Fully stabilized mid-infrared frequency comb for high-precision molecular spectroscopy

• Published in: Optics express Vol. 25; no. 4; pp. 4190 - 4200
• Main Authors: Vainio, Markku, Karhu, Juho
• Format: Journal Article
• Language: English
• Published: United States 20-02-2017
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.25.004190

A fully stabilized mid-infrared optical frequency comb spanning from 2.9 to 3.4 µm is described in this article. 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 2 × 10
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.