Concepedia

Infrared electric field sampled frequency comb spectroscopy

Abijith S. Kowligy, Henry Timmers, Alexander J. Lind, Ugaitz Elu, Flávio C. Cruz, Peter G. Schunemann, Jens Biegert, Scott A. Diddams

Science Advances · 2019 · 168 citations · 58 references

DOI Full text

Open access

TL;DR

Probing matter with light in the mid‑infrared provides unique insight into molecular composition, structure, and function with high sensitivity, but laser spectroscopy in this region lacks broadband or tunable light sources and efficient detectors available in the visible or near‑infrared. We overcome these challenges with an approach that unites a compact source of phase‑stable, single‑cycle mid‑infrared pulses with room‑temperature electric‑field‑resolved detection at video rates. The system combines a compact source of phase‑stable, single‑cycle mid‑infrared pulses with electric‑field‑resolved detection at video rates to achieve broadband, high‑resolution measurements. The resulting apparatus produces phase‑stable, single‑cycle mid‑infrared pulses that form frequency combs spanning 3–27 µm with a dynamic range >10⁶ and resolution 0.003 cm⁻¹, and its brightness and coherence are demonstrated in gas, liquid, and solid spectroscopy over bandwidths comparable to thermal or synchrotron sources, enabling rapid, molecular‑specific detection of biological, chemical, and physical properties.

Abstract

Probing matter with light in the mid-infrared provides unique insight into molecular composition, structure, and function with high sensitivity. However, laser spectroscopy in this spectral region lacks the broadband or tunable light sources and efficient detectors available in the visible or near-infrared. We overcome these challenges with an approach that unites a compact source of phase-stable, single-cycle, mid-infrared pulses with room temperature electric field-resolved detection at video rates. The ultrashort pulses correspond to laser frequency combs that span 3 to 27 μm (370 to 3333 cm-1), and are measured with dynamic range of >106 and spectral resolution as high as 0.003 cm-1. We highlight the brightness and coherence of our apparatus with gas-, liquid-, and solid-phase spectroscopy that extends over spectral bandwidths comparable to thermal or infrared synchrotron sources. This unique combination enables powerful avenues for rapid detection of biological, chemical, and physical properties of matter with molecular specificity.