Reflection micro-flow sensing device based on single-hole microstructure optical fiber
Technical Field
The invention belongs to the technical field of optical fiber sensors, and particularly relates to a reflective micro-flow sensing device based on a single-hole microstructure optical fiber.
Background
With the rapid development of science and technology and the gradual maturity of related conditions, the sensing technology gradually receives wide attention. The research and development of the current sensing technology, especially the development of a novel sensing technology based on photoelectric communication and biological principles, have become important marks and power for promoting the advancement of the national and even world information-based industries. The optical fiber sensing technology is a novel sensing technology developed in the 70 s of the 20 th century, when light propagates in an optical fiber, parameters such as amplitude, phase, polarization state and wavelength of light wave can be directly or indirectly changed through reflection, refraction, absorption effect, Doppler effect and the like of the light under the action of factors such as external temperature, pressure, displacement, magnetic field, electric field, rotation and the like, so that the optical fiber can be used as a sensing element to detect various physical quantities. Currently, the optical fiber sensor has been implemented to measure more than 70 kinds of physical quantities of displacement, pressure, temperature, speed, vibration, liquid level, angle, and the like. Since the sensor has dynamic characteristics such as frequency response and step response, and static characteristics such as drift, repeatability, accuracy, sensitivity, resolution, linearity, etc., changes and fluctuations of external factors inevitably cause instability of the characteristics of the sensor itself, thereby greatly affecting the practical application thereof. The performance parameters and indexes of the sensor are optimized to the greatest extent according to the working principle and structure of the sensor, such as high sensitivity, stability in resisting disturbance, linearity, easiness in adjustment, high precision, no hysteresis, long service life, repeatability, ageing resistance, high response rate, environmental impact resistance, interchangeability, low cost, wide measurement range, small size, light weight, high strength and the like. The reflecting micro-flow cavity has the characteristics of high resolution, high measurement precision and simple structure, and the capillary optical fiber is used as a natural micro-flow channel, so that the cost is low, the mechanical strength is high, the F-P cavity is easily formed, and the multi-cavity F-P sensor is combined with the micro-structure optical fiber to form the multi-cavity F-P sensor to realize the micro-flow sensing in the fiber.
Disclosure of Invention
The invention aims to provide a reflective micro-flow sensing device based on a single-hole microstructure optical fiber according to the requirements in the background technology so as to realize high-precision measurement of the internal refractive index of the optical fiber. A reflection micro-flow sensing device based on a single-hole microstructure optical fiber is composed of a single-mode optical fiber (1), a hole-opening capillary optical fiber (2), a single-hole microstructure optical fiber (3) and a capillary optical fiber (4), wherein the hole-opening capillary optical fiber (2) is used as a liquid inlet, and the tail end (4) of the capillary optical fiber is used as a liquid outlet.
The technical scheme adopted for realizing the technical purpose is as follows:
further, the preparation method of the reflective micro-flow sensing device of the single-hole microstructure optical fiber comprises the following steps:
1) removing a coating layer of a section of single-mode optical fiber (1) and a capillary optical fiber (2), wiping with alcohol, flattening the end face with a cutting knife, and aligning and welding the capillary optical fiber and the single-mode optical fiber by using an optical fiber online micro-processing platform;
2) punching the wall of the capillary optical fiber by using a carbon dioxide laser at a position 30 microns away from the fusion point in the single-mode optical fiber-capillary optical fiber structure obtained in the step 1), wherein the aperture is controlled to be 10 microns;
3) cutting the single-mode fiber-holey capillary fiber obtained in the step 2) at a position 80 microns away from the fusion point by using an optical fiber online micromachining platform;
4) removing a coating layer of a section of single-hole microstructure optical fiber (3), wiping with alcohol, cutting the end face to be flat by using a cutting knife, aligning and welding the single-mode optical fiber-holed capillary optical fiber (2) obtained in the step (3) and the single-hole microstructure optical fiber (3) by using an optical fiber online micro-processing platform, and cutting at a position 200 micrometers away from a welding point;
5) and removing a coating layer of the other section of capillary optical fiber (4), wiping the coating layer with alcohol, flattening the end face with a cutting knife, aligning and welding the structure obtained in the step 4) and the capillary optical fiber (4) by using an optical fiber online micro-processing platform, and cutting the part 3 cm away from a welding point.
Further, the outer diameter of the capillary optical fiber in the step 1) is 125 micrometers, the inner diameter of the capillary optical fiber is 50 micrometers, the diameter of a cladding of the single-mode optical fiber is 125 micrometers, the diameter of a fiber core is 8.2 micrometers, the diameter of the cladding of the single-hole microstructure optical fiber in the step 4) is 127 micrometers, the diameter of the fiber core is 9.2 micrometers, the diameter of an air hole is 36 micrometers, and the outer diameter of the capillary optical fiber in the step 5) is 125 micrometers and the inner diameter of the capillary optical fiber is 50 micrometers.
A detection method of a reflective micro-flow sensing device based on a single-hole micro-structure optical fiber is characterized in that a super-continuum spectrum light source (5), an optical fiber circulator (6), a single-hole micro-structure optical fiber reflective micro-flow sensing probe (7) and a spectrum analyzer (8) are sequentially connected.
Compared with the prior art, the invention has the following advantages:
the Fabry-Perot structure is adopted as the sensing probe, the high sensitivity is achieved, the capillary optical fiber and the single-hole microstructure optical fiber are combined to serve as a micro-fluid channel and a detection micro-cavity, the multi-cavity F-P interference principle is analyzed, the micro-fluid sensing in the fiber is achieved, the anti-interference performance is strong, the structure is novel, the manufacturing is simple, and the Fabry-Perot structure has wide application prospects in the fields of medicine development, disease detection, environment monitoring and the like.
Drawings
Fig. 1 is a schematic structural diagram of a reflective micro-fluidic sensing device based on a single-hole micro-structured optical fiber provided by the invention.
Fig. 2 is a schematic diagram of an optical path of a reflective micro-fluidic sensing device based on a single-hole micro-structured optical fiber provided by the invention.
Fig. 3 is a flow chart for manufacturing a probe of a single-hole micro-structured optical fiber of a reflective micro-fluidic sensing device based on a single-hole micro-structured optical fiber according to the present invention.
Fig. 4 is a diagram of a detection device of a reflective micro-fluidic sensing device based on a single-hole micro-structured optical fiber provided by the invention.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and the detailed description.
Example 1
The invention provides a reflective micro-flow sensing device based on a single-hole microstructure optical fiber, which consists of a single-mode optical fiber, an open-hole capillary optical fiber, a single-hole microstructure optical fiber and a capillary optical fiber, wherein the structural schematic diagram is shown in figure 1. When light of a supercontinuum light source enters the sensor through the optical fiber circulator, a part of light can be reflected from a first end face formed by the single-mode optical fiber and the open-pore capillary optical fiber, a part of light can be reflected when being continuously transmitted to the interface of the open-pore capillary optical fiber and the single-pore microstructure optical fiber, the light is continuously transmitted to the single-pore microstructure optical fiber, a part of light is reflected from the right end face of the single-pore microstructure optical fiber, and three beams of reflected light generate interference due to different phases. A shift in the interference spectrum can be observed when the refractive index of the microfluidic changes. The measurement of the microfluid is realized by utilizing the wavelength change of the wave valley/wave peak in the interference spectrum.
The working principle of the invention is as follows: as shown in fig. 2, the sensor comprises 3F-P cavities, three reflecting end faces are M1, M2 and M3 respectively, and FP1 cavities are formed by the reflecting end faces M1 and M2; the reflecting end surfaces M2 and M3 form an FP2 cavity, and the reflecting end surfaces M1 and M3 form an FP3 cavity. When light is emitted from the supercontinuum light source, the light reflected back through the three reflecting end faces interferes. The reflected light interference spectral intensity is:
wherein I
1、I
2、I
3The amplitudes of the reflected light of M1, M2, M3, respectively; λ is the wavelength of the incident light;
phase of FP1 and FP2, respectively:
wherein L is1、L2The lengths of FP1, FP2, respectively; n iseffN are the refractive index of the microfluid in the open capillary FP1 and the refractive index of the FP2 cavity, respectively. When the phase matching condition is satisfied, the sensor will form a stable interference pattern. The measurement is carried out by utilizing the change of the wave valley/wave peak wavelength in the interference spectrum along with the refractive index of the microfluid.
With reference to fig. 3, a process for manufacturing a reflective microfluidic sensing device based on a single-hole micro-structured optical fiber includes the following steps:
the method comprises the following steps: removing coating layers of a section of capillary optical fiber and a section of single-mode optical fiber, wiping with alcohol, cutting the end face to be flat by using a cutting knife, and aligning and welding the capillary optical fiber and the single-mode optical fiber by using an optical fiber online micro-processing platform;
step two: punching the wall of the capillary optical fiber by using a carbon dioxide laser at a position 30 microns away from the fusion point in the single-mode optical fiber-capillary optical fiber structure obtained in the step one, wherein the aperture is controlled to be 10 microns;
step three: cutting the single-mode fiber-holey capillary fiber obtained in the step two by 80 microns away from the welding point by using an optical fiber online micromachining platform;
step four: removing the coating layer of a section of the single-hole microstructure optical fiber, wiping the section of the single-hole microstructure optical fiber with alcohol, cutting the end face to be flat by using a cutter, aligning and welding the single-mode optical fiber-holed capillary optical fiber obtained in the step three with the single-hole microstructure optical fiber by using an optical fiber online micro-processing platform, and cutting the single-mode optical fiber-holed capillary optical fiber at a position 200 micrometers away from a welding point;
step five: and removing the coating layer of the other section of capillary optical fiber, wiping the coating layer with alcohol, flattening the end face with a cutting knife, aligning and welding the structure obtained in the step four with the capillary optical fiber by using an optical fiber online micro-processing platform, and cutting the structure at a position 3 cm away from a welding point.
With reference to fig. 4, the detection of the reflective micro-flow sensing device based on the single-hole micro-structure optical fiber comprises a super-continuum spectrum light source (5), an optical fiber circulator (6), a reflective micro-flow sensing probe (7) of the single-hole micro-structure optical fiber and a spectrometer (8) which are sequentially connected. The probe (7) of the single-hole microstructure fiber reflection micro-flow sensor is provided with a liquid inlet formed by an open-hole capillary fiber (2) and a liquid outlet formed by the tail end (4) of the capillary fiber.
In conclusion, the optical fiber F-P microfluidic sensor is easy to manufacture, strong in anti-interference performance and high in sensitivity, and has wide development potential in the fields of medicine development, disease detection, environmental monitoring and the like.