4.7 µm-emitting leaky-wave-coupled quantum cascade laser phase-locked array

Phase-locking, via leaky-wave coupling, of five 4.7 μm-emitting quantum cascade lasers is demonstrated for coherent-power scaling. Non-resonant devices fabricated by two-step MOCVD operate in a mixture of in-phase and out-of-phase modes to 3.85 W peak pulsed output power. Design analysis shows pure in-phase-mode operation under resonant-coupling occurs for optimized devices.