Fully Stabilized Mid-Infrared Frequency Comb for High-Precision Molecular Spectroscopy

TL;DR

This paper presents a fully stabilized mid-infrared frequency comb generated via half-harmonic generation in a femtosecond optical parametric oscillator, enabling high-precision molecular spectroscopy without complex locking systems.

Contribution

It introduces a simple method to produce a stabilized mid-infrared comb with high coherence transfer from near-infrared lasers, eliminating the need for phase-locked loops or reference lasers.

Findings

Achieved sub-20 mHz frequency locking precision.

Transferred phase coherence from near-infrared to mid-infrared region.

Demonstrated suitability for high-precision molecular spectroscopy.

Abstract

A fully stabilized mid-infrared optical frequency comb spanning from 2.9 to 3.4 um is described. The comb is based on half-harmonic generation in a femtosecond optical parametric oscillator, which transfers the high phase coherence of a fully stabilized near-infrared Er-doped fiber laser comb to the mid-infrared region. The method is simple, as no phase-locked loops or reference lasers are needed. Precise locking of optical frequencies of the mid-infrared comb to the pump comb is experimentally verified at sub-20 mHz level, which corresponds to a fractional statistical uncertainty of 2x10-16 at the center frequency of the mid-infrared comb. The fully stabilized mid-infrared comb is an ideal tool for high-precision molecular spectroscopy, as well as for optical frequency metrology in the mid-infrared region, which is difficult to access with other stabilized frequency comb techniques.