Mid-Infrared Optical Frequency Combs based on Difference Frequency Generation for Molecular Spectroscopy

TL;DR

This paper demonstrates mid-infrared optical frequency combs generated via difference frequency generation in MgO:PPLN, enabling broadband, high-resolution molecular spectroscopy with high power and spectral coverage.

Contribution

The authors present a novel method for producing mid-infrared femtosecond frequency combs using difference frequency generation, achieving high power and broad spectral coverage for spectroscopy.

Findings

Achieved >500 mW power in the mid-infrared range.

Demonstrated broadband spectral coverage from 2.8 to 3.5 μm.

Showcased high-resolution molecular spectroscopy applications.

Abstract

Mid-infrared femtosecond optical frequency combs were produced by difference frequency generation of the spectral components of a near-infrared comb in a 3-mm-long MgO:PPLN crystal. We observe strong pump depletion and 9.3 dB parametric gain in the 1.5 \mu m signal, which yields powers above 500 mW (3 \mu W/mode) in the idler with spectra covering 2.8 \mu m to 3.5 \mu m. Potential for broadband, high-resolution molecular spectroscopy is demonstrated by absorption spectra and interferograms obtained by heterodyning two combs.