SE1350785A2 - Optical waveguide gas sensor - Google Patents
Optical waveguide gas sensor Download PDFInfo
- Publication number
- SE1350785A2 SE1350785A2 SE1350785A SE1350785A SE1350785A2 SE 1350785 A2 SE1350785 A2 SE 1350785A2 SE 1350785 A SE1350785 A SE 1350785A SE 1350785 A SE1350785 A SE 1350785A SE 1350785 A2 SE1350785 A2 SE 1350785A2
- Authority
- SE
- Sweden
- Prior art keywords
- optical waveguide
- light guiding
- tubular element
- outer tubular
- guiding structure
- Prior art date
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- 230000003287 optical effect Effects 0.000 title claims abstract description 27
- 239000012530 fluid Substances 0.000 claims abstract description 9
- 238000004891 communication Methods 0.000 claims abstract description 5
- 239000013307 optical fiber Substances 0.000 claims description 11
- 238000005253 cladding Methods 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 238000001228 spectrum Methods 0.000 claims description 2
- 239000007789 gas Substances 0.000 description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 239000000835 fiber Substances 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 230000007613 environmental effect Effects 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000001066 destructive effect Effects 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- ORQBXQOJMQIAOY-UHFFFAOYSA-N nobelium Chemical compound [No] ORQBXQOJMQIAOY-UHFFFAOYSA-N 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
Classifications
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- 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
- 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
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
- C03B37/01211—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube
-
- 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
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
- G01N21/65—Raman scattering
-
- 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
-
- 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
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
An open hollow core optical waveguide (100,200) for a gas sensor comprising: an outer tubular element (102) having a sidewall, comprising an elongated opening (104) in the sidewall extending in the longitudinal direction along the length of a portion of the tubular element; a transparent inner hollow light guiding structure (106)forming a light guiding core, attached to an inner wall of the outer tubular element, the inner hollow light guiding structure comprising an elongated opening (108), arranged such that the light guiding core is in fluid communication with the elongated opening of the outer tubular element.Fig.2
Description
OPTICAL WAVEGUIDE GAS SENSOR Field of the Invention The present invention relates to an optical waveguide. In particular, the present invention relates to a hollow core optical waveguide suitable for use in an environmental sensor.
Technical Background Optical fibers are capable of guiding light for long distances and can therefore be used as distributed sensors. Even in shorter distances (meters range), optical fibers find applications in which the light beam does not spread in space.
Develpments in the field of fiber optics has led to development of hollow core fibers, where light is guided primarily in the hollow of a fiber, and the glass structure around the hollow core only guarantees that light does not escape transversally. Even wavelengths that would normally be absorbed by silica can be guided in this way. Capillaries coated with metal on the inside and fibers with a periodic distribution of longitudinally arranged holes, so-called photonic bandgap fibers, have been used to guide light in the hollow core. If water vapor or gas is inserted in the core, light can detect its presence by the characteristic absorption lines. Such a sensor is effective as all of the optical field interacts with the gas, and not just the evanescent field.
There are applications where it is desirable to measure, in a distributed way, the presence of gases or liquids. Two examples are given in the following. First, in a refinery it may be crucial to be able to detect in various locations the presence of a gas that may be leaking. Secondly, it can be advantageous to be able to detect the presence of water vapor, for example inside a bathroom wall, which would indicate water leakage. In both examples, the wavelength region of interest is the mid-infrared, where most gas absorption lines are located (3-5 urn), and where water has its main peak (2.8 um). Note that the cut-off of silica is at around 2 um.
Optical fibers having a hollow core are known in the art. Such hollow cores typically guides light by way of a photonic bandgap structure (PBG) arranged within the fiber.
One example of an optical waveguide environmental sensor can be found in US 7,343,074 which disclose a waveguide in the form of an optical fiber, where the cladding contains a photonic bandgap structure having a lattice-type microstructure enveloping a light conducting hollow core portion. The cladding further includes at least one elongated side opening so that the hollow core portion is exposed to the ambient environment.
However, in order to form the elongated opening, the cladding must be chemically etched or laser machined. Such a process is both complicated and time consuming, thereby increasing the cost of manufacturing the sensor. The process of forming the opening may furthermore damage or disrupt the photonic bandgap structure in an uncontrolled manner such that the performance of the light guide is degraded.
Summary of the Invention In view of the above-mentioned and other drawbacks of the prior art, a general object of the present invention is to provide an improved device for use as an optical waveguide environmental sensor.
According to a first aspect of the present invention, it is therefore provided an open hollow core optical waveguide for a gas sensor comprising: an outer tubular element having a sidewall, comprising an elongated opening in said sidewall extending in the longitudinal direction along the length of a portion of said tubular element; a transparent inner hollow light guiding structure forming a light guiding core, attached to an inner wall of the outer tubular element, the inner hollow light guiding structure comprising an elongated opening, arranged such that the light guiding core is in fluid communication with the elongated opening of the outer tubular element.
The hollow core optical waveguide can be understood as an optical fiber having a hollow core, and an additional structure within the hollow core forming a confinement region for light propagating in the core. Through the openings in the inner element and the outer element, the environment outside of the optical waveguide can come into contact with the light guiding core. Thereby, a change in environment can be detected by analyzing the spectra of light having passed through the waveguide, and the waveguide can thus be used in a gas or fluid sensor. Even though the open hollow core optical waveguide is discussed in reference to its use in a gas sensor, it may obviously equally well be used in a fluid sensor. The hollow core may for example be filled by water or other fluids, thereby making it possible to analyze the fluid by studying the properties of light having propagated through a specific fluid.
Accordingly, an advantage of the present invention is that an optical fiber design allowing free communication between the hollow light guiding core and the outside environment without additional disturbance of the guidance of light is provided.
A further advantage of a hollow core waveguide according to various embodiments of the invention is that it may advantageously be used in a sensor in a hydrocarbon rich environment, where a conventional optical fiber may darken due to the creation of OH radicals. This will not be the case here as light is guided in an air-core.
Both the outer tubular element and the inner light guiding structure may advantageously be made from materials used in conventional optical fibers, such as silica.
In one embodiment of the invention, the inner hollow light guiding structure may comprise a tubular structure fixedly attached to the sidewall of the outer tubular element at a plurality of separate locations spaced apart from each other. One way to achieve a light guiding hollow core is to provide a second tubular structure within the outer tubular structure, and attaching the inner structure to the outer at specific locations, so that the distance between the two tubular structures is fixed.
According to one embodiment of the invention, the inner hollow light guiding structure may comprises a plurality of elongate elements arranged adjacent to each other, extending longitudinally along the length of a portion of the outer tubular element, and wherein at least two of the elongate elements are arranged at a distance from each other to form the opening of the inner hollow light guiding structure. A light guiding core may be provided through a plurality of tubular elongate element arranged adjacent to each other to form a confining circle within the outer tubular element. In the same manner as described above, destructive and constructive interference determined by the dimension of the elongate elements determines which wavelengths may propagate in the light guiding core. Furthermore, by arranging at least two of the elements at a distance from each other in the circumferential direction, an opening is formed, an by aligning the opening with the opening in the outer tubular element, the environment outside of the optical waveguide can reach the core.
In one embodiment of the invention, a distance from an inner wall of the inner hollow light guiding structure to an inner wall of outer tubular element may advantageously be selected such that only light of selected wavelengths may propagate in said waveguide. Interference between the inner wall of the outer tubular structure and the opposite wall of the inner hollow light guiding structure gives specific allowed wavelengths/modes due to destructive/constructive interference. Thus, the allowable wavelengths within the optical waveguide can be selected by selecting the distance between the outer tubular structure and the inner hollow light guiding structure.
Brief Description of the Drawings These and other aspects of the present invention will now be described in more detail with reference to the appended drawings showing an example embodiment of the invention, wherein: Fig. 1 schematically illustrates a waveguide according to an embodiment of the invention; Figs. 2a-b schematically illustrates a waveguide according to an embodiment of the invention; and Fig. 3 schematically illustrates a waveguide according to an embodiment of the invention.
Detailed Description of Preferred Embodiments of the Invention Figs. 1a-b illustrates examples an open hollow core optical waveguide 100 for a gas sensor comprising an outer tubular element 102 having a sidewall, comprising an elongated opening 104 in said sidewall extending in the longitudinal direction along the length of a portion of said tubular element; a transparent inner hollow light guiding structure 106 forming a light guiding core, attached to an inner wall of said outer tubular element, said inner hollow light guiding structure comprising an elongated opening 108, arranged such that the light guiding core is in fluid communication with the elongated opening of said outer tubular element.
Typical dimensions are: outer diameter 125 Mm. Inner core 60 um. Openings 1 pm. The openings do not need to be aligned. Thickness: outer structure: 25 um. Inner: 1 urn.
Fig. 2 and Fig. 3 shows an open hollow core optical waveguide 200, 300 for a gas sensor wherein the inner hollow light guiding structure comprises tubular structures 202,302 fixedly attached to the sidewall of the outer tubular element at a plurality of separate locations. In Fig. 3, the tubular structures 302 are spaced apart from each other.
Claims (8)
1. An open hollow core optical waveguide (100,200) for a gas sensor comprising: an outer tubular element (102) having a sidewall, comprising an elongated opening (104) in said sidewall extending in the longitudinal direction along the length of a portion of said tubular element; a transparent inner hollow light guiding structure (106) forming a light guiding core, attached to an inner wall of said outer tubular element, said inner hollow light guiding structure comprising an elongated opening (108), arranged such that said light guiding core is in fluid communication with said elongated opening of said outer tubular element.
2. The optical waveguide according to claim 1, wherein said inner hollow light guiding structure comprises a tubular structure (202, 302) fixedly attached to said sidewall of said outer tubular element at a plurality of separate locations spaced apart from each other.
3. The optical waveguide according to claim 1, wherein said inner hollow light guiding structure comprises a plurality of elongate elements arranged adjacent to each other, extending longitudinally along the length of a portion of said outer tubular element, and wherein at least two of said elongate elements are arranged at a distance from each other to form said opening of said inner hollow light guiding structure.
4. The optical waveguide according to claim 3, wherein said elongate element is a hollow circular element.
5. The optical waveguide according to any one of the preceding claims, wherein said outer tubular element is a circular element.
6. The optical waveguide according to any one of the preceding claims, wherein a distance from an inner wall of said inner hollow light guiding structure to an inner wall of outer tubular element is selected such that only light of selected wavelengths may propagate in said waveguide.
7. The optical waveguide according to any one of the preceding claims, in a first end optically coupled to a first optical fiber and in a second end optically coupled to a second optical fiber.
8. A gas sensor comprising: a light source configured to couple light into an optical waveguide according to any one of the preceding claims; and an optical receiver configured to receive light having passed through said optical waveguide; and a spectrum analyzer configured to analyze said received light. 10. Method for manufacturing an optical waveguide gas sensor, said method comprising the steps of. forming a perform comprising a tubular cladding; forming an elongated opening along a portion of the length of said tubular cladding; arranging a hollow light guiding structure within said tubular cladding; drawing an optical fiber from said perform.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE1350785A SE1350785A2 (en) | 2013-06-27 | 2013-06-27 | Optical waveguide gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE1350785A SE1350785A2 (en) | 2013-06-27 | 2013-06-27 | Optical waveguide gas sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| SE1350785A1 SE1350785A1 (en) | 2013-06-27 |
| SE1350785A2 true SE1350785A2 (en) | 2015-11-10 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| SE1350785A SE1350785A2 (en) | 2013-06-27 | 2013-06-27 | Optical waveguide gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| SE (1) | SE1350785A2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110501781A (en) * | 2019-08-30 | 2019-11-26 | 北京智芯微电子科技有限公司 | The forming method of waveguide and SF6 gas passive sensor comprising the waveguide |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10133017B2 (en) * | 2015-08-07 | 2018-11-20 | Pgs Geophysical As | Vented optical tube |
-
2013
- 2013-06-27 SE SE1350785A patent/SE1350785A2/en not_active Application Discontinuation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110501781A (en) * | 2019-08-30 | 2019-11-26 | 北京智芯微电子科技有限公司 | The forming method of waveguide and SF6 gas passive sensor comprising the waveguide |
Also Published As
| Publication number | Publication date |
|---|---|
| SE1350785A1 (en) | 2013-06-27 |
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| NAV | Patent application has lapsed |