Quartz-enhanced multiheterodyne resonant photoacoustic spectroscopy

Quartz-enhanced multiheterodyne resonant photoacoustic spectroscopy

2024 | Jiapeng Wang, Hongpeng Wu, Angelo Sampaolo, Pietro Patimisco, Vincenzo Spagnolo, Suotang Jia, Lei Dong
This paper introduces an innovative technique called quartz-enhanced multiheterodyne resonant photoacoustic spectroscopy (QEMR-PAS), which extends the capabilities of dual-comb spectroscopy (DCS) to all wavelengths of light. QEMR-PAS down-converts the beat frequency response from a dual comb into the audio frequency domain, allowing gas molecules to act as optical-acoustic converters through the photoacoustic effect. Unlike conventional DCS, which relies on wavelength-dependent photoreceivers, QEMR-PAS uses a quartz tuning fork (QTF) as a high-Q sound transducer, working in conjunction with a phase-sensitive detector to extract the resonant sound component from multiple heterodyne acoustic tones. This approach enables wavelength-independent DCS detection for gas sensing, offering a dynamic range of 63 dB, a spectral resolution of 43 MHz (or ~0.3 pm), and a noise equivalent absorption of 5.99 × 10⁻⁵ cm⁻¹ Hz⁻¹/². The QEMR-PAS technique is demonstrated through experiments using a 1% C₂H₂N₂ mixture, showing excellent linearity and high spectral resolution. The system's performance is compared with conventional DCS and dual-frequency comb photoacoustic spectroscopy (DC-PAS), highlighting its advantages in dynamic range, spectral resolution, and noise performance. The study also discusses the potential for further improvements, including the use of mid-infrared combs and higher average power optical frequency combs.This paper introduces an innovative technique called quartz-enhanced multiheterodyne resonant photoacoustic spectroscopy (QEMR-PAS), which extends the capabilities of dual-comb spectroscopy (DCS) to all wavelengths of light. QEMR-PAS down-converts the beat frequency response from a dual comb into the audio frequency domain, allowing gas molecules to act as optical-acoustic converters through the photoacoustic effect. Unlike conventional DCS, which relies on wavelength-dependent photoreceivers, QEMR-PAS uses a quartz tuning fork (QTF) as a high-Q sound transducer, working in conjunction with a phase-sensitive detector to extract the resonant sound component from multiple heterodyne acoustic tones. This approach enables wavelength-independent DCS detection for gas sensing, offering a dynamic range of 63 dB, a spectral resolution of 43 MHz (or ~0.3 pm), and a noise equivalent absorption of 5.99 × 10⁻⁵ cm⁻¹ Hz⁻¹/². The QEMR-PAS technique is demonstrated through experiments using a 1% C₂H₂N₂ mixture, showing excellent linearity and high spectral resolution. The system's performance is compared with conventional DCS and dual-frequency comb photoacoustic spectroscopy (DC-PAS), highlighting its advantages in dynamic range, spectral resolution, and noise performance. The study also discusses the potential for further improvements, including the use of mid-infrared combs and higher average power optical frequency combs.
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