4.7 μm-Emitting Near-Resonant Leaky-Wave-Coupled Quantum Cascade Laser Phase-Locked Arrays

Five-element phase-locked arrays of 4.7 μm-emitting quantum cascade lasers are demonstrated which operate either in a near-diffraction-limited (D.L.) beam to 3.6 W peak pulsed power or in a narrow beam (<; 3.5 × D.L.) up to 6.1 W peak pulsed power. Devices are fabricated by a two-step MOCVD process and operate predominantly in an in-phase array mode, in agreement with design-simulation studies. Analysis based on the actual device dimensions indicate that near-resonant leaky-wave coupling occurs. Scaling to a larger number of array elements and optimization for resonant operation is expected to lead to further increases in output power while maintaining high beam quality.