Michelson mode field interference refractive index sensor based on single-mode fiber

Abstract

The invention relates to a Michelson mode field interference refractive index sensor based on single-mode fiber. The Michelson mode field interference refractive index sensor comprises a laser source, a circulator, a spectrometer and a section of single-mode fiber with a notch formed by high-frequency CO2 laser etching, wherein the laser source is connected with a first port of the circulator, the single-mode fiber with the notch formed by the high-frequency CO2 laser etching is accessed to a second port of the circulator, and the spectrometer is accessed to a third port of the circulator. Due to the high-frequency CO2 laser etching, the notch can be formed in a fiber cladding of common fiber, when light transmitted from the circulator to the fiber passes through the notch, part of the light enters the fiber cladding and then is reflected back by a high-reflecting surface, and the light in the cladding is coupled into a fiber core of the fiber when the part of the light passes through the notch again. Certain phase difference of the light can be formed due to the difference of refractive indexes in the cladding and the fiber core, so that the interference occurs. When the external refractive index changes, the wavelength of an interference peak shifts, and the measurement of the external environment such as the refractive index can be realized by detecting the shift of the interference peak.

Description

technical field [0001] The invention belongs to the field of optical fiber components, and in particular relates to a Michelson mode field interference refractive index sensor which can be used in the field of optical fiber sensing. Background technique [0002] Refractive index is a very important parameter in the fields of physics, biology, chemistry and other disciplines, and its accurate measurement is of great significance and application in chemical industry, medicine, food and other related departments. Therefore, many methods for measuring the refractive index have emerged. Traditional measurement methods include grazing incidence method, diffraction grating method, laser irradiation method and CCD measurement method, as well as measurement methods such as broadband absorption spectroscopy, titration and fluorescence quenching, but most of these methods are limited to the visible light range and are The sampling method cannot be monitored in real time. Subsequently,...

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Problems solved by technology

Traditional measurement methods include grazing incidence method, diffraction grating method, laser irradiation method and CCD measurement method, as well as measurement methods such as broadband absorption spectroscopy, titration method and fluorescence quenching, but most of these methods are limited to the visible light range and are The sampling method cannot be monitored in real time. Subsequently, some new technologies such as photoacoustics, SPR sensors and Raman spectroscopy have emerged one after another, and now many refractive index sensors generally use photonic crystal fiber gratings, but these methods are expensive and difficult to operate.

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