A Wavelength Stabilized GaN based Laser Utilizing Distributed Bragg Reflector

GaN-based short wavelength laser diode is a promising lasing source for a variety of applications in the visible light spectrum. In this work, we report on a wavelength stabilized blue laser utilizing distributed bragg reflector (DBR) based on InGaN/GaN. The passive DBR is located on the rear side of the ridge waveguide, acting as a high-reflective reflector to the cavity. The uniform grating structure has a period of 1.55μm, duty ratio of 75% and etched depth of 500nm, and is defined by electron-beam lithography (EBL) and etched by Inductively Coupled Plasma (ICP). The electrical and optical characterizes of 19th order DBR laser emitting at a wavelength of 403nm are measured under the pulse drive condition to avoid thermal accumulation in the diode. A minimum emission linewidth of 0.45nm is observed, indicating the mode selection function is realized by the DBR. High wavelength stabilization with driving currents can be obtained due to the separation of active area and grating region in DBR laser. Experiment results also show that temperature stable emission with a wavelength shift of 0.013 nm/K is obtained within the DBR laser.