency (IQE).