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Tapered multimode interference-based high-sensitivity optical fiber methane sensing device

A multi-mode interference, multi-mode optical fiber technology, applied in the field of high-sensitivity optical fiber methane sensing, can solve the problems of low sensitivity, low sensor sensitivity, changing the structure of the sensitive film, etc., and achieve the effect of high response speed and high porosity

Active Publication Date: 2015-12-02
重庆科知源科技有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the sensitive films of these methods are derived from the coating of cage molecules mixed with polysiloxane and styrene-acrylonitrile resins. Most of the cage molecules are wrapped in the film materials, and methane molecules are prone to appear in these films. Due to the problems of high migration resistance in the material and difficulty in contact with cage molecules, the response speed of the sensor is slow (2 to 5 minutes) and the sensitivity is low.
[0005] It can be seen that the above technologies all have a common problem, that is, the cage molecules are not directly exposed to methane gas, which affects the ability of the cage molecules to respond to methane molecules, making the sensor sensitivity low, and it is necessary to change the structure of the sensitive film

Method used

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  • Tapered multimode interference-based high-sensitivity optical fiber methane sensing device
  • Tapered multimode interference-based high-sensitivity optical fiber methane sensing device
  • Tapered multimode interference-based high-sensitivity optical fiber methane sensing device

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Effect test

Embodiment 1

[0050]Example 1: A section of multimode fiber MMF and two sections of single-mode fiber SMF-28 are fused to form a SMF-MMF-SMF structure, the length of the multimode fiber is 42 mm, the tapered area of ​​the multimode fiber after tapering is 0.68 mm, and the beam waist diameter is 30 μm ; After the surface of the tapered area is pre-coated with a silane coupling agent nano-covering layer, the surface of the tapered optical fiber is coated with α-hydrogen-ω-hydroxyl-polydimethylsiloxane containing cage molecule A with a thickness of 350nm Methane-sensitive membranes are porous. Taking methane standard gas with a concentration of 0-3.5% (v / v) as the object, it interacts with the sensitive film on the surface of the optical fiber respectively. The characteristic wavelength of the transmission interference spectrum moves to the short wavelength direction with the increase of the methane gas concentration, and the transmission interference spectrum The amount of movement of the cha...

Embodiment 2

[0055] Embodiment 2: The experiment adopts the tapered optical fiber methane sensor with tapered region 0.55mm, beam waist diameter 25μm, sensitive film thickness 380nm, and with known concentration of 0, 0.1, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5% (v / v) methane standard gas is used for detection, and the characteristic wavelength of the trough of the corresponding transmission interference spectrum moves to the short wavelength direction with the increase of the methane gas concentration, and the movement amount of the characteristic wavelength of the trough of the interference spectrum Δλ c 0, 0.42, 0.82, 1.24, 1.62, 2.02, 2.48, 3.02, 3.48nm respectively, the linear regression equation is: Δλ c =0.9246c+0.2293, correlation coefficient R 2 =0.9916, that is, k and b in the linear regression equation are 0.9242 and 0.2293 respectively.

[0056] When the methane gas to be measured is in contact with the sensor, the characteristic wavelength shift of the transmission interference sp...

Embodiment 3

[0057] Embodiment 3: adopt the tapered optical fiber methane sensor of tapered area 0.76mm, beam waist diameter 32 μ m, sensitive film thickness 330nm, and with known concentration 0,0.1,0.5,1.0,1.5,2.0,2.5,3.0,3.5 % (v / v) methane standard gas for detection, the corresponding transmission interference spectrum trough characteristic wavelength moves to the short wavelength direction with the increase of methane gas concentration, and the interference spectrum trough characteristic wavelength shift amount Δλ c 0, 0.42, 0.88, 1.24, 1.72, 2.16, 2.32, 3.04, 3.46nm respectively, the linear regression equation is: Δλ c =0.9115c+0.2654, correlation coefficient R 2 =0.9846, that is, k and b in the linear regression equation are 0.9115 and 0.2654 respectively.

[0058] When the methane gas to be measured is in contact with the sensor, the characteristic wavelength shift of the transmission interference spectrum trough Δλ c is 3.18nm, it can be calculated that the concentration of meth...

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Abstract

The invention discloses a tapered multimode interference-based high-sensitivity optical fiber methane sensing device. The device comprises a broadband light source, a STMS-structure tapered multimode porous sensitive film-coated optical fiber sensing device, a testing air chamber, a switch valve, a mass flow controller, a spectrum analyzer and a computer. The STMS-structure optical fiber sensing device is prepared by single-mode optical fiber-multimode optical fiber-single-mode optical fiber melting connection and then multimode optical fiber tapering. The outer surface of the tapered multimode optical fiber is pre-treated by a silane coupling agent. The sensitive film is a cage molecule A-containing alpha-hydro-omega-hydroxy-polydimethylsiloxane porous methane-sensitive film. When methane gas to be detected reacts with the porous methane-sensitive film, a sensitive film refractive index is fast changed so that sensor interference spectrum characteristic wavelength lambda c is moved. Through analysis of interference spectrum characteristic wavelength movement amount delta lambda c before and after contact between the sensor and methane gas, a concentration of methane to be detected is obtained. The device has the characteristics of high sensitivity, fast response speed, good selectivity and good stability.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, and in particular relates to a high-sensitivity optical fiber methane sensing method and device for obtaining methane concentration through conical multi-mode interference. Background technique [0002] With the rapid development of optical fiber sensing technology, the research of optical fiber gas sensor has received widespread attention. It is suitable for inflammable and explosive environments in harsh environments because of its good electrical insulation, anti-strong electromagnetic interference, explosion-proof, and long-distance long-term online measurement. Gas monitoring. [0003] Single-mode fiber (SMF)-tapered multimode fiber (TMMF)-single-mode fiber (SMF) structure (STMS) is a fiber structure based on the mode interference mechanism of tapered multimode fiber, which is embedded by a section of multimode fiber It is made by tapering multimode fiber after reaching a sect...

Claims

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Application Information

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IPC IPC(8): G01N21/45
Inventor 杨建春王开武周浪车鑫陈伟民
Owner 重庆科知源科技有限公司
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