Improving transmission of partial parabolic single layer crossing for silicon-on-insulator nanophotonic waveguides by composite subwavelength structures

Abstract

We design a waveguide crossing with composite subwavelength (SW) structures, i.e., bridged SW grating (BSWG) waveguide structures and diagonally periodic holes (DPHs), on a partial parabolic single layer crossing (PPSLC) to improve its transmission. The BSWG is located before/after the input/output regions of the PPSLC and the DPHs are in the crossing region of the PPSLC. This waveguide crossing occupies a footprint of 6.2 μm × 6.2 μm upon a silicon-on-insulator wafer with 220-nm silicon device layer on 2-μm buried oxide. We successfully gain simulated results of the transmission up to 98.72% (−0.056 dB) and the crosstalk as low as −65 dB at an input wavelength of 1.55 μm.