Method for measuring refractive index by using conical coreless optical-fiber-cascaded hollow-core optical fiber structure

Abstract

The invention discloses a method for measuring a refractive index by using a conical coreless optical-fiber-cascaded hollow-core optical fiber structure. The specific refractive index measurement process is implemented as follows: arranging a conical coreless optical-fiber-cascaded hollow-core optical fiber as a sensing head in a room temperature environment and fixing the prepared sensing head ona slide stably and horizontally by using ultraviolet glue to prevent fiber bending; immersing the sensor into NaCl aqueous solutions with different concentrations, namely different refractive indexes, recording a transmission spectrum, purifying the sensing head by using deionized water, recovering an original spectrum in air, then immersing the sensing head into a new NaCl aqueous solution, recording a new transmission spectrum, and finally acquiring a corresponding linear relationship between the changes of the wavelength and intensity of the transmission spectrum and the refractive index and realizing the measurement of the refractive index according to the corresponding linear relationship. According to the invention, the thermal expansion coefficient of the coreless optical fiber islow and thus the sensor has extremely low temperature sensitivity, so that a problem of temperature crosstalk can be effectively solved.

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 tapered coreless optical fiber cascaded hollow-core optical fiber structure. Background technique [0002] In recent years, refractive index measurement has played an important role in chemical and biological fields such as chemical experiments, food quality and safety monitoring, environmental monitoring, and biological reactions. Optical fiber refractive index sensors are characterized by their compact structure, high detection accuracy, good aging resistance, and energy The unique advantages of working in a chemically hazardous environment and the inherent ability to resist external electromagnetic interference have been extensively studied. Among various optical fiber refractive index sensors, sensors based on Mach-Zehnder interferometers have attracted widespread attention due to their ...

AI Technical Summary

Problems solved by technology

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

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