We report on a compact scheme for absolute referencing and coherent averaging for dual-comb based spectrometers, exploiting a single continuous-wave (CW) laser in a transfer oscillator configuration. The same CW laser is used for both absolute calibration of the optical frequency axis and the generation of a correction signal which is used for a real-time jitter compensation in a fully electrical feed-forward scheme. The technique is applied to a near-infrared spectrometer based on a pair of free-running mode-locked Er: fiber lasers, allowing to perform real-time absolute-frequency measurements over an optical bandwidth of more than 25 nm, with coherent interferogram averaging over 1-s acquisition time, leading to a signal-to-noise ratio improvement of 29 dB over the 50 mu s single shot acquisition. Using 10-cm single pass cell, a value of 1.9 x 10(-4) cm(-1) Hz(-0.5) noise-equivalent-absorption over 1 s integration time is obtained, which can be further scaled down with a multi-pass or resonant cavity. The adoption of a single CW laser, together with the absence of optical locks, and the full-fiber design makes this spectrometer a robust and compact system to be employed in gas-sensing applications. (C) 2014 AIP Publishing LLC.

Absolute dual-comb spectroscopy at 1.55 mu m by free-running Er:fiber lasers

Laporta Paolo;Galzerano Gianluca
2014

Abstract

We report on a compact scheme for absolute referencing and coherent averaging for dual-comb based spectrometers, exploiting a single continuous-wave (CW) laser in a transfer oscillator configuration. The same CW laser is used for both absolute calibration of the optical frequency axis and the generation of a correction signal which is used for a real-time jitter compensation in a fully electrical feed-forward scheme. The technique is applied to a near-infrared spectrometer based on a pair of free-running mode-locked Er: fiber lasers, allowing to perform real-time absolute-frequency measurements over an optical bandwidth of more than 25 nm, with coherent interferogram averaging over 1-s acquisition time, leading to a signal-to-noise ratio improvement of 29 dB over the 50 mu s single shot acquisition. Using 10-cm single pass cell, a value of 1.9 x 10(-4) cm(-1) Hz(-0.5) noise-equivalent-absorption over 1 s integration time is obtained, which can be further scaled down with a multi-pass or resonant cavity. The adoption of a single CW laser, together with the absence of optical locks, and the full-fiber design makes this spectrometer a robust and compact system to be employed in gas-sensing applications. (C) 2014 AIP Publishing LLC.
2014
Istituto di fotonica e nanotecnologie - IFN
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/267475
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