A hydraulic pressure sensor based on optical fiber induction transparency effect and its measurement method

Abstract

The present invention provides a hydraulic pressure sensor based on the fiber-optic induced transparency effect and its measurement method. The light output end of the light source is connected to the first light input end of a first fiber coupler. The second light input end and second light output end of the first fiber coupler are connected to a first fiber ring resonator. The first and second fiber ring resonators are connected via a second fiber coupler. The known liquid section of the first and second fiber ring resonators are connected via an outer jacket. The outer jacket is filled with a third section of air; this third section of air communicates with the external measured liquid through a small hole in the jacket. The first light output end of the first fiber coupler is connected to the light input end of a spectrometer. The electrical output end of the spectrometer is connected to the electrical input end of a processing system. The electrical output end of the processing system outputs the sensor output signal. This invention overcomes the problems of current hydraulic sensors, such as complex structure, susceptibility to electromagnetic interference, poor corrosion resistance, slow response speed, and low intelligence and integration.

Description

Technical Field

[0001] The present invention relates to the technical field of optical sensing, and in particular to a hydraulic pressure sensor based on optical fiber induction transparency effect and a measurement method thereof. Background Art

[0002] Hydraulic sensors are instruments used to measure liquid pressure. Liquid pressure, essentially the collision of liquid atoms or molecules against the container walls, is of vital importance to people's production and daily lives. Hydraulic sensors are the most commonly used sensors in production, daily life, and industrial practice. They are widely used in various industries and aspects of the national economy, such as water supply and drainage, oil pipelines, railway transportation, aerospace, intelligent buildings, hydraulic machinery, military industry, hydropower, oil wells, ships, machine tools, thermal power, metallurgy, and other processes for on-site measurement and control.

[0003] The hydraulic sensor, which is currently widely used, works by applying liquid pressure directly to the sensor's diaphragm, causing the diaphragm to produce a micro-displacement proportional to the medium pressure, thereby changing the sensor's resistance. This change is detected by electronic circuitry and a standard electrical signal corresponding to the pressure is output. When the liquid medium flows through the sensor, the fluid pressure acts on the stainless steel mounted on the sensor housing, and is then transmitted to the diffused silicon diaphragm through the sealing silicone oil. The pressure at the reference end acts on the other side of the diaphragm. The pressure differential applied on both sides of the diaphragm generates a stress, causing one side of the diaphragm to be compressed and the other side to be tensile. At the same time, one pair of strain gauges is located in the compression zone, and the other pair of strain gauges is located in the tension zone. The two pairs of strain gauges are connected to form a full dynamic bridge to amplify the output signal. When the pressure changes, the resistance of the bridge arm changes, causing the output voltage to change. After amplification and conversion by the differential normalization amplifier, it is converted into a corresponding current signal. After compensation by the nonlinear correction loop, this current generates a DC output signal that is approximately linear with the input pressure signal.

[0004] However, the current hydraulic sensors have complex strain structures and circuit systems, which are easily affected by various factors, resulting in poor stability, such as pressure disturbances in the measured environment, voltage fluctuations inside the sensor, aging of the circuit system, etc., and are extremely susceptible to the influence of electromagnetic fields in the environment. Therefore, the current hydraulic sensors have the disadvantages of complex structure, large size, high noise, low precision, susceptibility to electromagnetic interference, poor corrosion resistance, and slow response speed. Especially with the rapid advancement of information technology, people's lives, production, and various industries such as industry and agriculture have higher and higher requirements for intelligence, while the current hydraulic sensors have low intelligence and integration levels, which can hardly meet the needs of the rapid development of modern society.

[0005] Fiber optic devices have the advantages of simple structure, small size, light weight, low loss, flexible and diverse optical property design, and good stability. At present, the application of optical fiber in the field of sensing is becoming more and more extensive, and the huge advantages of fiber optic sensors are gradually becoming prominent, such as high precision, anti-electromagnetic interference, small impact on the measured environment, fast response speed, etc. Moreover, fiber optic sensors are suitable for working in harsh environments. In the fields of biology, chemistry and various engineering industries, they can be used in complex environments with strong electromagnetic radiation, strong nuclear radiation, and strong corrosion. In particular, fiber optic sensors have the advantages of high intelligence and integration, which can greatly meet the needs of modern society and the development of various industries. Summary of the Invention

[0006] The present invention provides a hydraulic sensor based on the optical fiber induction transparency effect and a measurement method thereof, which overcomes the problems of the current hydraulic sensor such as complex structure, susceptibility to electromagnetic interference, poor corrosion resistance, slow response speed, low intelligence and integration.

[0007] The present invention is achieved through the following technical solutions:

[0008] A hydraulic sensor based on the optical fiber-induced transparency effect, comprising a light source 1, a first optical fiber ring resonator, a second optical fiber ring resonator, a jacket 10, a third air section 11, a jacket aperture 12, a spectrometer 13, and a processing system 14;

[0009] The light output end of the light source 1 is connected to the first light input end of the first fiber coupler 2. The first fiber ring resonator and the second fiber ring resonator are connected via a second fiber coupler 6. The known liquid section of the first fiber ring resonator and the known liquid section of the second fiber ring resonator are connected via a jacket 10. The jacket 10 is filled with the known liquid, and the tail end of the jacket 10 is filled with a third section of air 11.

[0010] The third air section 11 is connected to the external measured liquid through the outer shell hole 12; the first optical output end of the first optical fiber coupler 2 is connected to the optical input end of the spectrometer 13, the electrical output end of the spectrometer 13 is connected to the electrical input end of the processing system 14, and the electrical output end of the processing system 14 outputs the sensor output signal;

[0011] A hydraulic sensor based on the optical fiber induced transparency effect, wherein the first optical fiber ring resonator comprises a first optical fiber coupler 2, a first optical fiber ring 3, a first section of air 4, a first section of known liquid 5, and a second optical fiber coupler 6;

[0012] The first optical fiber ring 3 is an unclosed optical fiber ring, and is respectively connected to the second optical input end of the first optical fiber coupler 2, the second optical output end of the first optical fiber coupler 2, the first optical input end of the second optical fiber coupler 6, and the first optical output end of the second optical fiber coupler 6;

[0013] The outer sleeve 10 is outside the first optical fiber ring 3 and wraps the unclosed portion of the first optical fiber ring 3 , thereby forming a first section of air 4 and a first section of known liquid 5 in the unclosed portion of the first optical fiber ring 3 .

[0014] A hydraulic sensor based on the optical fiber induced transparency effect, wherein the second optical fiber ring resonator comprises a second optical fiber coupler 6, a second optical fiber ring 7, a second section of air 8 and a second section of known liquid 9;

[0015] The second optical fiber ring 7 is an unclosed optical fiber ring, and is connected to the second optical input end and the second optical output end of the second optical fiber coupler 6, respectively.

[0016] The outer sleeve 10 is outside the second optical fiber ring 7 and wraps the unclosed portion of the second optical fiber ring 7, thereby forming a second section of air 8 and a second section of known liquid 9 at the unclosed portion of the second optical fiber ring 7;

[0017] Inside the outer shell 10 , the area surrounded by the first section of known liquid 5 , the second section of known liquid 9 and the third section of air 11 is filled with known liquid.

[0018] A hydraulic sensor based on the optical fiber-induced transparency effect, wherein the first section of known liquid 5, the second section of known liquid 9, and the known liquid inside the outer casing 10 are the same known liquid, the various sections of known liquid are interconnected and can flow freely, and the transmittance of light per unit length in the known liquid is known;

[0019] The light transmittance of the first section of known liquid 5 is less than the light transmittance of the first section of air 4;

[0020] The light transmittance of the second section of known liquid 9 is less than the light transmittance of the second section of air 8 .

[0021] A hydraulic sensor based on the optical fiber induction transparency effect, wherein the transmittance of light transmitted through the first section of air 4 and the first section of known liquid 5 is similar to the transmittance of light transmitted through the first optical fiber ring 3;

[0022] The transmittance of light after passing through the second section of air 8 and the second section of known liquid 9 is similar to the transmittance of light after passing through the second optical fiber ring 7.

[0023] The third section of air 11 separates the known liquid inside the jacket 10 from the external liquid to be measured;

[0024] A hydraulic sensor based on the optical fiber induction transparency effect, wherein the outer cover 10 does not deform under the action of external pressure;

[0025] Part of the optical fibers of the first optical fiber ring 3 is wrapped by the outer jacket 10, and the wrapped optical fibers are fixed inside the outer jacket 10;

[0026] Part of the optical fiber of the second optical fiber ring 7 is wrapped by the outer jacket 10, and the wrapped optical fiber is fixed inside the outer jacket 10;

[0027] A hydraulic sensor based on optical fiber induction transparency effect, wherein the length of the first section of known liquid 5 is the same as the length of the second section of known liquid 9;

[0028] The first air section 4 and the second air section 8 are both sealed, and the length of the first air section 4 is the same as the length of the second air section 8;

[0029] The length of the first optical fiber ring 3 is the same as that of the second optical fiber ring 7 .

[0030] A hydraulic sensor based on the optical fiber induced transparency effect, wherein the circumference of the first optical fiber ring resonator cavity is the same as the circumference of the second optical fiber ring resonator cavity, and the radius of the first optical fiber ring resonator cavity is the same as the radius of the second optical fiber ring resonator cavity;

[0031] The power of the output light of the light source 1 is constant, and the line width of the light is much larger than the free spectral range of the first fiber ring resonator and the free spectral range of the second fiber ring resonator;

[0032] The first optical fiber coupler 2 is a 2×2 optical fiber coupler with a coupling ratio of 16:84;

[0033] The second optical fiber coupler 6 is a 2×2 optical fiber coupler with a coupling ratio of 16:84;

[0034] The processing system 14 is composed of an acquisition circuit 14-1, an analysis circuit 14-2, and an output circuit 14-3;

[0035] The electrical input end of the acquisition circuit 14-1 is the electrical input end of the processing system 14, and the electrical output end of the output circuit 14-3 is the electrical output end of the processing system 14; the electrical output end of the spectrometer 13 is connected to the electrical input end of the acquisition circuit 14-1, the electrical output end of the acquisition circuit 14-1 is connected to the electrical input end of the analysis circuit 14-2, the electrical output end of the analysis circuit 14-2 is connected to the electrical input end of the output circuit 14-3, and the electrical output end of the output circuit 14-3 outputs the sensor output signal.

[0036] A method for measuring a hydraulic pressure sensor based on the optical fiber induction transparency effect, wherein the method uses the hydraulic pressure sensor based on the optical fiber induction transparency effect as described in any one of claims 1 to 8, and the method comprises the following steps:

[0037] Step 1: Place the small hole 12 of the outer shell of the hydraulic pressure sensor at the position where the measurement is required in the measured liquid;

[0038] Step 2: Based on the placement position in step 1, determine the maximum transmittance change of the transmission peak generated by the induced transparency effect in the transmission spectrum to determine the pressure change of the measured liquid;

[0039] Step 3: Based on the judgment in step 2, the pressure of the unknown liquid is judged and plans are made for subsequent industrial production.

[0040] 10. The method for measuring a hydraulic pressure sensor based on the optical fiber-induced transparency effect according to claim 1, wherein the step 2 specifically comprises:

[0041] When the maximum transmittance of the transmission peak produced by the induced transparency effect in the transmission spectrum decreases, the pressure of the measured liquid increases;

[0042] When the maximum transmittance of the transmission peak generated by the induced transparency effect in the transmission spectrum increases, the pressure of the measured liquid decreases.

[0043] The beneficial effects of the present invention are:

[0044] The present invention comprises two mutually coupled fiber ring resonators that can produce an induced transparency effect. The fiber ring resonator comprises an unclosed fiber ring, a section of known liquid, and a section of sealed air. When the pressure of the measured liquid changes, the loss of the fiber ring resonator changes, thereby changing the maximum transmittance of the transmission peak generated by the induced transparency effect. Therefore, the present invention has the advantages of simple structure, good electromagnetic interference resistance, corrosion resistance, fast response speed, and high intelligence and integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a structural schematic diagram of the present invention.

[0046] Figure 2 In the present invention, when the transmittance a of light transmitted in the optical fiber ring resonator is different, Figure 1 The transmission spectrum outputted from the first light output end of the first optical fiber coupler 2.

[0047] Figure 3 yes Figure 1 Schematic diagram of the circuit structure of the processing system 14. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] A hydraulic sensor based on the optical fiber-induced transparency effect, comprising a light source 1, a first optical fiber ring resonator, a second optical fiber ring resonator, a jacket 10, a third air section 11, a jacket aperture 12, a spectrometer 13, and a processing system 14;

[0050] The light output end of the light source 1 is connected to the first light input end of the first fiber coupler 2. The first fiber ring resonator and the second fiber ring resonator are connected via a second fiber coupler 6. The known liquid section of the first fiber ring resonator and the known liquid section of the second fiber ring resonator are connected via a jacket 10. The jacket 10 is filled with the known liquid, and the tail end of the jacket 10 is filled with a third section of air 11.

[0051] The third air section 11 is connected to the external measured liquid through the outer shell hole 12; the first optical output end of the first optical fiber coupler 2 is connected to the optical input end of the spectrometer 13, the electrical output end of the spectrometer 13 is connected to the electrical input end of the processing system 14, and the electrical output end of the processing system 14 outputs the sensor output signal;

[0052] A hydraulic sensor based on the optical fiber induced transparency effect, wherein the first optical fiber ring resonator comprises a first optical fiber coupler 2, a first optical fiber ring 3, a first section of air 4, a first section of known liquid 5, and a second optical fiber coupler 6;

[0053] The first optical fiber ring 3 is an unclosed optical fiber ring, and is respectively connected to the second optical input end of the first optical fiber coupler 2, the second optical output end of the first optical fiber coupler 2, the first optical input end of the second optical fiber coupler 6, and the first optical output end of the second optical fiber coupler 6;

[0054] The outer cover 10 is outside the first optical fiber ring 3 and wraps the unclosed portion of the first optical fiber ring 3 , thereby forming a first section of air 4 and a first section of known liquid 5 in the unclosed portion of the first optical fiber ring 3 .

[0055] A hydraulic sensor based on the optical fiber induced transparency effect, wherein the second optical fiber ring resonator comprises a second optical fiber coupler 6, a second optical fiber ring 7, a second section of air 8 and a second section of known liquid 9;

[0056] The second optical fiber ring 7 is an unclosed optical fiber ring, and is connected to the second optical input end and the second optical output end of the second optical fiber coupler 6, respectively.

[0057] The outer sleeve 10 is outside the second optical fiber ring 7 and wraps the unclosed portion of the second optical fiber ring 7, thereby forming a second section of air 8 and a second section of known liquid 9 at the unclosed portion of the second optical fiber ring 7;

[0058] Inside the outer shell 10 , the area surrounded by the first section of known liquid 5 , the second section of known liquid 9 and the third section of air 11 is filled with known liquid.

[0059] A hydraulic sensor based on the optical fiber-induced transparency effect, wherein the first section of known liquid 5, the second section of known liquid 9, and the known liquid inside the outer casing 10 are the same known liquid, the various sections of known liquid are interconnected and can flow freely, and the transmittance of light per unit length in the known liquid is known;

[0060] The light transmittance of the first section of known liquid 5 is less than the light transmittance of the first section of air 4;

[0061] The light transmittance of the second section of known liquid 9 is less than the light transmittance of the second section of air 8 .

[0062] A hydraulic sensor based on the optical fiber induction transparency effect, wherein the transmittance of light transmitted through the first section of air 4 and the first section of known liquid 5 is similar to the transmittance of light transmitted through the first optical fiber ring 3;

[0063] The transmittance of light after passing through the second section of air 8 and the second section of known liquid 9 is similar to the transmittance of light after passing through the second optical fiber ring 7.

[0064] The third section of air 11 separates the known liquid inside the jacket 10 from the external liquid to be measured;

[0065] A hydraulic sensor based on the optical fiber induction transparency effect, wherein the outer cover 10 does not deform under the action of external pressure;

[0066] Part of the optical fibers of the first optical fiber ring 3 is wrapped by the outer jacket 10, and the wrapped optical fibers are fixed inside the outer jacket 10;

[0067] Part of the optical fiber of the second optical fiber ring 7 is wrapped by the outer jacket 10, and the wrapped optical fiber is fixed inside the outer jacket 10;

[0068] A hydraulic sensor based on optical fiber induction transparency effect, wherein the length of the first section of known liquid 5 is the same as the length of the second section of known liquid 9;

[0069] The first air section 4 and the second air section 8 are both sealed, and the length of the first air section 4 is the same as the length of the second air section 8;

[0070] The length of the first optical fiber ring 3 is the same as that of the second optical fiber ring 7 .

[0071] A hydraulic sensor based on the optical fiber induced transparency effect, wherein the circumference of the first optical fiber ring resonator cavity is the same as the circumference of the second optical fiber ring resonator cavity, and the radius of the first optical fiber ring resonator cavity is the same as the radius of the second optical fiber ring resonator cavity;

[0072] The power of the output light of the light source 1 is constant, and the line width of the light is much larger than the free spectral range of the first fiber ring resonator and the free spectral range of the second fiber ring resonator;

[0073] The first optical fiber coupler 2 is a 2×2 optical fiber coupler with a coupling ratio of 16:84;

[0074] The second optical fiber coupler 6 is a 2×2 optical fiber coupler with a coupling ratio of 16:84;

[0075] The processing system 14 is composed of an acquisition circuit 14-1, an analysis circuit 14-2, and an output circuit 14-3;

[0076] The electrical input end of the acquisition circuit 14-1 is the electrical input end of the processing system 14, and the electrical output end of the output circuit 14-3 is the electrical output end of the processing system 14; the electrical output end of the spectrometer 13 is connected to the electrical input end of the acquisition circuit 14-1, the electrical output end of the acquisition circuit 14-1 is connected to the electrical input end of the analysis circuit 14-2, the electrical output end of the analysis circuit 14-2 is connected to the electrical input end of the output circuit 14-3, and the electrical output end of the output circuit 14-3 outputs the sensor output signal.

[0077] Working principle of the present invention:

[0078] The first fiber coupler 2, the first fiber ring 3, the first section of air 4, the first section of known liquid 5, and the second fiber coupler 6 constitute a first fiber ring resonator; the second fiber coupler 6, the second fiber ring 7, the second section of air 8, and the second section of known liquid 9 constitute a second fiber ring resonator.

[0079] The output light of the light source 1 enters the first fiber optic ring resonator through the first fiber optic coupler 2. Since the transmittance of the light after passing through the first section of air 4 and the first section of known liquid 5 is similar to the transmittance of the light after passing through the first fiber optic ring 3, the light can be transmitted in the first fiber optic ring resonator and resonate in the first fiber optic ring resonator. Then, the light enters the second fiber optic ring resonator through the second fiber optic coupler 6. Since the transmittance of the light after passing through the second section of air 8 and the second section of known liquid 9 is similar to the transmittance of the light after passing through the second fiber optic ring 7, the light can be transmitted in the second fiber optic ring resonator. The light is transmitted and resonates in the second fiber ring resonator. Then, the light enters the first fiber ring resonator through the second fiber coupler 6. In this way, the light can be coupled between the first fiber ring resonator and the second fiber ring resonator, and an induced transparency effect is generated. The light transmitted in the first fiber ring resonator can be output by the first fiber coupler 2 and enter the spectrometer 13. The spectrometer 13 collects the spectrum and then converts the spectrum into a spectral voltage signal. The spectral voltage signal is sent to the processing system 14. The processing system 14 performs voltage signal acquisition, data analysis, and finally outputs a sensor output signal. The sensor output signal includes the pressure of the liquid being measured.

[0080] The outer jacket 10 is located outside the first optical fiber ring 3 and covers the unclosed portion of the first optical fiber ring 3, thereby sealing the first section of air 4 between the first optical fiber ring 3 and the first section of known liquid 5. The outer jacket 10 is located outside the second optical fiber ring 7 and covers the unclosed portion of the second optical fiber ring 7, thereby sealing the second section of air 8 between the second optical fiber ring 7 and the second section of known liquid 9. The various sections of known liquid inside the outer jacket 10 can flow freely. The third section of air 11 is connected to the external liquid to be measured through the small holes 12 in the outer jacket.

[0081] When light enters a fiber ring resonator, there are certain wavelengths of light whose phase after one transmission cycle in the fiber ring resonator is an integer multiple of 2π. These wavelengths are called the "resonance wavelengths" of the fiber ring resonator, and the optical frequency corresponding to the resonant wavelength of the fiber ring resonator is called the "resonance frequency" of the fiber ring resonator. The frequency interval between any two adjacent resonant frequencies of the fiber ring resonator is equal, and this frequency interval is called the "free spectral range" of the fiber ring resonator. All light with a frequency equal to the resonant frequency of the fiber ring resonator will resonate in the fiber ring resonator.

[0082] Since the length of the first fiber ring 3 is the same as that of the second fiber ring 7, the length of the first air section 4 is the same as that of the second air section 8, and the length of the first known liquid section 5 is the same as that of the second known liquid section 9, the circumference of the first fiber ring resonator is the same as that of the second fiber ring resonator, and the radius of the first fiber ring resonator is the same as that of the second fiber ring resonator, the phase of light transmitted through one cycle in the first fiber ring resonator is equal to the phase of light transmitted through one cycle in the second fiber ring resonator. Thus, the resonant frequency of the first fiber ring resonator is the same as that of the second fiber ring resonator, and the free spectral range of the first fiber ring resonator is the same as that of the second fiber ring resonator. The free spectral ranges of the two fiber ring resonators are represented by "FSR". Furthermore, the transmittance of light transmitted through one cycle in the first fiber ring resonator is equal to the transmittance of light transmitted through one cycle in the second fiber ring resonator. The transmittance of light transmitted through one cycle in the first fiber ring resonator and the transmittance of light transmitted through one cycle in the second fiber ring resonator are represented by "a".

[0083] Since light is coupled between the first fiber ring resonator and the second fiber ring resonator, an induced transparency effect is generated at the resonant frequency of the first fiber ring resonator and the second fiber ring resonator. Figure 2 The transmission spectrum shown is: when a=0.90, the transmission spectrum is shown as a blue dotted line; when a=0.85, the transmission spectrum is shown as a red dashed line; when a=0.80, the transmission spectrum is shown as a green solid line. The transmission spectrum is periodic, and the period is FSR. Figure 2 The horizontal axis of the black vertical line corresponds to the resonant frequency. It can be seen that due to the induced transparency effect, a transmission peak is generated near the resonant frequency. The horizontal axis of the peak position of the transmission peak corresponds to the resonant frequency, and the vertical axis of the peak position of the transmission peak is the maximum transmittance of the transmission peak. In each cycle (including a complete transmission peak generated by the induced transparency effect), the transmission spectrum is about the straight line (i.e. Figure 2 The black vertical line in the figure is symmetrical. When the transmittance a of light transmitted in the fiber ring resonator increases, as shown in Figure 2 As shown, the maximum transmittance of the transmission peak generated by the induced transparency effect (i.e., the transmittance at the resonant frequency) increases;

[0084] Since the output power of light source 1 is constant and the line width of the light is much larger than the free spectrum range of the two fiber ring resonators, it can be obtained Figure 2 The transmission spectrum shown;

[0085] A method for measuring a hydraulic pressure sensor based on an optical fiber-induced transparency effect, wherein the method applies the above-mentioned hydraulic pressure sensor based on an optical fiber-induced transparency effect, and the method comprises the following steps:

[0086] Step 1: When the present invention measures the pressure at different positions of the measured liquid, the outer shell hole 12 is placed at the position where the measurement is required in the measured liquid;

[0087] When the outer shell hole 12 is placed at the desired measurement position in the measured liquid, since the outer shell 10 does not deform under the action of external pressure, the first air section 4 and the second air section 8 are both sealed. The optical fiber of the first optical fiber ring 3 wrapped by the outer shell 10 is fixed inside the outer shell 10, and the optical fiber of the second optical fiber ring 7 wrapped by the outer shell 10 is fixed inside the outer shell 10. The third air section 11 separates the known liquid inside the outer shell 10 from the external measured liquid.

[0088] Step 2: Based on the placement position in step 1, determine the maximum transmittance change of the transmission peak generated by the induced transparency effect in the transmission spectrum to determine the pressure change of the measured liquid;

[0089] Step 3: Based on the judgment in step 2, the pressure of the unknown liquid is judged and plans are made for subsequent industrial production.

[0090] A method for measuring a hydraulic pressure sensor based on an optical fiber-induced transparency effect, wherein step 2 determines the maximum transmittance change of a transmission peak generated by the induced transparency effect in a transmission spectrum to thereby determine the pressure change of the measured liquid, specifically:

[0091] When the pressure of the measured liquid increases, the length of the first section of air 4 and the length of the second section of air 8 are both reduced, and the length of the first section of air 4 and the length of the second section of air 8 are still the same. Since the first section of known liquid 5, the second section of known liquid 9 and the known liquid inside the outer shell 10 are the same known liquid, each part of the known liquid is interconnected and can flow freely. Therefore, the length of the first section of known liquid 5 and the length of the second section of known liquid 9 are both increased, and the length of the first section of known liquid 5 and the length of the second section of known liquid 9 are still the same. In this way, the resonant frequency of the first fiber optic ring resonator cavity and the resonant frequency of the second fiber optic ring resonator cavity are still the same. The free spectral range of the resonant cavity is still the same as the free spectral range of the second fiber ring resonator. Since the light transmittance of the first section of the known liquid 5 is less than the light transmittance of the first section of the air 4, and the light transmittance of the second section of the known liquid 9 is less than the light transmittance of the second section of the air 8, the transmittance of light transmitted once in the first fiber ring resonator and the transmittance of light transmitted once in the second fiber ring resonator are both reduced, and the transmittance of light transmitted once in the first fiber ring resonator and the transmittance of light transmitted once in the second fiber ring resonator are still equal, then the maximum transmittance of the transmission peak generated by the induced transparency effect in the transmission spectrum is reduced, that is, the transmittance at the resonant frequency is reduced.

[0092] When the pressure of the measured liquid decreases, the length of the first section of air 4 and the length of the second section of air 8 both increase, and the length of the first section of air 4 and the length of the second section of air 8 remain the same. Since the first section of known liquid 5, the second section of known liquid 9 and the known liquid inside the outer shell 10 are the same known liquid, each part of the known liquid is interconnected and can flow freely. Therefore, the length of the first section of known liquid 5 and the length of the second section of known liquid 9 both decrease, and the length of the first section of known liquid 5 and the length of the second section of known liquid 9 remain the same. In this way, the resonant frequency of the first fiber optic ring resonator cavity and the resonant frequency of the second fiber optic ring resonator cavity remain the same. The free spectral range of the resonant cavity is still the same as the free spectral range of the second fiber ring resonator. Since the light transmittance of the first section of the known liquid 5 is less than the light transmittance of the first section of the air 4, and the light transmittance of the second section of the known liquid 9 is less than the light transmittance of the second section of the air 8, the transmittance of light transmitted once in the first fiber ring resonator and the transmittance of light transmitted once in the second fiber ring resonator are both increased, and the transmittance of light transmitted once in the first fiber ring resonator and the transmittance of light transmitted once in the second fiber ring resonator are still equal. Therefore, the maximum transmittance of the transmission peak generated by the induced transparency effect in the transmission spectrum increases, that is, the transmittance at the resonant frequency increases.

[0093] Since the transmittance of light per unit length in a known liquid is known, the pressure of the measured liquid can be obtained from the maximum transmittance of the transmission peak generated by the induced transparency effect in the transmission spectrum, that is, the transmittance at the resonant frequency;

[0094] The transmission spectrum output from the first optical output end of the first optical fiber coupler 2 enters the spectrometer 13, which collects the transmission spectrum and then converts the transmission spectrum into a transmission spectrum voltage signal, and then sends the transmission spectrum voltage signal to the processing system 14. The processing system 14 collects the transmission spectrum voltage signal and then performs data analysis on the transmission spectrum voltage signal to obtain the maximum transmittance of the transmission peak generated by the induced transparency effect in the transmission spectrum, that is, the transmittance at the resonant frequency, and then derives the pressure of the liquid being measured. Finally, the processing system 14 outputs a sensor output signal, and the sensor output signal includes the pressure of the liquid being measured.

[0095] Working principle of processing system 14:

[0096] The spectrometer 13 sends the transmission spectrum voltage signal to the acquisition circuit 14-1. The acquisition circuit 14-1 collects the transmission spectrum voltage signal and sends the transmission spectrum voltage signal to the analysis circuit 14-2. The analysis circuit 14-2 intercepts one cycle of the transmission spectrum voltage signal, which includes a complete transmission peak generated by the induced transparency effect, and then obtains the maximum transmittance of this transmission peak, which is also the transmittance at the resonant frequency. Then, the analysis circuit 14-2 calculates the pressure of the measured liquid from this transmittance. The analysis circuit 14-2 then sends the pressure information of the measured liquid to the output circuit 14-3. The output circuit 14-3 outputs the sensor output signal, which includes the pressure of the measured liquid.

Claims

1. A hydraulic sensor based on optical fiber induction transparency effect, characterized in that: The hydraulic sensor comprises a light source (1), a first optical fiber ring resonator, a second optical fiber ring resonator, an outer shell (10), a third section of air (11), an outer shell aperture (12), a spectrometer (13) and a processing system (14); The light output end of the light source (1) is connected to the first light input end of the first optical fiber coupler (2); the first optical fiber ring resonator and the second optical fiber ring resonator are connected via a second optical fiber coupler (6); the known liquid section of the first optical fiber ring resonator and the known liquid section of the second optical fiber ring resonator are connected via a jacket (10); the jacket (10) is filled with the known liquid, and the tail end of the jacket (10) is filled with a third section of air (11); The third section of air (11) is connected to the external measured liquid through the outer shell hole (12); the first optical output end of the first optical fiber coupler (2) is connected to the optical input end of the spectrometer (13), the electrical output end of the spectrometer (13) is connected to the electrical input end of the processing system (14), and the electrical output end of the processing system (14) outputs the sensor output signal; The first fiber ring resonator comprises a first fiber coupler (2), a first fiber ring (3), a first section of air (4), a first section of known liquid (5), and a second fiber coupler (6); The first optical fiber ring (3) is an unclosed optical fiber ring, and the first optical fiber ring (3) is respectively connected to the second optical input end of the first optical fiber coupler (2), the second optical output end of the first optical fiber coupler (2), the first optical input end of the second optical fiber coupler (6), and the first optical output end of the second optical fiber coupler (6); The outer sleeve (10) is outside the first optical fiber ring (3) and wraps the unclosed portion of the first optical fiber ring (3), thereby forming a first section of air (4) and a first section of known liquid (5) at the unclosed portion of the first optical fiber ring (3); The second fiber ring resonator comprises a second fiber coupler (6), a second fiber ring (7), a second section of air (8) and a second section of known liquid (9); The second optical fiber ring (7) is an unclosed optical fiber ring, and the second optical fiber ring (7) is connected to the second optical input end and the second optical output end of the second optical fiber coupler (6), respectively. The outer sleeve (10) is outside the second optical fiber ring (7) and wraps the unclosed portion of the second optical fiber ring (7), thereby forming a second section of air (8) and a second section of known liquid (9) at the unclosed portion of the second optical fiber ring (7); Inside the outer shell (10), the area surrounded by the first section of known liquid (5), the second section of known liquid (9) and the third section of air (11) is filled with known liquid; The outer jacket (10) will not be deformed under the action of external pressure; A portion of the optical fibers of the first optical fiber ring (3) is wrapped by a jacket (10), and the wrapped portion of the optical fibers is fixed inside the jacket (10); Part of the optical fibers of the second optical fiber ring (7) is wrapped by a jacket (10), and the wrapped part of the optical fibers is fixed inside the jacket (10).

2. The hydraulic pressure sensor according to claim 1, characterized in that: The first section of known liquid (5), the second section of known liquid (9) and the known liquid inside the outer shell (10) are the same known liquid, each section of known liquid is interconnected and can flow freely, and the transmittance of light per unit length in the known liquid is known; The light transmittance of the first section of known liquid (5) is less than the light transmittance of the first section of air (4); The light transmittance of the second section of known liquid (9) is less than the light transmittance of the second section of air (8).

3. The hydraulic pressure sensor according to claim 2, characterized in that: The transmittance of light after passing through the first section of air (4) and the first section of known liquid (5) is similar to the transmittance of light after passing through the first optical fiber ring (3); The transmittance of light after passing through the second section of air (8) and the second section of known liquid (9) is similar to the transmittance of light after passing through the second optical fiber ring (7); The third section of air (11) separates the known liquid inside the outer shell (10) from the external liquid to be measured.

4. The hydraulic pressure sensor according to claim 1, characterized in that: The length of the first section of known liquid (5) is the same as the length of the second section of known liquid (9); The first section of air (4) and the second section of air (8) are both sealed, and the length of the first section of air (4) is the same as the length of the second section of air (8); The length of the first optical fiber ring (3) is the same as the length of the second optical fiber ring (7).

5. The hydraulic pressure sensor according to claim 1, characterized in that: The circumference of the first fiber ring resonator is the same as the circumference of the second fiber ring resonator, and the radius of the first fiber ring resonator is the same as the radius of the second fiber ring resonator; The power of the output light of the light source (1) is constant, and the line width of the light is much larger than the free spectral range of the first fiber ring resonator and the free spectral range of the second fiber ring resonator; The first optical fiber coupler (2) is a 2×2 optical fiber coupler, and its coupling ratio is 16:84; The second optical fiber coupler (6) is a 2×2 optical fiber coupler with a coupling ratio of 16:84; The processing system (14) is composed of an acquisition circuit (14-1), an analysis circuit (14-2), and an output circuit (14-3); The electrical input end of the acquisition circuit (14-1) is the electrical input end of the processing system (14), and the electrical output end of the output circuit (14-3) is the electrical output end of the processing system (14); the electrical output end of the spectrometer (13) is connected to the electrical input end of the acquisition circuit (14-1), the electrical output end of the acquisition circuit (14-1) is connected to the electrical input end of the analysis circuit (14-2), the electrical output end of the analysis circuit (14-2) is connected to the electrical input end of the output circuit (14-3), and the electrical output end of the output circuit (14-3) outputs the sensor output signal.

6. A method for measuring a hydraulic pressure sensor based on an optical fiber-induced transparency effect, characterized in that: The measuring method uses a hydraulic pressure sensor based on the optical fiber-induced transparency effect as described in any one of claims 1 to 5, and the measuring method comprises the following steps: Step 1: Place the small hole (12) of the outer shell of the hydraulic pressure sensor at the position required for measurement in the measured liquid; Step 2: Based on the placement position in step 1, determine the maximum transmittance change of the transmission peak generated by the induced transparency effect in the transmission spectrum to determine the pressure change of the measured liquid; Step 3: Based on the judgment in step 2, the pressure of the unknown liquid is judged and plans are made for subsequent industrial production.

7. The measurement method of a hydraulic pressure sensor based on the optical fiber induced transparency effect according to claim 6, characterized in that: The step 2 is specifically as follows: When the maximum transmittance of the transmission peak produced by the induced transparency effect in the transmission spectrum decreases, the pressure of the measured liquid increases; When the maximum transmittance of the transmission peak generated by the induced transparency effect in the transmission spectrum increases, the pressure of the measured liquid decreases.

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