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David F. Plusquellic

Publications and source records attributed to David F. Plusquellic.

7 recordsLinked to original sources
arXiv2026

Cavity enhanced UV combs generated by sum frequency mixing with near-IR chirped-pulse electro-optic combs for Rb atom sensing at 323 nm

A chirped-pulse electro-optic (EO) dual comb system operating near 821 nm is used to generate cavity enhanced dual combs in the ultraviolet (UV) region near 323 nm with an optical bandwidth of up to 90 GHz. The UV combs result from intracavity sum frequency mixing of the non-resonant near-IR combs with a cavity enhanced field at 532 nm in a nonlinear crystal. The cavity is pumped with 1 W at 532 nm and seeded with less than 10 mW in the near-IR region to generate a few uW of UV power within a detection bandwidth of < 20 MHz. The UV power is enhanced by 100-fold relative to single pass methods and is readily detectable using an avalanche photodiode. The system is used to measure the high-resolution UV comb spectra of Rb atoms near 323 nm (9 2P3/2 <- 5 2S1/2). This method is easily extendable across the 300 nm to 400 nm region using telecom and near-IR dual EO comb sources for seeding.

physics.optics↗
arXiv2024

Frequency-doubled chirped-pulse dual-comb generation in the near-UV: Combined vs separated beam investigations of Rb atoms near 420 nm

We describe an electro-optic dual-comb system that operates in the near-infrared (near-IR) region to generate optical frequency combs in the near-UV by sum frequency generation in two configurations. The near-IR frequency combs are generated using chirped pulses that down convert the optical information into the radio frequency (RF) domain by a difference in the chirp bandwidths. Near (UV) combs at twice the near-IR bandwidth are obtained by sum frequency generation in a nonlinear crystal and detected by a hybrid photon counting detection system. We compare the results of studies of Rb near 420 nm using two optical arrangements where the near-IR combs are mixed in the crystal as combined or as separated beams. While the latter method enables phase retrievals, the combined beam method is superior for phase stability, power throughput for detection, and ease of alignment. High order interleaving enables near-UV bandwidths near 4 cm-1 for faint photonic sensing and spectroscopic applications. The harmonic generation method is easily extendable across much of the titanium sapphire tuning range.

physics.optics↗
arXiv2022

A dual chirped-pulse electro-optical frequency comb method for simultaneous molecular spectroscopy and dynamics studies: Formic acid in the THz region

An electro-optic dual comb system based on chirped-pulse waveforms is used to simultaneously acquire temporally magnified rapid passage signals and normal spectral line shapes from the back-transformation to the time domain. Multi-heterodyne THz wave generation and detection is performed with the difference frequency mixing of two free-running lasers. The method is used to obtain THz spectra of formic acid in the 10 cm-1 to 20 cm-1 (300 GHz to 600 GHz) region over a range of pressures. The method is widely applicable across other spectral regions for investigations of the transient dynamics and spectroscopy of molecular systems.

physics.optics↗
arXiv2021

Interleaved Electro-Optic Dual Comb Generation to Expand Bandwidth and Scan Rate for Molecular Spectroscopy and Dynamics Studies near 1.6 μm

A chirped-pulse interleaving method is reported for generation of dual optical frequency combs based on electro-optic phase modulators (EOM) in a free-running all-fiber based system. Methods are discussed to easily modify the linear chirp rate and comb resolution by more than three orders of magnitude and to significantly increase the spectral bandwidth coverage. The agility of the technique is shown to both capture complex line shapes and to magnify rapid passage effects in spectroscopic and molecular dynamics studies of CO2. These methods are well-suited for applications in the areas of remote sensing, reaction dynamics, and sub-Doppler studies across the wide spectral regions accessible to EOMs.

physics.optics↗
arXiv2016

Multiplexed sub-Doppler spectroscopy with an optical frequency comb

An optical frequency comb generated with an electro-optic phase modulator and a chirped radiofrequency waveform is used to perform saturation and pump-probe spectroscopy on the $D_1$ and $D_2$ transitions of atomic potassium. With a comb tooth spacing of 200 kHz and an optical bandwidth of 2 GHz the hyperfine transitions can be simultaneously observed. Interferograms are recorded in as little as 5 $μ$s (a timescale corresponding to the inverse of the comb tooth spacing). Importantly, the sub-Doppler features can be measured as long as the laser carrier frequency lies within the Doppler profile, thus removing the need for slow scanning or a priori knowledge of the frequencies of the sub-Doppler features. Sub-Doppler optical frequency comb spectroscopy has the potential to dramatically reduce acquisition times and allow for rapid and accurate assignment of complex molecular and atomic spectra which are presently intractable.

physics.atom-ph↗
arXiv2016

Coherent cavity-enhanced dual-comb spectroscopy

Dual-comb spectroscopy allows for the rapid, multiplexed acquisition of high-resolution spectra without the need for moving parts or low-resolution dispersive optics. This method of broadband spectroscopy is most often accomplished via tight phase locking of two mode-locked lasers or via sophisticated signal processing algorithms, and therefore, long integration times of phase coherent signals are difficult to achieve. Here we demonstrate an alternative approach to dual-comb spectroscopy using two phase modulator combs originating from a single continuous-wave laser capable of > 2 hours of coherent real-time averaging. The dual combs were generated by driving the phase modulators with step-recovery diodes where each comb consisted of > 250 teeth with 203 MHz spacing and spanned > 50 GHz region in the near-infrared. The step-recovery diodes are passive devices that provide low-phase-noise harmonics for efficient coupling into an enhancement cavity at picowatt optical powers. With this approach, we demonstrate the sensitivity to simultaneously monitor ambient levels of CO2, CO, HDO, and H2O in a single spectral region at a maximum acquisition rate of 150 kHz. Robust, compact, low-cost and widely tunable dual-comb systems could enable a network of distributed multiplexed optical sensors.

physics.optics↗