Optical frequency combs have numerous applications across the sciences. One of the most powerful applications is in molecular spectroscopy, which takes advantage of both the coherence of lasers and combs’ inherent broad bandwidth. One well-established design is the erbium fiber comb, which is popular due to its low cost and relative ease of construction. I have modified the traditional all-fiber design by introducing an adjustable free-space section which allows for adjustments to the path length, and thus the comb’s repetition rate. This low-cost addition allows for repetition rate matching, a necessity for dual-comb spectroscopy, and active repetition rate stabilization, which is essential for long-term stability and precision measurement. Stabilization is achieved through passive and active means; active stabilization involves both temperature control and a piezoelectric transducer in the free-space section. Preliminary results, frequency comb spectra, and other diagnostic measurements are presented. This comb will be implemented in a dual-comb spectrometer to conduct rotationally-resolved measurements of small molecules such as hydrogen cyanide, and in a supersonic beam apparatus to measure larger molecules such as benzene.
Carter, Matthew, "Design, Construction, and Stabilization of an Adjustable Repetition Rate Frequency Comb for Precision Spectroscopy" (2023). Physics, Astronomy and Geophysics Honors Papers. 9.
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