Method for measuring refractive index by utilizing broken line type conical multi-mode fiber cascade coreless optical fiber structure

Abstract

The invention discloses a method for measuring refractive index by utilizing a broken line type conical multi-mode fiber cascade coreless optical fiber structure. The specific refractive index measurement process is that a broken line type conical multi-mode fiber cascade coreless optical fiber serves as a sensing head and is placed in a room temperature environment, in order to prevent the optical fibers from being bent, the prepared sensing head is stably and horizontally fixed on a slide by using ultraviolet glue, then, the sensing head is immersed in NaCl aqueous solutions with different concentrations, namely different refractive indexes, after a transmission spectrum is recorded, deionized water is used for purifying the sensing head, the original spectrum in the air is restored, then, the sensing head is immersed in a new NaCl aqueous solution, a new transmission spectrum is recorded, the corresponding linear relation between the change of the wavelengths of the transmission spectrums and the refractive index is obtained, and the refractive index is measured according to the corresponding linear relation. The sensor in the invention has relatively high sensitivity in a low-refractive-index range, and the tiny refractive index change of the periphery can be accurately measured within a wide temperature range.

Description

technical field [0001] The invention belongs to the technical field of optical fiber spectrum sensing, and in particular relates to a method for measuring the refractive index by using a broken-line tapered multimode optical fiber cascaded coreless optical fiber structure. Background technique [0002] Refractive index measurements play an important role in biological, physical and chemical sensing systems. In recent years, fiber optic sensors have attracted extensive attention from researchers at home and abroad due to their unique advantages including compact structure, high-resolution detection, anti-aging ability, and inherent anti-interference ability. Among various optical fiber refractive index sensors, the sensor based on Mach-Zehnder interferometer has attracted widespread attention due to its simple structure, good repeatability, and low manufacturing cost. The transmission of various physical quantities can be realized by observing the change of the wavelength of ...

AI Technical Summary

Problems solved by technology

[0003] In order to solve the problems of poor stability, low sensitivity and resolution in the low refractive index range of the optical fiber spectral refractive index sensing system based on the Mach-Zehnder interferometer, the present invention provides a cascaded multimode optical fiber using broken line type tapered A method for measuring the refractive index of a coreless fiber structure. This method realizes the measurement of the refractive index by analyzing and studying the influence of different refractive indices on the interference peak wavelength of the transmission spectrum of the folded-line tapered multimode fiber cascaded coreless fiber structure.

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