Novel Architecture for High Power MOPA Phased Arrays

Directed energy missile defense applications require a new generation of compact and efficient high power solid-state electrical lasers. Scalability of current state-of-the-art kW-class solid-state Master Oscillator/Power Amplifier (MOPA) systems is limited by thermo-optic aberrations in the gain medium, and by heat transport/disposal. Beam-combining by multiplexing several 1-10kW class MOPAs provides a path for further power scaling to MW levels, but present techniques using coherent phased arrays, diffractive couplers, spectral beam-combining or temporal-multiplexing are currently limited by losses, aberrations, damage to diffractive components at high average or peak powers, and system complexity. CTI proposes an innovative proprietary technology that can be applied to retain spatial and spectral coherence both in power-scaling of a MOPA and in coherent beam-combining. In a MOPA, the technology can maximize extraction efficiency and minimize thermo-optic aberrations. In a coherent beam-combiner, high power beams can be co-phased and combined with low loss, negligible aberrations and without using vulnerable components. Together the technologies provide a path to extremely compact and rugged ladar or weapons-class lasers. In the highly successful Phase I program, CTI has: (1) demonstrated the beam combining technique in a low power prototype; (2) conducted design trades, and developed a detailed engineering design for the Phase II co-phased beam-combined diffraction-limited 4 element array; and (3) extended this to develop a conceptual design for a MW laser. Phase II will deliver the 1 kW class co-phased laser, and a detailed design of the MW laser. The designs will leverage CTI's experience in kW-class lasers and in flight qualified laser systems.