Broadband dual-comb hyperspectral imaging and adaptable spectroscopy with programmable frequency combs

Published

January 29, 2024

Author(s)

Fabrizio Giorgetta, Jean-Daniel deschenes, Richard L. LIEBER, Ian Coddington, Nathan Newbury, Esther Baumann

Abstract

We explore the advantages of a free-form dual-comb spectroscopy (DCS) platform based on the time programmable frequency comb for real time penalty-free apodized scanning. In traditional DCS, the fundamental spectral resolution equals the comb repetition rate, which can be excessively high for many applications. While the excess resolution is not itself problematic, it comes with the penalty of excess acquisition time and therefore reduced signal-to-noise ratio (SNR). Apodization (windowing) can be applied to tailor the resolution to the sample, but only with a deadtime penalty proportional to the degree of apodization. The excess acquisition time remains. With free-form DCS, one can avoid this deadtime by programming a pattern that dynamically reverses the pulse periods between the dual frequency combs. In this way, one can tailor the spectrometer's resolution and update rate to multiple different applications without penalty. We show operation of a DCS system where the spectral resolution is varied from the intrinsic high resolution of 160 MHz up to 822 GHz by applying dynamic real-time apodization. Because there is no deadtime penalty, the spectral SNR increases linearly with resolution by 1000x over this full range, as opposed to the square root increase observed when apodizing traditional DCS measurements in post-processing. We explore the flexibility to change resolution and update rate to perform hyperspectral imaging at low camera frame rates, where the penalty-free apodization allows for optimal use of each camera frame. We obtain dual-comb hyperspectral movies at a frame rate of 20 Hz and broad optical spectral coverage of over 10 THz.

Citation

Applied Physics Letters Photonics

Volume

9

Pub Type

Journals

Download Paper

https://doi.org/10.1063/5.0179270

Local Download

Keywords

dual-comb, spectroscopy, hyperspectral, apodization

Citation

Giorgetta, F. , Deschenes, J. , LIEBER, R. , Coddington, I. , Newbury, N. and Baumann, E. (2024), Broadband dual-comb hyperspectral imaging and adaptable spectroscopy with programmable frequency combs, Applied Physics Letters Photonics, [online], https://doi.org/10.1063/5.0179270, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=956745 (Accessed April 27, 2024)