Optical communications-based platform uses Uni-Travelling-Carrier Photodiode for ultra-high resolution software-defined THz spectroscopy and reveals LiYF4:Ho intrinsic spectral line shape

TL;DR

This paper demonstrates a high-resolution THz spectroscopy platform using a Uni-Travelling-Carrier Photodiode and optical frequency combs, enabling software-defined, magnetic-field-free spectral analysis of LiYF4:Ho with detailed spectral line shape insights.

Contribution

It introduces a novel THz spectroscopy method combining UTC-PD and optical combs for software-controlled, high-resolution spectral measurements without magnetic fields.

Findings

Achieved 900 Hz spectral resolution near 0.2 THz.

Enabled separation of homogeneous and inhomogeneous spectral contributions.

Demonstrated spectral line shape analysis of LiYF4:Ho.

Abstract

High resolution (900 Hz full-width at half maximum) frequency domain spectroscopy near 0.2Terahertz is achieved using an exact frequency spacing comb-source in the optical communications band, filtering and photo-mixing in a custom Uni-Travelling-Carrier Photodiode (UTC-PD) for THz signal generation and coherent down-conversion for detection. Via time domain modulation of one of the comb lines, a fully controllable spectrometer can be defined in software, and this principle is demonstrated for magnetic field-free readout of the electronuclear spectrum for the Ho ions in \lihof, a material often used for demonstration experiments in quantum science. In particular, homogeneous and inhomogeneous contributions to the spectrum are readily separated.