Optimization for Ultrabroadband Polarization Beam Splitters Using a Genetic Algorithm

We present a design method for a directional coupler-type polarization beam splitter (PBS) for ultrabroadband operation based on a genetic algorithm (GA). The PBS is discretized into short sections, with the geometric parameters of each section optimized using a GA. For PBSs with an operating wavelength range
λ
= 1400–1650 nm, the insertion losses are less than 0.14 and 0.58 dB, and the maximum crosstalk is −20.6 and −16.2 dB for the TE and TM modes, respectively. We also analyze the fabrication tolerance in this study.