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Dual optical frequency comb spectroscopy allows for high speed, broadband measurements without any moving parts. Here, we combine differential chirp down conversion to probe large spectral bandwidths in the near-infrared (NIR) and serrodyne modulation to separate the positive and negative sidebands in a single modulator. As an initial demonstration we apply this approach to measure a sharp cavity resonance to illustrate the system performance. We then measure methane transitions in the near-infrared and compare the resulting spectra to models based upon the current spectroscopic databases. The serrodyne method has lower hardware requirements compared to many existing approaches and its simplicity enables a high degree of mutual coherence between the two combs. Further, this method is readily amenable to chip-scale photonic integration.
Stroud, J.
, Long, D.
and Plusquellic, D.
(2024),
SINGLE-MODULATOR, DUAL COMB SERRODYNE SPECTROSCOPY, Optics Letters, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=957592
(Accessed October 10, 2025)