Polarization-Insensitive Waveguide Schottky Photodetectors Based on Mode Hybridization Effects in Asymmetric Plasmonic Waveguides

Abstract

Two types of configurations are theoretically proposed to achieve high responsivity polarization-insensitive waveguide Schottky photodetectors, i.e., a dual-layer structure for 1.55 µm and a single-layer structure for 2 µm wavelength band. Mode hybridization effects between quasi-TM modes and sab1 modes in plasmonic waveguides are first presented and further investigated under diverse metal types with different thicknesses in this work. By utilizing the mode hybridization effects between quasi-TE mode and aab0 mode, and also quasi-TM and sab1 mode in our proposed hybrid plasmonic waveguide, light absorption enhancement can be achieved under both TE and TM incidence within ultrathin and short metal stripes, thus resulting in a considerable responsivity for Si-based sub-bandgap photodetection. For 1.55 µm wavelength, the Au-6 nm-thick device can achieve absorptance of 99.6%/87.6% and responsivity of 138 mA·W−1/121.2 mA·W−1 under TE/TM incidence. Meanwhile, the Au-5 nm-thick device can achieve absorptance of 98.4%/90.2% and responsivity of 89 mA·W−1/81.7 mA·W−1 under TE/TM incidence in 2 µm wavelength band. The ultra-compact polarization-insensitive waveguide Schottky photodetectors may have promising applications in large scale all-Si photonic integrated circuits for high-speed optical communication.

Universal Design of Ultra-Broadband and Ultra-Compact High Order Mode Pass Filters Based on Enhanced Absorption in Ultrathin Metal Layers

“…Bound modelarge Re(neff) and large Im(neff) Combined with previous investigations [30], [31], it can be extended to general cases that quasi-TE2n and quasi-TM2n+1 modes would be hybridized with aab m modes, while quasi-TE2n+1 and quasi-TM2n modes would be hybridized with sab k modes (m and n are both natural numbers, k is a positive integer) with certain metal widths, provided that the Si waveguide is wide enough.…”