Improving beam quality of tapered laser diodes by integrated metalens

Abstract

High-power and high-beam-quality laser sources are required in numerous applications. Here, we theoretically investigate a tapered laser diode with integrated metalens, which can improve the lateral beam quality. By carefully designing the slot length and width at different lateral positions behind the front facet, the mode mismatch between the ridged cavity and the tapered cavity is overcome while ensuring high transmittance (>96%). The beam quality is greatly improved, and the lateral far-field divergence is reduced. The simulation results show that the lateral far-field divergence (second-moment level) decreases from 7.2° to 5.9°, and the M2 (second-moment level) decreases from 2.3 to 1.2. The proposed structure shows a good thermal stability in the simulation.