Author Affiliations
Abstract
Shanghai Jiao Tong University, State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai, China
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.
frequency comb reconstructive wavemeter spectroscopy Advanced Photonics
2024, 6(1): 016006
Author Affiliations
Abstract
State Key Laboratory of Advanced Optical Communication Systems and Networks, Shanghai Jiao Tong University, Shanghai 200240, Chin
Accurate spectral measurement and wavelength determination are fundamental and vital for many fields. A compact spectrum analyzer with high performance is expected to meet the growing requirements, and speckle-based spectrum analyzer is a potential solution. The basic principle is based on using the random medium to establish a speckle-to-wavelength mapping relationship for spectrum reconstruction. This article introduces current speckle-based spectrum analyzers with different schemes and reviews recent advances in this field. Besides, some applications by using speckle-based spectrum analyzers are also introduced. Finally, the existing challenges and the future prospects of using speckle for spectrum recovery are discussed.
Speckle spectrum analyzer random medium spectroscopy Photonic Sensors
2021, 11(2): 187
