Wideband dispersion-free THz waveguide platform

TL;DR

This paper introduces a low-loss, dispersion-free THz waveguide platform with strong field confinement, enabling advanced spectroscopy and nonlinear interactions across 0.1 to 1.5 THz frequencies.

Contribution

It presents a novel metallic double ridged waveguide design that achieves vacuum-like dispersion and strong mode confinement for integrated THz applications.

Findings

Low propagation and bending losses measured

Successful demonstration of junctions and interferometers

Broadband single- to few-cycle pulse propagation

Abstract

We present an integrated THz spectroscopy and sensing platform featuring low loss, vacuum-like dispersion, and strong field confinement in the fundamental mode. Its performance was characterized experimentally for frequencies between 0.1 THz and 1.5 THz. While linear THz spectroscopy and sensing gain mostly from low loss and an extended interaction length, nonlinear THz spectroscopy would also profit from the field enhancement associated to strong mode confinement. Moreover, the vacuum-like dispersion allows for a reshaping-free propagation of broadband single- to few-cycle pulses in gas-phase samples or velocity matching between THz pump and visible to infrared probe pulses. Our platform is based on a metallic structure and falls in the category of double ridged waveguides. We characterize essential waveguide properties, for instance, propagation and bending losses, but also demonstrate junctions and interferometers, essentially because those elements are prerequisites for integrated THz waveform synthesis, and hence, for coherently controlled linear and nonlinear interactions.