Dielectric waveguide interconnects for hybrid mm-Waves and terahertz system integration

Abstract

Abstract In this work, we propose interconnection structures for substrateless all-silicon dielectric waveguides, a platform for terahertz (THz) hybrid integration that currently relies on traditional tapered interfaces. We demonstrate two dielectric waveguide-to-waveguide interconnect approaches: a truncated termination and a quarter-wave-matched (QWM) slot termination. Both designs maintain a confined coupling point, enabling consistent coupling. Experimental results show maximum interconnection coupling losses of 5 dB $5\,\mathrm{dB}$ <mml:math xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mnf="http://cambridge.org/core/manifest" xmlns:cup="http://contentservices.cambridge.org" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:m="http://cambridge.org/core/metadata" xmlns:core="http://cambridge.org/core" xmlns:c="http://cambridge.org/core/content" display="inline"> <mml:mrow> <mml:mn>5</mml:mn> <mml:mspace width="0.167em"/> <mml:mrow> <mml:mi mathvariant="normal">d</mml:mi> <mml:mi mathvariant="normal">B</mml:mi> </mml:mrow> </mml:mrow> </mml:math> and 2.5 dB $2.5\,\mathrm{dB}$ <mml:math xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mnf="http://cambridge.org/core/manifest" xmlns:cup="http://contentservices.cambridge.org" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:m="http://cambridge.org/core/metadata" xmlns:core="http://cambridge.org/core" xmlns:c="http://cambridge.org/core/content" display="inline"> <mml:mrow> <mml:mn>2.5</mml:mn> <mml:mspace width="0.167em"/> <mml:mrow> <mml:mi mathvariant="normal">d</mml:mi> <mml:mi mathvariant="normal">B</mml:mi> </mml:mrow> </mml:mrow> </mml:math> for the truncated and QWM-slot terminations, respectively, across the 220–330 GHz band. The QWM-slot transmission coefficient remains above minus 3 dB $-3\,\mathrm{dB}$ <mml:math xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mnf="http://cambridge.org/core/manifest" xmlns:cup="http://contentservices.cambridge.org" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:m="http://cambridge.org/core/metadata" xmlns:core="http://cambridge.org/core" xmlns:c="http://cambridge.org/core/content" display="inline"> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> <mml:mspace width="0.167em"/> <mml:mrow> <mml:mi mathvariant="normal">d</mml:mi> <mml:mi mathvariant="normal">B</mml:mi> </mml:mrow> </mml:mrow> </mml:math> with a misalignment tolerance up to 100 mu m $100\,\mu\mathrm{m}$ <mml:math xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mnf="http://cambridge.org/core/manifest" xmlns:cup="http://contentservices.cambridge.org" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:m="http://cambridge.org/core/metadata" xmlns:core="http://cambridge.org/core" xmlns:c="http://cambridge.org/core/content" display="inline"> <mml:mrow> <mml:mn>100</mml:mn> <mml:mspace width="0.167em"/> <mml:mi>μ</mml:mi> <mml:mi>m</mml:mi> </mml:mrow> </mml:math> , representing a 2.5 times $2.5\times$ <mml:math xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mnf="http://cambridge.org/core/manifest" xmlns:cup="http://contentservices.cambridge.org" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:m="http://cambridge.org/core/metadata" xmlns:core="http://cambridge.org/core" xmlns:c="http://cambridge.org/core/content" display="inline"> <mml:mrow> <mml:mn>2.5</mml:mn> <mml:mo>×</mml:mo> </mml:mrow> </mml:math> improvement over the truncated design. Offset characterization along three axes reveals smooth decoupling behavior over a 1 mm range, validating the potential for broadband, contactless interconnects between dielectric waveguide interfaces. These results establish a compact THz interconnect concept with substantially relaxed translational alignment tolerances, making it well-suited for deployment in scalable 6G multi-chip arrays and THz sensing modules.