Optical fiber temperature and salt sensor for multi-parameter measurement and use method thereof

Abstract

The invention discloses an optical fiber temperature-salinity sensor for multi-parameter measurement and a use method thereof. The optical fiber temperature-salinity sensor comprises a broadband light source, an optical fiber coupler, a spectrograph, a circulator, a salinity interferometer and a temperature interferometer, the broadband light source is in communication connection with the first end of the circulator; the second end of the circulator is in two-way communication connection with the salinity interferometer; the third end of the circulator is in communication connection with the first end of the optical fiber coupler; the second end of the optical fiber coupler is in communication connection with the first end of the temperature interferometer; the second end of the temperature interferometer is in communication connection with the third end of the optical fiber coupler; and the fourth end of the optical fiber coupler is in communication connection with the spectrometer. According to the invention, the two interferometers are cascaded and combined through the circulator to generate a vernier effect, so that accurate measurement of thermohaline change and synchronous measurement of two parameters of temperature and salinity are realized, and the measurement precision and the measurement sensitivity of the optical fiber thermohaline sensor are improved; the optical fiber sensor has high anti-electromagnetic interference capability, and the operation stability in a complex environment is improved.

Description

Technical Field

[0001] The invention relates to the field of optical fiber temperature-salinity sensing, and in particular to an optical fiber temperature-salinity sensor for multi-parameter measurement and a use method thereof. Background Art

[0002] At present, marine monitoring equipment mainly relies on electrical sensors or fiber optic sensing technology for data collection. Among them, electrical sensors have the characteristics of mature technology and wide application, and can provide relatively stable measurement data. In the field of fiber optic sensing, FBG coating technology is a commonly used salinity sensing method. It changes the grating structure of the optical fiber through coating to achieve sensitive response to salinity, and is supplemented by bare fiber grating for temperature compensation. This fiber optic sensing technology has the advantages of low cost and simple production.

[0003] However, although electrical sensors are mature in technology, they are expensive, have complex maintenance requirements, and are limited by electromagnetic interference and seabed power supply. All of the above limitations have increased the limitations of electrical sensors in ocean monitoring and restricted the popularization of electrical sensors. In comparison, although FBG coating technology has certain advantages in salinity sensing, its sensitivity is relatively limited and it is difficult to meet the needs of high-precision measurements, especially in complex and changeable marine environments, where its measurement accuracy and stability are often easily challenged. Summary of the invention

[0004] The present invention provides a multi-parameter optical fiber temperature-salinity sensor and a method for using the same, so as to achieve the technical effect of improving the sensor's measurement accuracy for temperature and salinity and the sensor's anti-interference ability, while reducing the sensor's operation and maintenance cost and complexity.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a multi-parameter measurement optical fiber temperature-salinity sensor, including a broadband light source, an optical fiber coupler and a spectrometer, as well as a circulator, a salinity interferometer and a temperature interferometer;

[0006] The broadband light source is communicatively connected to the first end of the circulator;

[0007] The second end of the circulator is connected to the salinity interferometer for bidirectional communication;

[0008] The third end of the circulator is communicatively connected to the first end of the optical fiber coupler;

[0009] The second end of the optical fiber coupler is communicatively connected to the first end of the temperature interferometer;

[0010] The second end of the temperature interferometer is communicatively connected to the third end of the optical fiber coupler;

[0011] The fourth end of the optical fiber coupler is communicatively connected to the spectrometer.

[0012] The optical fiber temperature-salinity sensor provided by the present invention comprises two interferometers, and a vernier effect can be generated by cascading the two interferometers, thereby amplifying the influence of temperature-salinity changes on the sensing signal, and thus improving the sensor's measurement accuracy for temperature and salinity. Since the two interferometers in the optical fiber temperature-salinity sensor provided by the present invention are respectively sensitive to different measurement parameters, the salinity interferometer has a sensitive response to both salinity changes and temperature changes, while the temperature interferometer has a sensitive response to temperature changes. The present invention cascades the above two interferometers through a circulator to produce a vernier effect, thereby amplifying temperature-salinity changes, and then accurately measuring temperature-salinity changes, thereby improving the measurement accuracy and measurement sensitivity of the optical fiber temperature-salinity sensor provided by the present invention. At the same time, since the two interferometers have different responses to temperature-salinity, by constructing a sensitivity coefficient matrix, the optical fiber temperature-salinity sensor provided by the present invention can realize the synchronous measurement of the dual parameters of temperature and salinity, thereby improving the measurement accuracy and measurement efficiency.

[0013] In addition, the optical fiber sensor provided by the present invention has better anti-electromagnetic interference capability than point sensors, so it has higher operating stability when working in complex environments. Moreover, compared with the electrical sensors in the prior art, the cost of optical fiber sensors is lower and the operation and maintenance cost is simpler, so the optical fiber temperature-salinity sensor provided by the present invention reduces the operation and maintenance cost and complexity of the sensor.

[0014] As a preferred example, the salinity interferometer is a Fabry-Perot interferometer.

[0015] The salinity interferometer used in the present invention is a Fabry-Perot interferometer, which is not only sensitive to salinity changes, but also sensitive to temperature changes, that is, the interferometer has high sensitivity to temperature-salinity changes.

[0016] As a preferred example, the salinity interferometer is composed of two sections of single-mode optical fiber and polyimide; wherein:

[0017] The end faces of the two sections of single-mode optical fibers are aligned and there is a gap between the two sections of single-mode optical fibers, and the polyimide is filled in the gap.

[0018] The salinity interferometer provided by the present invention is composed of two sections of single-mode optical fibers and polyimide filled between the two sections of single-mode optical fibers. Since the polyimide material is sensitive to salinity and its thermal expansion coefficient is much larger than that of the single-mode optical fiber, the sensitivity of the sensor when the temperature changes can be significantly improved by filling the gap between the single-mode optical fibers with polyimide, thereby providing more accurate data for environmental monitoring.

[0019] As a preferred example, the temperature interferometer is a Sagnac interferometer.

[0020] The temperature interferometer used in the present invention is a Sagnac interferometer, which has high sensitivity to temperature changes.

[0021] As a preferred example, the temperature interferometer is composed of polarization-maintaining optical fibers forming a Sagnac loop.

[0022] As a preferred example, the optical fiber coupler is a 2x2 single-mode optical fiber coupler.

[0023] The optical fiber coupler used in the present invention is a 2x2 single-mode optical fiber coupler, which can distribute and couple the optical signal output by the circulator in a certain ratio, such as a 50:50 ratio. Accordingly, an embodiment of the present invention also provides a method for using a multi-parameter optical fiber temperature-salinity sensor, which is applied to a multi-parameter optical fiber temperature-salinity sensor described in any of the above items, and the method includes the following steps:

[0024] Sending a first optical signal to a first end of a circulator through a broadband light source, wherein the first optical signal is transmitted to a salinity interferometer through a second end of the circulator, so that the salinity interferometer processes the first optical signal and feeds back a processed second optical signal to the circulator;

[0025] The circulator receives the second optical signal fed back by the salinity interferometer, and transmits the fed back second optical signal to the optical fiber coupler through the third end;

[0026] The optical fiber coupler transmits the second optical signal to the temperature interferometer, so that the temperature interferometer processes the second optical signal and feeds back the processed third optical signal to the optical fiber coupler;

[0027] The optical fiber coupler transmits the fed-back third optical signal to the spectrometer for spectral analysis.

[0028] As a preferred example, the optical fiber coupler transmits the feedback third optical signal to a spectrometer for spectrum analysis, including:

[0029] When the spectrometer is in salinity monitoring mode, the salinity interferometer is determined to be a sensing interferometer, the temperature interferometer is determined to be a reference interferometer, and the spectrometer obtains the salinity to be measured by measuring the wavelength change of the spectral envelope in the third optical signal;

[0030] When the spectrometer is in temperature monitoring mode, the salinity interferometer is determined to be the reference interferometer, the temperature interferometer is determined to be the sensing interferometer, and the spectrometer obtains the temperature to be measured according to the change in the wavelength of the spectral envelope in the third optical signal.

[0031] When the spectrometer is in different modes, it will adjust the positioning of the two interferometers accordingly. When the spectrometer is in salinity monitoring mode, the spectrometer determines the salinity interferometer as the main interferometer, i.e., the sensor interferometer, that is, the spectral data output by the interferometer is the main sensor data, and the corresponding temperature interferometer is the reference interferometer, and the spectral data output by the corresponding reference interferometer is the reference data, which means that the spectrometer will adjust the main sensor data according to the reference data.

[0032] As a preferred example, when the spectrometer is in salinity monitoring mode, the spectrometer determines the wavelength corresponding to the salinity interferometer in the third optical signal as the main wavelength, and the wavelength corresponding to the temperature interferometer as the reference wavelength, and after determination, performs spectral analysis on the spectral envelope wavelength in the third optical signal according to the determination result to obtain the salinity to be measured.

[0033] As a preferred example, when the spectrometer is in temperature monitoring mode, the spectrometer determines the wavelength corresponding to the temperature interferometer in the third optical signal as the main wavelength, and the wavelength corresponding to the salinity interferometer as the reference wavelength, and after determination, performs spectral analysis on the spectral envelope wavelength in the third optical signal according to the determination result to obtain the temperature to be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 : A structural diagram of an embodiment of a multi-parameter measurement optical fiber temperature-salinity sensor provided by the present invention;

[0035] Figure 2 : A flow chart of an embodiment of a method for using the multi-parameter measurement optical fiber temperature-salinity sensor provided by the present invention;

[0036] Among them, 1. broadband light source; 2. circulator; 3. single-mode optical fiber; 4. polyimide; 5. optical fiber coupler; 6. temperature interferometer; 7. spectrometer. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Embodiment 1

[0039] Please refer to Figure 1, which is a structural diagram of an embodiment of the multi-parameter measurement optical fiber temperature-salinity sensor provided by the present invention, including a broadband light source, an optical fiber coupler and a spectrometer, as well as a circulator, a salinity interferometer and a temperature interferometer;

[0040] The broadband light source is communicatively connected to the first end of the circulator;

[0041] The second end of the circulator is connected to the salinity interferometer for bidirectional communication;

[0042] The third end of the circulator is communicatively connected to the first end of the optical fiber coupler;

[0043] The second end of the optical fiber coupler is communicatively connected to the first end of the temperature interferometer;

[0044] The second end of the temperature interferometer is communicatively connected to the third end of the optical fiber coupler;

[0045] The fourth end of the optical fiber coupler is communicatively connected to the spectrometer.

[0046] The optical fiber temperature-salinity sensor provided by the embodiment of the present invention includes two interferometers, and a vernier effect can be generated by cascading the two interferometers, thereby amplifying the influence of temperature-salinity changes on the sensing signal, and thus improving the sensor's measurement accuracy for temperature and salinity. Since the two interferometers in the optical fiber temperature-salinity sensor provided by the present invention are sensitive to different measurement parameters, respectively, the salinity interferometer has a sensitive response to both salinity changes and temperature changes, while the temperature interferometer has a sensitive response to temperature changes. The present invention cascades the above two interferometers through a circulator to produce a vernier effect, thereby amplifying temperature-salinity changes, and then accurately measuring temperature-salinity changes, thereby improving the measurement accuracy and measurement sensitivity of the optical fiber temperature-salinity sensor provided by the present invention. At the same time, since the two interferometers have different responses to temperature-salinity, by constructing a sensitivity coefficient matrix, the synchronous measurement of the dual parameters of temperature and salinity can be achieved, thereby improving the measurement accuracy and measurement efficiency.

[0047] In addition, the optical fiber sensor provided by the present invention has better anti-electromagnetic interference capability than point sensors, so it has higher operating stability when working in complex environments. Moreover, compared with the electrical sensors in the prior art, the cost of optical fiber sensors is lower and the operation and maintenance cost is simpler, so the optical fiber temperature-salinity sensor provided by the present invention reduces the operation and maintenance cost and complexity of the sensor.

[0048] In this embodiment, see Figure 1 , Figure 1The ASE (Amplified Spontaneous Emission) light source is the broadband light source 1 described in this embodiment, 2 is a circulator 2, 3 is a single-mode optical fiber 3, 4 is polyimide 4, 5 is an optical fiber coupler 5, 6 is a temperature interferometer 6, and 7 is a spectrometer 7.

[0049] Among them, Figure 1 It can be seen that the three ports of the circulator 2 are respectively connected to the broadband light source 1, the single-mode optical fiber 3 and the optical fiber coupler 5 for transmitting the optical signal output by the broadband light source 1. While the optical fiber coupler 5 is connected to the circulator 2 for communication, it is also connected to the temperature interferometer 6 and the spectrometer 7 for communication.

[0050] Specifically, the salinity interferometer described in this embodiment is a Fabry-Perot interferometer.

[0051] The salinity interferometer used in the present invention is a Fabry-Perot interferometer, which is not only sensitive to salinity changes, but also sensitive to temperature changes, that is, the interferometer has high sensitivity to temperature-salinity changes.

[0052] Furthermore, the salinity interferometer described in this embodiment is composed of two sections of single-mode optical fiber and polyimide; wherein:

[0053] The end faces of the two sections of single-mode optical fibers are aligned and there is a gap between the two sections of single-mode optical fibers, and the polyimide is filled in the gap.

[0054] The salinity interferometer provided by the present invention is composed of two sections of single-mode optical fibers and polyimide filled between the two sections of single-mode optical fibers. Since the polyimide material is sensitive to salinity and its thermal expansion coefficient is much larger than that of the single-mode optical fiber, the sensitivity of the sensor when the temperature changes can be significantly improved by filling the gap between the single-mode optical fibers with polyimide, thereby providing more accurate data for environmental monitoring.

[0055] In this embodiment, the salinity interferometer is composed of two sections of single-mode optical fibers 3 whose end faces are aligned and polyimide 4 is filled in the gap formed by the two sections of single-mode optical fibers 3. Since a small gap is left between the end faces of the two sections of single-mode optical fibers 3 after the end faces are aligned and merged, the gap needs to be filled with polyimide 4. For the salinity interferometer provided in this embodiment, the user can adjust the cavity length of the salinity interferometer to ensure the measurement stability and measurement accuracy of the salinity interferometer during the sensing measurement process, and also further improve the measurement accuracy of the salinity interferometer.

[0056] Specifically, the temperature interferometer described in this embodiment is a Sagnac interferometer.

[0057] The temperature interferometer used in the present invention is a Sagnac interferometer, which has high sensitivity to temperature changes.

[0058] Furthermore, the temperature interferometer described in this embodiment is composed of polarization-maintaining optical fibers forming a Sagnac loop.

[0059] In this embodiment, the temperature interferometer 6 is composed of a Sagnac loop formed by a polarization-maintaining optical fiber. For the temperature interferometer 6 provided in this embodiment, the user can adjust the arm length of the temperature interferometer 6 to ensure the measurement stability and measurement accuracy of the temperature interferometer 6 during the measurement process, and at the same time, the measurement accuracy of the temperature-salinity sensor can be further improved.

[0060] With respect to the cavity length of the salinity interferometer and the arm length of the temperature interferometer 6 provided in this embodiment, it is preferred that the free spectral ranges of the two interferometers are close but not equal, so as to further improve the measurement accuracy of the temperature-salinity sensor of this embodiment.

[0061] In addition, the two interferometers provided in this embodiment are cascaded to produce a vernier effect, which can further improve the measurement accuracy and change sensitivity of the temperature and salinity sensor for temperature and salinity. Since the salinity interferometer provided in this embodiment, i.e., the Fabry-Perot interferometer, has high sensitivity to temperature changes and salinity changes, and the temperature interferometer 6, i.e., the Sagnac interferometer, has high sensitivity to temperature changes, the construction of the sensitivity measurement matrix is ​​realized by cascading the different characteristics of the above two interferometers, i.e., the temperature-salinity sensor provided in this embodiment, which can also be called a dual-parameter measurement interferometer, can realize simultaneous high-precision measurement of temperature and salinity.

[0062] Furthermore, the optical fiber coupler provided in this embodiment is a 2x2 single-mode optical fiber coupler.

[0063] The fiber coupler used in the embodiment of the present invention is a 2x2 single-mode fiber coupler, which can distribute and couple the optical signal output by the circulator in a certain ratio, such as a 50:50 ratio. In summary, the core working mechanism of the temperature-salinity sensor provided in this embodiment lies in its unique spectral envelope characteristic, which is formed by the precise product of the spectra independently generated by the two interferometers. The optical signal output by the width light source 1 passes through the dual filtering effect of the two interferometers, and the spectrum diagram of the sensor can show clear periodic interference fringes, and these fringes can be further combined into a periodic spectral envelope, thereby significantly improving the measurement sensitivity of the sensor.

[0064] Accordingly, see Figure 2 , Figure 2 A flow chart of an embodiment of a method for using a multi-parameter optical fiber temperature-salinity sensor provided by the present invention. Figure 2 As shown, the method of use comprises the following steps:

[0065] Sending a first optical signal to a first end of a circulator through a broadband light source, wherein the first optical signal is transmitted to a salinity interferometer through a second end of the circulator, so that the salinity interferometer processes the first optical signal and feeds back a processed second optical signal to the circulator;

[0066] The circulator receives the second optical signal fed back by the salinity interferometer, and transmits the fed back second optical signal to the optical fiber coupler through the third end;

[0067] The optical fiber coupler transmits the second optical signal to the temperature interferometer, so that the temperature interferometer processes the second optical signal and feeds back the processed third optical signal to the optical fiber coupler;

[0068] The optical fiber coupler transmits the fed-back third optical signal to the spectrometer for spectral analysis.

[0069] In this embodiment, the working principle of the temperature-salinity sensor specifically includes: the optical signal emitted by the broadband light source 1 first enters the first end of the circulator 2, and then the light output from the port at the second end of the circulator enters the salinity interferometer, the salinity interferometer processes the received optical signal and reflects the processed optical signal back to the second end of the circulator 2, and the reflected optical signal will enter the circulator 2 again and be output from the third end of the circulator 2 to the optical fiber coupler 5.

[0070] In the fiber coupler 5, the optical signal is first split into two beams of light with the same intensity, and the two split beams of light will propagate in two opposite directions. When the two beams of light with the same intensity pass through the temperature interferometer 6, Figure 1 When the two light beams pass through the optical fiber coupler 5 again, the optical fiber coupler 5 couples the two light beams to achieve interference, and outputs the optical signal after coupling interference to the spectrometer 7 for spectral analysis. Specifically, the optical fiber coupler in this embodiment transmits the feedback third optical signal to the spectrometer for spectral analysis, including:

[0071] When the spectrometer is in salinity monitoring mode, the salinity interferometer is determined to be a sensing interferometer, the temperature interferometer is a reference interferometer, and the spectrometer obtains the salinity to be measured according to the change in the wavelength of the spectral envelope in the third optical signal;

[0072] When the spectrometer is in temperature monitoring mode, the salinity interferometer is determined to be the reference interferometer, the temperature interferometer is determined to be the sensing interferometer, and the spectrometer obtains the temperature to be measured according to the change in the wavelength of the spectral envelope in the third optical signal.

[0073] When the spectrometer is in different modes, it will adjust the positioning of the two interferometers accordingly. When the spectrometer is in salinity monitoring mode, the spectrometer determines the salinity interferometer as the main interferometer, i.e., the sensor interferometer, that is, the spectral data output by the interferometer is the main sensor data, and the corresponding temperature interferometer is the reference interferometer, and the spectral data output by the corresponding reference interferometer is the reference data, which means that the spectrometer will adjust the main sensor data according to the reference data.

[0074] Furthermore, when the spectrometer described in this embodiment is in salinity monitoring mode, the spectrometer determines the wavelength corresponding to the salinity interferometer in the third optical signal as the main wavelength, and the wavelength corresponding to the temperature interferometer as the reference wavelength, and after determination, performs spectral analysis on the third optical signal according to the determination result.

[0075] Furthermore, when the spectrometer described in this embodiment is in temperature monitoring mode, the spectrometer determines the wavelength corresponding to the temperature interferometer in the third optical signal as the main wavelength, and the wavelength corresponding to the salinity interferometer as the reference wavelength, and after determination, performs spectral analysis on the third optical signal according to the determination result.

[0076] In this embodiment, when the spectrometer 7 is in the temperature monitoring mode, the temperature-salinity sensor of this embodiment determines the temperature interferometer 6 as a sensing interferometer, which is responsible for sensitively responding to changes in the external environment, and the salinity interferometer acts as a reference interferometer to provide a stable reference signal. As the ambient temperature fluctuates, the polarization-maintaining optical fiber of the temperature interferometer 6 will change in length and the difference in refractive index between the fast axis and the slow axis under the combined effects of its thermal expansion effect and thermo-optic effect. This change will cause the wavelength of the temperature interferometer 6 to drift, and this change will also be directly reflected in the spectral envelope of the sensor, thereby achieving high-precision temperature measurement.

[0077] Correspondingly, when the spectrometer 7 is in the salinity monitoring mode, the temperature interferometer 6 of this embodiment will become a reference interferometer that provides a stable reference signal, and the corresponding salinity interferometer will be transformed into a sensing interferometer. When the concentration of the salt solution in which the salinity interferometer is located increases, the polyimide material contained therein will shrink in volume due to the release of water molecules, resulting in a decrease in the cavity length of the salinity interferometer, and at the same time, the refractive index of the polyimide in the interferometer will also change. The above-mentioned effects work together to cause the wavelength of the salinity interferometer to drift, thereby changing the spectral envelope of the sensor and achieving high-precision measurement of salinity.

[0078] In summary, the embodiment of the present invention provides a multi-parameter measurement optical fiber temperature-salinity sensor and a method of using the same, including a broadband light source, an optical fiber coupler and a spectrometer, as well as a circulator, a salinity interferometer and a temperature interferometer; the broadband light source is communicatively connected to the first end of the circulator; the second end of the circulator is bidirectionally communicatively connected to the salinity interferometer; the third end of the circulator is communicatively connected to the first end of the optical fiber coupler; the second end of the optical fiber coupler is communicatively connected to the first end of the temperature interferometer; the second end of the temperature interferometer is communicatively connected to the third end of the optical fiber coupler; the fourth end of the optical fiber coupler is communicatively connected to the spectrometer. The present invention cascades two interferometers through a circulator to produce a vernier effect, realizes accurate measurement of temperature-salinity changes and synchronous measurement of dual parameters of temperature and salinity, and improves the measurement accuracy and measurement sensitivity of the optical fiber temperature-salinity sensor; the optical fiber sensor has a high ability to resist electromagnetic interference and improves the operation stability in complex environments.

[0079] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-parameter optical fiber temperature-salinity sensor, comprising a broadband light source, an optical fiber coupler and a spectrometer, characterized in that: The optical fiber temperature-salinity sensor also includes a circulator, a salinity interferometer and a temperature interferometer; The broadband light source is communicatively connected to the first end of the circulator; The second end of the circulator is connected to the salinity interferometer for bidirectional communication; The third end of the circulator is communicatively connected to the first end of the optical fiber coupler; The second end of the optical fiber coupler is communicatively connected to the first end of the temperature interferometer; The second end of the temperature interferometer is communicatively connected to the third end of the optical fiber coupler; The fourth end of the optical fiber coupler is communicatively connected to the spectrometer.

2. The optical fiber temperature-salinity sensor for multi-parameter measurement according to claim 1, characterized in that: The salinity interferometer is a Fabry-Perot interferometer.

3. The optical fiber temperature-salinity sensor for multi-parameter measurement according to claim 2, characterized in that: The salinity interferometer is composed of two sections of single-mode optical fiber and polyimide; wherein: The end faces of the two sections of single-mode optical fibers are aligned and there is a gap between the two sections of single-mode optical fibers, and the polyimide is filled in the gap.

4. The optical fiber temperature-salinity sensor for multi-parameter measurement according to claim 1, characterized in that: The temperature interferometer is a Sagnac interferometer.

5. The optical fiber temperature-salinity sensor for multi-parameter measurement according to claim 4, characterized in that: The temperature interferometer is composed of polarization-maintaining optical fibers forming a Sagnac loop.

6. The optical fiber temperature-salinity sensor for multi-parameter measurement according to claim 1, characterized in that: The optical fiber coupler is a 2x2 single-mode optical fiber coupler.

7. A method for using a multi-parameter optical fiber temperature-salinity sensor, characterized in that: An optical fiber temperature-salinity sensor for multi-parameter measurement according to any one of claims 1 to 6, wherein the method of use comprises the following steps: Sending a first optical signal to a first end of a circulator through a broadband light source, wherein the first optical signal is transmitted to a salinity interferometer through a second end of the circulator, so that the salinity interferometer processes the first optical signal and feeds back a processed second optical signal to the circulator; The circulator receives the second optical signal fed back by the salinity interferometer, and transmits the fed back second optical signal to the optical fiber coupler through the third end; The optical fiber coupler transmits the second optical signal to the temperature interferometer, so that the temperature interferometer processes the second optical signal and feeds back the processed third optical signal to the optical fiber coupler; The optical fiber coupler transmits the fed-back third optical signal to the spectrometer for spectral analysis.

8. The method for using the optical fiber temperature-salinity sensor for multi-parameter measurement according to claim 7, characterized in that: The optical fiber coupler transmits the feedback third optical signal to the spectrometer for spectrum analysis, including: When the spectrometer is in salinity monitoring mode, the salinity interferometer is determined to be a sensing interferometer, the temperature interferometer is determined to be a reference interferometer, and the spectrometer obtains the salinity to be measured by measuring the wavelength change of the spectral envelope in the third optical signal; When the spectrometer is in temperature monitoring mode, the salinity interferometer is determined to be the reference interferometer, the temperature interferometer is determined to be the sensing interferometer, and the spectrometer obtains the temperature to be measured by the wavelength change of the spectral envelope in the third optical signal.

9. The method for using the optical fiber temperature-salinity sensor for multi-parameter measurement according to claim 8, characterized in that: When the spectrometer is in salinity monitoring mode, the spectrometer determines the wavelength corresponding to the salinity interferometer in the third optical signal as the main wavelength, and the wavelength corresponding to the temperature interferometer as the reference wavelength, and after determination, performs spectral analysis on the spectral envelope wavelength in the third optical signal according to the determination result to obtain the salinity to be measured.

10. The method for using the optical fiber temperature-salinity sensor for multi-parameter measurement according to claim 8, characterized in that: When the spectrometer is in temperature monitoring mode, the spectrometer determines the wavelength corresponding to the temperature interferometer in the third optical signal as the main wavelength, and the wavelength corresponding to the salinity interferometer as the reference wavelength, and after determination, performs spectral analysis on the spectral envelope wavelength in the third optical signal according to the determination result to obtain the temperature to be measured.

Images