CN111290074B - Intermediate infrared Bragg optical fiber and gas qualitative and quantitative detection device thereof - Google Patents
Intermediate infrared Bragg optical fiber and gas qualitative and quantitative detection device thereof Download PDFInfo
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 70
- 238000001514 detection method Methods 0.000 title claims abstract description 37
- 239000000835 fiber Substances 0.000 claims abstract description 120
- 239000011521 glass Substances 0.000 claims abstract description 95
- XHGGEBRKUWZHEK-UHFFFAOYSA-L tellurate Chemical compound [O-][Te]([O-])(=O)=O XHGGEBRKUWZHEK-UHFFFAOYSA-L 0.000 claims abstract description 69
- 239000005387 chalcogenide glass Substances 0.000 claims abstract description 56
- 238000010521 absorption reaction Methods 0.000 claims abstract description 27
- 239000007789 gas Substances 0.000 claims description 76
- 238000000862 absorption spectrum Methods 0.000 claims description 27
- 230000005540 biological transmission Effects 0.000 claims description 23
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 14
- 229910017000 As2Se3 Inorganic materials 0.000 claims description 10
- 238000001228 spectrum Methods 0.000 claims description 10
- 238000003475 lamination Methods 0.000 claims description 9
- 238000000034 method Methods 0.000 claims description 9
- 229910052717 sulfur Inorganic materials 0.000 claims description 9
- 239000011593 sulfur Substances 0.000 claims description 9
- 229910052786 argon Inorganic materials 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- SITVSCPRJNYAGV-UHFFFAOYSA-L tellurite Chemical compound [O-][Te]([O-])=O SITVSCPRJNYAGV-UHFFFAOYSA-L 0.000 claims description 6
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims description 5
- FPHIOHCCQGUGKU-UHFFFAOYSA-L difluorolead Chemical compound F[Pb]F FPHIOHCCQGUGKU-UHFFFAOYSA-L 0.000 claims description 5
- 229910003069 TeO2 Inorganic materials 0.000 claims description 4
- 238000004451 qualitative analysis Methods 0.000 claims description 4
- LAJZODKXOMJMPK-UHFFFAOYSA-N tellurium dioxide Chemical compound O=[Te]=O LAJZODKXOMJMPK-UHFFFAOYSA-N 0.000 claims description 4
- 238000012545 processing Methods 0.000 claims description 3
- 238000004445 quantitative analysis Methods 0.000 claims description 3
- 230000009467 reduction Effects 0.000 claims description 3
- 238000005553 drilling Methods 0.000 claims description 2
- 230000006698 induction Effects 0.000 claims 2
- 238000005259 measurement Methods 0.000 abstract description 4
- 230000035945 sensitivity Effects 0.000 abstract description 2
- 239000000126 substance Substances 0.000 description 17
- 150000004770 chalcogenides Chemical class 0.000 description 14
- 238000005253 cladding Methods 0.000 description 13
- LELOWRISYMNNSU-UHFFFAOYSA-N hydrogen cyanide Chemical compound N#C LELOWRISYMNNSU-UHFFFAOYSA-N 0.000 description 13
- 239000010453 quartz Substances 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 6
- 235000013405 beer Nutrition 0.000 description 6
- 238000002329 infrared spectrum Methods 0.000 description 6
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 6
- 229910052714 tellurium Inorganic materials 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 230000003287 optical effect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000010030 laminating Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000004080 punching Methods 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 2
- 238000009423 ventilation Methods 0.000 description 2
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000004476 mid-IR spectroscopy Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000012916 structural analysis Methods 0.000 description 1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/032—Optical fibres with cladding with or without a coating with non solid core or cladding
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02295—Microstructured optical fibre
- G02B6/02309—Structures extending perpendicularly or at a large angle to the longitudinal axis of the fibre, e.g. photonic band gap along fibre axis
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
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- Optics & Photonics (AREA)
- Spectroscopy & Molecular Physics (AREA)
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- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
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Abstract
A mid-infrared Bragg fiber and a gas qualitative and quantitative detection device thereof belong to the technical field of optics and laser photons. The intermediate infrared Bragg fiber comprises a Bragg structure layer and a hollow core region formed by surrounding the Bragg structure layer, wherein the Bragg structure layer is formed by alternately stacking tellurate glass layers and chalcogenide glass layers at intervals; a chalcogenide glass layer and a tellurate glass layer are used as a group of laminated layers, and the Bragg structure layer is at least provided with three groups of laminated layers; the middle infrared Bragg fiber is provided with two rows of through holes along the axial direction, each row is uniformly provided with a plurality of through holes, and two corresponding holes in the two opposite rows of holes are uniformly distributed on the circumference of the fiber. The optical fiber can detect the position and the intensity of an infrared absorption peak in gas, and has high measurement precision and good sensitivity. After measurement, the medium-infrared Bragg optical fiber does not need to be replaced, and gas detection can be realized.
Description
Technical Field
The invention relates to the technical field of optics and laser photons, in particular to the technical field of sensing optical fibers and detection devices, and particularly relates to a mid-infrared Bragg optical fiber and a gas qualitative and quantitative detection device thereof.
Background
With the development of the technology, the optical fiber sensing technology has been widely applied.
The optical fiber sensing technology comprises two functions of sensing and transmitting a substance to be detected, wherein the sensing is that an external signal changes according to the change rule of the external signal so that an optical fiber transmission signal, and the measured optical parameter changes to sense the substance to be detected, such as: intensity, wavelength, frequency, etc. The transmission refers to the process that the optical fiber transmits the light wave of the substance to be measured to the optical detector.
Among them, the infrared absorption method is most commonly used in gas monitoring to detect a substance component and determine a gas concentration according to the lambert beer's law. The traditional infrared absorption method adopts the quartz optical fiber to only transmit near-infrared laser, and most gases have obvious characteristic absorption spectrum in a middle infrared spectrum region (fingerprint region), so that the quartz optical fiber cannot be used for detecting the characteristic spectrum of the middle infrared gas, and the middle infrared Bragg optical fiber can be used for detecting the infrared absorption peak in the gases, so that the precision and the sensitivity are greatly improved. For example, the absorption peak intensity at infrared 3.3 μm in methane is 1000 times or more the absorption peak intensity at infrared 1.5 μm. Moreover, when the quartz optical fiber is used for measuring the substance to be measured, the optical fiber for sensing may need to be replaced every time, and the optical fiber may be welded and cut off when various substances are detected, which may cause loss of an optical fiber interface and cause an error in a detection result.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides the intermediate infrared Bragg fiber and the gas qualitative and quantitative detection device thereof. After measurement, the medium-infrared Bragg optical fiber does not need to be replaced, and gas detection can be realized.
The invention relates to a mid-infrared Bragg fiber, which has a tellurium-sulfur hollow Bragg structure and comprises a Bragg structure layer and a hollow core area formed by surrounding the Bragg structure layer, wherein the Bragg structure layer is formed by alternately stacking tellurate glass layers and chalcogenide glass layers at intervals; according to the refractive indexes of tellurate glass layer components and chalcogenide glass layer components, from the hollow core region to the outside, the first layer is a glass layer with a relatively large refractive index, the second layer is a glass layer with a relatively small refractive index, and the arrangement is repeated for a plurality of times according to the arrangement principle; a glass layer with a relatively large refractive index according to the thickness ratio: a glass layer with relatively small refractive index is 1 (1-4);
the method specifically comprises the following two arrangement modes:
firstly, when the refractive index of the tellurate glass layer is less than that of the chalcogenide glass layer, the first layer is the chalcogenide glass layer, the second layer is the tellurate glass layer and the like from the hollow core region to the outside; according to the thickness ratio, a chalcogenide glass layer: a tellurate glass layer 1 (1-4);
secondly, when the refractive index of the tellurate glass layer is greater than that of the chalcogenide glass layer, the tellurate glass layer is arranged from the hollow core region to the outside, the first layer is the tellurate glass layer, the second layer is the chalcogenide glass layer, and the rest is done in sequence; according to the thickness ratio, a tellurate glass layer: one chalcogenide glass layer (1-4);
the above-mentioned alternative interval is laminated and arranged, regard a layer of chalcogenide glass layer and a layer of tellurate glass layer as a pack of lamination, the Bragg structural layer has at least three groups of laminations;
the middle infrared Bragg fiber is provided with two rows of through holes along the axial direction, each row is uniformly provided with a plurality of through holes, and two corresponding holes in the two opposite rows of holes are uniformly distributed on the circumference of the fiber.
The Bragg structure layer can enable the sensing light to be transmitted in the hollow core with low loss and low interference, and the purpose of controlling the transmission bandwidth (namely the detection range) of the sensing spectrum can be achieved by adjusting the refractive index difference (more than 0.5) between the tellurite glass layer and the chalcogenide glass layer and the thickness of the glass layer;
the intermediate infrared Bragg fiber is used for transmitting intermediate infrared laser.
The refractive index difference between the tellurate glass layer and the chalcogenide glass layer is determined by adjusting the components of the tellurate glass layer and the chalcogenide glass layer.
The transmission bandwidth (namely the detection range) of the sensing spectrum can be adjusted by changing the thickness of the stack of the tellurite glass layer and the chalcogenide glass layer; the loss of the transmission bandwidth of the sensing spectrum can be optimized by adjusting the lamination times of the tellurate glass layer and the chalcogenide glass layer.
The through holes are arranged in the Bragg structure layer and are uniformly distributed in a straight line in the central axis direction of the optical fiber;
preferably, the through hole is used for enabling the substance to be measured to enter the hollow core region of the intermediate infrared Bragg fiber.
Preferably, the substance to be detected is a mixed gas or a single gas.
Preferably, the through hole is processed by laser drilling.
Preferably, said sulfur systemThe component of the glass layer is preferably As2S5Or As2Se3The tellurate glass layer preferably has TeO as the component2·ZnO·PbO·PbF2·Na2O (TZPNP) or TeO2·ZnO·Li2·BiO3(TZLB)。
The invention relates to a gas qualitative and quantitative detection device based on a mid-infrared Bragg optical fiber, which comprises the mid-infrared Bragg optical fiber; the device also comprises an incoming optical fiber, an outgoing optical fiber, a light source and a spectrometer;
one end of the intermediate infrared Bragg fiber is welded with the light inlet fiber, and the other end of the intermediate infrared Bragg fiber is welded with one end of the light outlet fiber; the light source is arranged at one end of the light inlet optical fiber, and the other end of the light outlet optical fiber is connected with the spectrometer.
Preferably, the spectrometer can also be connected with a computer.
Preferably, the light-entering optical fiber is a single-mode optical fiber, and the light-exiting optical fiber is a single-mode optical fiber.
The use method of the gas qualitative and quantitative detection device based on the infrared Bragg fiber comprises the following steps:
step 1: noise reduction
The absorption spectrum of the intermediate infrared Bragg fiber in an air state; or argon is directly introduced into the intermediate infrared Bragg fiber to form an argon environment;
step 2: qualitative and quantitative detection
Through the through hole axially arranged on the side surface of the intermediate infrared Bragg fiber, the gas to be detected enters the hollow-core area of the intermediate infrared Bragg fiber through the through hole, and the light transmitted inside the intermediate infrared Bragg fiber is absorbed to obtain an absorption spectrum in a gas-introduced state;
and step 3: data processing
Comparing the absorption spectrum in the gas-introduced state with the absorption spectrum in the air state to obtain the absorption spectrum of the gas, or directly obtaining the absorption spectrum of the gas in the argon state; detecting the components of the gas according to different infrared absorption peaks in the absorption spectrum of the gas so as to achieve qualitative analysis; and obtaining the content of the components in the gas through the intensity of the absorption peak, so as to achieve quantitative analysis.
In the designed Bragg structure layer, the glass layer with higher refractive index is used as the first layer of the sulfur tellurium hollow Bragg structure, and the lamination times are changed and the loss is reduced by adjusting the thickness ratio of the glass layers, so that the inductive light is transmitted in the intermediate infrared Bragg optical fiber hollow with low loss and low interference.
The invention relates to a mid-infrared Bragg optical fiber and a qualitative and quantitative gas detection device thereof, which have the following principles: and (3) analyzing and identifying the substance molecules by using mid-infrared spectroscopy. A continuous beam of mid-infrared light is irradiated on a molecule of a substance, and mid-infrared light with certain specific wavelengths is absorbed to form a mid-infrared absorption spectrum of the molecule. Each molecule has a unique mid-infrared absorption spectrum determined by the composition and structure of the molecule, so that the molecule can be subjected to structural analysis and identification, and qualitative analysis is performed on the gas to be detected;
the concentration of the determined gas is measured by lambert beer's law from the attenuation of the mid-infrared light, with greater concentrations having greater attenuation of the light.
Compared with the prior art, the intermediate infrared Bragg optical fiber and the gas qualitative and quantitative detection device thereof have the beneficial effects that:
the mid-infrared spectrum can be fully utilized to obtain a faster and better test effect, a single gas or mixed gas is detected, the layered thickness of tellurate glass and chalcogenide glass components and a sulfur-tellurium hollow Bragg structure and the number of laminated groups can be adjusted according to use requirements, the transmission range can be customized, low-interference and low-loss transmission is realized, and the measurement accuracy is improved. When the gas is detected, the through holes can improve the portability and speed of detection.
Drawings
FIG. 1 shows As provided in example 1 of the present invention2S5And a schematic cross-sectional view of a mid-infrared Bragg fiber of the TZPNP component;
fig. 2 is a schematic side view of a mid-ir bragg fiber according to embodiment 1 of the present invention;
fig. 3 is a schematic structural diagram of a qualitative and quantitative detection apparatus for mid-infrared bragg fiber gas according to embodiment 1 of the present invention;
FIG. 4 is a wavelength-loss curve measured in example 2 of the present invention;
FIG. 5 shows As in example 4 of the present invention2Se3A schematic cross-sectional view of a mid-infrared bragg fiber with a TZLB component;
in the above figures, 1 is a hollow area, 2 is a tellurate TZPNP glass layer, and 3 is chalcogenide As2S5A glass layer, 4 is a through hole, 5 is chalcogenide As2Se3A glass layer 6 is a tellurate TZLB glass layer; i is a light source, II is a light inlet optical fiber, III is a middle infrared Bragg optical fiber for qualitative and quantitative gas detection, IV is a light outlet optical fiber, and V is a spectrometer.
Detailed Description
In order to make the implementation objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The embodiments of the invention generally described and illustrated in the figures herein may be arranged and designed according to different laser transmission requirements;
thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive work based on the embodiments of the present invention, are within the scope of the present invention;
it should be noted that: like symbols and letters represent like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. In the description of the present invention, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as merely or implying relative importance.
In the description of the present invention, unless specifically defined and limited, the terms "cover", "laminate", "selected", "core", "cladding" are to be construed broadly, e.g., as covering completely, covering partially, etc. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In the following examples, the light source model used was ARCLIGHT-MIR-20, and the spectrometer was a PerkinElmer plate-making.
Example 1
The cross section schematic diagram of the intermediate infrared Bragg fiber is shown in figure 1, the side schematic diagram is shown in figure 2, and the intermediate infrared Bragg fiber is described as a fiber with a sulfur-tellurium hollow core Bragg structure; the intermediate infrared Bragg fiber consists of tellurate TZPNP glass layer 2 and chalcogenide As2S5A cladding region formed by laminating glass layers 3 and a hollow core region 1 surrounded by the cladding region; wherein the cladding region is a Bragg structure layer, the first layer is a tellurate TZPNP glass layer 2, and chalcogenide As2S5The glass layer 3 is formed by analogy, a tellurate glass layer and a chalcogenide glass layer are used as a group of laminated layers, and the Bragg structure layer comprises five groups of laminated layers.
Two rows of through holes 4 are arranged on the side surface of the intermediate infrared Bragg fiber, and each through hole 4 is uniformly arranged on a straight line parallel to the central axis along the central axis direction of the intermediate infrared Bragg fiber; two opposite holes in the two rows of through holes are uniformly distributed along the circumferential direction of the intermediate infrared Bragg fiber.
Specifically, the cladding region of the intermediate infrared Bragg fiber at least comprises 6 glass layers, at least 3 tellurate TZPNP glass layers and 3 chalcogenide As layers2S5Glass layers, stacked distribution. The thickness ratio of the tellurate glass layer to the chalcogenide glass layer is adjusted to 1:1 to 1:4, and the tellurate TZPNP glass layer is adopted in the embodiment: chalcogenide As2S5The glass layer is 1:2, and the thickness can be designed according to the refractive index and functional requirements. Specific components of the tellurate and the sulfur system can be selected and adjusted according to requirements; in this embodiment, the composition of the chalcogenide glass layer is preferably As2S5The composition of the tellurite glass layer is preferablyTeO2·ZnO·PbO·PbF2·Na2O(TZPPN)。
The intermediate infrared Bragg fiber is used as the transmission fiber for gas qualitative and quantitative detection, the transmission bandwidth can be adjusted according to the requirement, and the loss is low. Compared with the traditional quartz optical fiber, the measuring range is larger, the reaction is more sensitive, the device can be used for middle infrared wave bands, and the test result is more accurate. The traditional quartz optical fiber has strong absorption effect on the mid-infrared with the wavelength of more than 2 microns, but the optical fiber can transmit in the mid-infrared band, so that the gas (methane and the like) with the strong absorption peak in the mid-infrared region or the gas can be detected efficiently. The invention can detect gas.
On the basis of the embodiment, the through hole can be obtained by punching the mid-infrared Bragg fiber through laser.
The gas qualitative and quantitative detection device based on the mid-infrared Bragg fiber has a structural schematic diagram shown in FIG. 3, and comprises: a light source I, a spectrometer V and a mid-infrared Bragg fiber III provided in the above embodiments.
One end of the intermediate infrared Bragg fiber III is welded with the light inlet fiber II, and the other end of the intermediate infrared Bragg fiber III is welded with one end of the light outlet fiber IV; the light source I is arranged at one end of the light inlet optical fiber II and connects the other end of the light outlet optical fiber IV with the spectrometer V.
The light source I generates a wide-spectrum light beam, the wide-spectrum light beam is transmitted through the intermediate infrared Bragg fiber III through the light inlet fiber II, a substance to be detected enters a hollow-core area of the intermediate infrared Bragg fiber III through the air through hole 4 in the intermediate infrared Bragg fiber III at the moment, the transmitted wide-spectrum light beam is absorbed by the substance to be detected and then passes through the light outlet fiber IV, the light beam is received by the spectrometer V, the spectrometer V analyzes the received light beam, the substance component is determined according to the absorption spectrum, and the substance quantity to be detected is finally detected according to the Lambert beer law.
In this example, a 2.95 μm vicinity transmission belt was used, the radius of the hollow area was 30 μm, the thickness of one layer of tellurate TZPNP was 3 μm, and one layer of chalcogenide As2S5The thickness is 6 μm, 5 groups are repeated, the intermediate infrared Bragg fiber forms a specific transmission band around 2.9 μm-3.0 μm, the loss is below 10E-6dB/cm, and the data band is hydrogen cyanideIn the middle infrared strong absorption peak area of (HCN), hydrogen cyanide detection can be carried out;
the use method of the device for qualitatively and quantitatively detecting the gas based on the mid-infrared Bragg fiber comprises the following steps:
step 1: noise reduction
Detecting an absorption spectrum of the intermediate infrared Bragg fiber in an air state;
step 2: qualitative and quantitative detection
Through the through hole axially arranged on the side surface of the intermediate infrared Bragg fiber, the gas to be detected enters the hollow-core area of the intermediate infrared Bragg fiber through the through hole, and the light transmitted inside the intermediate infrared Bragg fiber is absorbed to obtain an absorption spectrum in a gas-introduced state;
and step 3: data processing
The absorption spectrum of the gas is obtained by comparing the absorption spectrum in the gas-in state with the absorption spectrum in the air state, and the components of the gas are detected according to the difference of mid-infrared absorption peaks in the absorption spectrum of the gas, so that qualitative analysis is achieved; and obtaining the content of the components in the gas through the intensity of the absorption peak, so as to achieve quantitative analysis.
Example 2
The intermediate infrared Bragg fiber is provided with a tellurium-sulfur hollow Bragg structure and comprises a Bragg structure layer and a hollow core area formed by surrounding the Bragg structure layer, wherein the Bragg structure layer is formed by alternately stacking tellurate glass layers and chalcogenide glass layers at intervals; in this embodiment, the tellurate glass layer is made of TeO2·ZnO·PbO·PbF2·Na2O (TZPP) and As As the component of the chalcogenide glass layer2S5。
According to the refractive index contrast, the chalcogenide glass layer is designed as the first layer of the Bragg structure;
specifically, the cladding region of the intermediate infrared Bragg fiber at least comprises 6 glass layers, at least 3 tellurate glass layers and 3 chalcogenide glass layers which are distributed in a laminated manner. The thickness ratio of the tellurate glass layer to the chalcogenide glass layer is adjusted to 1:1 to 1:4, and the tellurate glass layer is adopted in the embodimentGlass layer: the chalcogenide glass layer is 1:2, and the thickness can be selected according to the refractive index and the functional requirement. Specific components of the tellurate and the sulfur system can be selected and adjusted according to requirements; in this embodiment, the composition of the tellurite glass layer is preferably TeO2·ZnO·PbO·PbF2·Na2O (TZPP), the component of the chalcogenide glass layer is preferably As2S5。
Two rows of through holes are arranged on the side surface of the intermediate infrared Bragg fiber, and each through hole is uniformly arranged on a straight line parallel to the central axis along the central axis direction of the intermediate infrared Bragg fiber for qualitative and quantitative gas detection; two opposite holes in the two rows of through holes are uniformly distributed along the circumferential direction of the optical fiber.
Simulating by simulation software COMSOL, and adjusting the thickness ratio of the tellurate glass layer to the chalcogenide glass layer to be 1:2 by adjusting related parameters in the software according to the condition that the mid-infrared absorption peak of cyanide is 2.95-3.0 μm, namely a tellurate glass layer: a chalcogenide glass layer 1: 2; obtaining a hollow area with the radius of 30 mu m, a layer of tellurate TZPP with the thickness of 3 mu m and a layer of chalcogenide As2S5Thickness of 6 μm, repeating 5 groups, wherein the infrared laser transmission band is 2.85-3.0 μm, and loss is less than 10E-6dB/cm。
The device for qualitatively and quantitatively detecting the gas based on the intermediate infrared Bragg optical fiber is used for qualitatively and quantitatively detecting hydrogen cyanide and comprises the intermediate infrared Bragg optical fiber; the device also comprises an incoming optical fiber, an outgoing optical fiber, a light source and a spectrometer;
one end of the intermediate infrared Bragg fiber is welded with the light inlet fiber, and the other end of the intermediate infrared Bragg fiber is welded with one end of the light outlet fiber; the light source is arranged at one end of the light inlet optical fiber, and the other end of the light outlet optical fiber is linked with the spectrometer.
Firstly, argon is introduced into a mid-infrared Bragg optical fiber in a gas qualitative and quantitative detection device based on the mid-infrared Bragg optical fiber, air in the mid-infrared Bragg optical fiber is evacuated, interference of other gases is reduced as much as possible, hydrogen cyanide gas is introduced into the mid-infrared Bragg optical fiber, an optical signal is transmitted to a spectrometer from a light-emitting optical fiber, and the obtained mid-infrared absorption spectrum is analyzed.
By comparing the spectrograms of the unvented gas and the ventilated gas, the absorption peak appears between 2.9 and 3.0 mu m (the wavelength-loss curve is shown in figure 4, and the low-loss transmission band exists between 2.85 and 3.0 mu m through figure 4), the hydrogen cyanide is proved to be contained in the mixed gas, so that the mixed gas is qualitatively detected, and the amount of the substance to be detected is finally detected according to the intensity of the absorption peak and the Lambert beer law, so that the quantitative determination is carried out.
Example 3
The intermediate infrared Bragg fiber is an optical fiber with a sulfur tellurium hollow core Bragg structure; the intermediate infrared Bragg fiber is a hollow core region surrounded by a cladding region formed by stacking tellurate glass layers and chalcogenide glass layers and the cladding region; the cladding region is a Bragg structure layer, the first layer is a chalcogenide glass layer, the second layer is a tellurate glass layer, and the process is repeated in the same way, wherein the chalcogenide glass layer and the tellurate glass layer are used as a group of laminated layers, and the Bragg structure layer comprises five groups of laminated layers.
Two rows of through holes are arranged on the side surface of the intermediate infrared Bragg fiber, and each through hole is uniformly arranged on a straight line parallel to the central axis along the central axis direction of the intermediate infrared Bragg fiber; two opposite holes in the two rows of through holes are uniformly distributed along the circumferential direction of the intermediate infrared Bragg fiber.
Specifically, the present embodiment has a sulfur-tellurium hollow bragg structure, which includes a bragg structure layer and a hollow core region surrounded by the bragg structure layer, wherein the bragg structure layer is formed by alternately stacking tellurate glass layers and chalcogenide glass layers at intervals; in this embodiment, the chalcogenide glass layer is selected from As2Se3The tellurate glass layer has TeO component2·ZnO·Li2·BiO3(TZLB)。
This example uses a 2.5-3.2 μm vicinity belt, a 60 μm radius hollow core region, a layer of chalcogenide As2Se3The thickness of the tellurate TZLB layer is 6 mu m, 5 groups are repeated, and the middle infrared Bragg fiber forms a specific transmission band around 2.5-3.2 mu m.
By passingSimulation software COMSOL carries out simulation according to HCN, HF and C2H2The mid-infrared absorption peak of (2.5-3.2) mu m, the thickness ratio of the chalcogenide glass layer and the tellurate glass layer is 1:2 by adjusting software, and a chalcogenide glass layer: a tellurate glass layer 1: 2; the infrared laser transmission band was determined to be 2.5 to 3.2 μm.
And adjusting the lamination times to five groups, with loss less than 10E-6dB/cm。
The infrared spectrum range can be used for detecting HF, HCN and C2H2The mid-infrared spectrum peaks of the above three gases are at 2.6 μm (HF), 2.9 μm (HCN), 3.1 μm (C)2H2)。
Secondly, a gas qualitative and quantitative detection device based on the intermediate infrared Bragg fiber comprises the intermediate infrared Bragg fiber; the device also comprises an incoming optical fiber, an outgoing optical fiber, a light source and a spectrometer;
one end of the intermediate infrared Bragg fiber is welded with the light inlet fiber, and the other end of the intermediate infrared Bragg fiber is welded with one end of the light outlet fiber; the light source is arranged at one end of the light inlet optical fiber, and the other end of the light outlet optical fiber is connected with the spectrometer.
Firstly, air is introduced into a designed gas qualitative and quantitative detection device based on the mid-infrared Bragg fiber, the interference of other gases is reduced as much as possible, then the mixed gas to be detected is introduced into the mid-infrared Bragg fiber, and the light signal transmitted from the light-emitting fiber is transmitted to a spectrometer for analysis, so that the mid-infrared absorption spectrum is obtained.
By comparing the spectrograms of the unvented gas and the ventilated gas, the absorption peaks appear between 2.5 mu m and 3.2 mu m, and the absorption peaks are used for HCN, HF and C contained in the mixed gas2H2And (4) performing qualitative detection, and finally detecting the mass of the substance to be detected according to the Lambert beer law and the intensity of the absorption peak, and performing quantitative detection.
Example 4
The cross section schematic diagram of the intermediate infrared Bragg fiber is shown in figure 5, and the intermediate infrared Bragg fiber for qualitative and quantitative gas detection is an optical fiber with a sulfur-tellurium hollow Bragg structure; the mid-infrared Bragg for qualitative and quantitative detection of gasThe optical fiber consists of tellurate TZLB glass layer 6 and chalcogenide As2Se3A cladding region formed by laminating glass layers 5 and a hollow-core region 1 surrounded by the cladding region; wherein the cladding region is a Bragg structure layer, the first layer is chalcogenide As2Se3A glass layer 5, a tellurate TZLB glass layer 6 As the second layer, and a layer of chalcogenide As2Se3The glass layer and the tellurate TZLB glass layer form a group of laminated layers, and the Bragg structure layer comprises five groups of laminated layers
Two rows of through holes 4 are arranged on the side surface of the intermediate infrared Bragg fiber, and each through hole 4 is uniformly arranged on a straight line parallel to the central axis along the central axis direction of the intermediate infrared Bragg fiber; two opposite holes in the two rows of through holes are uniformly distributed along the circumferential direction of the intermediate infrared Bragg fiber.
Specifically, the cladding region of the intermediate infrared Bragg fiber at least comprises 3 glass layers, at least 3 chalcogenide glass layers and 3 tellurate glass layers which are distributed in a laminated mode. The thickness ratio of the chalcogenide glass layer and the tellurate glass layer is adjusted to 1:1 to 1:4, and in this example, 5 glass layers are laminated, and chalcogenide As is used2Se3Glass layer 5: the tellurate TZLB glass layer 6 is 1:3, and the thickness can be designed according to refractive index and functional requirements. Specific components of the tellurate and the sulfur system can be selected and adjusted according to requirements; in this embodiment, the composition of the chalcogenide glass layer is preferably As2Se3The composition of the tellurate glass layer is preferably TeO 2. ZnO. Li 2. BiO3(TZLB), as shown in fig. 5.
The intermediate infrared Bragg fiber is used as the transmission fiber, the transmission bandwidth can be adjusted according to the requirement, and the loss is low. Compared with the traditional quartz optical fiber, the measuring range is larger, the reaction is more sensitive, the device can be used for middle infrared wave bands, and the test result is more accurate. Because the traditional quartz fiber has strong absorption effect on the mid-infrared spectrum of more than 2 microns, and the mid-infrared Bragg fiber can transmit light in the region, the invention can efficiently detect the gas (methane and the like) or the gas with the strong absorption peak in the mid-infrared region.
On the basis of the embodiment, the through hole can be obtained by punching the laser intermediate infrared Bragg fiber.
Simulation is carried out through simulation software COMSOL, the thickness ratio of the chalcogenide glass layer to the tellurate glass layer is 1:3, and a chalcogenide glass layer is formed: a tellurate glass layer 1: 3; determining the infrared laser low-loss transmission band to be 0.8-3.3 μm and the loss to be 10E-7dB/cm or less.
This embodiment uses a 0.8 μm to 3.3 μm belt, a 60 μm radius hollow core region, and a layer of chalcogenide As2Se3The thickness of the middle infrared Bragg fiber is 3 mu m, the thickness of one layer of tellurate TZLB is 9 mu m, 5 groups are repeated, the middle infrared Bragg fiber forms a specific transmission band near 0.8 mu m to 3.3 mu m, and the loss is 10E-7dB/cm below, can be used for gas detection with infrared absorption peak area of 0.8-3.3 μm, including but not limited to CO2、C2H2、HF、CH4HCN, HBr, NO, etc.
Secondly, a qualitative and quantitative gas detection device based on mid-infrared Bragg fiber comprises: a light source, a spectrometer and a mid-infrared bragg fiber as provided in the above embodiments.
One end of the intermediate infrared Bragg fiber is welded with the light inlet fiber, and the other end of the intermediate infrared Bragg fiber is welded with one end of the light outlet fiber; the light source is arranged at one end of the light inlet optical fiber, and the other end of the light outlet optical fiber is connected with the spectrometer.
Firstly, air is introduced into a designed gas qualitative and quantitative detection device based on the mid-infrared Bragg fiber, the interference of other gases is reduced as much as possible, then the gas to be detected is introduced into the mid-infrared Bragg fiber, and the optical signal transmitted from the light-emitting fiber is transmitted to a spectrometer for analysis, so that the obtained infrared absorption spectrum is obtained.
Comparing the spectrograms after ventilation and before ventilation to compare the absorption peak in the infrared range of 0.8-3.2 microns, comparing the infrared spectrum of the gas, verifying the gas components in the mixed gas, determining the nature, finally detecting the mass of the substance to be detected according to the intensity of the absorption peak and the Lambert beer law, and quantifying.
Finally, the method of the present invention is only a preferred embodiment and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made without departing from the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (10)
1. The intermediate infrared Bragg fiber is characterized by having a tellurium-sulfur hollow Bragg structure, and comprising a Bragg structure layer and a hollow core area formed by surrounding the Bragg structure layer, wherein the Bragg structure layer is formed by alternately stacking tellurate glass layers and chalcogenide glass layers at intervals; according to the refractive indexes of tellurate glass layer components and chalcogenide glass layer components, from the hollow core region to the outside, the first layer is a glass layer with a relatively large refractive index, the second layer is a glass layer with a relatively small refractive index, and the arrangement is repeated for a plurality of times according to the arrangement principle; a glass layer with a relatively large refractive index according to the thickness ratio: a glass layer with relatively small refractive index is 1 (1-4);
the above-mentioned alternative interval is laminated and arranged, regard a layer of chalcogenide glass layer and a layer of tellurate glass layer as a pack of lamination, the Bragg structural layer has at least three groups of laminations;
the middle infrared Bragg fiber is provided with two rows of through holes along the axial direction, each row is uniformly provided with a plurality of through holes, and two corresponding holes in the two opposite rows of holes are uniformly distributed on the circumference of the fiber.
2. The mid-infrared bragg fiber of claim 1, wherein the alternating intervals are stacked in a manner of arrangement, specifically one of:
firstly, when the refractive index of the tellurate glass layer is less than that of the chalcogenide glass layer, the first layer is the chalcogenide glass layer, the second layer is the tellurate glass layer and the like from the hollow core region to the outside; according to the thickness ratio, a chalcogenide glass layer: a tellurate glass layer 1 (1-4);
secondly, when the refractive index of the tellurate glass layer is greater than that of the chalcogenide glass layer, the tellurate glass layer is arranged from the hollow core region to the outside, the first layer is the tellurate glass layer, the second layer is the chalcogenide glass layer, and the rest is done in sequence; according to the thickness ratio, a tellurate glass layer: one chalcogenide glass layer is 1 (1-4).
3. The mid-infrared bragg fiber of claim 1, wherein the bragg structure layer is configured to transmit the sensing light in the hollow core with low loss and low interference, and the refractive index difference is greater than or equal to 0.5 by adjusting the tellurate glass layer and the chalcogenide glass layer, and the transmission bandwidth of the sensing spectrum is controlled by adjusting the thickness of the glass layer.
4. The mid-infrared bragg fiber according to claim 3, wherein a refractive index difference between the tellurate glass layer and the chalcogenide glass layer is determined by adjusting components of the tellurate glass layer and the chalcogenide glass layer;
the transmission bandwidth of the induction spectrum is optimized by adjusting the lamination thickness of the tellurite glass layer and the chalcogenide glass layer; the loss of the transmission bandwidth of the induction spectrum is optimized by adjusting the lamination times of the tellurite glass layer and the chalcogenide glass layer.
5. A mid-infrared bragg fiber as claimed in claim 1, wherein the through holes are formed in the bragg structure layer and are uniformly arranged in a straight line in a central axis direction of the fiber.
6. The mid-ir bragg fiber of claim 1, wherein the through hole is adapted to allow the gas to be measured to enter the hollow core region of the mid-ir bragg fiber; the through hole is processed in a laser drilling mode.
7. A mid-infrared bragg fiber As claimed in claim 1, wherein the chalcogenide glass layer has a composition of As2S5Or As2Se3The tellurate glass layer has TeO component2·ZnO·PbO·PbF2·Na2O or TeO2·ZnO·Li2·BiO3。
8. A qualitative and quantitative gas detection device based on mid-infrared Bragg fiber, which is characterized by comprising the mid-infrared Bragg fiber of claims 1-7; the device also comprises an incoming optical fiber, an outgoing optical fiber, a light source and a spectrometer;
one end of the intermediate infrared Bragg fiber is welded with the light inlet fiber, and the other end of the intermediate infrared Bragg fiber is welded with one end of the light outlet fiber; the light source is arranged at one end of the light inlet optical fiber, and the other end of the light outlet optical fiber is connected with the spectrometer.
9. The device according to claim 8, wherein the light-entering optical fiber is a single-mode optical fiber, and the light-exiting optical fiber is a single-mode optical fiber.
10. The use method of the device for qualitative and quantitative detection of gas based on mid-infrared Bragg fiber as claimed in claim 8, characterized by comprising the following steps:
step 1: noise reduction
The absorption spectrum of the intermediate infrared Bragg fiber in an air state; or argon is directly introduced into the intermediate infrared Bragg fiber to form an argon environment;
step 2: qualitative and quantitative detection
Through the through hole axially arranged on the side surface of the intermediate infrared Bragg fiber, the gas to be detected enters the hollow core region of the intermediate infrared Bragg fiber, and the light transmitted inside the intermediate infrared Bragg fiber is absorbed to obtain an absorption spectrum in a gas-introduced state;
and step 3: data processing
Comparing the absorption spectrum in the gas-introduced state with the absorption spectrum in the air state to obtain the absorption spectrum of the gas, or directly obtaining the absorption spectrum of the gas in the argon state; detecting the components of the gas according to different wavelengths of mid-infrared absorption peaks in the absorption spectrum of the gas, thereby achieving qualitative analysis; and obtaining the content of the components in the gas through the intensity of the absorption peak, so as to achieve quantitative analysis.
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