Electromagnetically induced transparency in vacuum and buffer gas potassium cells probed via electro-optic frequency combs

Abstract

Electromagnetically induced transparency (EIT) in 39K and 41K was probed using electro-optic frequency combs generated by applying chirped waveforms to a phase modulator. The carrier tone of the frequency comb served as the pump beam and induced the necessary optical cycling. Comb tooth spacings as narrow as 20 kHz were used to probe potassium in both buffer gas and evacuated cells at elevated temperatures. Atomic absorption features as narrow as 33(5) kHz were observed allowing for the 39K lower state hyperfine splitting to be optically measured with a fit uncertainty of 2 kHz. Due to the ultranarrow width of the EIT features, long-lived optical free induction decays were also observed which allowed for background-free detection.

Ultra-Dense CEO-Stabilized Broadband Optical Frequency Comb Generation Through Simple, Programmable, and Lossless 1000-Fold Frequency-Spacing Division

“…However, for fast (eventually, single-shot) measurements, the frequency resolution is directly dictated by the comb's FSR. Hence, available broadband CEO-stabilized combs have FSRs that are far too large to interrogate spectral features narrower than a few MHz, such as those found in electromagnetically-induced resonances [16], and hyperfine transitions [17], [18]. An accurate characterization of these features would require many comb lines to fit within each feature, thus calling for comb FSRs in the sub-MHz range or below.…”

“…To address the lack of ultra-dense OFCs, different solutions have been proposed, most prominently electro-optic OFC generation [7], [16], [17], FSR reduction using pulse-picking [24], and pseudo-random binary phase modulation [28]. Most of these methods allow for FSR reduction, down to the sub-MHz regime [7], [16], [17], [28]. However, pulse picking is inherently very lossy, as it implies the deliberate discarding of a large portion of the original comb energy.…”

Quantitative modeling of complex molecular response in coherent cavity-enhanced dual-comb spectroscopy

“…Optical frequency combs (OFCs) [1][2][3][4] enable increasingly precise applications of atomic and molecular spectroscopy [5], including primary thermometry [6,7], optical radiocarbon dating [8], sub-Doppler and Doppler-free spectroscopy [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], ultrafast and multidimensional spectroscopy [27][28][29][30], survey spectroscopy of molecular ions and cold molecules [31][32][33], and time-resolved spectroscopy for fundamental chemical kinetics [34][35][36][37]. Applied spectroscopies [38] also make novel use of optical frequency combs for actively monitoring greenhouse gas fluxes [39][40][41], methane for open-path detection [42] and unambiguous source attribution [43] and reactive atmospheric species [44], elucidating the chemical composition of combustion and open flames…”

Precision spectroscopy of H13CN using a free-running, all-fiber dual electro-optic frequency comb system

“…Electro-optic (EO) frequency combs are one such new tool [5–14]. Capable of rapid acquisition via dual-comb spectroscopy (DCS) [15], and with a relative frequency axis defined by a radiofrequency (RF) clock, EO frequency comb spectroscopy avoids many systematic phenomena that ultimately limit even fast-scanning continuous-wave (CW) spectroscopies.…”

“…In combination with an all-fiber system, including fiber-coupled reference and sample gas cells, these properties enable rapid acquisition and therefore invite deep averaging of spectroscopic parameters. Notability, our all-fiber system outperforms an earlier fiber-based comb spectrometer [16] in several key metrics: signal-to-noise ratio (4-fold), acquisition time (5-fold), and achievable resolution [14].…”