A Dual-Polarization Multi-Mode Multi-Drop Dielectric Waveguide Channel for Sub-Terahertz High-Capacity Interconnect

This paper presents a dual-polarization multi-mode multi-drop silicon dielectric waveguide channel for sub-terahertz interconnect, which utilizes both polarization-division multiplexing and mode-division multiplexing techniques to expand the channel capacity. The waveguide channel transmits four modes <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{E}_{11}^{\mathrm{K}},\ \mathrm{E}_{11}^{\mathrm{y}},\ \mathrm{E}_{21}^{\mathrm{K}},\ \mathrm{E}_{21}^{\mathrm{y}})$</tex> with two orthogonal polarizations on a single bus waveguide. The system consists of five mode couplers for mode conversions, i.e., the quasi-transverse electromagnetic mode from metallic microstrip lines to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{E}_{11}^{\mathrm{x}}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{E}_{11}^{\mathrm{y}}$</tex> mode, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{E}_{11}^{\mathrm{y}}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{E}_{11}^{\mathrm{y}}$</tex> mode, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{E}_{11}^{\mathrm{y}}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{E}_{21}^{\mathrm{y}}$</tex> mode, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{E}_{11}^{\mathrm{x}}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{E}_{21}^{\mathrm{x}}$</tex> mode. Numerical simulation results show that the optimal coupling losses for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{E}_{11}^{\mathrm{x}}, \mathrm{E}_{11}^{\mathrm{y}}, \mathrm{E}_{21}^{\mathrm{x}}$</tex>, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{E}_{21}^{\mathrm{y}}$</tex> modes are 3.7 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{dB}, 4.8\text{dB}, 5.7\text{dB}$</tex>, and 3.1 dB, respectively. The respective 3-dB bandwidths are 137–170 GHz, 146–176 GHz, 140–170 GHz, and 142–183 GHz, with mode crosstalk lower than -19 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{dB}, -15\text{dB}, -19\text{dB}$</tex>, and -15 dB, respectively.