Novel Architecture for High Power MOPA Phased Arrays

Directed energy missile defense applications require a new generation of high power solid-state electrical lasers. Scalability of current state-of-the-art kW-class solid-state MOPA systems is limited by thermo-optic aberrations in the gain medium, andby heat transport and disposal. Beam-combining by multiplexing several 1-10kW class MOPAs provides a path for further power scaling to 100kW and MW levels, but present techniques using coherent phased arrays, diffractive couplers, spectral beam-combiningor temporal multiplexing are currently limited by losses, 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 spectralcoherence 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 withlow loss, negligible aberrations and without using vulnerable components. Phase I will (1) demonstrate the beam combining technique in a low power prototype, (2) conduct design trades, and develop a detailed deign for a power-scaled Phase II demonstrationof the MOPA systems and the beam-combining technique, and (3) extend this to develop a conceptual design for a MW laser. Phase II will develop the >200W class co-phased laser, and a detailed design of the MW laser. The designs will leverage CTI'sexperience in kW-class lasers and in flight qualified laser systems. In addition to DoD directed energy applications, high brightness, high average power solid state lasers are required for applications in materials processing in semiconductormanufacturing and in automotive and aircraft industries, and for destruction of unwanted ordnance.