Document Type

Honors Paper

Advisor

Daniel Maser

Publication Date

2026

Abstract

Two affordably home-built optical frequency combs are stabilized for use in molecular spectroscopy. Each comb is paired with a multi-tiered stabilization scheme that will enable the dual-comb spectrometer to perform precision measurements. The two degrees of freedom for an optical frequency comb, the repetition rate frequency and offset frequency, are accounted for in this stabilization scheme. The repetition rate is directly stabilized through control of the laser enclosure temperature and the fiber laser cavity length. The offset frequency is controlled indirectly via the stabilization of an optical beat note, the heterodyned signal resulting from a narrow linewidth laser and the nearest comb tooth. The stabilization of the optical beat requires a control system for the current of the pump laser diode in the frequency comb. Individual stabilization of both combs resulted in the standard deviation of the repetition rate frequency error being on the order of 1 mHz, while the standard deviation of the optical beat’s frequency error is on the order of 100 mHz. Additionally, the phase noise of the repetition rate phase-locks is in the regime of 0.01 radrms, while the locks for the optical beat are a factor of 10 higher. Given our analysis of the noise performance, once simultaneous stabilization of both combs to a comparable standard is achieved, we anticipate this system will be suitable to perform rotationally resolved dual-comb spectroscopy. The total cost of producing this dual-comb system is approximately $30,000, a fraction of the standard commercial price ($250,000-500,000). The dual-comb spectrometer will be tested as a proof of concept by performing a precision measurement of hydrogen cyanide. Given the dual-comb system performs suitably, it will later be utilized to measure the spectrum of benzene. This work aims to provide an affordable alternative for dual-comb experiments that other small liberal arts institutions may utilize.

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The views expressed in this paper are solely those of the author.