Low-Loss and Low-Dispersion Transmission Line Over DC-to-THz Spectrum

Abstract

Transmission lines or waveguides are the most fundamental building blocks of all electronic and photonic circuits and systems. Efforts have been made to incrementally evolve and improve existing transmission line structures to meet the increasingly stringent demands for signal transmission bandwidth and performance. However, a potentially revolutionary scheme or disruptive concept is required in support of future technological needs and bridging the gap between electronics and photonics. In this paper, we report on a fully integrated transmission line with simple structure that overcomes the long-standing bottleneck problems of high attenuation, strong dispersion, and low mode confinement in the guided-wave signal transmission from dc to terahertz (THz). This so-called mode-selective transmission line (MSTL) supports super-broadband and/or ultrafast pulse signal propagation, making it a disruptive solution for building future high-performance analog and digital integrated electronics and photonics. To demonstrate this scheme, an MSTL on fused silica substrate is designed, fabricated, and experimentally measured from near-dc to 0.5 THz, showing less than 0.35 dB/mm attenuation and low dispersion characteristics over the entire frequency range.