Compact stretcher/compressor for high power ultrafast lasers based on volume chirped Bragg gratings in PTR glass

The objective of this proposal is to extend the technology of chirped pulse amplification in ultrashort pulse lasers based on chirped volume Bragg gratings (CBGs) to higher stretching/ compression ratio and make the device more robust. In Phase I OptiGrate demonstrated high quality stretching and compression by CBGs fabricated in photo-thermo-refractive (PTR) glass. Phase II research and development enabled reliable manufacturing of CBGs designed for ultrashort pulse laser systems and extended the stretching time to the unprecedented level of 1 ns while this pulse could be compressed to the level of 200 fs. Record average power of 200 W has been demonstrated. The benefits of usage of such gratings are based on a compact geometry, unprecedented stability to optical radiation, high diffraction efficiency, absence of polarization dependence and durability to environmental conditions. However the most strategic importance of this technology is its scalability to large apertures and thickness which enable scaling to higher power and longer stretching. The specific target set for Phase II.5 of this project is a demonstration of multipass CBGs where 2-ns stretching time which is combined with large aperture up to 1010 mm capable of compressing pulses with energies more than 20 mJ.