High refractive index sensor based on mode excitation thin-core optical fiber

Abstract

The invention provides a high refractive index sensor based on a mode excitation thin-core optical fiber. The high refractive index sensor based on the mode excitation thin-core optical fiber is characterized by comprising a single-mode optical fiber (1), a thin-core optical fiber (2) and a micro-arc area (3); the single-mode optical fiber (1), the thin-core optical fiber (2) and the micro-arc area (3) are connected with each other to form an all-fiber Michelson interferometer; the end surface of the micro-arc area (3) is used for exciting cladding modes with higher levels. When reaching a first fusion point, a fundamental mode transmitted in a single-mode optical fiber core is split and excited to form cladding modes of the partial thin-core optical fibers; when fiber core modes are coupled together with the cladding modes at the first fusion point, certain phase delay exists, so as to realize mode interference between the fiber core modes and the cladding modes. The high refractive index sensor based on the mode excitation thin-core optical fiber, provided by the invention, has the advantages that the cost is low, the high refractive index sensor is easy to make, the highest sensitivity of the high refractive index sensor within a refractive index range of 1.3321 RIU (Refractive Index Unit)-1.3823 RIU is 228.85 nm / RIU and -158.75 dB / RIU, the sensor is not sensitive to the temperature, can conduct both wavelength demodulation and intensity demodulation and can be used for refractive index monitoring in actual life.

Description

technical field [0001] The invention provides a high-refractive index sensor based on mode-excited thin-core optical fiber, which belongs to the technical field of optical fiber sensing. Background technique [0002] As a kind of fiber optic sensor, fiber optic refractive index sensor has attracted extensive attention because of its small structure, high sensitivity, and easy fabrication. In recent years, optical fiber refractive index sensors based on SPR (SurfacePlasmon Resonance), cladding erosion, thin tapered structure, fiber grating, etc. Etching and corroding thin core fiber on the core fiber, etc. Although these methods have improved the sensitivity of the refractive index to a certain extent, there are still some defects. For example, the fiber grating-based structure has temperature cross-sensitivity temperature, the dislocation-based structure has poor flexibility, and some processing processes that require chemical corrosion all increase the difficulty in the m...

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Problems solved by technology

For example, the fiber grating-based structure has temperature cross-sensitivity temperature, the dislocation-based structure has poor flexibility, and some processing processes that require chemical corrosion all increase the difficulty in the fabrication process.

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