# High-power frequency comb source tunable from 2.7 to 4.2 {\mu}m based on difference frequency generation pumped by an Yb-doped fiber laser

## TL;DR

This paper presents a high-power, tunable mid-infrared frequency comb source based on difference frequency generation using a Yb-doped fiber laser, suitable for spectroscopy applications.

## Contribution

The authors demonstrate a broadband, high-power MIR frequency comb tunable from 2.7 to 4.2 μm using DFG in PPLN pumped by a Yb-doped fiber laser, with verified coherence and spectroscopy utility.

## Key findings

- Tunable MIR comb from 2.7 to 4.2 μm with 237 mW power.
- Pulse duration as short as 115 fs.
- Successful spectroscopy measurement of acetylene absorption.

## Abstract

We demonstrate a broadband mid-infrared (MIR) frequency comb source based on difference frequency generation (DFG) in periodically poled lithium niobate (PPLN) crystal. Mid-infrared radiation is obtained via mixing of the output of a 125 MHz repetition rate Yb-doped fiber laser with Raman-shifted solitons generated from the same source in a highly nonlinear fiber. The resulting idler is tunable in the range of 2.7 - 4.2 {\mu}m with average output power reaching 237 mW, and pulses as short as 115 fs. The coherence of the MIR comb is confirmed by spectral interferometry and heterodyne beat measurements. Applicability of the developed DFG source for laser spectroscopy is demonstrated by measuring absorption spectrum of acetylene at 3.0 - 3.1 {\mu}m.

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Source: https://tomesphere.com/paper/1703.03277