Optical Anisotropic Coatings For Polarization Control In High-Power Lasers

In this work, a novel multi-layer approach of high band-gap birefringent columnar coatings was proposed and investigated. The growth of anisotropic columnar nano-structures with elliptical shape cross-section was initiated by self-shadowing effect, which was induced by placing the substrate at oblique angle during the deposition process. Amorphous silica was deposited in so-called serial bi-deposition manner to form anisotropic films with high thickness uniformity. The combination of birefringent nano-structured and isotropic layers allows to form zero-order wave-plates with desirable phase delay difference (as an example, lambda/4). Low optical losses and high transparency (T similar to 99%) are demonstrated while indicating the potential to withstand laser fluences of 40 J/cm(2) and 15 J/cm(2) in nanosecond regime at 355 nm and 266 nm wavelengths, respectively.