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CN219871005U - All-fiber annular cavity sensing device for carbon isotope detection - Google Patents

All-fiber annular cavity sensing device for carbon isotope detection Download PDF

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Publication number
CN219871005U
CN219871005U CN202320711689.3U CN202320711689U CN219871005U CN 219871005 U CN219871005 U CN 219871005U CN 202320711689 U CN202320711689 U CN 202320711689U CN 219871005 U CN219871005 U CN 219871005U
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optical fiber
fiber
port
hollow
detection
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靳伟
姜寿林
赵双祥
郑凯元
何海律
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Shenzhen Research Institute HKPU
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Shenzhen Research Institute HKPU
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Abstract

The utility model discloses an all-fiber annular cavity sensing device for carbon isotope detection, which comprises: the delay optical fiber and the input optical fiber are both used for connecting a detection light source, and the delay of the detection light after passing through the delay optical fiber and the input optical fiber is different; the optical fiber annular passage comprises a hollow optical fiber air chamber, wherein two opposite ends of the hollow optical fiber air chamber are respectively connected with the output end of the delay optical fiber and the output end of the input optical fiber, and detection light propagates in the optical fiber annular passage and circulates through the hollow optical fiber air chamber; the hollow fiber gas chamber is filled with gas with carbon isotopes to be detected, and is used for introducing pump light, and the gas changes the phase of the detection light under the action of the pump light; and the photoelectric detector is used for receiving the detection light returned by the delay optical fiber and the input optical fiber. The problems of large air consumption, high cost and large volume of the space optical resonant cavity caused by large optical air chamber are solved.

Description

All-fiber annular cavity sensing device for carbon isotope detection
Technical Field
The utility model relates to the technical field of gas concentration detection, in particular to an all-fiber annular cavity sensing device for carbon isotope detection.
Background
Carbon isotope detection plays an important role in the fields of atmospheric science, energy exploration, medical detection and the like. In the field of atmospheric science, carbon isotope detection is an important method for understanding global carbon circulation and defining carbon source and sink changes; in the field of energy exploration, carbon co-location detection is an important means for deducting characteristics of oil and gas reservoirs and identifying and positioning mineral sources; in the medical field, carbon isotope detection in exhaled breath of human body has become a gold standard for noninvasive diagnosis of helicobacter pylori infection.
The change in carbon isotope content in nature is extremely small, the relative change in isotope abundance ratio is usually characterized by a deviation from a reference base, and the change in carbon isotope ratio of a sample relative to a reference substance can be expressed as:
wherein% 13 C/ 12 C) Sample And% 13 C/ 12 C) Reference The carbon isotope ratio of the sample to be detected and the reference standard substance are respectively. Isotope ratio mass spectrometers (Isotope Ratio Mass Spectroscopy, IRMS) are the most commonly used carbon isotope detection instruments, and the typical detection accuracy can reach 0.01-0.1 per mill, but the mass spectrometer has large volume, complex operation, high price and low detection speed, requires complex sample gas pretreatment, and is not suitable for in-situ detection application. In addition, for exampleCN113109292 discloses a tunable laser absorption spectrum (TDLAS) based carbon isotope detection system and method, which can work under normal pressure through an optimized algorithm, but the modulating device part of the detector has large gas consumption due to a long optical path space optical air chamber, and is difficult to be used for detection under a high concentration gas environment.
The modulator part of the existing carbon isotope detection device generally has the problems of large gas consumption, high cost and large volume caused by large optical air chamber of the space optical resonant cavity. Accordingly, the prior art is still in need of improvement and development.
Disclosure of Invention
In view of the shortcomings of the prior art, the utility model aims to provide an all-optical fiber annular cavity sensing device for carbon isotope detection, which solves the problems of large air consumption, high cost and large volume caused by large optical air chamber of a space optical resonant cavity of a current carbon isotope detection device.
The technical scheme of the utility model is as follows:
an all-fiber toroidal cavity sensing device for carbon isotope detection, comprising:
the delay optical fiber and the input optical fiber are both used for being connected with a detection light source, wherein the delay of the detection light after passing through the delay optical fiber and the input optical fiber is different;
the optical fiber annular passage comprises a hollow optical fiber air chamber, wherein two opposite ends of the hollow optical fiber air chamber are respectively connected with the output end of the delay optical fiber and the output end of the input optical fiber, and detection light propagates in the optical fiber annular passage and circulates through the hollow optical fiber air chamber; the hollow fiber gas chamber is filled with gas with carbon isotopes to be detected, and is used for introducing pump light, and the gas changes the phase of the detection light under the action of the pump light;
and the photoelectric detector is used for receiving the detection light after the phase changes returned by the delay optical fiber and the input optical fiber.
Optionally, the fiber optic annular passage further comprises: the first optical fiber coupler is provided with a first port, a second port and a first public port, the first port is connected with the delay optical fiber, and the first public port is connected with one end of the hollow optical fiber air chamber;
the second optical fiber coupler is provided with a third port, a fourth port and a second public port, the third port is connected with the input optical fiber, and the second public port is connected with the other end of the hollow optical fiber air chamber;
the second port is connected with the fourth port, so that the detection light propagates in the first optical fiber coupler, the second optical fiber coupler and the hollow optical fiber air chamber and passes through the hollow optical fiber air chamber for a plurality of times.
Optionally, in the splitting ratio, the second port is larger than the first port and the fourth port is larger than the third port.
Optionally, the split ratio of the second port and the first port of the first fiber coupler is not less than 7:3, a step of;
the split ratio of the fourth port and the third port of the second optical fiber coupler is not less than 7:3.
optionally, the first port has a split ratio of 2% and the second port has a split ratio of 98%;
the third port has a split ratio of 2% and the fourth port has a split ratio of 98%.
Optionally, the second common port is connected with the other end of the hollow fiber air chamber through a wavelength division multiplexer, and the wavelength division multiplexer is used for connecting a pump light source and combining pump light and probe light emitted by the pump light source.
Optionally, the delay optical fiber and the input optical fiber are connected with a detection light source through an optical fiber coupler;
the optical fiber coupler comprises at least three input ports and two output ports;
one input port of the optical fiber coupler is connected with the detection light source, and the other two input ports are respectively connected with the photoelectric detector;
one output port of the optical fiber coupler is connected with the delay optical fiber, and the other output port is connected with the input optical fiber.
Optionally, the hollow fiber air chamber comprises a hollow fiber body and a solid single-mode fiber tail fiber, and the solid single-mode fiber tail fiber is respectively fixed at two ends of the hollow fiber body.
Optionally, the hollow fiber body comprises one or more of a hollow photonic bandgap fiber, a hollow antiresonant fiber, and a hollow waveguide.
Optionally, the all-fiber annular cavity sensing device further comprises a temperature control module, and the temperature control module is used for refrigerating and heating the hollow fiber air chamber.
Optionally, the photodetector is a balanced photodetector having two optical input ports, and the common mode noise rejection ratio of the balanced photodetector is not less than 20dB.
The beneficial effects are that: compared with the prior art, the full-optical fiber annular cavity sensing device for carbon isotope detection provided by the utility model adopts an optical fiber annular passage way, so that detection light can circularly enter an air core optical fiber air chamber, thereby realizing effective amplification of a phase signal of the detection light, reducing the volume of the air chamber while meeting detection precision, optimizing a structure in an annular light-passing way, reducing gas consumption for calibration and detection, being applicable to application scenes with less gas sample amount such as expiration detection and deep sea solution gas detection, and obviously reducing the power consumption of a temperature control system while ensuring temperature control precision of the small air chamber; the full-optical fiber structure is adopted, so that the full-optical fiber annular cavity sensing device has a more compact structure, does not need complex space light path alignment, and is convenient to use and maintain; in addition, the characteristic of high optical power density in the hollow fiber is fully utilized, the effective optical path can be further shortened, the normal operation can be realized even under the condition of high gas concentration, and the detectable gas concentration range is larger.
Drawings
FIG. 1 is a schematic block diagram of an all-fiber ring cavity sensing device for carbon isotope detection according to the present utility model;
FIG. 2 is a schematic block diagram of a hollow fiber air chamber of an all-fiber annular cavity sensing device for carbon isotope detection according to the present utility model;
FIG. 3 is a schematic cross-sectional view of a hollow anti-resonant fiber of an all-fiber toroidal cavity sensing device for carbon isotope detection in accordance with the present utility model;
FIG. 4 is a graph showing carbon dioxide isotope absorption spectra in the wavelength tunable range of pump light employed by an all-fiber ring cavity sensor device for carbon isotope detection according to the present utility model;
FIG. 5 shows the natural isotope abundance of 5% CO concentration measured by the full-fiber ring cavity sensor for carbon isotope detection 2 Second harmonic signals of (a);
FIG. 6 is a graph showing the peak carbon isotope absorption measured within 6 hours when the all-fiber ring cavity sensor for carbon isotope detection according to the present utility model is applied;
FIG. 7 is a graph showing the relative change of the carbon isotope ratio within 6 hours measured by an all-fiber ring cavity sensor for carbon isotope detection according to the present utility model;
FIG. 8 shows the application of the all-fiber ring cavity sensor for carbon isotope detection in different COs 2 And (5) detecting the carbon isotope under the concentration.
The reference numerals in the drawings: 100. detecting a light source; 200. an all-fiber annular cavity sensing device; 210. a delay optical fiber; 220. an input optical fiber; 230. an optical fiber annular passageway; 231. a hollow fiber air chamber; 232. a hollow fiber body; 233. a solid single-mode fiber pigtail; 234. a first optical fiber coupler; 235. a second fiber coupler; 236. a wavelength division multiplexer; 240. a photodetector; 250. an optical fiber coupler; 260. a temperature control module; 300. and pumping the light source.
Detailed Description
The utility model provides an all-optical fiber annular cavity sensing device for carbon isotope detection, which is used for making the purposes, technical schemes and effects of the utility model clearer and more definite, and is optionally described in detail below by referring to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.
As shown in fig. 1, the present embodiment proposes an all-optical fiber ring cavity sensing device 200 for carbon isotope detection, which can be used for detecting the concentration of different carbon isotopes in a gas. The all-fiber ring cavity sensing device 200 for carbon isotope detection of the present solution mainly includes: delay fiber 210 and input fiber 220, fiber optic annular channel 230, and photodetector 240. The delay optical fiber 210 and the input optical fiber 220 are both used for connecting the detection light source 100, the detection light emitted by the detection light source 100 is transmitted through the delay optical fiber 210 and the input optical fiber 220 respectively, so that the detection light is divided into two paths, the detection light is delayed differently after passing through the delay optical fiber 210 and the input optical fiber 220, namely, the detection light has different transmission time in the delay optical fiber 210 and the input optical fiber 220, and as the other end of the delay optical fiber 210 and the other end of the input optical fiber 220 are respectively connected into the optical fiber annular passage 230, the time for the two paths of detection light to reach the optical fiber annular passage 230 is different, and the difference can be used for conveniently processing different detection lights in the subsequent detection process, so that the phase change of the detection light can be obtained. The optical fiber annular passage 230 comprises a hollow optical fiber air chamber 231, opposite ends of the hollow optical fiber air chamber 231 are respectively connected with the output end of the delay optical fiber 210 and the output end of the input optical fiber 220, the hollow optical fiber air chamber 231 is filled with gas with carbon isotopes to be detected, and two paths of detection light respectively pass through the gas to be detected in the opposite directions of the hollow optical fiber air chamber 231, so that one path of the two paths of detection light propagates in the optical fiber annular passage 230 in the clockwise direction, and the other path propagates in the optical fiber annular passage 230 in the anticlockwise direction, and passes through the hollow optical fiber air chamber 231 for multiple times in the circulating propagation process. The hollow fiber air chamber 231 is used for introducing pump light, and the gas changes the phase of the probe light under the action of the pump light; specifically, the pump light enters the hollow fiber air chamber 231, interacts with the gas in the hollow fiber air chamber 231 to release heat, and causes a change in the temperature and refractive index of the gas, and the gas after the change in the temperature and refractive index causes a phase change of the probe light on the same path. The detection light with the changed phase enters the photodetector 240 through the input optical fiber 220 and the delay optical fiber 210, respectively, and the photodetector 240 is used for receiving the detection light with the changed phase returned by the delay optical fiber 210 and the input optical fiber 220. By analyzing the phase change of the received probe light, the change of the refractive index can be detected, and the higher the concentration of the carbon isotope in the gas molecule is, the larger the corresponding change of the refractive index is, so that the concentration of the carbon isotope in the gas molecule can be detected by the change of the refractive index.
In this embodiment, the scanned pump light enters the hollow fiber chamber 231 through the wavelength division multiplexer 236, and interacts with the gas molecules to release heat and change the refractive index of the gas, so that the phase of the probe light changes after the probe light passes through the hollow fiber chamber 231. Based on the principle that the higher the concentration of the carbon isotope in the gas molecule is, the larger the refractive index change is, the amount of change in refractive index can be obtained by detecting the amount of change in phase of the probe light after the phase is changed, and thus the concentration information of the carbon isotope can be reflected. Moreover, the optical paths of the two paths of light of the optical fiber annular passage 230 can be completely matched by adopting a mode of detecting light in two paths of clockwise and anticlockwise directions in the hollow optical fiber air chamber 231, so that the automatic locking of the working point can be realized without any feedback control, and the detection precision is improved. The probe light passes through the hollow fiber air chamber 231 for multiple times in the fiber annular passage 230, so that the effective amplification of the photo-thermal phase signal can be realized, more accurate gas concentration information is obtained, the probe light can pass through the hollow fiber air chamber 231 for multiple times through the fiber annular passage 230, the extension of the optical passage is realized in a limited area, and the air chamber structure is greatly reduced while the requirement of the extension of the optical passage is met.
In addition to detecting the concentration of a single carbon isotope in a gas molecule by a change in refractive index, the present embodiment can detect the concentration of different carbon isotopes in a gas molecule, and its working principle is as follows: because different carbon isotopes have different absorption wavelength lines (such as carbon dioxide isotope absorption lines shown in fig. 4), when pump light with different wavelengths respectively enters the hollow fiber air chamber 231 in a scanning manner and interacts with the gas to release heat, if the wavelength of the current pump light corresponds to the absorption wavelength of the gas with one carbon isotope, the heat change and the refractive index change of the gas in the wavelength input period are large, and after the probe light passes through the hollow fiber air chamber 231, the phase change of the probe light is large. Therefore, the pump light with different wavelengths is input through scanning, the phase change amplitude is closely related to the wavelength of the pump light, and different carbon isotopes have different absorption wavelength lines, so the concentration of the carbon isotopes with different absorption wavelengths can be reflected through the phase change amplitude, and the concentration information of the carbon isotopes with different absorption wavelengths can be reflected. The same set of detection light path can be used for simultaneously scanning different absorption lines of the carbon isotope, so that the influence of common mode noise such as power drift, wavelength drift, environment slow disturbance and the like of a light source can be effectively restrained, and the system stability and the carbon isotope detection precision are improved; thanks to the shorter optical path, the method can realize carbon isotope detection in a large gas concentration range.
Further, the spectrum width of the detection light generated by the detection light source 100 in this embodiment is 30nm, and the light power is 10mW. The detection light is beneficial to the follow-up acquisition of the detection light after the phase change, and the detection precision is improved.
As shown in fig. 1, further, the optical fiber annular passage 230 in the present embodiment further includes: a first fiber coupler 234 and a second fiber coupler 235. The first fiber coupler 234 has a first port connected to the delay fiber 210, a second port connected to one end of the hollow fiber plenum 231, and a first common port. The second fiber coupler 235 has a third port connected to the input fiber 220, a fourth port connected to the other end of the hollow fiber air cell 231, and a second common port. The second port is connected to the fourth port such that the probe light propagates within the first optical fiber coupler 234, the second optical fiber coupler 235, and the hollow fiber air chamber 231 and passes through the hollow fiber air chamber 231 a plurality of times. One path of detection light in the delay optical fiber 210 enters a first port, then enters a hollow optical fiber air chamber 231 from a first public port, the detection light enters a second public port of a second optical fiber coupler 235 after being subjected to gas phase change, the rear part of the detection light is emitted through an input optical fiber 220, and the rear part of the detection light enters a second port through a fourth port to form a circulation process; in the same way, the second path of the probe light circulates in the fiber optic annular passage 230 in this manner, passing through the hollow fiber optic plenum 231 a plurality of times. The second port and the fourth port are ports with higher light splitting ratio and are directly connected, so that the formed annular light path not only realizes the miniaturization of the structure, but also ensures that the probe light carries out long-distance phase change in the hollow fiber air chamber 231 and improves the detection precision.
Further, the split ratio of the second port and the first port of the first optical fiber coupler 234 is not less than 7:3, a step of; the split ratio of the fourth port and the third port of the second optical fiber coupler 235 is not less than 7:3. the ports with higher values of the two splitting ratios are directly connected, so that when the detection light is split, a larger amount of the detection light still remains in the optical fiber annular passage 230, so that most of the detection light can circulate in the annular light path, and the detection light can pass through the hollow optical fiber air chamber 231 for multiple times, so that the acting distance of the detection light is prolonged.
Further, the first port has a split ratio of 2% and the second port has a split ratio of 98%; the third port has a split ratio of 2% and the fourth port has a split ratio of 98%. The first optical fiber coupler 234 and the second optical fiber coupler 235 with the proportion enable the detection light to have more circulation times in the optical fiber annular passage 230, so that the subsequent effective amplification of the photo-thermal phase signal of the detection light can be realized, more accurate gas concentration information can be obtained, and the detection result is more accurate.
Further, as shown in fig. 1, the second common port in this embodiment is connected to the other end of the hollow fiber air chamber 231 through a wavelength division multiplexer 236, and the wavelength division multiplexer 236 is further used for connecting the pump light source 300, and for combining the pump light and the probe light emitted by the pump light source 300. The wavelength division multiplexer 236 is connected to the optical fiber annular passage 230, and allows the pump light to enter the hollow fiber gas chamber 231, thereby changing the temperature and refractive index by interacting with the gas to be detected in the hollow fiber gas chamber 231. In this embodiment, to realize the detection of the concentration of different carbon isotopes, the wavelength tunable range of the pump light emitted by the pump light source 300 can cover different carbon isotope absorption spectrum lines, and the tunable range is not less than 0.5nm, such as pump lightThe wavelength adjustable range of (2) is: 1991-1995nm. In the 1991-1995nm band, 12CO 2 And 13CO 2 The absorption line with larger intensity and similar frequency can obtain two different carbon isotope concentration information by scanning the wavelength by the same pumping light source. In addition, the wavelength of the pumping light is simultaneously modulated at high frequency and scanned at low frequency, the modulation frequency is not less than 1kHz and can be between 1kHz and 100 kHz; if the modulation frequency is too low, the system is susceptible to interference from ambient low frequency noise, resulting in excessive noise. The modulation frequency is too high, and the process of refractive index change due to interaction of light with gas requires a certain time (typically on the order of us), which results in that the refractive index change cannot keep pace with the modulation rate, resulting in a reduced signal and thus is disadvantageous in obtaining an optimal signal-to-noise ratio. The modulation frequency is thus preferably between 1kHz and 100kHz, for example 25kHz may be used. The scanning frequency is not less than 1mHz and is between 1mHz and 1Hz, and the scanning frequency mainly determines the time of single measurement. The scanning frequency is low, the single measurement time is long, and the measurement speed is low. On the other hand, scanning is realized by temperature tuning, and when the scanning frequency is too high, the temperature adjustment cannot keep pace with the scanning speed, and signal distortion can be caused. Therefore, the scanning frequency is preferably between 1mHz-1 Hz. The optical power is not less than 1mW. By the parameters, the detected signal after the phase of the detected light changes is clearer, and the detection accuracy of the concentration of different carbon isotopes is greatly improved.
The wavelength division multiplexer 236 is used to combine the white light probe light with a center wavelength of 1550nm with the pump light with a center wavelength of 1993nm, wherein a port for passing the wavelength of 1550nm is connected to the second optical fiber coupler 235, and a port for passing the wavelength of 1993nm is connected to the pump light source 300.
Further, the delay fiber 210 and the input fiber 220 are connected to the detection light source 100 through a fiber coupler 250, and the fiber coupler 250 may be an optical fiber 3X3 coupler, where the optical fiber 3X3 coupler has three input ports and three output ports; one input port of the optical fiber coupler 250 is connected with the detection light source 100, and the other two input ports are respectively connected with the photoelectric detector 240; one output port of the fiber coupler is connected to the delay fiber 210, another output port is idle and beveled to suppress reflections, and a third output port is connected to the input fiber 220. The optical fiber coupler can be used for transmitting detection light and receiving detection light after phase change, and the coupler can be used for transmitting and receiving detection light, so that the structure is simplified, and the device is miniaturized. Wherein the ideal spectral ratio of the optical fiber 3x3 coupler is 1:1:1, the relative error of the beam splitting ratio is not more than 20%, so that the detection precision can be improved.
Further, the delay fiber 210 is a single-mode fiber for communication, and has a length of 1km. Therefore, on the premise of limited length, the delay effect is effectively realized, and the subsequent detection light receiving and detecting are facilitated.
As shown in fig. 2, further, the hollow fiber air chamber 231 includes a hollow fiber body 232 and a solid single-mode fiber pigtail 233, and the solid single-mode fiber pigtails 233 are respectively fixed at two ends of the hollow fiber body 232. The end faces of the tail fibers 233 of the solid single-mode optical fibers are all inclined at an angle of 8 degrees, and the tail fibers 233 of the solid single-mode optical fibers are connected with the hollow fiber bodies 232 in a mechanically fixed mode or a welded mode after being aligned in the middle. The hollow fiber body 232 has a length of not less than 1 cm and not more than 10 meters.
Further, the hollow fiber body 232 includes, but is not limited to, one or more of a hollow photonic bandgap fiber, a hollow antiresonant fiber, a hollow waveguide. As shown in fig. 3, the hollow fiber body 232 may be a hollow antiresonant fiber, and the length of the hollow fiber body 232 may be 15cm.
As shown in fig. 1, the all-fiber toroidal cavity sensor device 200 further includes a temperature control module 260, and the temperature control module 260 is configured to cool and heat the hollow fiber air chamber 231. The temperature control module 260 is arranged on the hollow fiber air chamber 231, and the temperature control module 260 controls the temperature of the hollow fiber air chamber 231, so that the precise control of the core temperature of the hollow fiber body 232 is realized, and the laser frequency stabilization is facilitated.
The temperature control module 260 can adopt a semiconductor refrigerating sheet to heat or refrigerate, and controls the current magnitude and the current direction passing through the semiconductor refrigerating sheet through PID, so as to control the temperature of the semiconductor refrigerating sheet, and the temperature control precision is better than 0.01 ℃.
Further, as shown in fig. 1, the photodetector 240 is a balanced photodetector 240 having two optical input ports, the two optical input ports are respectively connected to the two input ports of the optical fiber 3x3 coupler 250, and the common mode noise rejection ratio of the balanced photodetector 240 is not less than 20dB, and the response bandwidth may be 1MHz.
The inspection result of the all-fiber annular cavity sensing device for carbon isotope detection in the scheme is as follows:
as shown in FIG. 5, a catalyst containing 5% CO 2 The second harmonic signal corresponding to the absorption spectrum line of the graph can be measured by scanning the pumping light with different wavelengths under the concentration, wherein 12CO 2 R (68) and 13CO 2 The R (38) signal is clearly visible.
As shown in fig. 6, by continuously measuring for 6 hours and extracting peaks at corresponding positions of two spectral lines; as shown in FIG. 7, the relative deviation of the carbon isotope ratio is further calculated according to the equation, and the carbon isotope detection accuracy can reach 0.19 per mill under the 60-minute moving average.
As shown in FIG. 8, further for different concentrations of CO 2 The detection is carried out, the detection precision is better than 0.3 per mill in the concentration range of 1-100%, even at 1000ppm of CO 2 Under the concentration, the detection precision of about 3 per mill can be ensured. The detection accuracy can be further improved by increasing the hollow fiber length or the optical power of the pump light source.
In summary, the full-fiber annular cavity sensing device for carbon isotope detection provided by the utility model adopts the mode of an optical fiber annular passage, so that detection light can circularly enter the hollow optical fiber air chamber, thereby realizing effective amplification of a phase signal of the detection light, reducing the volume of the air chamber while meeting detection precision, optimizing the structure in an annular light-passing mode, reducing the air consumption for calibration and detection, being applicable to application scenes with less sample air consumption such as expiration detection and deep sea solution gas detection, and obviously reducing the power consumption of a temperature control system while ensuring temperature control precision by the small air chamber; moreover, the full optical fiber structure is adopted, so that the detection device has a more compact structure, does not need complex space optical path alignment and is convenient to use and maintain; in addition, the characteristic of high optical power density in the hollow fiber is fully utilized, the effective optical path can be further shortened, the normal operation can be realized even under the condition of high gas concentration, and the detectable gas concentration range is larger.
It is to be understood that the utility model is not limited in its application to the examples described above, but is capable of modification and variation in light of the above teachings by those skilled in the art, and that all such modifications and variations are intended to be included within the scope of the appended claims.

Claims (10)

1. An all-fiber toroidal cavity sensing device for carbon isotope detection, comprising:
the device comprises a delay optical fiber and an input optical fiber, wherein the delay optical fiber and the input optical fiber are both used for being connected with a detection light source, the detection light source emits detection light, and the delay of the detection light after passing through the delay optical fiber and the input optical fiber is different;
the optical fiber annular passage comprises a hollow optical fiber air chamber, two opposite ends of the hollow optical fiber air chamber are respectively connected with the output end of the delay optical fiber and the output end of the input optical fiber, and the detection light propagates in the optical fiber annular passage and circulates through the hollow optical fiber air chamber; the hollow fiber gas chamber is filled with gas with carbon isotopes to be detected, the hollow fiber gas chamber is used for introducing pump light, and the gas changes the phase of the detection light under the action of the pump light;
and the photoelectric detector is used for receiving the detection light after the phase changes returned by the delay optical fiber and the input optical fiber.
2. The all-fiber toroidal cavity sensing device for carbon isotope detection of claim 1 wherein said fiber toroidal passageway further comprises: the first optical fiber coupler is provided with a first port, a second port and a first public port, the first port is connected with the delay optical fiber, and the first public port is connected with one end of the hollow optical fiber air chamber;
the second optical fiber coupler is provided with a third port, a fourth port and a second public port, the third port is connected with the input optical fiber, and the second public port is connected with the other end of the hollow optical fiber air chamber;
the second port is connected with the fourth port, so that the detection light propagates in the first optical fiber coupler, the second optical fiber coupler and the hollow optical fiber air chamber and passes through the hollow optical fiber air chamber a plurality of times.
3. The all-fiber toroidal cavity sensing device for carbon isotope detection of claim 2 wherein in spectral ratio, the second port is larger than the first port and the fourth port is larger than the third port.
4. The all-fiber toroidal cavity sensing device for carbon isotope detection of claim 3 wherein the split ratio of said second port and said first port of said first fiber coupler is not less than 7:3, a step of;
the split ratio of the fourth port and the third port of the second optical fiber coupler is not less than 7:3.
5. the all-fiber ring cavity sensing device for carbon isotope detection of claim 2, wherein the second common port is connected with the other end of the hollow fiber air chamber through a wavelength division multiplexer, the wavelength division multiplexer is used for connecting a pump light source, and the pump light and the probe light emitted by the pump light source are used for wave combination.
6. The all-fiber toroidal cavity sensing device for carbon isotope detection of claim 1 wherein said delay fiber and said input fiber are connected to said detection light source by a fiber coupler;
the optical fiber coupler comprises at least three input ports and two output ports;
one input port of the optical fiber coupler is connected with the detection light source, and the other two input ports are respectively connected with the photoelectric detector;
one output port of the optical fiber coupler is connected with the delay optical fiber, and the other output port is connected with the input optical fiber.
7. The all-fiber annular cavity sensing device for carbon isotope detection of claim 1 wherein the hollow fiber air chamber comprises a hollow fiber body and solid single mode fiber pigtails, the solid single mode fiber pigtails being secured to respective ends of the hollow fiber body.
8. The all-fiber toroidal cavity sensing device for carbon isotope detection of claim 7 wherein said hollow fiber body comprises one or more of a hollow photonic bandgap fiber, a hollow antiresonant fiber, a hollow waveguide.
9. The all-fiber toroidal cavity sensing device for carbon isotope detection of claim 1 further comprising a temperature control module for cooling and heating said hollow fiber air chamber.
10. The all-fiber toroidal cavity sensing device for carbon isotope detection of any one of claims 1-9 wherein said photodetector is a balanced photodetector having two optical input ports.
CN202320711689.3U 2023-03-27 2023-03-27 All-fiber annular cavity sensing device for carbon isotope detection Active CN219871005U (en)

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