Enhanced birefringence of a Ta₂O₅ thin film obliquely deposited on a polymer grating

In this study, Ta₂O₅ was obliquely deposited on a polymer grating, resulting in a nanostructured thin film (NTF) with pronounced anisotropic optical properties. We measured and compared the principal indices and principal axes orientations of NTFs grown on both a grating and a smooth glass substrate. By adjusting the deposition angle, we observed a significant variation in the columnar angle and principal indices of the NTF on the grating, compared to the NTF on a smooth surface. Furthermore, the phase retardation and corresponding birefringence of the NTFs on the gratings were notably larger than those on a smooth substrate, highlighting the enhanced optical performance achieved through this method.