High-power mid-infrared frequency comb source based on a femtosecond Er:fiber oscillator

TL;DR

This paper presents a high-power, broadband mid-infrared frequency comb generated from an Er:fiber laser using difference frequency generation, with applications demonstrated in methane detection.

Contribution

The work introduces a high-power mid-infrared frequency comb source based on a femtosecond Er:fiber oscillator with stable coherence and broad spectral coverage.

Findings

Output power of 120 mW at 2.9-3.6 μm

Maintained coherence verified by heterodyne measurements

Successful methane spectrum measurement at ambient conditions

Abstract

We report on a high-power mid-infrared frequency comb source based on a femtosecond Er:fiber oscillator with a stabilized repetition rate at 250 MHz. The mid-infrared frequency comb is produced through difference frequency generation in a periodically poled MgO-doped lithium niobate crystal. The output power is about 120 mW with a pulse duration of about 80 fs, and spectrum coverage from 2.9 to 3.6 um. The coherence properties of the produced high-power broadband mid-infrared frequency comb are maintained, which was verified by heterodyne measurements. As the first application, the spectrum of a ~200 ppm methane-air mixture in a short 20 cm glass cell at ambient atmospheric pressure and temperature was measured.