Shot-noise-limited Doppler-broadened noise-immune cavity-enhanced optical heterodyne molecular spectrometry

Gang, Zhao; Hausmaninger, Thomas; Ma, Weiguang; Axner, Ove

doi:10.1364/ol.43.000715

Cited by 25 publications

(17 citation statements)

References 32 publications

(27 reference statements)

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“…A comparison between the panels (a) and (b) shows, in agreement with the results of Ref. [55], that the balanced detection can remove the wide structure of the background that mainly originates from the EOM and deteriorates the long-term performance of Db NICE-OHMS. It shows that it also eliminates the noise from the narrowest etalons (those with smallest FSR), presumed to originate from interference between the output surface of the output fiber of the laser and the f-C.…”

Section: System Evaluation -Reduction Of Influence Of Background Signalssupporting

confidence: 88%

“…1, is, to a large extent, based on that for balanced detection Db NICE-OHMS presented in Ref. [55]. In short, the system is constructed based on an EDFL that operates at around 1534 nm, addressing an acetylene transition at 6518.4858 cm -1 with a line strength of 8.572×10 -21 cm -1 /(mol cm -2 ) and a dipole moment of 8.0 mD.…”

Section: Methodsmentioning

confidence: 99%

“…As was alluded to above, to reduce the amount of background signals generated in the optical system before the PBS, especially in the f-EOM, a balanced detection scheme was implemented [55]. A part of the incoming light, deflected by the PBS, was detected by a third photodetector (PD3), whose signal was demodulated in the same way as the signal from the photodetector detecting the transmission NICE-OHMS signal, i.e.…”

Section: Methodsmentioning

confidence: 99%

“…Due to their narrow linewidth and intrinsic stable performance, a number of realizations of the NICE-OHMS technique, based on such lasers, with successively improved detection sensitivities for Db detection have been presented in a series of works [39, 40, 43, 46-49, 54, 55]. Most recently, based on balanced detection, a system for shot noise limited Db detection with an unprecedented detection sensitivity of 2.2 × 10 -14 cm -1 (for an integration time of 200 s) was demonstrated [55]. Despite the latter achievement, the experimental system used in that work was found not to be shot noise limited for sD detection.…”

Section: Introductionmentioning

confidence: 99%

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High-resolution trace gas detection by sub-Doppler noise-immune cavity-enhanced optical heterodyne molecular spectrometry: application to detection of acetylene in human breath

et al. 2019

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A sensitive high resolution sub-Doppler detecting spectrometer, based on noiseimmune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS), for trace gas detection of species whose transitions have severe spectral overlap with abundant concomitant species is presented. It is designed around a NICE-OHMS instrumentation utilizing balanced detection that provides shot-noise limited Doppler-broadened detection. By synchronous dithering the positions of the two cavity mirrors, the effect of residual etalons between the cavity and other surface in the system could be reduced. An Allan deviation of the absorption coefficient of 2.2 × 10 -13 cm -1 at 60 s, which, for the targeted transition in C2H2, corresponds to a 3σ detection sensitivity of 130 ppt, is demonstrated. It is shown that despite significant spectral interference from CO2 at the targeted transition, which precludes Db detection of C2H2, acetylene could be detected in exhaled breath of healthy smokers.

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Section: System Evaluation -Reduction Of Influence Of Background Signalssupporting

confidence: 88%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High-resolution trace gas detection by sub-Doppler noise-immune cavity-enhanced optical heterodyne molecular spectrometry: application to detection of acetylene in human breath

et al. 2019

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“…Of these, only CRDS is calibration-free, while the other techniques require an independent measurement of the cavity finesse to quantify the absorption. Simultaneous information about molecular absorption and dispersion is provided by noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS), which combines cavity enhancement with frequency modulation (FM) [6,7]. However, because of the use of the FM scheme, NICE-OHMS requires calibration using samples with a known concentration.…”

Section: Introductionmentioning

confidence: 99%

Broadband calibration-free cavity-enhanced complex refractive index spectroscopy using a frequency comb

Johansson¹,

Rutkowski²,

Filipsson³

et al. 2018

Opt. Express

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We present broadband cavity-enhanced complex refractive index spectroscopy (CE-CRIS), a technique for calibration-free determination of the complex refractive index of entire molecular bands via direct measurement of transmission modes of a Fabry-Perot cavity filled with the sample. The measurement of the cavity transmission spectrum is done using an optical frequency comb and a mechanical Fourier transform spectrometer with sub-nominal resolution. Molecular absorption and dispersion spectra (corresponding to the imaginary and real parts of the refractive index) are obtained from the cavity mode broadening and shift retrieved from fits of Lorentzian profiles to the individual cavity modes. This method is calibration-free because the mode broadening and shift are independent of the cavity parameters such as the length and mirror reflectivity. In this first demonstration of broadband CE-CRIS we measure simultaneously the absorption and dispersion spectra of three combination bands of CO in the range between 1525 nm and 1620 nm and achieve good agreement with theoretical models. This opens up for precision spectroscopy of the complex refractive index of several molecular bands simultaneously.

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Advances in cavity-enhanced methods for high precision molecular spectroscopy and test of fundamental physics

Gianfrani,

Hu,

Ubachs

2024

Riv. Nuovo Cim.

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Cavity-enhanced spectroscopic techniques are highly sensitive laser-based methods for interrogating the atomic and molecular constituents of any gaseous medium that is confined into an optical resonator. A first advantage over conventional absorption spectroscopy comes from the extremely long path length of the laser radiation inside the stable, high-finesse, optical cavity, which allows the sample to be probed over several tens of kilometers. After more than 30 years of research and development, techniques like cavity ring-down spectroscopy, cavity-enhanced absorption spectroscopy, and noise-immune cavity-enhanced optical-heterodyne molecular spectroscopy, have reached extraordinary levels of detection sensitivity, such that it is possible to measure light absorption from molecules in trace amounts or extremely weak spectral lines of more abundant species. A second advantage of the use of high-finesse cavities lies in the power amplification achieved inside the optical resonator, making it possible to saturate even weak transitions, thus reducing the width of spectral lines by some three orders of magnitude. Combining these methods with frequency comb technologies has further enhanced their capabilities, adding metrology-grade qualities to spectroscopic determinations such as transition frequencies of molecular resonances, which can be measured with sub-kHz accuracy. In this review article, we discuss the current status of highly precise and highly sensitive laser spectroscopy for fundamental tests and measurements. We describe state-of-the-art molecular spectroscopy methods and their application to a few selected molecules of fundamental importance in understanding quantum chemistry theories or testing quantum electrodynamics.

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Shot-noise-limited Doppler-broadened noise-immune cavity-enhanced optical heterodyne molecular spectrometry

Cited by 25 publications

References 32 publications

High-resolution trace gas detection by sub-Doppler noise-immune cavity-enhanced optical heterodyne molecular spectrometry: application to detection of acetylene in human breath

High-resolution trace gas detection by sub-Doppler noise-immune cavity-enhanced optical heterodyne molecular spectrometry: application to detection of acetylene in human breath

Broadband calibration-free cavity-enhanced complex refractive index spectroscopy using a frequency comb

Advances in cavity-enhanced methods for high precision molecular spectroscopy and test of fundamental physics

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