1-GHz mid-infrared frequency comb spanning 3 to 13 {\mu}m

TL;DR

This paper introduces the first broadband 1 GHz repetition rate mid-infrared frequency comb laser covering 3 to 13 μm, enabling high-resolution, rapid spectroscopy of complex, transient chemical and physical phenomena.

Contribution

The authors developed a novel, fully fiber-based MIR frequency comb source with broad spectral coverage and high repetition rate, filling a critical gap in spectroscopic technology.

Findings

Achieved spectral coverage from 3 to 13 μm at 1 GHz repetition rate.

Enabled dual-comb spectroscopy with μs time resolution.

Provided a new tool for studying fast, non-repetitive events.

Abstract

Mid-infrared (MIR) spectrometers are invaluable tools for molecular fingerprinting and hyper-spectral imaging. Among the available spectroscopic approaches, GHz MIR dual-comb absorption spectrometers have the potential to simultaneously combine the high-speed, high spectral resolution, and broad optical bandwidth needed to accurately study complex, transient events in chemistry, combustion, and microscopy. However, such a spectrometer has not yet been demonstrated due to the lack of GHz MIR frequency combs with broad and full spectral coverage. Here, we introduce the first broadband MIR frequency comb laser platform at 1 GHz repetition rate that achieves spectral coverage from 3 to 13 {\mu}m. This frequency comb is based on a commercially available 1.56 {\mu}m mode-locked laser, robust all-fiber Er amplifiers and intra-pulse difference frequency generation (IP-DFG) of few-cycle pulses in \c{hi}(2) nonlinear crystals. When used in a dual comb spectroscopy (DCS) configuration, this source will simultaneously enable measurements with {\mu}s time resolution, 1 GHz (0.03 cm-1) spectral point spacing and a full bandwidth of >5 THz (>166 cm-1) anywhere within the MIR atmospheric windows. This represents a unique spectroscopic resource for characterizing fast and non-repetitive events that are currently inaccessible with other sources.