Optical fiber LMR sensor probe system based on double-film layer structure

Abstract

The application discloses a kind of optical fiber LMR sensing probe systems based on double film layer structure, by supercontinuum spectrum light source, Y type optical fiber bundle, double film layer optical fiber LMR sensing probe, optical fiber spectrometer and host computer software composition;The double film layer optical fiber LMR sensing probe is sequentially removed by inside to outside cladding large core diameter multimode optical fiber, low refractive index matching layer, loss mode excitation layer, solve the LMR spectrum signal cross talk problem by TE / TM polarized light excitation, on spectrum, as TE / TM polarized light excitation LMR resonance wavelength does not affect each other, thus produce double resonance effect.The double film layer optical fiber LMR sensing probe system proposed in the application not only realizes the substantial improvement of detection precision, and double resonance sensing result can be verified each other, further guarantee the reliability of experimental result.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical fiber sensors, and particularly relates to an optical fiber LMR sensing probe system based on a double-film layer structure. BACKGROUND

[0002] As an important branch of optical fiber surface wave sensors, the optical fiber LMR (Lossy Mode Resonance) sensor has the advantages of easy preparation, high sensitivity, wide source of film materials, and low cost, and therefore, relevant research and application emerge in endlessly. However, it should be noted that, unlike the optical fiber SPR (Surface Plasmon Resonance) which can only be excited by TM (Transverse Magnetic wave) polarized light, the generation of the optical fiber LMR can be excited not only by TM polarized light, but also by TE (Transverse Electric wave) polarized light, and therefore, under the condition of natural light incidence, the resonance spectrum of the optical fiber LMR is a result of the excitation of TE / TM polarized light, which also leads to the superposition of the resonance spectrum signals of the two, and it is difficult to distinguish them, and the total resonance spectrum shows a relatively wide full width at half maximum, which reduces the detection accuracy. Therefore, the polarization control device becomes the first choice to solve such problems, so as to select the LMR excited by single polarization, and then obtain higher detection accuracy. However, the related optical polarization control device is not only expensive, but also needs a more complex optical system, and cannot achieve the effect of applying double resonance to sensing at the same time.

[0003] Therefore, it is of important research significance and application prospect to develop an optical fiber LMR sensor with high detection accuracy, low detection limit, high reliability, economy and convenience. SUMMARY

[0004] In view of the technical defects of the existing optical fiber LMR sensor, the application provides an optical fiber LMR sensing probe system based on a double-film layer structure, which aims to solve the LMR spectrum signal cross-talk problem excited by TE / TM polarized light by using the double-film layer structure, realize the resonance wavelength separation of the LMR excited by TE / TM polarized light, and achieve the effect of applying double resonance to sensing at the same time, which can not only improve the detection accuracy and reduce the detection limit, but also verify the experimental results of the double resonance with each other to ensure high reliability.

[0005] The application realizes the following technical scheme:

[0006] A kind of optical fiber LMR sensing probe system based on double film layer structure, the system includes supercontinuum light source, Y type optical fiber bundle, double film layer optical fiber LMR sensing probe, fiber spectrometer and host computer software;Wherein, the double film layer optical fiber LMR sensing probe is connected with the supercontinuum light source and the fiber spectrometer respectively by the Y type optical fiber bundle, and the fiber spectrometer transmits the resonance spectrum from the double film layer optical fiber LMR sensing probe to the host computer software for acquisition;

[0007] The wave band range of the supercontinuum light source is 400~2400 nm;

[0008] The core diameter of the Y type optical fiber bundle is 400 μm;

[0009] The double film layer optical fiber LMR sensing probe is in order from inside to outside as follows: large core diameter multimode fiber with plastic cladding removed, low refractive index matching layer, loss mode excitation layer;

[0010] The wavelength resolution of the fiber spectrometer is 0.24 nm.

[0011] Further, the low refractive index matching layer is MgF2 film layer, and the thickness is 100~500 nm.

[0012] Further, the loss mode excitation layer is ITO film layer, and the thickness is 300 nm.

[0013] A preparation method of optical fiber LMR sensing probe based on double film layer structure, comprising the following steps:

[0014] Step 1, using sharp blade to remove the plastic cladding of large core diameter multimode fiber, exposing the fiber core with centimeter length;After cleaning treatment of the fiber core, the fiber with exposed fiber core is cut by large core diameter multimode fiber cutting knife, to obtain large core diameter multimode fiber with plastic cladding removed and flat end face;

[0015] Step 2, using radio frequency magnetron sputtering equipment to uniformly sputter dense and flat low refractive index matching layer on the sidewall of large core diameter multimode fiber with plastic cladding removed from MgF2 target material: fix the large core diameter multimode fiber with plastic cladding removed in the radio frequency magnetron sputtering equipment, when the basic pressure of the cavity is lower than 1.0×10 -5 Pa, introduce Ar (99.999%) and SF6 (99.999%) mixed gas into the cavity to 0.60 Pa, the mixing ratio is Ar: SF6=200:3, and the sputtering power is 200 W;

[0016] Step 3, the large core multimode optical fiber with MgF2 film layer removed cladding is placed in the radio frequency magnetron sputtering device, and a dense and smooth loss mode excitation layer is uniformly sputtered on the large core multimode optical fiber with MgF2 film layer removed cladding by using an ITO target (In2O3: SnO2=90:10 wt%); when the basic pressure in the cavity is less than 1.0*10 -5 Pa, Ar (99.999%) is introduced into the cavity at a flow rate of 100 sccm to 1.0 Pa, and the sputtering power is 100 W, so as to obtain a double-film layer optical fiber LMR sensing probe.

[0017] Compared with the prior art, the beneficial effects and significant progress of the present application are that:

[0018] 1. The double-film layer structure is used to solve the LMR spectrum signal cross-talk problem caused by TE / TM polarized light excitation of the optical fiber LMR sensor, and the LMR resonance wavelengths excited by TE / TM polarized light are separated;

[0019] The moving amount of the LMR resonance wavelengths excited by TE / TM polarized light and the refractive index are respectively established, the refractive index sensing is realized, the double-resonance mutual verification effect is achieved, the detection precision is improved, the detection limit is reduced, and the experimental results of the TE / TM double-resonance wavelengths are mutually verified to ensure high reliability; BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a double-film layer optical fiber LMR sensing probe system for immunoassay;

[0021] Figure 2 It is a structural diagram of the double-film layer optical fiber LMR sensing probe;

[0022] Figure 3 It is a SEM diagram of the double-film layer optical fiber LMR sensing probe;

[0023] Figure 4 It is a spectrum diagram of the double-film layer optical fiber LMR sensing probe;

[0024] Figure 5 It is a resonance spectrum diagram of LMR measurement of different refractive index solutions excited by TE / TM polarized light;

[0025] Figure 6 It is a sensitivity fitting curve of the LMR measurement results excited by TE / TM polarized light.

[0026] REFERENCE NUMERALS:

[0027] 1. super-continuous light source, 2. Y-type optical fiber bundle, 3. double-film layer optical fiber LMR sensing probe, 4. optical fiber spectrometer, 5. upper computer software, 6. large core multimode optical fiber with removed cladding, 7. low refractive index matching layer, 8. loss mode excitation layer. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0029] like Figure 1 The diagram shows a schematic of a fiber optic LMR sensing probe system based on a dual-layer structure according to the present invention. The system includes a supercontinuum light source 1, a Y-shaped fiber bundle 2, a dual-layer fiber optic LMR sensing probe 3, a fiber optic spectrometer 4, and host computer software 5. The dual-layer fiber optic LMR sensing probe 3 is connected to both the supercontinuum light source 1 and the fiber optic spectrometer 4 via the Y-shaped fiber bundle 2. The fiber optic spectrometer 4 transmits the resonance spectrum from the dual-layer fiber optic LMR sensing probe 3 to the host computer software 5 for acquisition. The supercontinuum light source 1 has a wavelength range of 400–2400 nm. The core diameter of the Y-shaped fiber bundle 2 is 400 μm. The wavelength resolution of the fiber optic spectrometer 4 is 0.24 nm.

[0030] like Figure 2 The diagram shown is a structural diagram of a dual-layer fiber optic LMR sensing probe. The dual-layer fiber optic LMR sensing probe 3 consists of, from the inside out, a large-core multimode fiber with the cladding removed 6, a low-refractive-index matching layer 7, and a loss-mode excitation layer 8.

[0031] like Figure 3 The image shown is an SEM image of a double-layer fiber LMR sensing probe. The film boundary between the large-core multimode fiber 6 with its cladding removed and the low-refractive-index matching layer 7, as well as the film boundary between the low-refractive-index matching layer 7 and the loss mode excitation layer 8, can be clearly seen.

[0032] The low refractive index matching layer 7 is a MgF2 film with a thickness of 100~500 nm.

[0033] The loss mode excitation layer 8 is an ITO film with a thickness of 300 nm.

[0034] The method for fabricating the fiber optic LMR sensing probe with a dual-film structure of the present invention includes the following process steps:

[0035] Step 1: Use a sharp blade to remove the plastic cladding of the large-core multimode fiber to expose a fiber core of centimeter length; after cleaning the fiber core, use a large-core multimode fiber cleaver to cut the exposed fiber core to obtain a large-core multimode fiber 6 with a flat end face after removing the cladding.

[0036] Step 2, using a radio frequency magnetron sputtering device to uniformly sputter a dense and flat low refractive index matching layer 7 on the sidewall of the large core multimode optical fiber 6 from a MgF2 target: the large core multimode optical fiber 6 with the cladding removed is fixed in the radio frequency magnetron sputtering device, when the basic pressure in the cavity is less than 1.0*10 -5 Pa, Ar (99.999%) and SF6 (99.999%) mixed gas is introduced into the cavity to 0.60 Pa, the mixing ratio is Ar: SF6 = 200:3, and the sputtering power is 200 W;

[0037] Step 3, the large core multimode optical fiber 6 with the MgF2 film layer sputtered is placed in the radio frequency magnetron sputtering device, and a dense and flat loss mode excitation layer 8 is uniformly sputtered on it using an ITO target (In2O3: SnO2=90:10 wt%): when the basic pressure in the cavity is less than 1.0*10 -5 Pa, Ar (99.999%) is introduced into the cavity at a flow rate of 100 sccm to 1.0 Pa, the sputtering power is 100 W, and the double-film-layer optical fiber LMR sensing probe 3 is obtained.

[0038] As shown in Figure 4 , it is the spectral diagram of the double-film-layer optical fiber LMR sensing probe, and from the diagram, the LMR resonance wavelength separation excited by TE / TM polarized light can be clearly shown, the LMR spectral signal cross-talk problem excited by TE / TM polarized light is solved, and the detection accuracy is improved.

[0039] As shown in Figure 5 , it is the resonance spectrum diagram of LMR for measuring different refractive index solutions excited by TE / TM polarized light, and it can be found that the resonance wavelength appears red shift phenomenon with the increase of the refractive index.

[0040] Figure 6 As shown in , it is the sensitivity fitting curve of the LMR measurement result excited by TE / TM polarized light, the double resonance effect is verified, and it is found that the LMR refractive index sensitivity excited by TM polarized light is higher than that of the LMR refractive index sensitivity excited by TE polarized light.

[0041] The preparation method of the above-mentioned double-film-layer structure optical fiber LMR sensing probe solves the LMR spectral signal cross-talk problem excited by TE / TM polarized light, greatly improves the detection accuracy, establishes the relationship between the movement amount of the LMR resonance wavelength excited by TE / TM polarized light and the refractive index, realizes the refractive index sensing, and achieves the double resonance mutual verification effect, further ensuring the reliability of the experimental results.

[0042] The working process of the optical fiber LMR sensing probe system based on the double-film-layer structure is described as follows:

[0043] The output broadband light of the supercontinuum light source 1 is transmitted to the double-film layer optical fiber LMR sensing probe 3 through the Y-type optical fiber bundle 2. The double-film layer optical fiber LMR sensing probe 3 is placed in a solution with different refractive indexes. At this time, the light reflected back by the double-film layer optical fiber LMR sensing probe 3 carrying the LMR signal is transmitted to the optical fiber spectrometer 4 again through the Y-type optical fiber bundle 2. The upper computer software 5 is used for real-time signal acquisition, so as to realize refractive index sensing.

[0044] When the light is transmitted to the double-film layer optical fiber LMR sensing probe 3, the addition of the low-refractive-index matching layer 7 makes the light wave satisfy the total reflection principle, so that the light wave is transmitted in the low-refractive-index matching layer 7 in the form of an evanescent field. The light wave of the evanescent field is leaked in the high-refractive-index loss mode excitation layer 8 in the form of a loss mode, so that the fiber LMR effect is formed. At this time, the LMR resonance wavelengths excited by the TE / TM polarized light are completely separated, a double-resonance effect is exhibited, and double-resonance refractive index sensing can be realized, as shown in FIG. 3. Figures 5~6

[0045] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it. Although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some or all of the technical features can be replaced equivalently, without changing the essence of the corresponding technical solutions out of the scope of the technical solutions of the embodiments of the present application. The non-essential improvements, adjustments or replacements made by those skilled in the art according to the content of the present application are within the scope of the present application.​

Claims

1. A fiber-optic LMR sensing probe system based on a double-film layer structure, characterized by, The system comprises a supercontinuum light source, a Y-shaped fiber bundle, a double-film-layer fiber LMR sensing probe, a fiber spectrometer and a host computer software; wherein the double-film-layer fiber LMR sensing probe is connected with the supercontinuum light source and the fiber spectrometer through the Y-shaped fiber bundle, and the fiber spectrometer transmits the resonance spectrum from the double-film-layer fiber LMR sensing probe to the host computer software for collection; The wave band range of the supercontinuum light source is 400-2400 nm; The core diameter of the Y-shaped fiber bundle is 400 μm; The double-film-layer fiber LMR sensing probe comprises, from inside to outside, a large-core-diameter multimode fiber with a removed cladding, a low-refractive-index matching layer and a loss-mode excitation layer; The wavelength resolution of the fiber spectrometer is 0.24 nm.

2. A fiber-optic LMR sensor probe system based on a double-film layer structure according to claim 1, characterized in that, The low-refractive-index matching layer is an MgF2 film layer with a thickness of 100-500 nm.

3. A fiber-optic LMR sensor probe system based on a double-film layer structure according to claim 1, characterized in that, The loss-mode excitation layer is an ITO film layer with a thickness of 300 nm.

4. A method for preparing a fiber-optic LMR sensing probe based on a double-film layer structure, characterized in that, The method comprises the following steps: Step 1: a plastic cladding of a large-core-diameter multimode fiber is removed by using a sharp blade to expose a centimeter-length core; after cleaning the core, the fiber is cut by a large-core-diameter multimode fiber cutter to obtain a large-core-diameter multimode fiber with a removed cladding and a flat end face; Step 2, uniformly sputtering a dense and flat low refractive index matching layer on the sidewall of the large core multimode optical fiber with removed cladding from a MgF2 target by using a radio frequency magnetron sputtering device: fixing the large core multimode optical fiber with removed cladding in the radio frequency magnetron sputtering device, when the basic pressure in the cavity is less than 1.0×10 -5 Pa, introducing Ar (99.999%) and SF6 (99.999%) mixed gas into the cavity to 0.60 Pa, the mixing ratio is Ar: SF6 = 200:3, and the sputtering power is 200 W; Step 3, the large core multimode optical fiber with MgF2 film layer removed cladding is placed in the radio frequency magnetron sputtering equipment, and a dense and flat loss mode excitation layer is uniformly sputtered on it by using an ITO target (In2O3: SnO2=90:10 wt%): when the basic pressure in the cavity is lower than 1.0×10 -5 Pa, Ar (99.999%) is introduced into the cavity at a flow rate of 100 sccm to 1.0 Pa, the sputtering power is 100 W, and a double-film LMR sensing probe is obtained.

Images