Mid-infrared dual-comb spectroscopy with absolute frequency calibration using a passive optical reference.

M A Abbas,S M Cristescu,Q Pan,J Mandon,A Khodabakhsh,F J M Harren

doi:10.1364/oe.27.019282

Abstract

We demonstrate an absolute-frequency-calibrated mid-infrared dual-comb spectrometer by using a reference absorption cell. The source is based on a singly-resonant OPO containing two MgO:PPLN crystals in a common ring cavity, synchronously pumped by two mode-locked Yb-fiber lasers. The repetition-rate of the two pumps are stabilized while their offset frequencies and the OPO cavity length are not actively controlled. The reference spectrum is used to correct the frequency fluctuations in the sample spectrum providing a high-quality averaged spectrum with spectral resolution of 6 GHz and calibration precision of 120 MHz, without adding any complexity to the experimental setup or signal processing.

Highlights

Dual-comb spectroscopy (DCS) [1,2,3] is a powerful alternative for traditional or comb-based Fourier-transform spectroscopy (FTS) using a mechanical moving mirror [4,5]
The optical frequency comb (OFC) sources suitable for spectroscopy are usually generated from mode-locked femtosecond lasers
We used a passive optical reference for absolute-calibration of a dual-comb spectrometer based on femtosecond optical parametric oscillation (OPO), eliminating the need for the stabilization of the comb offset frequency and OPO cavity length

Summary

Introduction

Dual-comb spectroscopy (DCS) [1,2,3] is a powerful alternative for traditional or comb-based Fourier-transform spectroscopy (FTS) using a mechanical moving mirror [4,5]. Femtosecond DFGbased sources [10,11] do not need a resonance cavity and can generate carrier-envelopeoffset-free frequency combs, which simplifies the experimental setup and/or signal processing of dual-comb spectrometers [12]. Recent developments on dual-comb spectrometers based on both OPO [13] and DFG [14,15] enhance the available spectral bandwidth, spectral resolution, spectral precision and detection sensitivity of these systems. These improvements are achieved at the cost of more bulky and complicated experimental setups including f-2f interferometry, several stabilization loops and/or extensive signal processing

Methods

Results

Conclusion