Design of 1178 nm diode laser with step waveguide layers for reduced voltage and low vertical divergence

A 1178 nm diode laser with step waveguide layers (SWGLs) into the optical cavity is designed for frequency doubling. It is found that the mode field of the fundamental mode can be modulated easily for this kind of diode laser. A strong confinement for the fundamental mode can also be achieved by adopting a low Al content in the optical cavity. Diode lasers with SWGLs can deliver a high output power. Compared with diode lasers based on the conventional large optical cavity, the low Al content results in a reduced voltage, which is helpful to improve the electro-optical conversion efficiency. Based on an asymmetric large optical cavity with SWGLs, a beam divergence of 15.5 degrees in the vertical direction is obtained for the designed diode laser.