Two-octave frequency combs from all-silica-fiber implementation

TL;DR

This paper demonstrates the first all-silica-fiber mid-infrared frequency comb spanning over two octaves, with high power and stability, enabling diverse spectroscopy applications.

Contribution

It provides the first experimental demonstration and quantitative model of mid-infrared frequency comb generation in silica fibers, addressing previous complexity issues.

Findings

Frequency comb spans 0.8 to 3.5 μm with 100 mW power.

Carrier-envelope offset frequency SNR of 40 dB.

Bandwidth of 90 kHz in free-running conditions.

Abstract

Mid-infrared frequency comb spectroscopy enables measurement of molecular at megahertz spectral resolution, sub-hertz frequency accuracy and microsecond acquisition speed. However, the widespread adoption of this technique has been hindered by the complexity and alignment sensitivity of mid-infrared frequency comb sources. Leveraging the underexplored mid-infrared window of silica fibers presents a promising approach to address these challenges. In this study, we present the first experimental demonstration and quantitative numerical description of mid-infrared frequency comb generation in silica fibers. Our all-silica-fiber frequency comb spans over two octaves (0.8 $\mu$m to 3.5 $\mu$m) with a power output of 100 mW in the mid-infrared region. The amplified quantum noise is suppressed using four-cycle (25 fs) driving pulses, with the carrier-envelope offset frequency exhibiting a signal-to-noise ratio of 40 dB and a free-running bandwidth of 90 kHz. Our developed model provides quantitative guidelines for mid-infrared frequency comb generation in silica fibers, enabling all-fiber frequency comb spectroscopy in diverse fields such as organic synthesis, pharmacokinetics processes, and environmental monitoring.