Computational split-field finite-difference time-domain evaluation of simplified tilt-angle models for parallel-aligned liquid-crystal devices

Abstract

Simplified analytical models with predictive capability enable simpler and faster optimization of the performance in applications of complex photonic devices. We recently demonstrated the most simplified analytical model still showing predictive capability for parallel aligned liquid crystal on silicon devices (PA-LCoS), which provides the voltage dependent retardance for a very wide range of incidence angles and any wavelength in the visible. In this work we further show that the proposed model is not only phenomenological but it is also physically meaningful, since two of its parameters provide the correct values for important internal properties of these devices related with the birefringence, cell gap and director profile. Therefore, the proposed model can be used as a means to inspect internal physical properties of the cell. Also as a novelty, we also show the applicability of the split-field finite difference time domain (SF-FDTD) technique for phase-shift and retardance evaluation of PA-LCoS devices under oblique incidence. As simplified model for PA-LCoS devices we also consider the exact description of homogeneous birefringent slabs. However, we show that despite its higher degree of simplification the proposed model is more robust, providing unambiguous and physically meaningful solutions when fitting its parameters.