Beam quality improvement of mid-infrared laser diode with monolithically integrated sawtooth waveguide structures

High-power and high beam-quality semiconductor diode lasers emitting around 2 μm have sparked considerable interest owing to their potential applications across various industrial and medical fields. Here, we demonstrate a sawtooth waveguide (SW) structure to achieve enhanced lateral beam quality and power performance based on GaSb. A valid lateral mode discrimination capability is guaranteed by the integrated SW design and triple confirmed by simulation, near field and far field experimental measurement. The resulting SW laser exhibits an enhanced continuous-wave output power of 1.392 W around 2 μm with an increased power conversion efficiency. Moreover, a more concentrated and narrower beam profile is obtained across its whole measurement range, with lateral beam parameter product notably improved by up to 48 % compared to the conventional broad area laser. These results show significant promise for enhancing the performance of existing systems and enabling new applications.