Evanescent Field Coupling Refractometer Between Optical Fibers and Its Detection Method

Abstract

The invention discloses an optical fiber inter-fiber evanescent field coupling refractometer and a detection method thereof, comprising a light source, an optical fiber sensor probe, an optical fiber coupler / circulator, a first photodetector, a second photodetector and data acquisition And the processing module; the fiber optic sensor probe includes the optical fiber and the D-type fiber that are arranged in parallel and closely attached to each other. The optical fiber of the fiber grating is connected to the input end of the second photodetector through a fiber coupler / circulator, and one end of the D-type fiber is connected to the input end of the first photodetector through a single-mode optical fiber, and the optical fiber engraved with a tilted optical fiber grating is coupled with the optical fiber One end connected to the device / circulator is on the same side as the end connected to the D-type optical fiber and the first photodetector; the first photodetector and the second photodetector are respectively connected to the data acquisition and processing module. It has the advantage of higher measurement accuracy of the refractive index.

Description

technical field [0001] The invention relates to the design field of a refractive index sensor, in particular to an optical fiber inter-fiber evanescent field coupling refractometer and a detection method thereof. Background technique [0002] Refractive index is an important physical parameter of liquid, and the measurement of refractive index is very important in the fields of environmental monitoring, food, chemistry and so on. The refractive index of a liquid is usually related to its concentration, composition, substance content and other parameters, so its physical and chemical properties can be grasped by measuring the change of the refractive index. Tilted fiber grating is a new type of optical fiber sensor. Due to the introduction of the grating tilt angle, the core mode of the forward transmission can effectively excite the cladding mode of the backward transmission. These cladding modes have different effective refractive indices, which are harmful to the environme...

AI Technical Summary

Problems solved by technology

However, these probe-type refractive index measurement methods based on the modification of the internal structure of the optical fiber couple to a relatively narrow cladding mode spectrum, which limits the measurement range of the refractive index, especially for biomedical reagents with low refractive index (close to 1.33). measurement, its low sensitivity

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