Optical waveguide devices typically have dimensions transverse to the main propagation direction on the order of a
fraction of a millimeter and therefore, cannot be modeled by ray or beam tracing techniques. In this small domain,
numerical solutions of the fundamental field equations are usually employed. Two such implicit FD-BPM (Finite-
Difference Beam Propagation Method) techniques have been integrated into a general optical engineering code: a full
vector paraxial and scalar non-paraxial. Along with a more rigorous FDTD (Finite-Difference Time-Domain)
calculation, their relative accuracies and efficiencies are compared on the practical 3D problem of coupling an optical
system's focused spot into a single-mode fiber using a tapered mode converter. In all but the most extreme cases, the
agreement between all three is better than expected especially considering that the runtimes vary drastically on a manycore
desktop, with and without the help of a modern number-crunching GPU (Graphics Processing Unit).
|