Sub-femtometer-resolution absolute spectroscopy with sweeping electro-optic combs

Abstract

Optical frequency comb with evenly spaced lines over a broad bandwidth has revolutionized the fields of optical metrology and spectroscopy. Here, we propose a fast interleaved dual-comb spectroscopy with sub-femtometer-resolution and absolute frequency, in which two electro-optic frequency combs are swept. Electrically-modulated stabilized laser enables ultrahigh resolution of 0.16 fm (or 20 kHz in optical frequency) and single-shot measurement in 90 ms. Total 20 million points are recorded spanning 3.2 nm (or 400 GHz) bandwidth, corresponding to a spectral sampling rate of 2.5 × 10 8 points/s under Nyquist-limitation. Besides, considering the trade-off between the measurement time and spectral resolution, a fast single-shot measurement is also realized in 1.6 ms with 8 fm (or 1 MHz) resolution. We demonstrate the 25averaged result with 30.6 dB spectral measurement signal-to-noise ratio (SNR) by reducing the filter bandwidth in demodulation. The results show great prospect for precise measurement with flexibly fast refresh time, high spectral resolution, and high SNR.

High-sensitivity methane detection based on QEPAS and H-QEPAS technologies combined with a self-designed 8.7 kHz quartz tuning fork

“…Various technologies for gas detection such as the thermal, mechanical, electrochemical, and optical have been developed in recent years [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] . Among these, laser absorption spectroscopy (LAS) stands out as an optical technology that offers numerous benefits compared to others, such as fast responses, long-term stability, low baseline drift, and high sensitivity and selectivity [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] .…”

Whispering-gallery-mode barcode-based broadband sub-femtometer-resolution spectroscopy with an electro-optic frequency comb

“…EOFC can be generated by overdriving modulators using a high-voltage signal for high-order sidebands with a limited number of comb lines 30 , 31 . Recent demonstrations using tailored waveforms in electro-optic modulation could cost-effectively generate more comb lines.…”

“…EOFC can be generated by overdriving modulators using a high-voltage signal for high-order sidebands with a limited number of comb lines. 30,31 Recent demonstrations using tailored waveforms in electro-optic modulation could cost-effectively generate more comb lines. Tailored waveforms are designed by inverse Fourier transformation of equidistant frequency components, including pseudo-random bit sequence, 24,32 frequency chirp, 33,34 pulse, 35 or chirped pulse, 36,37 generated from arbitrary waveform generator, programmable pulse generator, step recovery diode, 38 and direct digital synthesizer.…”

Ultra-highly sensitive dual gases detection based on photoacoustic spectroscopy by exploiting a long-wave, high-power, wide-tunable, single-longitudinal-mode solid-state laser

“…Trace gas typically refers mixture with analytes in volume concentrations ranging from ppt (part-per-trillion, 10 −12 ) to ppm (part-per-million, 10 −6 ). Selective and sensitive trace gas monitoring embraces different applications, spanning from early fire alarm 1 , 2 to medical diagnosis 3 , 4 , together with air pollutant detection, which has caused severe environmental issues, such as the greenhouse effect 5 – 8 and photochemical smog 9 – 11 . Improving the sensitivity of trace gas detection is of great significance for the further developments of these applications.…”