Advanced Photonics, 2024, 6 (1): 016006, Published Online: Feb. 18, 2024
Whispering-gallery-mode barcode-based broadband sub-femtometer-resolution spectroscopy with an electro-optic frequency comb
Abstract
Spectroscopy is the basic tool for studying molecular physics and realizing biochemical sensing. However, it is challenging to realize sub-femtometer resolution spectroscopy over broad bandwidth. Broadband and high-resolution spectroscopy with calibrated optical frequency is demonstrated by bridging the fields of speckle pattern and electro-optic frequency comb. A wavemeter based on a whispering-gallery-mode barcode is proposed to link the frequencies of a probe continuous-wave laser and an ultrastable laser. The ultrafine electro-optic comb lines are generated from the probe laser to record spectrum of sample with sub-femtometer resolution. Measurement bandwidth is a thousandfold broader than comb bandwidth, by sequentially tuning the probe laser while its wavelength is determined. This approach fully exploits the advantages of two fields to realize 0.8-fm resolution with a fiber laser and 80-nm bandwidth with an external cavity diode laser. The spectroscopic measurements of an ultrahigh Q-factor cavity and gas molecular absorption are experimentally demonstrated. The compact system, predominantly constituted by few-gigahertz electronics and telecommunication components, shows enormous potential for practical spectroscopic applications.
Bingxin Xu, Yangyang Wan, Xinyu Fan, Zuyuan He. Whispering-gallery-mode barcode-based broadband sub-femtometer-resolution spectroscopy with an electro-optic frequency comb[J]. Advanced Photonics, 2024, 6(1): 016006.