An On-Chip Continuous Wave Terahertz Spectrometer

Continuous Wave (CW) Terahertz spectroscopy enabled by photomixing is a promising high precision spectroscopic tool for the examination of a wide variety of samples including biological, chemical, and solid state. However, often it would be of interest to examine isolated samples free from bulk effects that broaden spectral features. In this form samples with low concentrations of absorbers have a reduced cross section making coupling to an external driving field a challenge. By utilising THz metamaterials one can borrow the concepts of surface enhanced Raman spectroscopy to confine and concentrate the THz fields to increase sensitivity for samples with a small cross section. Our work combines high-speed photodiode technology and THz metamaterials to offer a solution to this challenge. We present here a proof of concept on-chip THz spectrometer integrated with a metamaterial waveguide.