Raman spectrum liquid detection method based on frequency doubling and hollow-core optical fiber in linear cavity

Abstract

The invention provides a Raman spectrum liquid detection method based on frequency doubling and hollow-core optical fiber in a linear cavity. The method comprises the steps that a continuous laser with the wavelength being 915 nanometers or 976 nanometers is used as a light source, a linear resonant cavity formed by a fiber bragg grating and an optical fiber total-reflection mirror is adopted, narrow-linewidth 532 nano laser is obtained through an active optical fiber and a lithium boric oxide frequency doubling crystal, and to-be-detected liquid is excited to generate Raman scattering light; meanwhile, the liquid detection method has the advantages of adopting few longitudinal modes, being good in coherence, compact in structure, high in detection efficiency and reliability and the like.

Description

technical field [0001] The invention relates to a Raman spectrum detection method, in particular to a Raman spectrum liquid detection method based on frequency doubling in a linear cavity and a hollow-core optical fiber. Background technique [0002] Raman spectroscopy is an analytical method to study the relationship between the scattering of compound molecules after being irradiated by light, the energy level difference between scattered light and incident light, and the vibration frequency and rotational frequency of compounds. Similar to infrared spectroscopy, Raman spectroscopy is a vibrational spectroscopy technique. The difference is that the former is related to the change of the dipole moment when the molecule vibrates, while the Raman effect is the result of the change of the polarizability of the molecule, and what is measured is the inelastic scattered radiation. In terms of liquid detection, Raman spectroscopy has technical advantages such as short analysis per...

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Problems solved by technology

[0003] However, Raman scattering is a kind of weak scattering, and there is a problem of insufficient sensitivity in practical operation. At present, it is more typical to adopt the method of multi-reflection enhancement. Although the multi-reflection cavity can greatly improve the Raman scattering intensity, many The secondary reflection cavity is enhanced by two high-reflectivity cavity mirrors, which have high requirements for optical path adjustment and system stability

At the same time, if the measurement object is a transparent organic liquid, it is easy to focus on the glass slide due to inaccurate focus

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