Effect of Sidewall-slope on Silicon Directional-coupler-type Polarization Beam Splitter with a Bridge Waveguide

초록

We investigate the effect of the sidewall slope of the silicon waveguide in performance of the polarization beam splitter (PBS) of a directional coupler (DC) scheme with a single bridge waveguide. The optimum parameters for the bridged PBS were calculated to provide a high polarization extinction ratio (PER), and checked through actually fabricated devices. Since the fabricated device performance deviated slighly from the original design with vertical sidewallslopes, a numerical investigation was performed to study the sidewall slope effect on the PER values. When the sidewall slope of the waveguide was in a range from 81 to 85 degree, a relatively high value of PER was obtained, while only low values were possible when it was in a range from 86 to 87 degree.