CN212083221U

CN212083221U - Reflection type optical fiber humidity sensor based on PVA and graphene

Info

Publication number: CN212083221U
Application number: CN202020414779.2U
Authority: CN
Inventors: 冯其瑞; 王彦鹏; 蒲连雄; 张绍广; 王怀锋; 简竹筠
Original assignee: CNOOC Safety and Technology Services Co Ltd
Current assignee: CNOOC Safety and Technology Services Co Ltd
Priority date: 2020-03-27
Filing date: 2020-03-27
Publication date: 2020-12-04
Anticipated expiration: 2030-03-27

Abstract

The invention provides a reflection type optical fiber humidity sensor based on PVA and graphene, wherein a circulator is provided with three interface ends, including a feedback end connected with a broadband light source, an outlet end connected with a sensing head and a feedback end connected with a spectrum analyzer; the method is characterized in that: the sensing head comprises a single-mode optical fiber and a coreless optical fiber, the right end of the single-mode optical fiber is connected with the left end of the coreless optical fiber, an inclined end face with an inclination angle of 10 degrees is designed at the right end of the coreless optical fiber, and a composite film is arranged on the inclined end face; the composite film is made of a PVA and graphene composite material. The invention has the advantages of reasonable structural design, convenient measurement due to the adoption of a reflection type structure for the sensing head, high sensitivity, simple manufacture, small volume, convenient use and good practicability. Moreover, the sensing head does not relate to dangerous medicines, so that the use is safe.

Description

Reflection type optical fiber humidity sensor based on PVA and graphene

Technical Field

The invention belongs to the technical field of optical fiber humidity sensing equipment, and particularly relates to a reflection type optical fiber humidity sensor based on PVA and graphene.

Background

In the fields of industry, agriculture, medical treatment, aerospace, storage and the like, strict requirements are required for the environmental humidity, so that the measurement of the humidity is particularly important. Conventional humidity sensors are primarily electronic in nature, such as by measuring the humidity of the environment through a change in resistance or capacitance. Electronic sensors, although fast in response, are susceptible to electromagnetic interference. Electronic sensors are therefore limited in extreme environments. The optical fiber sensor has the advantages of high sensitivity, strong anti-electromagnetic interference capability, high response speed and the like. The optical fiber humidity sensor can be widely applied to various fields. Although there are many humidity sensors available on the market, they are large in size, complex in structure, and low in sensitivity, which causes inconvenience in use, and thus need improvement.

Disclosure of Invention

In view of this, the present invention provides a reflective optical fiber humidity sensor based on PVA and graphene, which is provided to overcome the defects in the prior art.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a reflection-type optical fiber humidity sensor based on PVA and graphene comprises a circulator, a broadband light source, a sensing head and a spectrum analyzer; the circulator is provided with three interface ends, including a feedback end connected with the broadband light source, an outlet end connected with the sensing head and a feedback end connected with the spectrum analyzer; the sensing head comprises a single-mode optical fiber and a coreless optical fiber, the right end of the single-mode optical fiber is connected with the left end of the coreless optical fiber, an inclined end face is designed at the right end of the coreless optical fiber, and a composite film is arranged on the inclined end face; the composite film is made of a PVA and graphene composite material.

Further, the inclined angle of the inclined end face at the right end of the coreless optical fiber is 10 degrees.

Further, the wavelength range of the broadband light source is 1460nm-1620 nm.

Further, the coreless fiber has a diameter of 125 μm and a length of 2 mm.

Further, the composite film is solidified on the inclined end face of the coreless optical fiber by adopting a sol-gel method.

Further, the composite film is prepared from PVA and graphene according to a volume ratio of 1:1, preparing the mixed solution.

Furthermore, the single-mode optical fiber and the coreless optical fiber in the sensing head are welded and fixed by a welding machine.

Compared with the prior art, the invention has the following advantages:

the invention has the advantages of reasonable structural design, convenient measurement due to the adoption of a reflection type structure for the sensing head, high sensitivity, simple manufacture, small volume, convenient use and good practicability. Moreover, the sensing head does not relate to dangerous medicines, so that the use is safe.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the invention without limitation. In the drawings:

FIG. 1 is a schematic diagram of the structural arrangement of the present invention;

fig. 2 is a schematic view of a sensor head in an embodiment of the invention.

Description of reference numerals:

1-a circulator; 2-a broadband light source; 3-a sensor head; 4-spectrum analyzer; 5-single mode fiber; 6-coreless fiber; 7-inclined end faces; 8-composite film.

Detailed Description

It should be noted that the embodiments and features of the embodiments of the present invention may be combined with each other without conflict.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientation or positional relationship indicated in the drawings, which are merely for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be construed as limiting the invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the invention, the meaning of "a plurality" is two or more unless otherwise specified.

In the description of the invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted", "connected" and "connected" are to be construed broadly, e.g. as being fixed or detachable or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the creation of the present invention can be understood by those of ordinary skill in the art through specific situations.

The invention will be described in detail with reference to the following embodiments with reference to the attached drawings.

A reflective optical fiber humidity sensor based on PVA and graphene is disclosed, as shown in figures 1 and 2, and comprises a circulator 1, a broadband light source 2, a sensing head 3 and a spectrum analyzer 4; the circulator is provided with three interface ends, including a feedback end connected with the broadband light source, an outlet end connected with the sensing head and a feedback end connected with the spectrum analyzer; the wavelength range of the broadband light source is generally 1460nm-1620 nm.

The sensing head includes single mode fiber 5 and centreless optic fibre 6, the single mode fiber right-hand member links to each other with the centreless optic fibre left end, and single mode fiber and centreless optic fibre utilize the splicer butt fusion to be fixed.

An inclined end face 7 with an inclination angle of 10 degrees is designed at the right end of the coreless fiber, and a composite film 8 is arranged on the inclined end face. When the environmental humidity changes, the refractive index of the composite film changes, which causes the high-order mode in the coreless fiber to change, thereby causing the spectrum of mode interference to move. The wavelength value of the mode interference spectrum is read from the spectrometer through a one-to-one correspondence relation between the wavelength of the mode interference spectrum and the environmental humidity, which is calibrated in advance, so that the humidity can be measured. The structural design that the right end inclination angle of the coreless optical fiber is an inclined end face of 10 degrees can expand the exposed surface area on a small-sized sensor head as much as possible, improve the integration level of a product and ensure the service performance and sensitivity of the sensor.

The manufacturing method of the sensing head comprises the following steps: firstly, cutting an inclined end face at one end of a coreless optical fiber by using an optical fiber cutter, wherein the inclination angle is 10 degrees; secondly, preparing PVA and graphene into a mixed solution according to the volume ratio of 1: 1; thirdly, manufacturing a composite film on the inclined end face of the coreless optical fiber by using a sol-gel method; and fourthly, welding the single-mode optical fiber and the coreless optical fiber together by using a welding machine.

As an example of a preferable scheme, when the coreless fiber has a diameter of 125 μm and a length of 2mm, and the structure design of the end face with a 10 ° inclination angle can make the volume of the coreless fiber smaller, the coreless fiber can also meet the requirement of the sensitivity of the sensor, and the performance that a high-order mode is further excited and reflected back to a single-mode fiber is considered, that is, the product volume is reduced, the structural complexity is reduced, and the accuracy of the measurement structure can also be guaranteed.

The composite film arranged on the inclined end face is made of a PVA and graphene composite material. Generally, a composite film is prepared by mixing PVA and graphene in a volume ratio of 1:1 and curing the mixed solution on the inclined end face of the coreless optical fiber by adopting a sol-gel method. In an optional embodiment, a plurality of grooves (such as V-shaped grooves and U-shaped grooves) can be processed on the inclined end face, and by arranging the composite film on the inclined end face provided with the grooves, the surface area of the composite film can be increased to the maximum extent under the condition that the volume of the sensor is minimized, so that the accuracy of the detection structure is improved.

The working principle is as follows: light emitted by a broadband light source reaches a sensing head through a circulator, the light beam firstly reaches a single-mode fiber in the sensing head and then continues to be transmitted forwards to a coreless fiber, a high-order mode is excited to be transmitted in the coreless fiber due to mode field mismatch, and when the light beam reaches an inclined end face, the high-order mode is further excited and reflected back to the single-mode fiber to generate mode interference.

Since PVA and graphene are both materials sensitive to environmental humidity, the composite film prepared by mixing the PVA and the graphene is also sensitive to the environmental humidity, when the environmental humidity changes, the refractive index of the composite film changes, which causes the high-order mode in the coreless optical fiber to change, and thus causes the spectrum of mode interference to move. Finally, the light is transmitted to a spectrum analyzer through a circulator, and an interference pattern is displayed on the spectrum analyzer.

And reading the wavelength value of the mode interference spectrum from the spectrometer through a one-to-one correspondence relation between the wavelength of the mode interference spectrum and the environmental humidity, which is calibrated in advance, so that the humidity can be measured.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the invention, so that any modifications, equivalents, improvements and the like, which are within the spirit and principle of the present invention, should be included in the scope of the present invention.

Claims

1. A reflection-type optical fiber humidity sensor based on PVA and graphene comprises a circulator, a broadband light source, a sensing head and a spectrum analyzer; the circulator is provided with three interface ends, including a feedback end connected with the broadband light source, an outlet end connected with the sensing head and a feedback end connected with the spectrum analyzer; the method is characterized in that: the sensing head comprises a single-mode optical fiber and a coreless optical fiber, the right end of the single-mode optical fiber is connected with the left end of the coreless optical fiber, an inclined end face is designed at the right end of the coreless optical fiber, and a composite film is arranged on the inclined end face; the composite film is made of a PVA and graphene composite material.

2. A reflective PVA and graphene based fiber optic moisture sensor according to claim 1, wherein: the inclination angle of the inclined end face is 10 degrees.

3. A reflective PVA and graphene based fiber optic moisture sensor according to claim 1, wherein: the wavelength range of the broadband light source is 1460nm-1620 nm.

4. A reflective PVA and graphene based fiber optic moisture sensor according to any one of claims 1 to 3, wherein: the coreless fiber had a diameter of 125 μm and a length of 2 mm.

5. A reflective PVA and graphene based fiber optic moisture sensor according to claim 1, wherein: the composite film is solidified on the inclined end face of the coreless optical fiber by adopting a sol-gel method.

6. A reflective PVA and graphene based fiber optic moisture sensor according to claim 1, wherein: and the single-mode optical fiber and the coreless optical fiber in the sensing head are welded and fixed by a welding machine.