CN203337542U

CN203337542U - FBG (Fiber Bragg Grating) demodulation-based photonic crystal fiber refractive index sensor

Info

Publication number: CN203337542U
Application number: CN2013202686153U
Authority: CN
Inventors: 钱文文; 权鹏飞
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-05-14
Filing date: 2013-05-14
Publication date: 2013-12-11
Anticipated expiration: 2023-05-14

Abstract

The utility model discloses an FBG (Fiber Bragg Grating) demodulation-based photonic crystal fiber refractive index sensor which is characterized by comprising a light source, a 3-dB coupler, a photonic crystal fiber, an FBG and a light intensity detector, wherein two ports on one side of the 3-dB coupler are respectively connected with the light source and the light intensity detector through optical fibers, a port on the other side of the 3-dB coupler is connected with one end of the photonic crystal fiber through an optical fiber, the other end of the photonic crystal fiber is connected with the FBG through an optical fiber, and the connection of optical fibers at two ends of the photonic crystal fiber is a collapse welding of the photonic crystal fiber and an optical fiber. The FBG demodulation-based photonic crystal fiber refractive index sensor has the advantages of simple structure, low system manufacture cost, temperature insensitivity and the like and can be conveniently carried for outdoor work.

Description

A kind of photon crystal optical fibre refractivity sensor based on the FBG demodulation

Technical field

The utility model belongs to the index sensor technical field, relates to a kind of photon crystal optical fibre refractivity sensor based on Fiber Bragg Grating FBG (fiber Bragg grating, FBG) demodulation.

Background technology

Refractive index is a kind of basic physical property of material.Refractometry is the indispensable means of technology controlling and process in food production, by measuring the refractive index of food liquid, can identify the composition of food, determines the concentration of food, pure degree and the quality of judgement food.Refractometry simultaneously also is widely used in monitoring and the control of environmental pollution, by the refractive index size of monitoring water quality, can judge whether heavy metal pollution exceeds standard.So develop, one simple in structure, measurement is accurate, the rational index sensor of cost extremely is necessary also have very large use value and the market space.

The types of fiber index sensor relies on its simple in structure, advantages such as volume is little, anti-electromagnetic interference (EMI), by extensive exploitation, is applied.At present, the types of fiber index sensor mainly can be divided into two large classes.One class is fiber grating class index sensor, comprise FBG, long period fiber grating (long period grating after processing, LPG) and inclined optical fiber grating (titled fiber Bragg grating, TFBG), its main sensing principle is by extraneous refractive index, the impact of the resonance wavelength of fiber grating to be realized the monitoring of refractive index.Equations of The Second Kind is based on the optic fibre refractive index sensor of interfere type, comprises Febry-Perot structure, Michelson structure and single mode-multi-mode-single mode structure, and its cardinal principle is that the drift that affects interference fringe by refraction index changing realizes refractive index sensing.But existing types of fiber index sensor all needs a costliness and the spectroanalysis instrument that is difficult for carrying as monitoring terminal.

In sum, existing types of fiber index sensor all needs expensive spectroanalysis instrument as monitoring instrument, makes whole sensor-based system cost higher, and very not portable, be unfavorable for outdoor monitoring.

Summary of the invention

The purpose of this utility model is to overcome that existing fiber class index sensor cost is high, volume is large and the problem such as not portable, proposes a kind of photon crystal optical fibre refractivity sensor based on the FBG demodulation, and cost is low, simple in structure, and it is convenient to carry.

Technical solution of the present utility model is as follows:

A kind of photon crystal optical fibre refractivity sensor based on the FBG demodulation, is characterized in that, comprises light source, 3-dB coupling mechanism, photonic crystal fiber, FBG and light intensity detector; 3-dB coupling mechanism two ports on one side are connected with light intensity detector optical fiber with light source respectively, the port of 3-dB coupling mechanism another side is connected with an end optical fiber of photonic crystal fiber, the photonic crystal fiber other end is connected with FBG optical fiber, and the optical fiber at photonic crystal fiber two ends is connected to the welding of caving in of photonic crystal fiber and optical fiber.

The advantage that the utility model has is: a kind of photon crystal optical fibre refractivity sensor based on the FBG demodulation, by photonic crystal fiber as the refractive index sensing head, FBG is as light signal demodulation device, and light intensity detector, as sense terminals, is realized the sensing of refractive index.Compare with traditional Fibre Optical Sensor, use the light intensity detector that price is low, volume is little, easy to use to replace expensive, not portative spectroanalysis instrument, greatly reduce the cost of manufacture of whole sensor-based system, improve the portability of the outdoor use of sensor-based system.In addition, use photonic crystal fiber as sensing head, can realize the experimental error that temperature variation causes, realize the anti-interference to temperature.

The accompanying drawing explanation

Fig. 1 is structural representation of the present utility model.

Embodiment

Below in conjunction with accompanying drawing, the utility model is further described.

As shown in Figure 1, a kind of photon crystal optical fibre refractivity sensor based on the FBG demodulation, is characterized in that, comprises light source 1,3-dB coupling mechanism 2, photonic crystal fiber 3, FBG4 and light intensity detector 5; 3-dB coupling mechanism 2 two ports on one side are connected with light intensity detector 5 optical fiber with light source 1 respectively, the port of 3-dB coupling mechanism 2 another sides is connected with an end optical fiber of photonic crystal fiber 3, photonic crystal fiber 3 other ends are connected with FBG4 optical fiber, and the optical fiber at photonic crystal fiber 3 two ends is connected to the welding of caving in of photonic crystal fiber 3 and optical fiber.

The utility model is based on following principle:

The welding of being caved in of the optical fiber at photonic crystal fiber and two ends, thus a mode interferometer formed, and this mode interferometer is the refractive index sensitivity to external world.When extraneous refractive index changes, cause the pattern interference spectum of photonic crystal fiber to be offset, corresponding the variation will occur in the light intensity of a certain specific wavelength.When connect the FBG of a specific reflection wavelength in the photonic crystal fiber rear end, demodulation device by FBG as this system, FBG reflexes to light intensity detector by the light intensity with the refractive index signal at specific reflection wavelength place, thereby realizes the sensing of refractive index by the monitoring light intensity magnitude.The utlity model has simple in structurely, cost of manufacture is low, and the advantage such as be easy to carry, have good practical value and market application foreground.

Claims

1. the photon crystal optical fibre refractivity sensor based on the FBG demodulation, is characterized in that, comprises light source, 3-dB coupling mechanism, photonic crystal fiber, FBG and light intensity detector; 3-dB coupling mechanism two ports on one side are connected with light intensity detector optical fiber with light source respectively, the port of 3-dB coupling mechanism another side is connected with an end optical fiber of photonic crystal fiber, the photonic crystal fiber other end is connected with FBG optical fiber, and the optical fiber at photonic crystal fiber two ends is connected to the welding of caving in of photonic crystal fiber and optical fiber.