Efficient finite-element-based numerical modelling of large sub-wavelength patterned optical structures

Sub-wavelength patterned structures like cavity resonator integrated grating filters are relevant in various optical applications. Due to their highly resonant nature and due to their relatively large size it can be demanding to perform accurate optical simulations for such devices. In this contribution we investigate performance of hp finite-element based methods for this simulation problem. We demonstrate numerical convergence of the obtained solutions up to very high accuracy levels. We compare performance of our methods to results from the literature and investigate the influence of physical parameters on device performance, enhancing the Q-factor and reducing the horizontal size of the device.