Interference coatings for 1-2 $\mu $m high energy lasers by reactive ion beam sputtering*

The development of Joule-level chirped pulse amplification solid state diode pumped laser systems with numerous scientific and technological applications motivates our work in interference coatings for operation in the 1-2 \textmu m wavelength range. Interference coatings were designed using a combination of metal-oxides, and were grown by ion beam sputtering. Results will be presented on 1 \textmu m coatings based on Ta2O5/SiO2 in which by modifying the top few layers it is possible to achieve a laser damage fluence 2x that of a quarter wave Ta2O5/SiO2. Results will also be presented on interference coatings designed with metal oxides for 1.6-2 \textmu m operation. At-wavelength testing of the laser damage resistance of these coatings showed they can withstand fluences similar to that of the high quality infrared fused silica substrates when tested with a train of pulses of 2 picosecond duration. Work supported by the DoD Office of Naval Research, the Army Research Office and the High Energy Laser Program of the DoD Joint Technology Office.