Photoelectric hybrid long-period fiber grating sensor

Abstract

The invention discloses a photoelectric hybrid long-period fiber grating sensor. The photoelectric hybrid long-period fiber grating sensor comprises a micro-nano optical fiber, polydimethylsiloxane and a laser-induced graphene electrode array, two ends of the micro-nano optical fiber are respectively used as an optical signal input port and an optical signal output port; the micro-nanofiber is packaged by polydimethylsiloxane and patterned by laser-induced graphene to form a periodically arranged laser-induced graphene electrode array, and the laser-induced graphene electrode array generates a periodic refractive index modulation effect on the middle area of the lower-layer micro-nanofiber and meets the phase matching condition of the long-period grating. And the micro-nano fiber long-period fiber grating is formed. The large evanescent field characteristic of the micro-nano fiber and the high refractive index sensitivity characteristic of the long-period grating can be fully utilized, the conductive electrode of the modulation grating is used for sensing application, and the functions of electrical detection and optical detection are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical sensors, and particularly to a hybrid optoelectronic long-period fiber grating sensor. Background Art

[0002] A long-period fiber grating is an important passive optical sensor device. Through the periodic modulation of the refractive index, coupling occurs between the fundamental mode in the fiber core and the co-propagating cladding modes, and resonance peaks can be formed within a specific wavelength range. It is a transmissive all-fiber band-stop filter, and its working principle determines that the device is very sensitive to changes in the external environment. A long-period micro-nano fiber grating is a periodic structure constructed on a micro-nano fiber that can cause coupling of optical wave modes (its period is in the range of dozens of micrometers to hundreds of micrometers). By affecting the evanescent field energy distribution through environmental variables, the fluctuation of environmental variables is monitored by using the change in the received optical signal parameters. The working principle is that it performs periodic modulation on the conduction mode. When the resonance condition is met, coupling occurs between the forward-propagating core mode and the co-directional higher-order modes, which is manifested as the appearance of corresponding loss peaks in the output spectrum. When the measured value of the external environment changes, the refractive index within the evanescent field range changes, thereby affecting the change of the loss peak in the transmission spectrum. Therefore, long-period fiber gratings have a wide range of applications in the fields of sensing measurement, optical communication, etc.

[0003] Traditional long-period fiber gratings are directly written using methods such as phase masks in the uniform regions of single-mode fibers or micro-nano fibers. Therefore, only one-sided optical detection can be performed, which is insufficient for daily needs. There is an urgent need for a long-period fiber grating device that can perform both electrical detection and optical detection. Summary of the Invention

[0004] In order to overcome the defects and deficiencies existing in the prior art, the present invention provides a hybrid optoelectronic long-period fiber grating sensor. The present invention uses laser-induced graphene electrodes on polydimethylsiloxane to form periodic refractive index modulation, obtains a long-period grating, and realizes a sensor device with a compact structure, high precision, and both electrical detection and optical detection.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a hybrid optoelectronic long-period fiber grating sensor, including: a micro-nano fiber, polydimethylsiloxane, and a laser-induced graphene electrode array;

[0007] Both ends of the micro-nano fiber are respectively used as an optical signal input port and an optical signal output port;

[0008] The micro-nano optical fiber is encapsulated by polydimethylsiloxane and patterned with laser-induced graphene to form a periodically arranged laser-induced graphene electrode array. The laser-induced graphene electrode array produces a periodic refractive index modulation effect on the middle region of the underlying micro-nano optical fiber and satisfies the phase matching condition of the long-period grating, forming a long-period fiber grating of the micro-nano optical fiber.

[0009] As a preferred technical solution, the micro-nano optical fiber includes a first optical fiber end region, a second optical fiber end region, a first optical fiber taper region, a second optical fiber taper region, and an optical fiber uniform region.

[0010] The first optical fiber end region and the second optical fiber end region are respectively arranged at both ends of the micro-nano optical fiber. The optical fiber uniform region is arranged in the middle of the micro-nano optical fiber. The first optical fiber taper region is arranged between the first optical fiber end region and the optical fiber uniform region. The second optical fiber taper region is arranged between the second optical fiber end region and the optical fiber uniform region.

[0011] As a preferred technical solution, the first optical fiber end region serves as the optical signal input port of the micro-nano optical fiber, and the second optical fiber end region serves as the optical signal output port of the micro-nano optical fiber.

[0012] Laser-induced graphene is periodically inscribed in the corresponding region of the optical fiber uniform region, and the laser-induced graphene and the optical fiber uniform region satisfy the phase matching condition of the long-period fiber grating.

[0013] As a preferred technical solution, the laser-induced graphene is periodically inscribed in the corresponding region of the optical fiber uniform region, and is inscribed in a finger-like or parallel line manner.

[0014] As a preferred technical solution, the micro-nano optical fiber is any one of a micro-nano quartz optical fiber, a micro-nano glass optical fiber, or a micro-nano polymer optical fiber.

[0015] The present invention also provides a preparation method for an optoelectronic hybrid long-period fiber grating sensor, including the following steps:

[0016] The fiber without the coating layer is subjected to melting and tapering to obtain a micro-nano optical fiber. The middle region of the micro-nano optical fiber is encapsulated with polydimethylsiloxane. Based on the laser direct writing technology, a periodically arranged graphene electrode array is prepared on the polydimethylsiloxane. The graphene electrode array produces a periodic refractive index modulation effect on the middle region of the underlying micro-nano optical fiber, constituting a periodic structure that satisfies the phase coupling condition, forming a long-period fiber grating of the micro-nano optical fiber. At the same time, the graphene electrode array is used as an electrical sensor.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] In the present invention, laser-induced graphene is periodically inscribed in the uniform region of a micro-nano optical fiber, and the uniform region satisfies the phase matching condition of a long-period grating, ultimately forming a structural micro-nano optical fiber long-period grating. It can be seen that the required technologies and processes are relatively simple, and there is no need for high-cost processing equipment.

[0019] Moreover, compared with long-period fiber grating sensors, in the present invention, the first optical fiber end region of the micro-nano optical fiber is used as the input, and the periodically laser-induced graphene modulates the evanescent field in the uniform region of the optical fiber. The second optical fiber end region of the micro-nano optical fiber is used as the optical signal output end, and the laser-induced patterned laser-induced graphene electrode can also be used as an electrical sensor. It only requires a single grating to be formed, and the device size is in the millimeter to micrometer range. It has a large evanescent field, and the micro-nano optical fiber can be composed of micro-nano optical fibers of different materials. Laser-induced graphene inscription can form a strong periodic refractive index modulation here, thereby reducing the requirement for the number of grating periods. The present invention has the characteristics of flexibility and compactness, and can perform both electrical detection and optical detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of a photoelectric hybrid long-period fiber grating sensor with laser-induced graphene inscribed in a finger-crossing manner according to the present invention;

[0021] Figure 2 is a schematic structural diagram of a photoelectric hybrid long-period fiber grating sensor with laser-induced graphene inscribed in a parallel manner according to the present invention;

[0022] Figure 3 is a transmission spectrum diagram of the photoelectric hybrid long-period fiber grating sensor according to the present invention;

[0023] Figure 4 is a schematic diagram of the I-V characteristics of the graphene electrode of the photoelectric hybrid long-period fiber grating sensor according to the present invention under different pressures.

[0024] Wherein, 1 - the first optical fiber end region, 2 - the first optical fiber taper region, 3 - the optical fiber uniform region, 4 - laser-induced graphene, 5 - polydimethylsiloxane, 6 - the second optical fiber taper region, 7 - the second optical fiber end region. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] Embodiment

[0027] This embodiment provides a photoelectric hybrid long-period fiber grating sensor, including: a micro-nano optical fiber, a laser-induced graphene electrode array, and polydimethylsiloxane;

[0028] Among them, both ends of the micro-nano optical fiber serve as the input port and the optical signal output port of the external optical signal respectively. The micro-nano optical fiber encapsulated in polydimethylsiloxane includes a uniform region in the middle and tapered regions on both sides. A laser-induced graphene electrode array arranged periodically is prepared on the surface of the polydimethylsiloxane by laser direct writing technology. The electrode array can generate a periodic refractive index modulation effect on the uniform region of the underlying micro-nano optical fiber, thereby realizing the controllable adjustment of the optical waveguide characteristics and satisfying the phase matching condition of the long-period grating, forming a structural micro-nano optical fiber long-period grating;

[0029] The micro-nano optical fiber includes a first optical fiber end region 1, a second optical fiber end region 7, a first optical fiber tapered region 2, a second optical fiber tapered region 6, and an optical fiber uniform region 3; the first optical fiber tapered region 2 and the second optical fiber tapered region 6 are respectively located at both ends of the optical fiber uniform region 3, the first optical fiber end region 1 is located at the outer end of the first optical fiber tapered region 2, and the second optical fiber end region 7 is located at the outer end of the second optical fiber tapered region 6;

[0030] The first optical fiber end region 1 serves as the optical signal input source of the micro-nano optical fiber. The graphene electrode array can generate a periodic refractive index modulation effect on the uniform region of the underlying micro-nano optical fiber, modulate the light in the optical fiber uniform region through the periodically laser-induced graphene, and generate resonance to form a resonance peak. The light is then output via the second optical fiber tapered region 6 and the second optical fiber end region 7 of the micro-nano optical fiber;

[0031] In this embodiment, the first optical fiber end region and the second optical fiber end region of the micro-nano optical fiber serve as the input and output ports of the external optical signal respectively. The external light source is connected to the first optical fiber end region of the micro-nano optical fiber to input the optical signal, and the second optical fiber end region of the micro-nano optical fiber is connected to the optical signal detection device to monitor the output optical signal. The first optical fiber tapered region, the second optical fiber tapered region, the optical fiber uniform region of the micro-nano optical fiber and the laser-induced graphene together constitute the coupled optical signal path of this embodiment;

[0032] As Figure 1 shown, the laser-induced graphene 4 can be periodically inscribed in a finger-crossing manner in the optical fiber uniform region;

[0033] As Figure 2 shown, the laser-induced graphene 4 can be periodically inscribed in a parallel line manner in the optical fiber uniform region, and finally a parallel electrode is formed.

[0034] In this embodiment, the micro-nano optical fiber is encapsulated by polydimethylsiloxane 5 and patterned by laser-induced graphene. The laser-induced graphene is periodically inscribed on the optical fiber uniform region of the micro-nano optical fiber encapsulated in polydimethylsiloxane. The laser-induced graphene and the optical fiber uniform region satisfy the phase matching condition of the long-period fiber grating, forming a micro-nano optical fiber long-period fiber grating;

[0035] In this embodiment, the laser-induced graphene can be obtained by inducing graphene on polydimethylsiloxane with a laser. The formation principle of the laser-induced graphene mainly involves the interaction between the laser and the polymer and the structural transformation inside the material. Since the laser wavelength used is relatively long, the formation of the laser-induced graphene is caused by the photothermal effect. The energy generated by the laser irradiation causes lattice vibration, and then extremely high local temperatures are generated. This high temperature can easily break the chemical bonds in the polydimethylsiloxane, resulting in a significant reduction in the oxygen and nitrogen content in the polydimethylsiloxane, causing graphitization, and finally forming a porous graphene structure with conductivity.

[0036] In this embodiment, the micro-nano optical fiber is a micro-nano quartz optical fiber, a micro-nano glass optical fiber or a micro-nano polymer optical fiber. The micro-nano optical fiber can be obtained by removing the coating layer from a standard optical fiber made of the corresponding material and then performing melting and tapering.

[0037] In this embodiment, a method for preparing an optoelectronic hybrid long-period fiber grating sensor is also provided, including the following steps:

[0038] The fiber with the coating layer removed is subjected to melting and tapering to obtain a micro-nano optical fiber. The middle part of the micro-nano optical fiber, the uniform region, is encapsulated with polydimethylsiloxane. Then, a periodic graphene electrode array is prepared on the surface of the polydimethylsiloxane by using laser direct writing technology. This electrode array can produce a periodic refractive index modulation effect on the uniform region of the underlying micro-nano optical fiber, forming a periodic structure that satisfies the phase coupling condition and forming a long-period fiber grating. At the same time, the graphene electrode array can be used as an electrical sensor.

[0039] As Figure 3 shown, the transmission spectrum diagram of the optoelectronic hybrid long-period fiber grating sensor is obtained, and the figure shows the influence of three different periods on the resonant peak;

[0040] As Figure 4 shown, the I-V characteristics of the graphene electrode of the optoelectronic hybrid long-period fiber grating sensor under different pressures are obtained, demonstrating the changes in the electrical properties of the component under different pressure conditions. It can be seen that the optoelectronic hybrid long-period fiber grating sensor of the present invention is composed of a single long-period fiber grating and a conductive electrode, can make full use of the characteristics of the large evanescent field of the micro-nano optical fiber and the high refractive index sensitivity characteristics of the long-period grating, and at the same time can use the conductive electrode for modulating the grating for sensing applications, and is simple to manufacture, has a compact and small structure, and has both electrical detection and optical detection functions.

[0041] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A photoelectric hybrid long period fiber grating sensor, characterized in that: include: Micro-nano optical fiber, polydimethylsiloxane, and laser-induced graphene electrode arrays; The two ends of the micro-nano optical fiber serve as an optical signal input port and an optical signal output port respectively; The micro-nano optical fiber is encapsulated by polydimethylsiloxane and patterned by laser-induced graphene to form a periodically arranged laser-induced graphene electrode array. The laser-induced graphene electrode array produces a periodic refractive index modulation effect on the middle region of the lower micro-nano optical fiber and meets the phase matching condition of the long-period grating to form a micro-nano optical fiber long-period fiber grating.

2. The optoelectronic hybrid long-period fiber grating sensor according to claim 1, characterized in that: The micro-nano optical fiber comprises a first optical fiber end region, a second optical fiber end region, a first optical fiber taper region, a second optical fiber taper region and an optical fiber uniform region; The first fiber end region and the second fiber end region are respectively arranged at the two ends of the micro-nano optical fiber, the fiber uniform region is arranged in the middle of the micro-nano optical fiber, the first fiber taper region is arranged between the first fiber end region and the fiber uniform region, and the second fiber taper region is arranged between the second fiber end region and the fiber uniform region.

3. The optoelectronic hybrid long-period fiber grating sensor according to claim 2, characterized in that: The first optical fiber end region serves as an optical signal input port of the micro-nano optical fiber, and the second optical fiber end region serves as an optical signal output port of the micro-nano optical fiber; Laser-induced graphene is periodically inscribed in the region corresponding to the optical fiber uniform region, and the laser-induced graphene and the optical fiber uniform region satisfy the long-period fiber grating phase matching condition.

4. The optoelectronic hybrid long-period fiber grating sensor according to claim 3, characterized in that: The laser-induced graphene is periodically inscribed in the area corresponding to the uniform area of ​​the optical fiber, in an interdigital manner or a parallel line manner.

5. The optoelectronic hybrid long-period fiber grating sensor according to claim 1, characterized in that: The micro-nano optical fiber is any one of micro-nano quartz optical fiber, micro-nano glass optical fiber or micro-nano polymer optical fiber.

6. The method for preparing the optoelectronic hybrid long-period fiber grating sensor according to any one of claims 1 to 5, characterized in that: The steps include: The optical fiber with the coating removed is melt-tapered to obtain a micro-nano optical fiber, the middle region of the micro-nano optical fiber is encapsulated with polydimethylsiloxane, and a periodically arranged graphene electrode array is prepared in the polydimethylsiloxane based on laser direct writing technology. The graphene electrode array produces a periodic refractive index modulation effect on the middle region of the underlying micro-nano optical fiber, forming a periodic structure that meets the phase coupling conditions, forming a micro-nano optical fiber long-period fiber grating, and the graphene electrode array is used as an electrical sensor.

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