Wide operation range in-phase coherently coupled vertical cavity surface emitting laser array based on proton implantation

Abstract

In-phase coherently coupled vertical cavity surface emitting laser (VCSEL) hexagonal arrays were fabricated using proton implantation. The near-field profiles, far-field profiles, and emission spectra under different injection currents were tested and analyzed. The arrays can maintain in-phase single mode in a considerably wide current range from 10 mA (I(th)) to 35 mA (3.5×I(th)), exhibiting excellent beam quality. The far-field divergence angle of the in-phase coupled array is 2.5 degrees. Approximately 29% of total power is localized in the central lobe. Compared with square structure arrays, hexagonal arrays can maintain a more stable in-phase mode because of stronger coupling among the elements. The maximum output power of 4.9 mW was obtained under pulse wave condition. The simulation of far-field was carried out to match the in-phase operation test results. The performance enhancement of the array is attainable if the condition of heat dissipation is better. The process procedure of proton implantation is relatively simple and of low cost. It can be used as an alternative to coherently coupled array implementations.