On-chip, self-detected THz dual-comb spectrometer

TL;DR

This paper demonstrates an on-chip, self-detected THz dual-comb spectrometer using quantum cascade lasers, achieving high spectral bandwidth and precise mode equidistance measurement for advanced spectroscopic applications.

Contribution

It introduces a fully integrated on-chip dual-comb source at THz frequencies utilizing quantum cascade lasers as both emitters and detectors, with high bandwidth and mode accuracy.

Findings

Detected up to 30 modes over 630 GHz bandwidth

Achieved mode equidistance accuracy of 10^{-12}

Utilized quantum cascade active regions for detection

Abstract

We present a directly generated on-chip dual-comb source at THz frequencies. The multi-heterodyne beating signal of two free-running THz quantum cascade laser frequency combs is measured electrically using one of the combs as a detector, fully exploiting the unique characteristics of quantum cascade active regions. Up to 30 modes can be detected corresponding to a spectral bandwidth of 630 GHz, being the available bandwidth of the dual comb configuration. The multi-heterodyne signal is used to investigate the equidistance of the comb modes showing an accuracy of $10^{-12}$ at the carrier frequency of 2.5 THz.