Aquarius-Shaped Semiconductor Laser With High Directivity and Adjustable Coherence

By simulating the dependence of laser directionality and the possibility of multimode lasing on the sidewall angle of Aquarius-shaped cavity, we achieved the optimized parameters for low-coherence and high-directivity laser output. The measured divergence angle, the speckle contrast, and the output power are 7.2°, 4.53 %, 700 mW@4 A, respectively, in the experiment. Then we introduced patterned electrode on the P-side of the laser, and obtained adjustable coherence with the switched speckle contrast between 4.8 % and 27.8 %. This highly directional and adjustable coherence on-chip complex cavity laser prospectively offers a new choice for biological imaging.