High density THz frequency comb produced by coherent synchrotron radiation

TL;DR

This paper demonstrates that coherent synchrotron radiation can generate a dense, powerful terahertz frequency comb spanning a decade of frequency, offering new opportunities for high-resolution spectroscopy and metrology.

Contribution

It introduces a novel method of producing dense THz frequency combs using coherent synchrotron radiation, surpassing previous power and spectral limitations.

Findings

Generated a dense THz frequency comb over a decade of frequency.

Achieved unprecedented spectral characteristics in THz frequency combs.

Opened new perspectives for THz metrology and spectroscopy.

Abstract

Frequency combs (FC) have radically changed the landscape of frequency metrology and high-resolution spectroscopy investigations extending tremendously the achievable resolution while increasing signal to noise ratio. Initially developed in the visible and near-IR spectral regions, the use of FC has been expanded to mid-IR, extreme ultra-violet and X-ray. Significant effort is presently dedicated to the generation of FC at THz frequencies. One solution based on converting a stabilized optical frequency comb using a photoconductive terahertz emitter, remains hampered by the low available THz power. Another approach is based on active mode locked THz quantum-cascade-lasers providing intense FC over a relatively limited spectral extension. Alternatively, here we show that dense powerful THz FC is generated over one decade of frequency by coherent synchrotron radiation (CSR). In this mode, the entire ring behaves in a similar fashion to a THz resonator wherein electron bunches emit powerful THz pulses quasi-synchronously. This FC presents unprecedented spectral characteristics and opens new perspectives for metrology investigations.