Prism SPR (Surface Plasma wave Resonance) high-sensitivity fiber liquid refractive index sensor

Abstract

The invention relates to a prism SPR (Surface Plasma wave Resonance) high-sensitivity fiber liquid refractive index sensor, which is mainly characterized in that a laser light is coupled to a Y-shaped polarization-maintaining fiber coupler by a P-laser polarizer and a polarization-maintaining fiber collimator; the SPR is excited twice by the laser light outgoing from a sensing light branch polarization-maintaining fiber collimator; the reflection light reaches a sensing light branch optical-to-electrical converter after the two times of SPR excitation; a laser light outgoing from a reference light branch fiber collimator is coupled to a reference light branch optical-to-electrical converter; the light signals are converted into electrical signals by the reference light branch optical-to-electrical converter and the sensing light branch optical-to-electrical converter; the electrical signals are transmitted to an amplifier and an A / D converter; and the converted digital signals are transmitted to a data processing device for data processing. The invention has a simple structure, reduces the energy loss of P-laser, improves the signal-to-noise ratio and the sensitivity and allows long-distance application.

Description

technical field [0001] The invention belongs to the technique of measuring liquid refraction index based on SPR, in particular to an intensity modulation type prism SPR high-sensitivity optical fiber liquid refraction index sensor. Background technique [0002] Surface plasmon wave resonance (SPR) is a physical optical phenomenon that occurs at the interface between metals and dielectrics, and it is very sensitive to changes in the refractive index of the surrounding medium. At present, the sensor structure based on the SPR effect has been widely used in liquid substance detection technology, such as biochemistry, environmental monitoring, drug development and food safety, and has been widely used in the detection of gene mutations, the determination of biomolecular reaction kinetics, and the monitoring of industrial wastewater and waste gas. to make significant progress. There are four detection and analysis methods for prism sensors based on SPR: [0003] (1) Angle modul...

AI Technical Summary

Problems solved by technology

This sensing method does not use a polarization-maintaining fiber collimator and a polarization-maintaining fiber Y-shaped coupler, so the method proposed in Document 1 cannot be used to improve accuracy; nor is a total reflection prism used to make a beam of measurement light excite the SPR twice , so that the sensitivity cannot be further improved

In short, the method of Document 2 has shortcomings in eliminating background light interference, eliminating the influence of light source intensity fluctuations and improving measurement sensitivity

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