CN211043133U - Seawater salinity measuring device based on multi-section conical quartz fiber mode interference structure - Google Patents
Seawater salinity measuring device based on multi-section conical quartz fiber mode interference structure Download PDFInfo
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- CN211043133U CN211043133U CN201920788366.8U CN201920788366U CN211043133U CN 211043133 U CN211043133 U CN 211043133U CN 201920788366 U CN201920788366 U CN 201920788366U CN 211043133 U CN211043133 U CN 211043133U
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Abstract
The utility model aims to provide a seawater salinity measuring device based on multistage toper quartz fiber mode interference structure, including optical fiber reflector, transmission fiber, mode interference structure based on multistage toper quartz fiber structure, this mode interference structure is by three-section toper quartz fiber link to each other and fuse into one section optic fibre and constitute; one end of the structure is connected with an optical fiber reflector through a transmission optical fiber to form a reflection sensing head, and a double-sleeve structure is designed for watertight packaging of the sensing head, wherein a filter screen can filter impurities in seawater, and an ultraviolet light-emitting diode can sterilize and purify water; and fix the sensing head on this detection protection architecture through the epoxy glue, combine together with the metal stopper and can bear high water pressure, prevent that sensing optical fiber from adhering with marine organism molecule and plankton, guaranteed the reliability that sensing part exposes in the sea water. By adopting the sensor device, the measurement of the seawater refractive index can be realized, and the salinity information of the seawater can be obtained according to the response change of the output spectrum.
Description
Technical Field
The utility model relates to an optic fibre laser sensing field specifically says, relates to a sea water salinity measuring device based on structure is interfered to multistage toper quartz fiber mode, can be used to the measurement of sea water salinity information.
Background
In recent years, all-fiber sensors, particularly those with high sensitivity, have attracted considerable attention. With the popularization of fiber lasers, and because of the advantages of simple structure, high sensitivity, high signal-to-noise ratio, good stability and the like, people have increasingly growing demand for fiber laser sensors. Nowadays, various fiber laser sensors have been used to measure temperature, strain, refractive index, etc., and are widely used in various fields such as biology, medicine, environment, etc.
The measurement of seawater salinity plays an indispensable role in various scientific applications such as aquaculture, marine environment monitoring and management, oceanographic research and the like, and the traditional commercial salinity sensor based on electronic elements acquires salinity information by detecting seawater conductivity. In recent years, optical fiber salinity sensors have received much attention as a potentially attractive alternative. Salinity information can be obtained by measuring the refractive index of seawater. The existing forms of the optical fiber salinity sensor comprise a traditional long-period grating interferometer, a microfiber junction ring resonator in an optical fiber Fabry-Perot cavity, a side-polished dual-core optical fiber, a U-shaped single-mode optical fiber, and v various tapered special optical fibers and microfiber optical fibers. In order to improve the sensitivity of the optical fiber salinity sensor, a fused cone method or a laser drilling method is mostly adopted for manufacturing. Most of these sensors have high sensitivity, however, they are difficult to construct. In addition, the sensing heads of these sensors are either not robust or increase the temperature cross-sensitivity of the sensing fibers, and the fragile sensing structure becomes unreliable and unsuitable for measurement in extreme marine environments. Recently, optical fiber sensors based on optical fiber laser intracavity modulation have been applied to magnetic field and temperature measurement, and these sensors have the characteristics of high sensitivity, high signal-to-noise ratio, full width at half maximum and the like, and have great potential in the aspect of ocean exploration.
Disclosure of Invention
An object of the utility model is to provide a sea water salinity measuring device based on structure is interfered to multistage toper quartz fiber mode. The optical fiber multimode mode interference structure is used as an inner cavity sensing device, is formed by connecting a plurality of sections of conical quartz fibers and fusing the conical quartz fibers into a section of optical fiber, and is embedded into an annular cavity of an optical fiber laser so as to improve the working environment of the annular cavity. The fiber reflector is cascaded with a mode interference structure based on a multi-section conical quartz fiber to improve the modulation sensitivity. By adopting the sensor device, the refractive index of the seawater can be measured, and the salinity information of the seawater can be obtained according to the change of the output spectrum. Therefore, the utility model adopts the technical scheme that the method comprises the following steps: the device comprises a semiconductor laser, a wavelength division multiplexing coupler, a laser gain optical fiber, an isolator, a reflection sensing head structure, an optical circulator, an optical fiber Bragg grating, an optical coupler and a spectrum analyzer which are connected in sequence; the laser gain medium is a section of erbium-doped fiber with the length of 3 meters; the mode interference structure based on the multi-section conical quartz fiber and the optical fiber reflector are cascaded to form a reflection sensing head structure, so that the assembly of engineering equipment is facilitated; the output spectrum of the device is measured by a spectrum analyzer.
The semiconductor laser is used as a laser pumping source, 976nm pumping light is effectively coupled to the erbium-doped optical fiber through a 980nm/1550nm wavelength division multiplexer, and the fixed output wavelength of the laser is 976 nm.
A mode interference structure based on multiple sections of conical quartz fibers is cascaded with an optical fiber reflector to be used as a reflection sensing head, and the sensing depth of an inner cavity is improved, wherein the mode interference structure is formed by connecting multiple sections of conical quartz fibers with proper lengths and fusing the conical quartz fibers into a section of optical fiber. The reflection sensing head is embedded into the optical fiber annular cavity through the optical circulator to serve as a salinity information sensing device and have a certain filtering function.
The watertight packaging design of sensing head has adopted the double-sleeve structure for antifouling protection in the sea water, wherein the filter screen plays the effect of filtering impurity in the sea water, and ultraviolet emitting diode has the efficiency of disinfecting and purifying water quality for prevent sensing optical fiber and marine organism molecule and plankton adhesion, guaranteed the sensing head part and exposed the reliability in the sea water, and fix sensing head part on detecting protection architecture through the epoxy glue. Meanwhile, the sensing structure is sealed, so that high water pressure can be borne, and seawater is prevented from permeating into the instrument.
The isolator acts as an isolation device to maintain one-way light propagation and prevent the spatial hole from burning.
The spectrum analyzer is output through a 10: 90 coupler, where 10% of the light output is coupled to the spectrometer for data recording and analysis of the output laser characteristics, and 90% is returned to the ring cavity to form feedback. The spectral resolution was 0.02 nm.
The method for testing seawater salinity information is realized by utilizing the device, the reflection sensing head part is placed in a salinity environment to start measurement, then, a spectrogram and power change which change along with the change can be obtained at the output end of the device by changing the salinity around the sensing head, and the spectrogram and the power change are stored and correspondingly processed to obtain the seawater salinity information.
The utility model has the advantages of, based on multistage toper quartz fiber mode interference structure, cascade the optical fiber reflector with the mode interference structure based on multistage toper quartz fiber for the first time and be used as reflection sensing head mutually, the equipment of the engineering equipment of being convenient for is embedded into optic fibre laser annular chamber with it, can be used as salinity information sensing device, has certain filtering simultaneously in addition. For the packaging structure of the reflection sensing head, a double-sleeve structure design is adopted for antifouling protection in seawater, wherein a filter screen plays a role in filtering impurities in seawater, and an ultraviolet light-emitting diode has the effects of sterilizing and purifying water quality and is used for preventing the sensing optical fiber from being adhered to marine biomolecules and plankton, so that the reliability of exposing the sensing part in the seawater is ensured, and the reflection sensing head is fixed on a detection protection structure through epoxy glue. Meanwhile, the sensing head part is sealed by adopting a sealing structure and a metal plug, so that high water pressure can be borne, and seawater is prevented from permeating into the instrument during detection. And the multi-section conical quartz fiber mode interference structure has high transmission efficiency and low insertion loss, and the multi-mode interference of the structure is used for modulation, so that low-loss filtering sensing and high-precision salinity information sensing can be achieved. The sensor measuring device is hardly influenced by power fluctuation, and compared with the sensor measuring device, the sensor measuring device is good in strength stability and small in measuring error.
Drawings
Fig. 1 shows a watertight sealing structure of a reflection sensor head according to the present invention.
Fig. 2 is a schematic diagram of the mode interference structure based on multi-section conical quartz fiber used in the present invention.
Fig. 3 is a system diagram of the experimental device of the optical fiber salinity sensor of the present invention.
In the drawings, the components represented by the reference numerals are listed as follows:
1-a fiber optic reflector; 2-a transmission fiber; 3-mode interference structure based on multi-section conical quartz fiber; 4-sealing structure (can bear high water pressure and prevent infiltration into the instrument); 5-filter screen (filtering impurities in seawater); 6-ultraviolet light emitting diode (sterilization, water purification); 7-a metal plug; 8-single mode fiber; 9-tapered quartz fibers; 10-semiconductor laser (semiconductor laser with tail fiber output, fixed output wavelength of 976 nm); 11-wavelength division multiplexing coupler (WDM, 980/1550 nm); 12-laser gain medium (erbium doped fiber); 13-an isolator; 14-an optical circulator; 15-a reflective sensor head; 16-fiber bragg gratings; 17-optical coupler (split ratio 10: 90, 10% light output, 90% light back to ring cavity to form feedback); 18-Spectrum Analyzer (OSA, spectral resolution 0.02 nm).
Detailed Description
The utility model discloses in, realize for the first time that sea water salinity measuring device based on structure is interfered to multistage toper quartz fiber mode, erbium-doped fiber is as the laser gain medium, and the sensing reflection head that constitutes by the mode interference structure based on multistage toper quartz fiber and the fiber reflector can respond to sea water salinity information, through output spectrum and the power that detects the sensing head and change because of salinity changes on every side, can effectively record salinity sensing precision, can calculate according to the sea water refracting index and obtain sea water salinity information. The mode interference structure based on the multi-section conical quartz fiber is cascaded with the optical fiber reflector to be used as a reflection sensing head, and is embedded into a system device as an inner cavity sensing device, so that the working environment of an annular cavity system is improved, and the salinity sensing is modulated according to the loss in the induction cavity of the output intensity of the optical fiber laser.
The utility model discloses a sea water salinity measuring device based on structure is interfered to multistage toper quartz fiber mode, its technical scheme as follows:
the optical fiber Bragg grating optical spectrum analyzer mainly comprises a semiconductor laser pumping source, an active inner cavity perception modulation system, a reflection sensing head structure, an optical fiber Bragg grating and an optical spectrum analyzer.
The sensing device has simple structure. The 976nm laser of the pumping light source is effectively coupled into the gain medium erbium-doped optical fiber through a 980nm/1550nm wavelength division multiplexer, and an isolation device is adopted in order to keep unidirectional light propagation and prevent space hole burning. A fiber reflector is cascaded by a mode interference structure based on a multi-section conical quartz fiber and used as a reflection sensing head. The output spectrum is measured by a spectrum analyzer through a 10: 90 coupler, so that ocean salinity information sensing can be realized.
The semiconductor laser is used as a laser pumping source, 976nm pumping light is effectively coupled to the erbium-doped optical fiber through a 980nm/1550nm wavelength division multiplexer, and the fixed output wavelength of the laser is 976 nm.
The mode interference structure based on the multi-section conical quartz fiber is cascaded with the optical fiber reflector to be used as a reflection sensing head, and the reflection sensing head is embedded into an optical fiber annular cavity as an inner cavity sensing device, so that low-loss filtering sensing is achieved, and the working environment of the annular cavity is improved.
The double-sleeve structure is designed for protection in seawater, and the reliability of the sensing part exposed in seawater is guaranteed. The sealing structure can withstand high water pressure and prevent water from penetrating into the instrument.
The isolator acts as an isolation device to maintain one-way light propagation and prevent the spatial hole from burning.
The spectrum analyzer is output through a 10: 90 coupler, where 10% of the light output is coupled to the spectrometer for data recording and analysis of the output laser characteristics, and 90% is returned to the ring cavity to form feedback. The spectral resolution was 0.02 nm.
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Fig. 1 shows a watertight sealing structure of a reflection sensor head according to the present invention. One end of the sensing head structure 15 is connected with the transmission optical fiber 2, and the sealing structure 4 is combined with the metal plug 7, so that the sensing head structure can bear high water pressure and prevent seawater from permeating into an instrument. The double-sleeve structure is designed for preventing fouling, wherein the filter screen 5 filters impurities in seawater and the ultraviolet light emitting diode 6 for sterilization and water purification, and can prevent the sensing optical fiber from being adhered to marine biological molecules and plankton. The reflection sensing head 15 is fixed on the detection protection structure by epoxy glue.
FIG. 2 is a schematic diagram of a mode interference structure based on a multi-segmented, tapered quartz fiber in a system. The mode interference structure is formed by connecting three sections of conical quartz fibers and fusing the fibers into a section of optical fiber, and one end of the mode interference structure is connected with the optical fiber reflector 1 in a cascade mode to form a reflection sensing head 15. The ring cavity is embedded in the ring cavity of the fiber laser, so that the working loss environment of the ring cavity can be improved.
FIG. 3 is a system diagram of an experimental device of the optical fiber salinity sensor. The semiconductor laser 10 outputs pump light with a wavelength of 976nm, which is then efficiently coupled into the gain medium erbium-doped fiber 12 through the 980nm/1550nm wavelength division multiplexing coupler 11. And the isolator 13 of the isolating device is adopted, so that the unidirectional light transmission of the system is kept and the spatial hole burning is prevented. In order to play the filtering effect the utility model discloses in adopted sensing head 15 and optic fibre bragg grating 16 structure, adopted sensing head structure 15 still to improve the inner chamber perception degree of depth of fiber laser inner chamber, improved the operational environment of system. The salinity information of the seawater can be obtained by the output spectrogram of the optical spectrum analyzer 18.
The utility model discloses in, sensing head 15 is placed in the simulation sea water environment, and when changing its surrounding environment salinity, sensing system's output will change, just can obtain sea water salinity information through detecting the processing, realizes the high accuracy low-loss salinity sensing of system.
Claims (3)
1. A seawater salinity measuring device based on multi-section conical quartz fiber mode interference structure is characterized by comprising: the device comprises a semiconductor laser, a wavelength division multiplexer, a laser gain medium, an optical isolator, an optical circulator, a reflection sensing head structure, a fiber Bragg grating, an optical coupler and a spectrum analyzer which are connected in sequence; and the reflection sensing head is subjected to watertight packaging, and the device comprises a filter screen, an ultraviolet light-emitting diode, a sealing structure, a metal plug, a multi-section conical quartz fiber mode interference structure, a transmission optical fiber and an optical fiber reflector.
2. The seawater salinity measuring apparatus based on multi-section conical quartz fiber mode interference structure of claim 1, wherein the water-tight encapsulation structure of the reflection sensing head is as follows: the reflection sensing head is designed to be of a double-sleeve structure around, the cylindrical filter screen is located on the inner side, the outer side of the reflection sensing head is provided with the ultraviolet light emitting diode, the reflection sensing head is fixed on a detection protection structure of the double-sleeve structure through epoxy glue, the outer part of the double-sleeve structure is provided with a sealing structure, one side of the double-sleeve structure is provided with a micropore for communicating with a transmission optical fiber, and the other side of the double-sleeve structure is sealed by.
3. The seawater salinity measuring apparatus based on multi-section conical quartz fiber mode interference structure of claim 1, wherein, three sections of conical quartz fibers are connected and fused into a section of optical fiber to form a multi-section conical quartz fiber mode interference structure, and the structure is cascaded with an optical fiber reflector to form a reflection sensing head.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110907401A (en) * | 2019-05-28 | 2020-03-24 | 天津工业大学 | Seawater salinity measuring device based on multi-section conical quartz fiber mode interference structure |
| CN113607689A (en) * | 2021-07-08 | 2021-11-05 | 天津工业大学 | Fabry-Perot micro-flow cavity sensor based on double-hole microstructure optical fiber |
| CN117347287A (en) * | 2023-12-06 | 2024-01-05 | 山东大学 | Optical interference structural self-compensating seawater salinity measuring device |
-
2019
- 2019-05-28 CN CN201920788366.8U patent/CN211043133U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110907401A (en) * | 2019-05-28 | 2020-03-24 | 天津工业大学 | Seawater salinity measuring device based on multi-section conical quartz fiber mode interference structure |
| CN113607689A (en) * | 2021-07-08 | 2021-11-05 | 天津工业大学 | Fabry-Perot micro-flow cavity sensor based on double-hole microstructure optical fiber |
| CN113607689B (en) * | 2021-07-08 | 2024-04-09 | 天津工业大学 | Fabry-Perot micro-fluidic cavity sensor based on double-hole microstructure optical fiber |
| CN117347287A (en) * | 2023-12-06 | 2024-01-05 | 山东大学 | Optical interference structural self-compensating seawater salinity measuring device |
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