Phase-locked array of quantum cascade lasers with an integrated Talbot cavity

TL;DR

This paper demonstrates a phase-locked array of three quantum cascade lasers with an integrated Talbot cavity, achieving stable in-phase operation, increased power output, and a specific far-field pattern, advancing laser array technology.

Contribution

It introduces a diffraction coupling scheme with an integrated Talbot cavity to control phase locking in quantum cascade laser arrays, demonstrating stable in-phase operation and enhanced power.

Findings

Stable in-phase mode operation with Talbot cavity control

Output power about 1.5 times that of a single laser

Far-field pattern with three lobes and 10.5° interval

Abstract

We show a phase-locked array of three quantum cascade lasers with an integrated Talbot cavity at one side of the laser array. The coupling scheme is called diffraction coupling. By controlling the length of Talbot to be a quarter of Talbot distance (Zt/4), in-phase mode operation can be selected. The in-phase operation shows great modal stability under different injection currents, from the threshold current to the full power current. The far-field radiation pattern of the in-phase operation contains three lobes, one central maximum lobe and two side lobes. The interval between adjacent lobes is about 10.5{\deg}. The output power is about 1.5 times that of a single-ridge laser. Further studies should be taken to achieve better beam performance and reduce optical losses brought by the integrated Talbot cavity.