CN108981955B - A kind of optical fibre temperature survey apparatus - Google Patents

Abstract

The present invention discloses a kind of optical fibre temperature survey apparatus.The temperature measuring device includes: wideband light source, single-mode optical-fibre coupler, Polarization Controller, optical fiber circulator, refraction index solution covering ellipse micro-nano fiber, the spectrometer for plating silverskin mirror based fiber optica end；The wideband light source is connect with the single-mode optical-fibre coupler, and the light that the wideband light source issues is divided into two beams by the single-mode optical-fibre coupler；The interference of two polarization states of light occurs in the single-mode optical-fibre coupler for the reflected beams described in two beams, obtains interference spectrum；The single-mode optical-fibre coupler is connect with the spectrometer, and the interference spectrum is sent to the spectrometer by the single-mode optical-fibre coupler, and the spectrometer analyzes the interference spectrum, obtains ambient temperature.Remote, high-precision temperature measurement is realized by index liquid covering high birefringence micro-nano fiber.

Description

An optical fiber temperature measuring device

technical field

The invention relates to the field of optical fiber technology, in particular to an optical fiber temperature measuring device.

Background technique

Compared with other sensors, fiber optic sensors have the characteristics of small size, light weight, high sensitivity, no electromagnetic interference, and corrosion resistance, which makes fiber optic sensors have a wide range of applications, involving national defense and national economic fields and people's daily life.

Temperature is a physical quantity that expresses how hot or cold an object is. In meteorology, materials, industry, aviation, medicine and other fields, the accurate detection of temperature plays a pivotal role. At present, the more common optical fiber temperature sensors mainly include cascade type, fiber grating type, and Sagnac interference type. Among them, the interference type fiber grating can detect the distance change of the order of magnitude equivalent to the wavelength of the light wave, and has high sensitivity compared with other sensing methods.

As a kind of interferometric sensor, optical fiber environment has been widely studied and paid attention to in recent years due to its simple structure and flexible tuning method. Most of the sensing units are polarization maintaining optical fibers. However, the traditional polarization maintaining optical fiber has low sensitivity to temperature. The traditional closed-loop structure and transmissive sensing optical path make the sensor components not independent in the loop, which makes the operation inconvenient for long-distance measurement and cannot meet the needs of some long-distance and high-precision occasions.

Contents of the invention

The purpose of the present invention is to provide an optical fiber temperature measuring device capable of realizing long-distance and high precision.

To achieve the above object, the present invention provides the following scheme:

An optical fiber temperature measuring device, the temperature measuring device comprising: a broadband light source, a single-mode fiber coupler, a polarization controller, an optical fiber circulator, a refractive index solution cladding elliptical micro-nano optical fiber at the end of a silver-coated reflective optical fiber, and a spectrometer;

The broadband light source is connected with the single-mode fiber coupler, and the light emitted by the broadband light source is divided into two beams through the single-mode fiber coupler, one beam is directly transmitted to the fiber circulator along the first optical path, and the other beam is directly transmitted to the optical fiber circulator along the first optical path. The beam is transmitted to the fiber circulator through the polarization controller along the second optical path; the first optical path is a transmission optical path for the light to be transmitted from the single-mode fiber coupler to the optical fiber circulator; the second optical path The second optical path is a transmission optical path where light is transmitted from the single-mode fiber coupler to the optical fiber circulator through the polarization controller, and the first optical path and the second optical path are arranged symmetrically;

The optical fiber circulator is connected to the refractive index solution cladding elliptical micro-nano optical fiber at the end of the silver-coated reflective optical fiber, and the two beams with different polarization states in the optical fiber circulator are recoupled to obtain a coupled beam;

The coupled light beam is transmitted to the refractive index solution cladding elliptical micro-nano optical fiber at the end of the silver-coated reflective fiber and is reflected to obtain a reflected light beam;

After the reflected light beam is transmitted to the optical fiber circulator, it is divided into two beams, and the two reflected light beams are respectively transmitted to the single-mode fiber coupler along the first optical path and the second optical path;

The two reflected light beams interfere with the two polarization states of light in the single-mode fiber coupler to obtain an interference spectrum;

The single-mode fiber coupler is connected to the spectrometer, and the single-mode fiber coupler sends the interference spectrum to the spectrometer, and the spectrometer analyzes the interference spectrum to obtain the external temperature.

Optionally, the refractive index solution-clad elliptical micro-nano optical fiber at the silver-coated reflective fiber end specifically includes: an incident single-mode optical fiber end, an elliptical micro-nano optical fiber, a single-mode reflection section of the silver-coated film, and a glass filled with a refractive index solution. Tube;

The end of the incident single-mode fiber is sequentially provided with the single-mode reflection section of the elliptical micro-nano fiber and the silver-coated film;

The elliptical micro-nano fiber is sealed in the glass tube filled with the refractive index solution;

The interface between the glass tube filled with the refractive index solution and the incident single-mode fiber end is sealed with AB glue.

Optionally, the refractive index solution cladding elliptical micro-nano fiber at the end of the silver-coated reflective fiber is set in a temperature-controllable environment;

Gradually change the temperature in the environment, the spectrometer collects the output spectrum, and records the interference comb spectrum;

Calculating the length of the interference comb spectrum drift, and fitting the relationship curve of the interference comb spectrum drift with temperature;

The temperature of the environment to be tested is measured according to the relationship graph.

According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: An optical fiber temperature measuring device disclosed in the present invention realizes long-distance and high-precision temperature measurement through a high-birefringence micro-nano optical fiber with a refractive index liquid cladding, The method of spectral analysis is used for measurement, so that the measurement result will not affect the measurement accuracy due to the change of the external environment temperature, and the measurement accuracy is improved while ensuring the long-distance measurement.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without paying creative labor.

Fig. 1 is a structural diagram of an optical fiber temperature measuring device provided by the present invention;

Fig. 2 is the structural diagram of the refractive index solution cladding elliptical micro-nano optical fiber at the end of the silver-coated film reflecting optical fiber provided by the present invention;

Fig. 3 is the oscillogram of the comb spectrum drift changing with temperature provided by the present invention;

Fig. 4 is a graph showing the variation of comb spectrum wavelength with temperature provided by the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The purpose of the present invention is to provide an optical fiber temperature measuring device capable of realizing long-distance and high precision.

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, a kind of optical fiber temperature measurement device, described temperature measurement device comprises: broadband light source 1, single-mode optical fiber coupler 2, polarization controller 3, optical fiber circulator 4, the refractive index solution of silver-coated film reflection optical fiber end Clad elliptical micro-nano fiber 5, spectrometer 7;

The broadband light source 1 is connected to the single-mode fiber coupler 2, the light emitted by the broadband light source 1 is divided into two beams through the single-mode fiber coupler 2, and one beam is directly transmitted to the optical fiber ring along the first optical path 4, another beam is transmitted to the fiber circulator 4 through the polarization controller 3 along the second optical path; The transmission optical path of the device 4; the second optical path is the transmission optical path where light is transmitted from the single-mode fiber coupler 2 to the optical fiber circulator 4 through the polarization controller 3, and the first optical path and the second optical path Two optical paths are symmetrically set;

The optical fiber circulator 4 is connected to the refractive index solution cladding elliptical micro-nano optical fiber 5 at the end of the silver-coated reflective fiber, and two beams with different polarization states in the optical fiber circulator 4 are recoupled to obtain a coupled beam;

The coupled light beam is transmitted to the refractive index solution cladding elliptical micro-nano optical fiber 5 at the end of the silver-coated reflective fiber and is reflected to obtain a reflected light beam;

After the reflected light beam is transmitted to the optical fiber circulator 4, it is divided into two beams, and the two reflected light beams are respectively transmitted to the single-mode fiber coupler 2 along the first optical path and the second optical path;

The two reflected light beams interfere with the two polarization states of light in the single-mode fiber coupler 2 to obtain an interference spectrum;

The single-mode fiber coupler 2 is connected to the spectrometer 7, the single-mode fiber coupler 2 sends the interference spectrum to the spectrometer 7, and the spectrometer 7 analyzes the interference spectrum to obtain the external temperature .

As shown in Figure 2, the refractive index solution cladding elliptical micro-nano optical fiber at the silver-coated reflective fiber end specifically includes: an incident single-mode optical fiber end 8, an elliptical micro-nano optical fiber 12, a single-mode reflection section 11 of a silver-coated film, filled with Glass tube 10 of refractive index solution;

The incident single-mode fiber end 8 is sequentially provided with the elliptical micro-nano fiber 12 and the single-mode reflection section 11 of the silver-coated film;

The elliptical micro-nano fiber 12 is sealed in the glass tube 10 filled with a refractive index solution;

The interface between the glass tube 10 filled with the refractive index solution and the incident single-mode fiber end 8 is sealed with AB glue 9 .

As shown in Figures 3 and 4, the refractive index solution cladding elliptical micro-nano fiber 5 at the end of the silver-coated reflective fiber is set in a temperature-controllable environment, specifically the temperature-controllable environment is set as a temperature control box 6;

Gradually change the temperature in the environment, the spectrometer 7 collects the output spectrum, and records the interference comb spectrum;

Calculate the drift of the wavelength of the interference comb spectrum, and fit the relationship curve of the wavelength drift of the interference comb spectrum with temperature; the relationship curve of the wavelength drift of the comb spectrum with temperature changes is obtained by linear fitting or least squares multiplication for fitting;

The temperature of the environment to be tested is measured according to the relationship graph.

The core diameter of the incident and outgoing single-mode optical fiber is 9 μm, and the cladding diameter is 125 μm; the length of the elliptical micro-nano optical fiber is 0.6 cm, the major axis length is 2.8 μm, the ellipticity is 0.7, the inner diameter of the glass tube is 300 μm, and the outer The diameter is 500 μm and the length is 5 cm.

The principle of light in the transmission process:

The light is divided into two beams through the fiber coupler 2, and then coupled in the circulator 4 after passing through the two symmetrical optical paths of the fiber coupler 2 and the circulator 4, and a polarization controller 3 is added to one of the arms to control the polarization state of the transmitted light , the light beam enters the elliptical micro-nano optical fiber 5 clad in the refractive index solution after being recoupled, after being reflected by the end face 11 of the silver-coated film, it is divided into two beams by the circulator 4 again, and the optical fiber coupler 2 generates along the two arms of the coupler. The two polarization states of light interfere, and the spectrometer 7 records the interference comb spectrum. When the sensing unit is affected by the external temperature so that the optical path difference between the two polarization states of the transmitted light changes, the interference fringes move, as shown in FIG. 3 . Record the wavelength drift of a trough value of the comb spectrum as the temperature changes, fit the curve of the comb spectrum wavelength drift with temperature, and perform linear fitting to obtain the temperature sensitivity coefficient, as shown in Figure 4.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other. As for the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and for the related information, please refer to the description of the method part.

In this paper, specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; meanwhile, for those of ordinary skill in the art, according to the present invention Thoughts, there will be changes in specific implementation methods and application ranges. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims (2)

1. An optical fiber temperature measuring device, characterized in that, the temperature measuring device comprises: a broadband light source, a single-mode fiber coupler, a polarization controller, an optical fiber circulator, a silver-coated film reflective optical fiber end of the refractive index solution cladding ellipse micro Nano-fiber, spectrometer; The broadband light source is connected with the single-mode fiber coupler, and the light emitted by the broadband light source is divided into two beams through the single-mode fiber coupler, one beam is directly transmitted to the fiber circulator along the first optical path, and the other beam is directly transmitted to the optical fiber circulator along the first optical path. The beam is transmitted to the fiber circulator through the polarization controller along the second optical path; the first optical path is a transmission optical path for the light to be transmitted from the single-mode fiber coupler to the optical fiber circulator; the second optical path The second optical path is a transmission optical path where light is transmitted from the single-mode fiber coupler to the optical fiber circulator through the polarization controller, and the first optical path and the second optical path are arranged symmetrically; The optical fiber circulator is connected to the refractive index solution cladding elliptical micro-nano optical fiber at the end of the silver-coated reflective optical fiber, and the two beams with different polarization states in the optical fiber circulator are recoupled to obtain a coupled beam; The coupled light beam is transmitted to the refractive index solution cladding elliptical micro-nano optical fiber at the end of the silver-coated reflective fiber and is reflected to obtain a reflected light beam; After the reflected light beam is transmitted to the optical fiber circulator, it is divided into two beams, and the two reflected light beams are respectively transmitted to the single-mode fiber coupler along the first optical path and the second optical path; The two reflected light beams interfere with the two polarization states of light in the single-mode fiber coupler to obtain an interference spectrum; The single-mode fiber coupler is connected to the spectrometer, the single-mode fiber coupler sends the interference spectrum to the spectrometer, and the spectrometer analyzes the interference spectrum to obtain the external temperature; The refractive index solution-clad elliptical micro-nano optical fiber at the silver-coated reflective fiber end specifically includes: an incident single-mode optical fiber end, an elliptical micro-nano optical fiber, a single-mode reflection section of the silver-coated film, and a glass tube filled with a refractive index solution; The end of the incident single-mode fiber is sequentially provided with the single-mode reflection section of the elliptical micro-nano fiber and the silver-coated film; The elliptical micro-nano fiber is sealed in the glass tube filled with the refractive index solution; The interface between the glass tube filled with the refractive index solution and the incident single-mode fiber end is sealed with AB glue. 2. A kind of optical fiber temperature measuring device according to claim 1, characterized in that, the refractive index solution cladding elliptical micro-nano optical fiber at the end of the silver-coated reflective optical fiber is arranged in a temperature-controllable environment; Gradually change the temperature in the environment, the spectrometer collects the output spectrum, and records the interference comb spectrum; Calculating the length of the interference comb spectrum drift, and fitting the relationship curve of the interference comb spectrum drift with temperature; The temperature of the environment to be tested is measured according to the relationship graph.