CN211978166U - Active temperature sensitive device based on Mach-Zehnder structure - Google Patents
Active temperature sensitive device based on Mach-Zehnder structure Download PDFInfo
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- CN211978166U CN211978166U CN202020842726.0U CN202020842726U CN211978166U CN 211978166 U CN211978166 U CN 211978166U CN 202020842726 U CN202020842726 U CN 202020842726U CN 211978166 U CN211978166 U CN 211978166U
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Abstract
The utility model belongs to the technical field of this optical fiber sensing, the utility model discloses an active type temperature sensing device based on mach-zehnder structure, include: the annular cavity is formed by sequentially connecting a wavelength division multiplexer, an erbium-doped optical fiber, an optical fiber isolator, a Mach-Zehnder temperature sensitive element structure and a coupler end to end; the light source is connected with the wavelength division multiplexer through a single mode fiber, and the coupler is connected with the spectrometer through a single mode fiber. The utility model discloses a temperature sensitive device has with low costs and reliable and stable advantage.
Description
Technical Field
The utility model relates to an optical fiber sensing technical field, concretely relates to active type temperature sensing device based on mach-zehnder structure.
Background
The description of the background art of the present invention pertains to the related art related to the present invention, and is only for the purpose of illustrating and facilitating the understanding of the contents of the present invention, and it is not to be understood that the applicant definitely considers or presumes that the applicant considers the present invention as the prior art of the application date of the present invention which is filed for the first time.
In the optical fiber active temperature sensing system, the output wavelength, the output intensity and the like can be changed along with the changes of physical quantities such as external refractive index, temperature, strain, magnetic field, curvature and the like, so that the detection of the external physical quantities is realized.
However, the existing sensing system generally has the defects of high cost, poor adaptability and easy electromagnetic interference.
SUMMERY OF THE UTILITY MODEL
An embodiment of the utility model provides an aim at provides an active type temperature sensing device based on mach-zehnder structure. The utility model discloses a mach-zehnder structure's active type temperature sensing device uses mach-zehnder interference principle as the foundation, utilizes its temperature measurement to realize the fixed range to the sensitive characteristics of ambient temperature, chooses for use the material for use in the sensing region to be traditional single mode fiber and multimode fiber, and this sensing device has advantages such as with low costs, harmonious simple, convenient to use.
The utility model aims at realizing through the following technical scheme:
in a first aspect, the present invention provides an active temperature sensitive device based on mach-zehnder structure, including:
the annular cavity is formed by sequentially connecting a wavelength division multiplexer, an erbium-doped optical fiber, an optical fiber isolator, a Mach-Zehnder temperature sensitive element structure and a coupler end to end; the light source is connected with the wavelength division multiplexer through a single mode fiber, and the coupler is connected with the spectrometer through a single mode fiber.
Furthermore, the Mach-Zehnder temperature sensitive element structure comprises two multimode optical fibers, and a second single mode optical fiber is connected between the two multimode optical fibers.
Further, the length of the second single-mode fiber is 5cm or 6cm, and the length of the multimode fiber is 0.5 cm.
Further, the light source is a 980nmLD pump light source, the wavelength division multiplexer is a 980nm/1550nm wavelength division multiplexer, and the erbium-doped optical fiber is 10.4m long; the coupler split ratio was 40: 60.
In a second aspect, the present invention provides a method for manufacturing an active temperature-sensitive device based on a mach-zehnder structure, where the temperature-sensitive device is the above temperature-sensitive device, and the method includes the following steps:
adopting a single mode fiber to sequentially connect the wavelength division multiplexer, the erbium-doped fiber, the fiber isolator, the Mach-Zehnder temperature sensitive element structure and the coupler end to form an annular cavity, and connecting the light source with the wavelength division multiplexer through the single mode fiber to connect the light source into the annular cavity; and connecting the coupler with a spectrometer through a single-mode optical fiber, and connecting the spectrometer into the annular cavity to obtain the temperature sensitive device.
Further, the preparation of the Mach-Zehnder temperature sensitive element structure comprises the following steps:
and wiping the end faces of the second single-mode optical fiber and the multimode optical fiber respectively by alcohol cotton, then cutting the end faces to be flat, and carrying out optical fiber fusion according to the sequence of multimode-single mode-multimode to obtain a multimode-single mode-multimode temperature sensitive structure, namely the Mach-Zehnder temperature sensitive element structure.
The embodiment of the utility model provides a following beneficial effect has:
the utility model discloses a sensing device utilizes full optical fiber type structure to sense, has advantages such as anti-electromagnetic interference, electrical insulation, sensitivity height, small, the quality is light, appearance structure is nimble changeable strong adaptability, range of application is extensive, reliability height.
The utility model discloses an online mach-zehnder structure compares with traditional mach-zehnder structure, has that the structure is exquisite, and manufacturing cost is lower, tuning mode advantage such as many.
The utility model discloses a temperature-sensitive component of on-line type multimode-single mode-multimode Mach Zehnder structure in optic fibre active sensing structure very sensitive to the temperature.
The utility model discloses a sensing device has good stability.
Drawings
FIG. 1 is a schematic view of the sensing structure of the device of the present invention
1. An LD pumping light source; 2. a wavelength division multiplexer; 3. an erbium-doped fiber; 4. a fiber isolator; 5. a multimode-single mode-multimode Mach-Zehnder (MZI) temperature sensitive element structure (5-1 single mode fiber; 5-2 multimode fiber); 6. a 1 × 2 coupler; 7. a spectrometer; 8. a single mode optical fiber.
FIG. 2 is a linear temperature-output wavelength fit plot for a single mode length of 5 cm.
Detailed Description
The present application is further described below with reference to examples.
In order to more clearly illustrate embodiments of the present invention or technical solutions in the prior art, in the following description, different "one embodiment" or "an embodiment" means not necessarily the same embodiment. Various embodiments may be replaced or combined, and other embodiments may be obtained according to the embodiments without creative efforts for those skilled in the art.
As shown in fig. 1, an active temperature sensitive device based on a mach-zehnder structure includes:
the optical fiber ring cavity comprises a light source 1, an annular cavity and a spectrometer 7, wherein the annular cavity is formed by sequentially connecting a wavelength division multiplexer 2, an erbium-doped optical fiber 3, an optical fiber isolator 4, a Mach-Zehnder temperature sensitive element structure 5 and a coupler 6 end to end; the light source 1 is connected with the wavelength division multiplexing 2 multiplexer through a single mode fiber 8, and the coupler 6 is connected with the spectrometer 7 through the single mode fiber 8.
Further, the mach-zehnder temperature sensitive element structure 5 comprises two multimode optical fibers 5-2, and a second single mode optical fiber 5-1 is connected between the two multimode optical fibers.
Further, the length of the second single-mode optical fiber 5-1 is 5cm or 6cm, and the length of the multimode optical fiber 5-2 is 0.5 cm.
Further, the light source 1 is a 980nm LD pump light source, the wavelength division multiplexer 2 is a 980nm/1550nm wavelength division multiplexer, and the erbium-doped fiber 3 is 10.4m long; the splitting ratio of the coupler 5 is 40: 60.
A preparation method of an active temperature sensitive device based on a Mach-Zehnder structure is disclosed, wherein the temperature sensitive device is the temperature sensitive device, and the preparation method comprises the following steps:
adopting a single mode fiber 8 to sequentially connect the wavelength division multiplexer 2, the erbium-doped fiber 3, the fiber isolator 4, the Mach-Zehnder temperature sensitive element structure 5 and the coupler 6 end to form an annular cavity, and connecting the light source 1 with the wavelength division multiplexer 2 through the single mode fiber 8 to connect the light source 1 into the annular cavity; and connecting the coupler 6 with a spectrometer 7 through a single-mode optical fiber 8, and connecting the spectrometer 7 into the annular cavity to obtain the temperature sensitive device.
Further, the preparation of the mach-zehnder temperature sensitive element structure 6 includes the following steps:
and wiping the end surfaces of the second single-mode fiber 5-1 and the multimode fiber 5-2 by alcohol cotton, cutting the end surfaces to be flat, and performing fiber fusion according to the sequence of multimode-single mode-multimode to obtain a multimode-single mode-multimode temperature sensitive structure, namely the Mach-Zehnder temperature sensitive element structure.
An active temperature sensing device based on a Mach-Zehnder structure is shown in figure 1, an LD pumping light source is coupled into an annular cavity through a single-mode fiber Wavelength Division Multiplexer (WDM), and is connected with an optical fiber Isolator (ISO)4 after passing through an erbium-doped fiber (EDF)3, and a multimode-single-mode-multimode Mach-Zehnder (MZI) structure 5 serves as a filter to achieve temperature tuning. The light beam is split by the 1 x 2 optical fiber coupler 6, one path of the light beam is output to the spectrometer 7, and the other path of the light beam returns to the ring cavity for continuous transmission.
The Mach-Zehnder structure active temperature sensing device is provided with a coupler which selects 980nm LD pumping light, 980nm/1550nm Wavelength Division Multiplexers (WDM), 10.4m long erbium-doped fibers (EDF) and a light splitting ratio of 40: 60. In the multimode-single mode-multimode Mach-Zehnder (MZI) temperature sensitive element (5), the length of the second single mode optical fiber 5-1 is 5cm or 6cm, and the length of the multimode optical fiber 5-2 is 0.5 cm.
And a multimode-single mode-multimode structure is selected as a Mach-Zehnder temperature sensitive element, incident light is transmitted to a multimode fiber 5-2 structure through a single mode fiber 8, when the incident light is transmitted to a position of a welding end face of a second single mode fiber 5-1 in the middle, one part of light can be transmitted along a fiber core of the second single mode fiber 5-1, and the other part of light can enter a cladding of the second single mode fiber 5-1 to be transmitted continuously. When the two parts of light are transmitted to the other end of the second single-mode fiber 5-1 and the welding end face of the multimode fiber 5-2 at the same time, the two parts of light are coupled into the multimode fiber 5-2 again, and the light between the fiber core and the cladding generates intermode interference under the condition of meeting the phase matching condition, so that an output interference spectrum is obtained.
In which a phase difference is generated between light passing through a core and a cladding of a multimode optical fiber, respectively
ncoreRepresenting the effective refractive index, n, of the core of a multimode optical fibreclad represents the effective refractive index of the cladding of the multimode optical fiber, L represents the length of the multimode optical fiber, and λ represents the wavelength of transmitted light.
Due to thermo-optic effects, changes in temperature will cause changes in the refractive indices of the core, cladding and the length of the interference arms.
Wherein the thermal expansion coefficient of the optical fiber is:
α＝dL/LdT (3)
meanwhile, the refractive indexes of the fiber core and the cladding are also changed, and the thermo-optic coefficients of the fiber core and the cladding are respectively zetacoreAnd ζcladThe following can be obtained:
when the temperature changes, the length L of the interference arm and the phase difference between the modes change, and then the output interference wavelength is shifted.
Fig. 1 shows an active temperature sensing device based on a mach-zehnder structure. Wherein, 980nm LD pump light, 980nm/1550nm Wavelength Division Multiplexer (WDM), 10.4m Erbium Doped Fiber (EDF) are selected; coupler split ratio of 40: 60. In the multimode-single mode-multimode Mach-Zehnder (MZI) temperature sensitive element (5), the length of the second single mode optical fiber 5-1 is 5cm or 6cm, and the length of the multimode optical fiber 5-2 is 0.5 cm.
The manufacturing method of the sensing structure in the device comprises the following steps: the end faces of the second single-mode optical fiber 5-1 and the multimode optical fiber 5-2 are wiped clean by alcohol cotton, then cut flatly by an optical fiber cutting knife, and optical fiber fusion is carried out by a fusion splicer according to the sequence of multimode, single mode and multimode, wherein 5cm is selected for the second single-mode optical fiber 5-1, 0.5cm is adopted for the multimode optical fiber 5-2, and fusion splicing loss is well controlled in the fusion splicing process. According to the same operation mode, a 6cm single-mode optical fiber and a 0.5cm multi-mode optical fiber are made into a multi-mode-single-mode-multi-mode temperature sensitive structure.
The active sensing device is a coupler which selects 980nm LD pump light, 980nm/1550nm Wavelength Division Multiplexer (WDM), 10.4m long erbium-doped fiber (EDF) and the light splitting ratio is 40: 60. The LD pump light 1 is coupled into the cavity by connecting a single-mode fiber 8 with a Wavelength Division Multiplexer (WDM)2, the pump light is subjected to gain amplification through an erbium-doped fiber (EDF)3, and then an optical fiber Isolator (ISO)4 is connected to ensure unidirectional transmission of the light, so that part of returned light is prevented from affecting an optical path system. Then, the light in the optical path is filtered by a multimode-single mode-multimode Mach Zehnder (MZI) temperature sensitive element structure 5, and then a 1 × 2 Coupler16 is connected to form a loop. The Coupler with the splitting ratio of 40:60 is selected, light enters from the port 1 of the Coupler1 and is divided into two paths, one path is connected to the wavelength division multiplexer behind the LD pump light, and the other path is connected to the spectrometer (OSA) 7. If the temperature of the environment is controlled by the temperature control box, the transmission spectra under different temperature environments can be obtained.
And a multimode-single mode-multimode Mach-Zehnder (MZI) temperature sensitive element is used for filtering to form an active sensing device, the temperature of the temperature control box is controlled to rise, an output waveform is measured every time the temperature rises by 5 ℃ in the process that the temperature rises from 30 ℃ to 55 ℃, and the experimental result is fitted. And (4) analyzing the combined data. The sensitivity of the temperature sensitive device reached 0.216 nm/deg.C at 30 deg.C to 35 deg.C, as shown by the y1 fit curve in FIG. 2. The sensitivity of the temperature sensitive device reached 0.2115 nm/deg.C at 40 deg.C to 55 deg.C, as shown by the y2 fitted curve in FIG. 2. Wherein the sensitivity reaches 0.682 nm/DEG C from 35 ℃ to 40 ℃. The sensitivity of the active temperature sensitive device is 10 times that of a common multimode-single mode-multimode interference type sensing structure, and the active temperature sensitive device has good stability under the condition that the external environment is kept unchanged.
It should be noted that the above embodiments can be freely combined as necessary. The above description is only for the preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (4)
1. An active temperature-sensitive device based on a Mach-Zehnder structure, comprising:
the annular cavity is formed by sequentially connecting a wavelength division multiplexer, an erbium-doped optical fiber, an optical fiber isolator, a Mach-Zehnder temperature sensitive element structure and a coupler end to end; the light source is connected with the wavelength division multiplexer through a single mode fiber, and the coupler is connected with the spectrometer through a single mode fiber.
2. A mach-zehnder structure-based active temperature-sensitive device according to claim 1, characterized in that the mach-zehnder structure-based temperature-sensitive element comprises two multimode optical fibers, and a second single-mode optical fiber is connected between the two multimode optical fibers.
3. The active temperature-sensitive device according to claim 2, wherein the second single-mode fiber has a length of 5cm or 6cm, and the multimode fiber has a length of 0.5 cm.
4. The active temperature-sensitive device based on the Mach-Zehnder structure of claim 1, characterized in that the light source is a 980nm LD pump light source, the wavelength division multiplexer is a 980nm/1550nm wavelength division multiplexer, and the erbium-doped fiber has a length of 10.4 m; the coupler split ratio was 40: 60.
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