Ren Xinyi, Pan Jin, Yan Ming, Sheng Jiteng, Yang Cheng, Zhang Qiankun, Ma Hui, Wen Zhaoyang, Huang Kun, Wu Haibin, Zeng Heping
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200062, China.
Chongqing Key Laboratory of Precision Optics, Chongqing Institute of East China Normal University, Chongqing, 401120, China.
Nat Commun. 2023 Aug 18;14(1):5037. doi: 10.1038/s41467-023-40771-3.
Optical cavities are essential for enhancing the sensitivity of molecular absorption spectroscopy, which finds widespread high-sensitivity gas sensing applications. However, the use of high-finesse cavities confines the wavelength range of operation and prevents broader applications. Here, we take a different approach to ultrasensitive molecular spectroscopy, namely dual-comb optomechanical spectroscopy (DCOS), by integrating the high-resolution multiplexing capabilities of dual-comb spectroscopy with cavity optomechanics through photoacoustic coupling. By exciting the molecules photoacoustically with dual-frequency combs and sensing the molecular-vibration-induced ultrasound waves with a cavity-coupled mechanical resonator, we measure high-resolution broadband ( > 2 THz) overtone spectra for acetylene gas and obtain a normalized noise equivalent absorption coefficient of 1.71 × 10 cm·W·Hz with 30 GHz simultaneous spectral bandwidth. Importantly, the optomechanical resonator allows broadband dual-comb excitation. Our approach not only enriches the practical applications of the emerging cavity optomechanics technology but also offers intriguing possibilities for multi-species trace gas detection.
光学腔对于提高分子吸收光谱的灵敏度至关重要，分子吸收光谱在高灵敏度气体传感领域有着广泛的应用。然而，高精细度腔的使用限制了其工作波长范围，阻碍了更广泛的应用。在此，我们采用了一种不同的超灵敏分子光谱方法，即双梳光机械光谱法（DCOS），通过光声耦合将双梳光谱的高分辨率复用能力与腔光机械学相结合。通过用双频梳对分子进行光声激发，并利用与腔耦合的机械谐振器来检测分子振动引起的超声波，我们测量了乙炔气体的高分辨率宽带（>2太赫兹）泛音光谱，并在30吉赫兹的同时光谱带宽下获得了1.71×10厘米·瓦·赫兹的归一化噪声等效吸收系数。重要的是，光机械谐振器允许宽带双梳激发。我们的方法不仅丰富了新兴腔光机械学技术的实际应用，还为多物种痕量气体检测提供了有趣的可能性。
