Real-time dual frequency comb spectroscopy in the near infrared

TL;DR

This paper demonstrates a real-time, dual-frequency comb spectroscopy technique in the near infrared using femtosecond fiber lasers, enabling rapid broadband spectral measurements without moving parts.

Contribution

It introduces a novel method combining dual femtosecond fiber lasers with spectral filtering for fast, high-resolution spectroscopy in the near infrared.

Findings

Spectral measurement in less than 50 microseconds

Effective spectral filtering improves signal-to-noise ratio

Successful detection of gas mixture spectrum in real time

Abstract

We use two femtosecond Erbium-doped fiber lasers with slightly different repetition rates to perform a modern type of Fourier transform spectroscopy without moving parts. The measurements are done in real time, and it takes less than 50 microseconds. We work with somewhat different spectral outputs from two Erbium-doped fiber lasers and employ spectral filtering based on a 2f-2f grating setup to select the common spectral region of interest, thereby increasing the signal-to-noise ratio. The interferogram is taken with a 20 cm long gas cell, containing a mixture of acetylene and air at atmospheric pressure, and is fast-Fourier-transformed to obtain the broadband spectral fingerprint of the gas.