CN103076303A - Stress long-period fiber grating liquid refraction index sensor based on side hole single-mode fiber - Google Patents

Abstract

The invention belongs to the technical field of optical fiber sensing, and in particular relates to a stress long-period optical fiber grating liquid refractive index sensor based on a side-hole single-mode optical fiber. A section of side-hole single-mode optical fiber is placed in two periodic pressure grooves, and pressure is applied to the periodic pressure grooves to obtain a stressed long-period fiber grating. When the liquid is poured into the side hole of the stressed long-period fiber grating through the bare fiber adapter, the effective refractive index of the cladding of the long-period fiber grating is changed. Move accordingly. By monitoring the drift of the resonant peak of the long-period fiber grating with a spectrometer, the corresponding liquid refractive index information can be demodulated. The invention adopts the method of pouring the liquid to be measured into the side hole of the cladding, has higher sensitivity, can realize one-time sensing measurement, and has great development potential in the field of biosensing requiring high sensitivity.

Description

A Stressed Long Period Fiber Bragg Grating Liquid Refractive Index Sensor Based on Side Hole Single-mode Optical Fiber

technical field

The patent of the invention belongs to the technical field of optical fiber sensing, and specifically relates to a stress long-period optical fiber grating liquid refractive index sensor based on a side-hole single-mode optical fiber. the

Background technique

In the modern information society, sensors are the main ways and means to obtain accurate information in the fields of nature and production. Traditional sensors represented by piezoelectric, electromagnetic and semiconductor sensors are widely used due to their simple principle, high measurement accuracy and low cost. However, in the case of strong electromagnetic interference or flammable and explosive occasions, traditional sensors based on electrical signal measurement are difficult to detect effectively, so traditional sensors can no longer meet the needs of modern science and technology development. the

Compared with traditional sensors, fiber optic sensors have the advantages of corrosion resistance, anti-electromagnetic interference, and suitable for use in flammable and explosive environments. Stressed long-period fiber gratings use periodic pressure grooves to exert pressure on the single-mode fiber in the axial direction, so that the fiber undergoes periodic physical micro-bending deformation along the axial direction to form a long-period fiber grating. Compared with the traditional long-period fiber grating manufacturing method, this method has the advantages of simple manufacture and low cost. At the same time, the liquid to be measured is poured into the side hole of the cladding, which has higher sensitivity and can realize one-time sensing measurement, and has great development potential in the field of biosensing requiring high sensitivity. the

Contents of the invention

Aiming at the problems existing in the prior art, the purpose of the patent of the present invention is to provide a technical solution of a stress long-period fiber grating liquid refractive index sensor based on a side-hole single-mode optical fiber. the

The described stress long-period fiber grating liquid refractive index sensor based on side-hole single-mode fiber is characterized in that it includes a broadband light source, a spectrometer, two bare fiber adapters, a side-hole single-mode fiber, and a periodic pressure tank. One end of the first bare fiber adapter is connected to the broadband light source, the other end is connected to one end of the side-hole single-mode fiber, the other end of the side-hole single-mode fiber is connected to a port of the second bare fiber adapter, and the other end of the second bare fiber adapter is connected to the spectrometer, A section of the side-hole single-mode fiber is placed in two periodic pressure grooves, and pressure is applied to the periodic pressure grooves to obtain a stress long-period fiber grating on the side-hole single-mode fiber. the

The described stress long-period fiber grating liquid refractive index sensor based on side-hole single-mode optical fiber is characterized in that a section of the side-hole single-mode optical fiber is placed between two periodic pressure grooves, and passes through the periodic pressure groove. Apply pressure to get a stressed long-period fiber grating on an edge-hole single-mode fiber. the

Said a stress long-period fiber grating liquid refractive index sensor based on side-hole single-mode fiber is characterized in that the two ends of the side-hole single-mode fiber of the pressure long-period fiber grating are respectively connected with two bare fiber adapters to form an open liquid Refractive index measurement structure. the

Said a stress long-period fiber grating liquid refractive index sensor based on side-hole single-mode optical fiber is characterized in that the two small holes of the side-hole single-mode fiber of the pressure long-period fiber grating are located in the fiber cladding, and can be real-time in the holes. Pour in the liquid to be measured. the

The advantage of the patent of the present invention is that the long-period fiber grating is obtained by applying pressure to the side-hole single-mode optical fiber by periodic pressure grooves, which is simple to manufacture and low in cost, and long-period fiber gratings with different parameter structures can be obtained by changing the period of the pressure groove; in addition , the optical fiber used in this device is a side hole single-mode fiber. When the liquid enters the side hole of the single-mode fiber, compared with the conventional long-period liquid refractive index sensor, the change of the effective refractive index of the cladding is more sensitive, so a higher According to the liquid refraction measurement results, the sensor device has the advantages of compact structure, small volume, low cost, simple fabrication and high sensitivity, and can be widely used in various high-sensitivity biological sensing. the

Description of drawings

Fig. 1 is a schematic diagram of the structure of the patent of the present invention, and Fig. 2 is a schematic diagram of the end face of the periodic pressure groove required for the manufacture of the stress long-period fiber grating of the patent of the present invention. Fig. 3 is a schematic view of the end face of the patented side-hole single-mode optical fiber of the present invention. the

Detailed ways

The patent of the present invention will be further described below in conjunction with the accompanying drawings of the description. the

As shown in Figure 1, a stress long-period fiber grating liquid refractive index sensor based on a side-hole single-mode fiber, including a broadband light source 1, two bare fiber adapters 2, 3, a periodic pressure groove 4, and a side-hole single-mode fiber 5. Spectrometer 6, one end of the first bare fiber adapter 2 is connected to the broadband light source 1, the other end of the first bare fiber adapter 2 is connected to one end of the side-hole single-mode fiber 5, and the other end of the side-hole single-mode fiber 5 is connected to the second One end of the bare fiber adapter 3 is connected, and the other end of the second bare fiber adapter 3 is connected to the spectrometer 6. A section of the side-hole single-mode fiber 5 is placed in two periodic pressure grooves 4, and pressure is applied to the periodic pressure groove 4. Stressed long-period fiber gratings are obtained on the side-hole single-mode fiber 5 . When the light emitted by the broadband light source 1 passes through the stress long-period fiber grating, the transmission spectrum of the stress long-period fiber grating is output at the output port of the spectrometer 6 . the

The working mode of the patent of the present invention is: the light emitted by the broadband light source enters the side-hole single-mode fiber through the bare fiber adapter, propagates in the side-hole single-mode fiber, and then outputs to the spectrometer through the bare fiber adapter. The single-mode side-hole optical fiber is pressed by periodic pressure grooves, and it undergoes periodic physical micro-bending deformation along the axial direction, and the refractive index of the optical fiber also changes periodically due to the photoelastic effect, thereby forming a stress long-period grating. When the liquid is poured into the side hole of the stressed LPFG through the bare fiber adapter, the effective refractive index of the cladding of the LPFG is changed, thereby changing the transmission mode in the LPFG, which leads to a gap between the cladding mode and the guided mode. The change of coupling coefficient and phase matching wavelength is finally manifested by the change of absorption peak intensity and central wavelength in the transmission spectrum. As the external refractive index of the poured liquid changes, the central wavelength of the coupling resonance peak of the long-period grating moves correspondingly. By monitoring the drift of the resonant peak of the long-period fiber grating with a spectrometer, the corresponding liquid refractive index information can be demodulated. the

The key technology of the invention patent that can realize high-sensitivity measurement is: using periodic pressure grooves to apply stress to the side-hole single-mode fiber to produce a long-period fiber grating, which is simple to manufacture and low in processing cost; at the same time, through the bare fiber adapter in the fiber side hole The liquid is injected in real time. Since the side hole is in the cladding of the optical fiber, compared with the traditional liquid on the surface of the cladding of the optical fiber, the change of the refractive index of the liquid can change the effective refractive index of the cladding of the long-period fiber grating more sensitively. By detecting the long-term The refraction index of the liquid can be obtained from the drift of the resonant peak of the periodic fiber grating. the

In this embodiment, the selected side-hole single-mode fiber has a core diameter of a standard single-mode fiber, and a cladding diameter of 125 μm. There are two symmetrical side holes in the cladding, and the diameter of the holes is 30-50 μm. The periodic pressure groove period is 0.3-0.6mm, and the groove depth is about 0.3mm. the

Claims (4)

1. A stress long-period fiber grating liquid refractive index sensor based on side-hole single-mode optical fiber, characterized in that it comprises a broadband light source (1), two bare fiber adapters (2,3), periodic pressure tanks (4), Side-hole single-mode fiber (5), spectrometer (6), one end of the first bare fiber adapter (2) is connected to a broadband light source (1), and the other end of the first bare fiber adapter (2) is connected to the side-hole single-mode fiber (5) One end is connected, the other end of the side-hole single-mode fiber (5) is connected to one end of the second bare fiber adapter (3), the other end of the second bare fiber adapter (3) is connected to the spectrometer (6), and the side-hole single-mode fiber A section of (5) is placed in two periodic pressure grooves (4), and pressure is applied to the periodic pressure grooves (4) to obtain a stress long-period fiber grating on the side-hole single-mode optical fiber (5). 2. A kind of stress long-period fiber grating liquid refractive index sensor based on side-hole single-mode fiber according to claim 1, characterized in that a section of side-hole single-mode fiber (5) is placed in two periodic pressure tanks Between (4), stress long-period fiber gratings are obtained on side-hole single-mode fibers by applying pressure to periodic pressure grooves. 3. A kind of stress long-period fiber grating liquid refractive index sensor based on side-hole single-mode fiber according to claim 1, it is characterized in that the side-hole single-mode fiber (5) two ends of the pressure long-period fiber grating are respectively connected with two A bare fiber optic adapter (2, 3) is connected to form an open liquid refractive index measurement structure. 4. A kind of stress long-period fiber grating liquid refractive index sensor based on side-hole single-mode fiber according to claim 1, characterized in that the two small holes of the side-hole single-mode fiber (5) of the pressure long-period fiber grating are located at In the optical fiber cladding, the liquid to be measured can be poured into the hole in real time.

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