Optical-parametric-amplification-enhanced background-free spectroscopy

Creators: Liu, Mingchen; Gray, Robert M.; Roy, Arkadev; Ledezma, Luis; Marandi, Alireza¹

1. California Institute of Technology

Abstract

Traditional absorption spectroscopy has a fundamental difficulty in resolving small absorbance from a strong background due to the instability of laser sources. Existing background-free methods in broadband vibrational spectroscopy help to alleviate this problem but face challenges in realizing either low extinction ratios or time-resolved field measurements. Here, we introduce optical-parametric-amplification-enhanced background-free spectroscopy, in which the excitation background is first suppressed by an interferometer, and then the free-induction decay that carries molecular signatures is selectively amplified. We show that this method can improve the limit of detection in linear interferometry by order(s) of magnitude without requiring lower extinction ratios or a time-resolved measurement, which can benefit sensing applications in detecting trace species.

Copyright and License

Acknowledgement

The authors gratefully acknowledge support from the center for sensing to intelligence at Caltech, and JPL (NASA).

Funding

Air Force Office of Scientific Research (FA9550-23-1-0755); National Science Foundation (1846273).

Data Availability

Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.

See Supplement 1 for supporting content.

Conflict of Interest

AM and LL have financial interest in PINC Technologies Inc., which is developing photonic integrated nonlinear circuits.

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