Method and apparatus for determining refractive index and temperature, and storage medium

Abstract

The application provides a refractive index and temperature determination method and device and a storage medium, relates to the field of optical fiber sensing technology, and can solve the problems of low measurement accuracy and slow measurement speed of the refractive index. The method comprises the following steps: determining a first oscillation frequency corresponding to a first target optical signal and a first optical fiber and a second oscillation frequency corresponding to the first target optical signal and a second optical fiber; determining a third oscillation frequency corresponding to the first target optical signal and the first optical fiber and a fourth oscillation frequency corresponding to the second target optical signal and the second optical fiber; determining a first frequency shift based on the difference between the first oscillation frequency and the third oscillation frequency; determining a second frequency shift based on the difference between the second oscillation frequency and the fourth oscillation frequency; and determining the refractive index and temperature of an environment in which the second target optical signal is located based on the first frequency shift, the second frequency shift, the refractive index of the environment in which the first target optical signal is located, and the temperature. The application can quickly and accurately measure the refractive index and temperature, and avoid the cross influence of the temperature and the refractive index.

Description

Technical Field

[0001] This application relates to the field of fiber optic sensing technology, and in particular to a method, apparatus and storage medium for determining refractive index and temperature. Background Technology

[0002] Refractive index is one of the most important physical quantities in the fields of communication and sensing technology, and it can be used to sense changes in the surrounding environment. Currently, refractive index measurement mainly includes optical domain measurement methods based on microstructured optical fibers and dual parameters of refractive index and temperature, and refractive index measurement methods based on photoelectric oscillators and phase-shifting gratings.

[0003] The optical domain measurement method based on the dual parameters of refractive index and temperature in microstructured optical fibers considers the influence of temperature on refractive index sensing. It determines the refractive index and temperature values ​​by measuring the wavelength of the optical signal using a spectrometer. However, this spectrometer-based method suffers from low accuracy, slow measurement speed, and low efficiency. To address these issues, a refractive index measurement method based on an optoelectronic oscillator and a phase-shifting grating is proposed. This method offers high measurement speed and accuracy, but it does not consider the cross-influence of temperature on refractive index sensing, resulting in lower accuracy. Summary of the Invention

[0004] This application provides a method, apparatus, and storage medium for determining refractive index and temperature, which solves the problems of low accuracy and slow measurement speed of refractive index measurement due to the cross-influence of temperature in current refractive index measurement methods. It can quickly and accurately measure refractive index and temperature, and avoid the cross-influence of temperature and refractive index.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] In a first aspect, this application provides a method for determining refractive index and temperature. The method includes: determining a first oscillation frequency of a first target optical signal after it passes through a first optical fiber and a second oscillation frequency after it passes through a second optical fiber; the wavelength of the light beam passing through the first optical fiber is linearly related to the refractive index and temperature; the wavelength of the light beam passing through the second optical fiber is linearly related to the refractive index; determining a third oscillation frequency of the second target optical signal after it passes through the first optical fiber and a fourth oscillation frequency after it passes through the second optical fiber; determining a first frequency shift based on the difference between the first and third oscillation frequencies; determining a second frequency shift based on the difference between the second and fourth oscillation frequencies; and determining the refractive index and temperature of the environment where the second target optical signal is located based on the first frequency shift, the second frequency shift, and the refractive index and temperature of the environment where the first target optical signal is located.

[0007] In conjunction with the first aspect described above, in one possible implementation, the method further includes: sequentially passing a first target optical signal through a photodetector, converting the first target optical signal into a first microwave signal and a second microwave signal; the first microwave signal includes a first oscillation frequency; the second microwave signal includes a second oscillation frequency; passing the first microwave signal through a microwave coupler, separating the first microwave signal into a third microwave signal and a fourth microwave signal; the frequencies of the third microwave signal and the fourth microwave signal are both the first oscillation frequency; the power of the third microwave signal is greater than the power of the fourth microwave signal; passing the second microwave signal through a microwave coupler, separating the second microwave signal into a fifth microwave signal and a sixth microwave signal; the frequencies of the fifth microwave signal and the sixth microwave signal are both the second oscillation frequency; the power of the fifth microwave signal is greater than the power of the sixth microwave signal.

[0008] In conjunction with the first aspect above, in one possible implementation, the method further includes: coupling a first optical signal with a second optical signal to obtain a coupled optical signal; the coupled optical signal includes the frequency of the first optical signal and the frequency of the second optical signal; a third microwave signal and a fifth microwave signal are respectively modulated with the coupled optical signal through a phase modulator to obtain a first target optical signal; wherein the first target optical signal includes the frequency of the first optical signal, a first double-sideband frequency, a second optical signal frequency, and a second double-sideband frequency.

[0009] In conjunction with the first aspect above, in one possible implementation, the method further includes: passing the first target optical signal through the first optical fiber to obtain a first optical fiber signal; the first optical fiber signal mainly includes a first optical signal frequency, a first single-sideband frequency, a second optical signal frequency, and a second double-sideband frequency; and determining a first oscillation frequency based on the first optical signal frequency and the first single-sideband frequency.

[0010] In conjunction with the first aspect above, in one possible implementation, the method further includes: passing the first optical fiber signal through a second optical fiber to obtain a second optical fiber signal; the second optical fiber signal includes the first optical signal frequency, a first single-sideband frequency, a second optical signal frequency, and a second single-sideband frequency; and determining a second oscillation frequency based on the second optical signal frequency and the second single-sideband frequency.

[0011] In conjunction with the first aspect described above, in one possible implementation, the method further includes: determining the temperature sensitivity coefficient and refractive index sensitivity coefficient of the first optical fiber; determining the temperature sensitivity coefficient and refractive index sensitivity coefficient of the second optical fiber; determining the refractive index change and temperature change of the environment where the second target optical signal is located relative to the environment where the first target optical signal is located based on the temperature sensitivity coefficient of the first optical fiber, the refractive index sensitivity coefficient of the first optical fiber, the temperature sensitivity coefficient of the second optical fiber, the refractive index sensitivity coefficient of the second optical fiber, the first frequency shift, and the second frequency shift; and determining the refractive index and temperature of the environment where the second target optical signal is located based on the refractive index change and temperature change, as well as the refractive index and temperature of the environment where the first target optical signal is located.

[0012] In conjunction with the first aspect mentioned above, in one possible implementation, the method further includes: the refractive index change ΔR and the temperature change ΔT satisfying the following formula:

[0013]

[0014] Where ΔF1 is the first frequency shift, ΔF2 is the second frequency shift, c is the speed of light, N1 is the effective refractive index of the first optical fiber, N2 is the effective refractive index of the second optical fiber, and λ s1 Let λ be the wavelength of the first target optical signal. s2 λ is the wavelength of the second target optical signal. N1 λ is the wavelength of the transmission point of the reflection spectrum of the first optical fiber. N2 K represents the wavelength of the transmission point of the reflection spectrum of the second optical fiber. 1R K represents the refractive index sensitivity coefficient of the first optical fiber, which is related to parameters such as grating wavelength, external refractive index, and the structural dimensions of the first optical fiber; 2R K represents the refractive index sensitivity coefficient of the second optical fiber, which is related to parameters such as grating wavelength, external refractive index, and the structural dimensions of the second optical fiber; 1T K represents the temperature sensitivity coefficient of the first optical fiber, which is related to parameters such as the expansion coefficient of the first optical fiber; 2T The temperature sensitivity coefficient of the second optical fiber is related to parameters such as the expansion coefficient of the second optical fiber.

[0015] In conjunction with the first aspect described above, in one possible implementation, the method further includes: determining a first oscillation frequency by monitoring a fourth microwave signal using a spectrum analyzer; and determining a second oscillation frequency by monitoring a sixth microwave signal using a spectrum analyzer.

[0016] Secondly, this application provides a device for determining refractive index and temperature. The device includes: a light source system, a phase modulator, a first optical fiber, a second optical fiber, a photodetector, a microwave coupler, and a spectrum analyzer. The wavelength of the light beam passing through the first optical fiber is linearly related to the refractive index and temperature. The wavelength of the light beam passing through the second optical fiber is linearly related to the refractive index. The light source system is optically connected to the phase modulator. The phase modulator is optically connected to the first optical fiber. The first and second optical fibers are cascaded. An optical circulator is optically connected to the photodetector. The photodetector is optically connected to the microwave coupler. The microwave coupler is electrically connected to the phase modulator. The microwave coupler is optically connected to the spectrum analyzer. The first optical fiber is configured to: receive a first target optical signal; transmit the first target optical signal to the second optical fiber. The second optical fiber is configured to: receive the first target optical signal; transmit the first target optical signal to the first optical fiber. The first target optical signal; the first optical fiber, configured to: receive the first target optical signal from the second optical fiber and transmit the first target optical signal to a photodetector; the photodetector, configured to: receive the first target optical signal; convert the first target optical signal into a first microwave signal and a second microwave signal; transmit the first microwave signal and the second microwave signal to a microwave coupler; the microwave coupler, configured to: separate the first microwave signal into a third microwave signal and a fourth microwave signal; separate the second microwave signal into a fifth microwave signal and a sixth microwave signal; transmit the third microwave signal and the fifth microwave signal to a phase modulator; transmit the fourth microwave signal and the sixth microwave signal to a spectrum analyzer; the spectrum analyzer, configured to: receive the fourth microwave signal and the sixth microwave signal; monitor the fourth microwave signal to determine a first oscillation frequency; monitor the sixth microwave signal to determine a second oscillation frequency.

[0017] In conjunction with the second aspect above, in one possible implementation, the light source device includes a first laser, a second laser, and an optical coupler; the first laser is communicatively connected to the optical coupler; the second laser is communicatively connected to the optical coupler; the optical coupler is communicatively connected to a phase modulator; the first laser is configured to send a first optical signal to the optical coupler; the second laser is configured to send a second optical signal to the optical coupler; the optical coupler is configured to receive the first optical signal and the second optical signal; and couple the first optical signal and the second optical signal to obtain a coupled optical signal.

[0018] In conjunction with the second aspect above, in one possible implementation, the light source device further includes a first polarization controller and a second polarization controller; a first end of the first polarization controller is connected to the first laser; and a first end of the second polarization controller is connected to the second laser.

[0019] In conjunction with the second aspect above, in one possible implementation, the device for determining the refractive index and temperature further includes an optical circulator, an erbium-doped fiber amplifier, and a microwave amplifier; the optical circulator is communicatively connected to a phase modulator; the optical circulator is communicatively connected to a first optical fiber; the optical circulator is communicatively connected to the erbium-doped fiber amplifier; the erbium-doped fiber amplifier is communicatively connected to a photodetector; the microwave amplifier is communicatively connected to the photodetector; the microwave amplifier is communicatively connected to a microwave coupler; the optical circulator is configured to: receive a first target optical signal from the phase modulator; transmit the first target optical signal to the first optical fiber; receive the first target optical signal from the first optical fiber; transmit the first target optical signal to the erbium-doped fiber amplifier; the erbium-doped fiber amplifier is configured to: receive the first target optical signal; amplify the signal power of the first target optical signal; transmit the first target optical signal to the photodetector; the microwave amplifier is configured to: receive a first microwave signal and a second microwave signal from the microwave amplifier; amplify the signal power of the first microwave signal and the second microwave signal; transmit the first microwave signal and the second microwave signal to the microwave coupler.

[0020] Thirdly, this application provides an apparatus for determining refractive index and temperature, the apparatus comprising: a communication unit and a processing unit; the communication unit being configured to determine a first oscillation frequency of a first target optical signal after it sequentially passes through a first optical fiber and a second oscillation frequency after it passes through a second optical fiber; the processing unit being configured to determine a third oscillation frequency of a second target optical signal after it sequentially passes through the first optical fiber and a fourth oscillation frequency after it passes through the second optical fiber; the processing unit being further configured to determine a first frequency shift based on the difference between the first and third oscillation frequencies; the processing unit being further configured to determine a second frequency shift based on the difference between the second and fourth oscillation frequencies; and the processing unit being further configured to determine the refractive index and temperature of the environment in which the second target optical signal is located based on the first frequency shift, the second frequency shift, and the refractive index and temperature of the environment in which the first target optical signal is located.

[0021] In conjunction with the third aspect described above, in one possible implementation, the processing unit is further configured to: determine the temperature sensitivity coefficient and refractive index sensitivity coefficient of the first optical fiber; determine the temperature sensitivity coefficient and refractive index sensitivity coefficient of the second optical fiber; based on the temperature sensitivity coefficient of the first optical fiber, the refractive index sensitivity coefficient of the first optical fiber, the temperature sensitivity coefficient of the second optical fiber, the refractive index sensitivity coefficient of the second optical fiber, the first frequency shift, and the second frequency shift, determine the refractive index and temperature of the environment where the second target optical signal is located relative to the environment where the first target optical signal is located; and based on the refractive index and temperature changes, as well as the refractive index and temperature of the environment where the first target optical signal is located, determine the refractive index and temperature of the environment where the second target optical signal is located.

[0022] In conjunction with the third aspect above, in one possible implementation, the processing unit is specifically configured to satisfy the following formula for the refractive index change ΔR and the temperature change ΔT:

[0023]

[0024] Where ΔF1 is the first frequency shift, ΔF2 is the second frequency shift, c is the speed of light, N1 is the effective refractive index of the first optical fiber, N2 is the effective refractive index of the second optical fiber, and λ s1 Let λ be the wavelength of the first target optical signal. s2 λ is the wavelength of the second target optical signal. N1 λ is the wavelength of the transmission point of the reflection spectrum of the first optical fiber. N2 K represents the wavelength of the transmission point of the reflection spectrum of the second optical fiber. 1R K represents the refractive index sensitivity coefficient of the first optical fiber, which is related to parameters such as grating wavelength, external refractive index, and the structural dimensions of the first optical fiber; 2R K represents the refractive index sensitivity coefficient of the second optical fiber, which is related to parameters such as grating wavelength, external refractive index, and the structural dimensions of the second optical fiber; 1T K represents the temperature sensitivity coefficient of the first optical fiber, which is related to parameters such as the expansion coefficient of the first optical fiber; 2T The temperature sensitivity coefficient of the second optical fiber is related to parameters such as the expansion coefficient of the second optical fiber.

[0025] Fourthly, this application provides an apparatus for determining refractive index and temperature, the apparatus comprising: a processor and a communication interface; the communication interface and the processor are coupled, the processor being configured to run computer programs or instructions to implement the method for determining refractive index and temperature as described in the first aspect and any possible implementation thereof.

[0026] Fifthly, this application provides a computer-readable storage medium storing instructions that, when executed on a terminal, cause the terminal to perform a method for determining the refractive index and temperature as described in the first aspect and any possible implementation thereof.

[0027] In a sixth aspect, this application provides a computer program product containing instructions that, when the computer program product is run on a device for determining refractive index and temperature, cause the device for determining refractive index and temperature to perform the method for determining refractive index and temperature as described in the first aspect and any possible implementation thereof.

[0028] In a seventh aspect, this application provides a chip including a processor and a communication interface, the communication interface being coupled to the processor, the processor being used to run computer programs or instructions to implement the method for determining refractive index and temperature as described in the first aspect and any possible implementation thereof.

[0029] Specifically, the chip provided in this application also includes a memory for storing computer programs or instructions.

[0030] It should be noted that the aforementioned computer instructions may be stored, in whole or in part, on a computer-readable storage medium. This computer-readable storage medium may be packaged together with the processor of the device, or it may be packaged separately from the processor of the device; this application does not impose any limitation on this.

[0031] Eighthly, this application provides a system for determining refractive index and temperature, comprising: a photoelectric oscillator based on refractive index and temperature sensing and a device for determining refractive index and temperature, wherein the device for determining refractive index and temperature is used to perform the method for determining refractive index and temperature as described in the first aspect and any possible implementation thereof.

[0032] The descriptions of aspects two through eight in this application can be referenced to the detailed description of aspect one; and the beneficial effects of the descriptions of aspects two through eight can be referenced to the analysis of the beneficial effects of aspect one, which will not be repeated here.

[0033] In this application, the names of the aforementioned devices for determining refractive index and temperature do not limit the devices or functional modules themselves. In actual implementation, these devices or functional modules may appear under other names. As long as the functions of each device or functional module are similar to those in this application, they fall within the scope of the claims of this application and their equivalents.

[0034] These or other aspects of this application will become more readily apparent in the following description.

[0035] The above solution offers at least the following advantages: Based on the above technical solution, the method for determining refractive index and temperature provided in this application firstly determines the first oscillation frequency of the first target optical signal after it passes through the first optical fiber and the second oscillation frequency after it passes through the second optical fiber, and then determines the third oscillation frequency of the second target optical signal after it passes through the first optical fiber and the fourth oscillation frequency after it passes through the second optical fiber. Since the wavelength of the light beam passing through the first optical fiber is linearly related to the refractive index and temperature, and the wavelength of the light beam passing through the second optical fiber is also linearly related to the refractive index, the device for determining refractive index and temperature can obtain the frequency of the optical signal at different temperatures and refractive indices. Then, the device determines the first frequency shift based on the difference between the first and third oscillation frequencies; and the second frequency shift based on the difference between the second and fourth oscillation frequencies. Compared to current refractive index measurement methods, which suffer from low accuracy due to temperature cross-influence, and methods that measure the wavelength of the optical signal using a spectrometer to determine the refractive index and temperature, this method offers advantages over other methods. The device for determining refractive index and temperature in this technical solution determines the refractive index and temperature of the environment where the first target optical signal is located based on the first frequency shift, the second frequency shift, and the environment where the first target optical signal is located. It can quickly and accurately measure the refractive index and temperature of the environment where the second target optical signal is located through frequency changes, which greatly improves the measurement efficiency and accuracy of refractive index and temperature. Attached Figure Description

[0036] Figure 1 A schematic diagram of a device for determining refractive index and temperature provided in an embodiment of this application;

[0037] Figure 2 A schematic diagram of another device for determining refractive index and temperature provided in an embodiment of this application;

[0038] Figure 3 A schematic diagram illustrating a frequency variation provided in an embodiment of this application;

[0039] Figure 4 A schematic diagram of the hardware structure of a device for determining refractive index and temperature provided in an embodiment of this application;

[0040] Figure 5 A flowchart illustrating a method for determining refractive index and temperature provided in an embodiment of this application;

[0041] Figure 6 A flowchart illustrating another method for determining refractive index and temperature provided in an embodiment of this application;

[0042] Figure 7a A flowchart illustrating another method for determining refractive index and temperature provided in an embodiment of this application;

[0043] Figure 7b A flowchart illustrating another method for determining refractive index and temperature provided in an embodiment of this application;

[0044] Figure 8 This is a schematic diagram of another device for determining refractive index and temperature provided in an embodiment of this application. Detailed Implementation

[0045] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0046] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0047] The terms "first" and "second," etc., used in the specification and drawings of this application are used to distinguish different objects or to distinguish different treatments of the same object, rather than to describe a specific order of objects.

[0048] Furthermore, the terms "comprising" and "having," and any variations thereof, used in the description of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include other steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0049] It should be noted that in the embodiments of this application, the words "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of the words "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0050] In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0051] Refractive index is used to determine the speed at which light travels through a material. It is one of the most important physical quantities in the field of communication technology and plays a vital role in industrial production and marine exploration.

[0052] Optical fiber is lightweight, low-loss, and inexpensive, making it an excellent sensing medium. There are many methods for measuring the refractive index of optical fibers. For example, Mach-Zehnder interference spectra can be formed by interfering different optical paths; different refractive indices have different optical path differences, and the refractive index information can be obtained by marking the wavelength of the interference spectrum. Changes in the wavelength of a long-period Bragg grating can determine the refractive index changes in the surrounding environment, or a Fabry-Perot cavity can be formed using a fiber optic grating to determine the refractive index.

[0053] In grating or interferometer-based refractive index measurement schemes, temperature and refractive index often have a mutual influence, affecting the accuracy of the measurement results. For example, in proposed refractive index measurement methods based on photoelectric oscillators and phase-shifting gratings, the effect of temperature on refractive index sensing is not considered, resulting in low accuracy.

[0054] To address the above issues, a dual-parameter measurement method for refractive index and temperature is proposed. This method considers the influence of temperature on refractive index sensing and determines the values ​​of refractive index and temperature by measuring the wavelength of the light signal using a spectrometer. However, the spectrometer measurement method suffers from low accuracy, slow measurement speed, and low efficiency.

[0055] In the proposed refractive index measurement scheme based on photoelectric oscillators and phase-shifting gratings, phase-shifting optical fibers require etching, which is technically challenging. Furthermore, the physical and mechanical strength of the optical fibers is poor, and temperature can affect the refractive index sensing.

[0056] In view of this, the method for determining refractive index and temperature provided in this application firstly determines the first oscillation frequency of the first target optical signal after it passes through the first optical fiber and the second oscillation frequency after it passes through the second optical fiber, and then determines the third oscillation frequency of the second target optical signal after it passes through the first optical fiber and the fourth oscillation frequency after it passes through the second optical fiber. Since the wavelength of the light beam passing through the first optical fiber is linearly related to the refractive index and temperature, and the wavelength of the light beam passing through the second optical fiber is also linearly related to the refractive index, the method for determining refractive index and temperature can obtain the frequency of the optical signal at different temperatures and refractive indices. Then, the method for determining refractive index and temperature determines the first frequency shift based on the difference between the first and third oscillation frequencies; and the second frequency shift based on the difference between the second and fourth oscillation frequencies. Compared with current refractive index measurement methods, which suffer from low accuracy due to temperature cross-influence, and methods that measure the wavelength of the optical signal using a spectrometer to determine the refractive index and temperature, this method addresses the problems of low accuracy, slow measurement speed, and low efficiency associated with these methods. The device for determining refractive index and temperature in this technical solution determines the refractive index and temperature of the environment where the first target optical signal is located based on the first frequency shift, the second frequency shift, and the environment where the first target optical signal is located. It can quickly and accurately measure the refractive index and temperature of the environment where the second target optical signal is located through frequency changes, which greatly improves the measurement efficiency and accuracy of refractive index and temperature.

[0057] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0058] Figure 1 This is a schematic diagram of a device 10 for determining refractive index and temperature, provided in an embodiment of this application. Figure 1 As shown, the device 10 for determining refractive index and temperature includes: a light source device 101, a phase modulator 102, a first optical fiber 103, a second optical fiber 104, a photodetector 105, a microwave coupler 106, and a spectrum analyzer 107.

[0059] The light source device 101 is communicatively connected to the phase modulator 102; the phase modulator 102 is communicatively connected to the first optical fiber 103; the first optical fiber 103 is cascaded with the second optical fiber 104; the first optical fiber 103 is communicatively connected to the photodetector 105; the photodetector 105 is communicatively connected to the microwave coupler 106; the microwave coupler 106 is communicatively connected to the phase modulator 102; and the microwave coupler 106 is communicatively connected to the spectrum analyzer 107.

[0060] It should be noted that the light source device 101, phase modulator 102, first optical fiber 103, second optical fiber 104, photodetector 105, microwave coupler 106, and spectrum analyzer 107 are connected via a communication link. This communication link can be a wired communication link or a wireless communication link, and this application does not limit it in this regard.

[0061] It is understandable that the wavelength difference between the first-order sideband and the carrier wave of the beam passing through the first optical fiber 103 is linearly related to the refractive index and temperature; the wavelength difference between the first-order sideband and the carrier wave of the beam passing through the second optical fiber 104 is linearly related to the refractive index.

[0062] The light source device 101 is configured to send a coupled optical signal to the phase modulator 102.

[0063] The phase modulator 102 is configured to: modulate the third microwave signal and the fifth microwave signal with the coupled optical signal respectively to obtain the first target optical signal; and send the first target optical signal to the first optical fiber 103.

[0064] The first target optical signal includes a first optical signal frequency, a first double-sideband frequency, a second optical signal frequency, and a second double-sideband frequency.

[0065] The first optical fiber 103 is configured to: receive a first target optical signal; filter out any single sideband frequency in the first double sideband frequency; and transmit the first target optical signal to the second optical fiber 104.

[0066] The second optical fiber 104 is configured to: receive the first target optical signal; filter out any single-sideband frequency in the second double-sideband frequency; and transmit the first target optical signal to the first optical fiber 103.

[0067] The first optical fiber 103 is configured to: receive a first target optical signal from the second optical fiber 104; and send the first target optical signal to the photodetector.

[0068] The photodetector 105 is configured to receive a first target optical signal and convert the first target optical signal into a first microwave signal and a second microwave signal.

[0069] Microwave coupler 106 is configured to: separate a first microwave signal into a third microwave signal and a fourth microwave signal, and separate a second microwave signal into a fifth microwave signal and a sixth microwave signal; transmit the third and fifth microwave signals to phase modulator 102; and transmit the fourth and sixth microwave signals to spectrum analyzer 107.

[0070] The spectrum analyzer 107 is configured to monitor the fourth microwave signal and the sixth microwave signal to determine the first oscillation frequency and the second oscillation frequency.

[0071] Figure 2 This is another schematic diagram of a refractive index and temperature determination device 10 provided in an embodiment of this application. The light source device 101 includes a first laser 1011, a second laser 1012, a first polarization controller 1013, a second polarization controller 1014, and an optical coupler 1015.

[0072] The first laser 1011 is communicatively connected to the optical coupler 1015, the second laser 1012 is communicatively connected to the optical coupler 1015, the first end of the first polarization controller 1013 is connected to the first laser 1011, the first end of the second polarization controller 1014 is connected to the second laser 1012, and the optical coupler 1015 is communicatively connected to the phase modulator 102.

[0073] The first laser 1011 is configured to send a first optical signal to the optical coupler 1015.

[0074] The second laser 1012 is configured to send a second optical signal to the optical coupler 1015.

[0075] The first polarization controller 1013 is configured to control the polarization direction of the first optical signal to be the same as the main axis direction of the phase modulator.

[0076] The second polarization controller 1014 is configured to control the polarization direction of the second optical signal to be the same as the main axis direction of the phase modulator.

[0077] Optical coupler 1015 is configured to: receive a first optical signal and a second optical signal; couple the first optical signal and the second optical signal to generate a coupled target optical signal.

[0078] It should be noted that the first laser 1011 is used to emit a first optical signal. The second laser 1012 is used to emit a second optical signal. The first polarization controller 1013 is used to control the polarization direction of the first optical signal to be the same as the principal axis direction of the phase modulator 102. The second polarization controller 1014 is used to control the polarization direction of the second optical signal to be the same as the principal axis direction of the phase modulator 102. The optical coupler 1015 is used to receive the first optical signal and the second optical signal, and couple the first optical signal and the second optical signal to obtain a coupled optical signal.

[0079] Another possible implementation, such as Figure 2 As shown, the device 10 for determining refractive index and temperature also includes: an optical circulator 108, an erbium-doped fiber amplifier 109, and a microwave amplifier 110.

[0080] Among them, the optical circulator 108 is communicatively connected to the phase modulator 102; the optical circulator 108 is communicatively connected to the first optical fiber 103; the optical circulator 108 is communicatively connected to the erbium-doped fiber amplifier 109; the erbium-doped fiber amplifier 109 is communicatively connected to the photodetector 105; the microwave amplifier 110 is communicatively connected to the photodetector 105; and the microwave amplifier 110 is communicatively connected to the microwave coupler 106.

[0081] For example, the optical circulator 108 is configured to: send a first target optical signal to the first optical fiber 103 and the second optical fiber 104; and after the first target optical signal passes through the first optical fiber 103 and the second optical fiber 104, forward the first target optical signal to the photodetector 105.

[0082] The following describes the process of the first optical signal and the second optical signal passing through the optical coupler 1015 and the phase modulator 102.

[0083] In one possible implementation, the first optical signal and the second optical signal are coupled via an optical coupler 1015 to become a coupled optical signal. This coupled optical signal includes the frequencies of both the first and second optical signals. The coupled optical signal is then modulated by a phase modulator 102 with a third and a fifth microwave signal to obtain the first target optical signal. Wherein, as... Figure 3 As shown, the first target optical signal includes a first optical signal frequency, a first double-sideband frequency, a second optical signal frequency, and a second single-sideband frequency.

[0084] The following describes the process by which the first target optical signal passes through the optical circulator 108, the first optical fiber 103, and the second optical fiber 104 in sequence.

[0085] In one possible implementation, the first optical fiber 103 is a D-type fiber phase-shifted Bragg grating, and the second optical fiber 104 is a conventional single-mode fiber phase-shifted Bragg grating. The first target optical signal is transmitted through the optical circulator 108. The D-type fiber phase-shifted Bragg grating converts the first double-sideband frequency to the first single-sideband frequency, resulting in the first fiber optical signal. The first fiber optical signal then passes through a conventional single-mode fiber phase-shifted Bragg grating, converting the second double-sideband frequency to the second single-sideband frequency, resulting in the second fiber optical signal. The second fiber optical signal then passes through the optical circulator 108. Wherein, as... Figure 3 As shown, the first fiber optic signal includes a first optical signal frequency, a first single-sideband frequency, a second optical signal frequency, and a second double-sideband frequency. The second fiber optic signal includes the first optical signal frequency, the first single-sideband frequency, the second optical signal frequency, and the second single-sideband frequency.

[0086] The following describes in detail the process by which the second optical fiber signal passes through the erbium-doped fiber amplifier 109, the photodetector 105, and the microwave amplifier 110.

[0087] In one possible implementation, the second fiber optic signal is amplified by an erbium-doped fiber amplifier 109. The amplified second fiber optic signal is then converted into a first microwave signal and a second microwave signal by a photodetector (i.e., a photoelectric converter) 109. The first and second microwave signals are then amplified by a microwave amplifier 110, further amplifying their signal power. The first oscillation frequency of the first microwave signal is the difference between the frequency of the first optical signal and the first single-sideband frequency, and the second oscillation frequency of the second microwave signal is the difference between the frequency of the second optical signal and the second single-sideband frequency.

[0088] The following describes in detail the process of the first microwave signal and the second microwave signal passing through the microwave coupler 106 and the spectrum analyzer 107.

[0089] In one possible implementation, the first microwave signal is separated into a third microwave signal and a fourth microwave signal with the same frequency but different power by a microwave coupler 106; the second microwave signal is also separated into a fifth microwave signal and a sixth microwave signal with the same frequency but different power by the microwave coupler 106. The third and fifth microwave signals, which have higher power, are transmitted to a phase modulator 102. The fourth and sixth microwave signals, which have lower power, are transmitted to a spectrum analyzer 107 to monitor the frequencies of the fourth and sixth microwave signals.

[0090] It should be noted that the frequencies of the third and fourth microwave signals are the same as the frequency of the first microwave signal. The frequencies of the fifth and sixth microwave signals are the same as the frequency of the second microwave signal.

[0091] The following describes in detail the process of determining the first frequency shift and the second frequency shift based on the first oscillation frequency, the second oscillation frequency, the third oscillation frequency, and the fourth oscillation frequency.

[0092] In one possible implementation, the device for determining the refractive index and temperature determines, in the initial state, a first oscillation frequency of the target optical signal after sequentially passing through the first optical fiber 103 and a second oscillation frequency after passing through the second optical fiber 104; and in the target state, a third oscillation frequency of the target optical signal after sequentially passing through the first optical fiber 103 and a fourth oscillation frequency after passing through the second optical fiber 104. The device for determining the refractive index and temperature determines the difference between the first and third oscillation frequencies as a first frequency shift, and determines the difference between the second and fourth oscillation frequencies as a second frequency shift.

[0093] The following section details the process of determining the refractive index and temperature of the target environment based on the first and second frequency shifts.

[0094] The changes in refractive index ΔR and temperature ΔT satisfy the following formula:

[0095]

[0096] Where ΔF1 is the first frequency shift, ΔF2 is the second frequency shift, c is the speed of light, N1 is the effective refractive index of the first optical fiber, N2 is the effective refractive index of the second optical fiber, and λ s1 Let λ be the wavelength of the first target optical signal. s2 λ is the wavelength of the second target optical signal. N1 λ is the wavelength of the transmission point of the reflection spectrum of the first optical fiber. N2 K represents the wavelength of the transmission point of the reflection spectrum of the second optical fiber. 1R K represents the refractive index sensitivity coefficient of the first optical fiber, which is related to parameters such as grating wavelength, external refractive index, and the structural dimensions of the first optical fiber; 2R K represents the refractive index sensitivity coefficient of the second optical fiber, which is related to parameters such as grating wavelength, external refractive index, and the structural dimensions of the second optical fiber; 1T K represents the temperature sensitivity coefficient of the first optical fiber, which is related to parameters such as the expansion coefficient of the first optical fiber; 2T The temperature sensitivity coefficient of the second optical fiber is related to parameters such as the expansion coefficient of the second optical fiber.

[0097] It should be noted that, compared to the previously proposed refractive index measurement schemes based on photoelectric oscillators and phase-shifting gratings, phase-shifting fibers require etching, which is technically challenging, and the fibers have poor physical and mechanical strength; furthermore, temperature affects the refractive index sensing. In the aforementioned technical solution, the sensing units in the refractive index and temperature determination device 10 have high mechanical strength, and the core-cladding distance of the D-type fiber phase-shifting Bragg grating is small, making it easier to sense changes in the environmental refractive index without requiring fiber etching.

[0098] When implemented in hardware, the various modules in the device for determining refractive index and temperature can be integrated into, for example... Figure 4 The determination of refractive index and temperature is implemented in the hardware structure of the device shown. Specifically, as... Figure 4 The diagram illustrates the basic hardware structure of the device for determining refractive index and temperature.

[0099] Figure 4 This is a schematic diagram of a device for determining refractive index and temperature, provided as an embodiment of this application. Figure 4 As shown, the device for determining refractive index and temperature includes at least one processor 401, a communication line 402, and at least one communication interface 404, and may also include a memory 403. The processor 401, memory 403, and communication interface 404 are connected via the communication line 402.

[0100] The processor 401 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application, such as one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs).

[0101] Communication line 402 may include a path for transmitting information between the aforementioned components.

[0102] Communication interface 404 is used to communicate with other devices or communication networks. It can use any transceiver-like device, such as Ethernet, radio access network (RAN), wireless local area network (WLAN), etc.

[0103] The memory 403 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of including or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto.

[0104] In one possible design, the memory 403 can exist independently of the processor 401, meaning the memory 403 can be an external memory of the processor 401. In this case, the memory 403 can be connected to the processor 401 via a communication line 402 to store execution instructions or application code, and its execution is controlled by the processor 401 to implement the method for determining refractive index and temperature provided in the following embodiments of this application. In another possible design, the memory 403 can also be integrated with the processor 401, meaning the memory 403 can be an internal memory of the processor 401. For example, the memory 403 can be a cache, used to temporarily store some data and instruction information.

[0105] As one possible implementation, processor 401 may include one or more CPUs, for example Figure 4 CPU0 and CPU1 in the example. As another possible implementation, the device for determining the refractive index and temperature may include multiple processors, such as... Figure 4 The processors 401 and 407 are included. As another possible implementation, the refractive index and temperature determination device may further include an output device 405 and an input device 406.

[0106] It should be noted that the various embodiments of this application can be referenced or learned from each other. For example, the same or similar steps, method embodiments, system embodiments and device embodiments can be referenced from each other without limitation.

[0107] Figure 5 The flowchart illustrates a method for determining refractive index and temperature, provided in an embodiment of this application. This method can be applied to, for example... Figure 4 The apparatus shown is used to determine the refractive index and temperature. (For example...) Figure 5 As shown, the method includes the following: S501-S505.

[0108] S501, the device for determining refractive index and temperature determines the first oscillation frequency of the first target optical signal after it passes through the first optical fiber and the second oscillation frequency after it passes through the second optical fiber.

[0109] The wavelength of the light beam passing through the first optical fiber is linearly related to the refractive index and temperature, while the wavelength of the light beam passing through the second optical fiber is linearly related to the refractive index.

[0110] For example, in the initial state, the first target optical signal passes sequentially through the first optical fiber and then the second optical fiber. Taking a D-type fiber phase-shifted Bragg grating as the first fiber and a conventional single-mode phase-shifted Bragg grating as the second fiber, the refractive index and temperature determining device determines that after the first target optical signal passes through the D-type fiber phase-shifted Bragg grating, the difference between the frequency of the first optical signal and the reflection spectrum dip frequency of the D-type fiber phase-shifted Bragg grating is the first oscillation frequency. Then, the refractive index and temperature determining device determines that after the first target optical signal passes through the conventional single-mode phase-shifted Bragg grating, the difference between the frequency of the second optical signal and the reflection spectrum dip frequency of the conventional single-mode phase-shifted Bragg grating is the second oscillation frequency.

[0111] S502, the device for determining refractive index and temperature determines the third oscillation frequency of the second target optical signal after it passes through the first optical fiber and the fourth oscillation frequency after it passes through the second optical fiber.

[0112] For example, in the target state, the second target optical signal passes sequentially through the first optical fiber and the second optical fiber, forming photoelectric oscillations. Taking a D-type fiber phase-shifted Bragg grating as the first fiber and a conventional single-mode phase-shifted Bragg grating as the second fiber, the refractive index and temperature determining device determines that after the second target optical signal passes through the D-type fiber phase-shifted Bragg grating, the difference between the frequency of the third optical signal and the reflection spectrum dip frequency of the D-type fiber phase-shifted Bragg grating is the third oscillation frequency. Then, the refractive index and temperature determining device determines that after the second target optical signal passes through the conventional single-mode phase-shifted Bragg grating, the difference between the frequency of the fourth optical signal and the reflection spectrum dip frequency of the conventional single-mode phase-shifted Bragg grating is the fourth oscillation frequency.

[0113] S503, the device for determining refractive index and temperature determines the first frequency shift based on the difference between the first oscillation frequency and the third oscillation frequency.

[0114] For example, taking a first oscillation frequency of 10 GHz and a third oscillation frequency of 12 GHz as an example, the refractive index and temperature determining device determines that the difference between the third oscillation frequency of 12 GHz and the first oscillation frequency of 10 GHz is 2 GHz, and determines the difference of 2 GHz as the first frequency shift.

[0115] S504, the device for determining refractive index and temperature determines the second frequency shift based on the difference between the second oscillation frequency and the fourth oscillation frequency.

[0116] For example, taking a second oscillation frequency of 8 GHz and a fourth oscillation frequency of 11 GHz as an example, the refractive index and temperature determining device determines that the difference between the fourth oscillation frequency of 11 GHz and the second oscillation frequency of 8 GHz is 3 GHz, and determines the difference of 3 GHz as the second frequency shift.

[0117] S505, the device for determining refractive index and temperature determines the refractive index and temperature of the environment where the second target optical signal is located based on the first frequency shift, the second frequency shift, and the refractive index and temperature of the environment where the first target optical signal is located.

[0118] For example, the device for determining refractive index and temperature determines the wavelength change values ​​of the first optical signal's first-order sideband and the second optical signal's first-order sideband, respectively, corresponding to the first and second frequency shifts. It also determines the refractive index and temperature of the target environment based on factors such as the effective refractive index of the D-type fiber phase-shifting Bragg grating, the effective refractive index of a conventional single-mode phase-shifting Bragg grating, and the refractive index and temperature of the target light.

[0119] Optionally, the refractive index and temperature determination device determines the change in refractive index and temperature of the environment containing the second target optical signal relative to the environment containing the first target optical signal based on a first frequency shift and a second frequency shift. Then, the device determines the sum of the refractive index of the environment containing the first target optical signal and the change in refractive index as the refractive index of the environment containing the second target optical signal. The device also determines the sum of the temperature of the environment containing the first target optical signal and the temperature change as the temperature of the environment containing the second target optical signal.

[0120] Based on the above technical solution, the method for determining refractive index and temperature provided in this application firstly determines the first oscillation frequency of the first target optical signal after it passes through the first optical fiber and the second oscillation frequency after it passes through the second optical fiber, and then determines the third oscillation frequency of the second target optical signal after it passes through the first optical fiber and the fourth oscillation frequency after it passes through the second optical fiber. Since the wavelength of the light beam passing through the first optical fiber is linearly related to the refractive index and temperature, and the wavelength of the light beam passing through the second optical fiber is also linearly related to the refractive index, the method for determining refractive index and temperature can obtain the frequency of the optical signal at different temperatures and refractive indices. Then, the method determines the first frequency shift based on the difference between the first and third oscillation frequencies; and the second frequency shift based on the difference between the second and fourth oscillation frequencies. Compared with current refractive index measurement methods, which suffer from low accuracy due to temperature cross-influence, and methods that measure the wavelength of the optical signal using a spectrometer to determine the refractive index and temperature, this method offers advantages over other methods. The device for determining refractive index and temperature in this technical solution determines the refractive index and temperature of the environment where the first target optical signal is located based on the first frequency shift, the second frequency shift, and the environment where the first target optical signal is located. It can quickly and accurately measure the refractive index and temperature of the environment where the second target optical signal is located through frequency changes, which greatly improves the measurement efficiency and accuracy of refractive index and temperature.

[0121] The following describes the process of determining the refractive index and temperature using the apparatus for determining these parameters.

[0122] As one possible embodiment of this application, combined with Figure 5 ,like Figure 6 As shown, before S505 above, the following S601-S603 may also be included.

[0123] S601, the device for determining refractive index and temperature determines the temperature sensitivity coefficient and refractive index sensitivity coefficient of the first optical fiber, and the temperature sensitivity coefficient and refractive index sensitivity coefficient of the second optical fiber.

[0124] Optionally, the first optical fiber can be a D-type fiber phase-shifted Bragg grating, and the device for determining refractive index and temperature can obtain the temperature sensitivity coefficient and refractive index sensitivity coefficient of the D-type fiber phase-shifted Bragg grating.

[0125] Optionally, the second optical fiber can be a conventional single-mode fiber phase-shifted Bragg grating, and the device for determining refractive index and temperature can obtain the temperature sensitivity coefficient and refractive index sensitivity coefficient of the conventional single-mode fiber phase-shifted Bragg grating.

[0126] S602, the device for determining refractive index and temperature determines the amount of refractive index change and temperature change of the environment where the second target optical signal is located relative to the environment where the first target optical signal is located, based on the temperature sensitivity coefficient of the first optical fiber, the refractive index sensitivity coefficient of the first optical fiber, the temperature sensitivity coefficient of the second optical fiber, the refractive index sensitivity coefficient of the second optical fiber, the first frequency shift, and the second frequency shift.

[0127] In one possible implementation, the refractive index ΔR and temperature ΔT satisfy the following formula:

[0128]

[0129] Where ΔF1 is the first frequency shift, ΔF2 is the second frequency shift, c is the speed of light, N1 is the effective refractive index of the first optical fiber, N2 is the effective refractive index of the second optical fiber, and λ s1 Let λ be the wavelength of the first target optical signal. s2 λ is the wavelength of the second target optical signal. N1 λ is the wavelength of the transmission point of the reflection spectrum of the first optical fiber. N2 K represents the wavelength of the transmission point of the reflection spectrum of the second optical fiber. 1R K represents the refractive index sensitivity coefficient of the first optical fiber, which is related to parameters such as grating wavelength, external refractive index, and the structural dimensions of the first optical fiber; 2R K represents the refractive index sensitivity coefficient of the second optical fiber, which is related to parameters such as grating wavelength, external refractive index, and the structural dimensions of the second optical fiber; 1T K represents the temperature sensitivity coefficient of the first optical fiber, which is related to parameters such as the expansion coefficient of the first optical fiber; 2T The temperature sensitivity coefficient of the second optical fiber is related to parameters such as the expansion coefficient of the second optical fiber.

[0130] It should be noted that the change in the center wavelength of the fiber grating is positively correlated with the change in the effective refractive index of the external environment. The change in the center wavelength of the fiber grating and the change in the effective refractive index of the external environment satisfy the following formula:

[0131] Δλ=2*ΔN*Λ

[0132] Where Δλ is the change in the center wavelength of the fiber grating, ΔN is the change in the effective refractive index, and Λ is the grating period.

[0133] S603, the device for determining refractive index and temperature determines the refractive index and temperature of the environment where the second target optical signal is located based on the amount of refractive index change and temperature change, as well as the refractive index and temperature of the environment where the first target optical signal is located.

[0134] Optionally, the device for determining refractive index and temperature determines the sum of the refractive index of the environment where the first target optical signal is located and the change in that refractive index as the refractive index of the environment where the second target optical signal is located. The device for determining refractive index and temperature determines the sum of the temperature of the environment where the first target optical signal is located and the change in that temperature as the temperature of the environment where the second target optical signal is located.

[0135] Based on the above technical solution, the device for determining refractive index and temperature determines the temperature sensitivity coefficient and refractive index sensitivity coefficient of the first optical fiber, and the temperature sensitivity coefficient and refractive index sensitivity coefficient of the second optical fiber. This allows the device to determine the change in refractive index and temperature of the environment where the second target optical signal is located relative to the environment where the first target optical signal is located, based on the temperature sensitivity coefficient of the first optical fiber, the refractive index sensitivity coefficient of the first optical fiber, the temperature sensitivity coefficient of the second optical fiber, and the refractive index sensitivity coefficient of the second optical fiber.

[0136] As one possible embodiment of this application, such as Figure 7a As shown, the specific process of generating the first target optical signal can be implemented through the following steps S701-S702.

[0137] S701, the first optical signal is coupled with the second optical signal to obtain a coupled optical signal. The coupled optical signal is then sent to the phase modulator.

[0138] The coupled optical signal includes the first optical signal frequency and the second optical signal frequency.

[0139] S702, the third microwave signal, and the fifth microwave signal are modulated with the coupled optical signal through a phase modulator to obtain the first target optical signal. The first target optical signal is then transmitted to the first optical fiber.

[0140] The first target optical signal includes a first optical signal frequency, a first double-sideband frequency, a second optical signal frequency, and a second double-sideband frequency.

[0141] Based on the above technical solution, the first optical signal is coupled with the second optical signal to obtain a coupled optical signal. Then, the third microwave signal and the fifth microwave signal are modulated with the coupled optical signal by a phase modulator to obtain a first target optical signal containing the frequency of the first optical signal, the first double-sideband frequency, the frequency of the second optical signal, and the second double-sideband frequency.

[0142] As one possible embodiment of this application, such as Figure 7a As shown, the process of determining that the first target optical signal passes through the first optical fiber and determining the first oscillation frequency can be achieved through the following steps S703-S704.

[0143] S703. The first target optical signal passes through the first optical fiber to obtain the first optical fiber signal. The first optical fiber signal is then sent to the second optical fiber.

[0144] The first optical fiber signal includes a first optical signal frequency, a first single-sideband frequency, a second optical signal frequency, and a second double-sideband frequency.

[0145] For example, taking a conventional single-mode phase-shifted Bragg grating as the second fiber, after the first target optical signal passes through the D-type fiber phase-shifted Bragg grating, one of the single-sideband frequencies in the first double-sideband frequency of the first target optical signal is filtered out, resulting in the first single-sideband frequency.

[0146] The first single-sideband frequency value is the same as the reflection spectrum dip frequency of the D-type fiber phase-shifted Bragg grating.

[0147] S704. Determine the first oscillation frequency based on the first optical signal frequency and the first single-sideband frequency.

[0148] For example, the device for determining refractive index and temperature determines the frequency difference between the first optical signal frequency and the first single-sideband frequency as the first oscillation frequency.

[0149] Based on the above technical solution, the first target optical signal passes through the first optical fiber to obtain the first fiber optical signal. Then, the device for determining the refractive index and temperature can determine the first oscillation frequency based on the first optical signal frequency and the first single-sideband frequency in the first fiber optical signal.

[0150] As one possible embodiment of this application, such as Figure 7a As shown, the process of determining the first optical fiber signal passing through the second optical fiber and the second oscillation frequency can be achieved through the following steps S705-S706.

[0151] S705. The first fiber optic signal passes through the second fiber optic cable to obtain a second fiber optic signal. The second fiber optic signal is then sent to the photodetector.

[0152] The second optical fiber signal includes a first optical signal frequency, a first single-sideband frequency, a second optical signal frequency, and a second single-sideband frequency.

[0153] For example, taking a conventional single-mode phase-shifted Bragg grating as the first optical fiber, after the optical signal from the first fiber passes through the conventional single-mode phase-shifted Bragg grating, one of the single-sideband frequencies of the second double-sideband frequency in the first fiber optical signal is filtered out, resulting in the second single-sideband frequency.

[0154] The second single-sideband frequency value is the same as the reflection spectrum dip frequency of a conventional single-mode phase-shifted Bragg grating.

[0155] S706. Determine the second oscillation frequency based on the second optical signal frequency and the second single-sideband frequency.

[0156] For example, the device for determining refractive index and temperature determines the frequency difference between the second optical signal frequency and the second single-sideband frequency as the second oscillation frequency.

[0157] Based on the above technical solution, the first optical fiber signal passes through the second optical fiber to obtain the second optical fiber signal. Then, the device for determining the refractive index and temperature can determine the second oscillation frequency based on the second optical signal frequency and the second single-sideband frequency in the second optical fiber signal.

[0158] As one possible embodiment of this application, such as Figure 7b As shown, the specific process by which the first target optical signal passes through the photodetector and the microwave coupler in sequence can be achieved through the following steps S707-S709.

[0159] S707, the first target light signal passes through the photodetector in sequence, and the first target light signal is converted into a first microwave signal and a second microwave signal.

[0160] The first microwave signal includes a first oscillation frequency; the second microwave signal includes a second oscillation frequency.

[0161] S708, the first microwave signal is separated into a third microwave signal and a fourth microwave signal by a microwave coupler.

[0162] The frequencies of the third and fourth microwave signals are both the first oscillation frequency; the power of the third microwave signal is greater than the power of the fourth microwave signal.

[0163] S709, the second microwave signal passes through a microwave coupler and is separated into a fifth and a sixth microwave signal. The third and fifth microwave signals are sent to the phase modulator, and the fourth and sixth microwave signals are sent to the spectrum analyzer.

[0164] The fifth and sixth microwave signals both have the second oscillation frequency; the power of the fifth microwave signal is greater than that of the sixth microwave signal.

[0165] Specifically, the third and fifth microwave signals are transmitted to a phase modulator for modulation with the first target optical signal. The fourth and sixth microwave signals are transmitted to a spectrum analyzer to determine the first and second oscillation frequencies.

[0166] Based on the above technical solution, the first target optical signal sequentially passes through a photodetector, and is converted into a first microwave signal and a second microwave signal. The second microwave signal then passes through a microwave coupler, and is separated into a fifth microwave signal and a sixth microwave signal. Compared to existing technologies that determine refractive index by measuring changes in wavelength using a spectrometer, which suffers from low measurement accuracy and slow scanning speed, the above technical solution converts optical information into microwave signals, enabling rapid and accurate measurement of refractive index and temperature information.

[0167] As one possible embodiment of this application, such as Figure 7b As shown, the specific process of determining the first oscillation frequency and the second oscillation frequency using a spectrum analyzer can be achieved through the following steps S7010-S7011.

[0168] S7010. The first oscillation frequency is determined by monitoring the fourth microwave signal through a spectrum analyzer.

[0169] S7011. The second oscillation frequency is determined by monitoring the sixth microwave signal through the spectrum analyzer.

[0170] It should be noted that the specific process for determining the third and fourth oscillation frequencies can be referred to the specific process for determining the first and second oscillation frequencies, and will not be repeated here.

[0171] This application embodiment can divide the refractive index and temperature determination device into functional modules or functional units according to the above method example. For example, each function can be divided into a separate functional module or functional unit, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware or in software functional modules or functional units. The module or unit division in this application embodiment is illustrative and only represents one logical functional division; other division methods may be used in actual implementation.

[0172] like Figure 8The diagram shows a structural schematic of a refractive index and temperature determination device 80 provided in an embodiment of this application. The device includes: a communication unit 801 and a processing unit 802; the communication unit 801 is used to determine a first oscillation frequency of a first target optical signal after it passes through a first optical fiber and a second oscillation frequency after it passes through a second optical fiber; the processing unit 802 is used to determine a third oscillation frequency of a second target optical signal after it passes through a first optical fiber and a fourth oscillation frequency after it passes through a second optical fiber; the processing unit 802 is also used to determine a first frequency shift based on the difference between the first and third oscillation frequencies; the processing unit 802 is also used to determine a second frequency shift based on the difference between the second and fourth oscillation frequencies; the processing unit 802 is also used to determine the refractive index and temperature of the target environment based on the first and second frequency shifts.

[0173] The processing unit 802 is further configured to: determine the temperature sensitivity coefficient and refractive index sensitivity coefficient of the first optical fiber; determine the temperature sensitivity coefficient and refractive index sensitivity coefficient of the second optical fiber; based on the temperature sensitivity coefficient of the first optical fiber, the refractive index sensitivity coefficient of the first optical fiber, the temperature sensitivity coefficient of the second optical fiber, the refractive index sensitivity coefficient of the second optical fiber, the first frequency shift, and the second frequency shift, determine the refractive index change and temperature change of the environment where the second target optical signal is located relative to the environment where the first target optical signal is located; and based on the refractive index change and temperature change, as well as the refractive index and temperature of the environment where the first target optical signal is located, determine the refractive index and temperature of the environment where the second target optical signal is located.

[0174] Processing unit 802 is specifically used to ensure that the refractive index change ΔR and temperature change ΔT satisfy the following formula:

[0175]

[0176] Where ΔF1 is the first frequency shift, ΔF2 is the second frequency shift, c is the speed of light, N1 is the effective refractive index of the first optical fiber, N2 is the effective refractive index of the second optical fiber, and λ s1 Let λ be the wavelength of the first target optical signal. s2 λ is the wavelength of the second target optical signal. N1 λ is the wavelength of the transmission point of the reflection spectrum of the first optical fiber. N2 K represents the wavelength of the transmission point of the reflection spectrum of the second optical fiber. 1R K represents the refractive index sensitivity coefficient of the first optical fiber, which is related to parameters such as grating wavelength, external refractive index, and the structural dimensions of the first optical fiber; 2R K represents the refractive index sensitivity coefficient of the second optical fiber, which is related to parameters such as grating wavelength, external refractive index, and the structural dimensions of the second optical fiber; 1T K represents the temperature sensitivity coefficient of the first optical fiber, which is related to parameters such as the expansion coefficient of the first optical fiber; 2TThe temperature sensitivity coefficient of the second optical fiber is related to parameters such as the expansion coefficient of the second optical fiber.

[0177] In one possible implementation, the refractive index and temperature determination device 80 may further include a storage unit 803. Figure 8 (shown in dashed box) The storage unit 803 stores a program or instruction. When the processing unit 802 executes the program or instruction, the refractive index and temperature determination device 80 can perform the refractive index and temperature determination method described in the above method embodiment.

[0178] Through the above description of the embodiments, those skilled in the art will clearly understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. The specific working process of the system, device, and unit described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0179] This application provides a computer program product containing instructions that, when run on a computer, cause the computer to execute the method for determining refractive index and temperature described in the above method embodiments.

[0180] This application also provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the method for determining refractive index and temperature in the method flow shown in the above method embodiments.

[0181] The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: electrical connections having one or more wires; portable computer disks; hard disks; random access memory (RAM); read-only memory (ROM); erasable programmable read-only memory (EPROM); registers; hard disks; optical fibers; portable compact disc read-only memory (CD-ROM); optical storage devices; magnetic storage devices; or any suitable combination thereof; or any other form of computer-readable storage medium known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium may also be a component of the processor. The processor and the storage medium may reside in an application-specific integrated circuit (ASIC). In the embodiments of this application, the computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0182] Since the refractive index and temperature determination device, computer-readable storage medium, and computer program product in the embodiments of this application can be applied to the above method, the technical effects that can be obtained can also be referred to the above method embodiments. The embodiments of this application will not be repeated here.

[0183] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0184] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0185] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0186] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for determining refractive index and temperature, characterized in that, The method includes: The first oscillation frequency corresponding to the first target optical signal passing through the first optical fiber and the second oscillation frequency corresponding to the second optical fiber are determined; the wavelength of the light beam passing through the first optical fiber is linearly related to the refractive index and temperature; the wavelength of the light beam passing through the second optical fiber is linearly related to the refractive index. The third oscillation frequency corresponding to the second target optical signal passing through the first optical fiber and the fourth oscillation frequency corresponding to the second optical fiber are determined sequentially. The first frequency shift is determined based on the difference between the first oscillation frequency and the third oscillation frequency; The second frequency shift is determined based on the difference between the second oscillation frequency and the fourth oscillation frequency; Based on the first frequency shift, the second frequency shift, and the refractive index and temperature of the environment where the first target optical signal is located, the refractive index and temperature of the environment where the second target optical signal is located are determined. The first target optical signal passes through a photodetector in sequence, and the first target optical signal is converted into a first microwave signal and a second microwave signal; the first microwave signal includes the first oscillation frequency; the second microwave signal includes the second oscillation frequency. The first microwave signal is separated into a third microwave signal and a fourth microwave signal by a microwave coupler; the frequencies of the third microwave signal and the fourth microwave signal are both the first oscillation frequency; the power of the third microwave signal is greater than the power of the fourth microwave signal. The second microwave signal is separated into a fifth microwave signal and a sixth microwave signal by the microwave coupler; the frequencies of the fifth microwave signal and the sixth microwave signal are both the second oscillation frequency; the power of the fifth microwave signal is greater than the power of the sixth microwave signal. A first optical signal is coupled with a second optical signal to obtain a coupled optical signal; the coupled optical signal includes the frequency of the first optical signal and the frequency of the second optical signal. The third microwave signal and the fifth microwave signal are respectively modulated with the coupled optical signal by a phase modulator to obtain the first target optical signal; The first target optical signal includes a first optical signal frequency, a first double-sideband frequency, a second optical signal frequency, and a second double-sideband frequency.

2. The method according to claim 1, characterized in that, Determining the first oscillation frequency of the first target optical signal after it passes through the first optical fiber includes: The first target optical signal passes through the first optical fiber to obtain a first fiber optical signal; the first fiber optical signal includes a first optical signal frequency, a first single-sideband frequency, a second optical signal frequency, and a second double-sideband frequency; The first oscillation frequency is determined based on the first optical signal frequency and the first single-sideband frequency.

3. The method according to claim 2, characterized in that, After the first target optical signal passes through the first optical fiber, determining the second oscillation frequency corresponding to the first target optical signal after it passes through the second optical fiber includes: The first optical fiber signal passes through the second optical fiber to obtain a second optical fiber signal; the second optical fiber signal includes a first optical signal frequency, a first single-sideband frequency, a second optical signal frequency, and a second single-sideband frequency. The difference between the frequency of the second optical signal and the frequency of the second single-sideband signal is the second oscillation frequency.

4. The method according to claim 1, characterized in that, Determining the refractive index and temperature of the environment where the second target optical signal is located based on the first frequency shift, the second frequency shift, and the refractive index and temperature of the environment where the first target optical signal is located includes: Determine the temperature sensitivity coefficient and refractive index sensitivity coefficient of the first optical fiber; Determine the temperature sensitivity coefficient and refractive index sensitivity coefficient of the second optical fiber; Based on the temperature sensitivity coefficient of the first optical fiber, the refractive index sensitivity coefficient of the first optical fiber, the temperature sensitivity coefficient of the second optical fiber, the refractive index sensitivity coefficient of the second optical fiber, the first frequency shift, and the second frequency shift, the amount of refractive index change and temperature change of the environment where the second target optical signal is located relative to the environment where the first target optical signal is located is determined. Based on the changes in refractive index and temperature, as well as the refractive index and temperature of the environment where the first target optical signal is located, the refractive index and temperature of the environment where the second target optical signal is located are determined.

5. The method according to claim 4, characterized in that, The change in refractive index and temperature change Satisfy the following formula: = = in, For the first frequency shift, The second frequency shift is given, and c is the speed of light. The effective refractive index of the first optical fiber is . The effective refractive index of the second optical fiber is . The wavelength of the first target optical signal is denoted as . The wavelength of the second target optical signal; The wavelength of the transmission point of the reflection spectrum of the first optical fiber is denoted as . The wavelength of the transmission point of the reflection spectrum of the second optical fiber; The refractive index sensitivity coefficient of the first optical fiber; The refractive index sensitivity coefficient of the second optical fiber; The temperature sensitivity coefficient of the first optical fiber; The temperature sensitivity coefficient of the second optical fiber is denoted as .

6. The method according to claim 1, characterized in that, The method further includes: The first oscillation frequency is determined by monitoring the fourth microwave signal using a spectrum analyzer. The second oscillation frequency is determined by monitoring the sixth microwave signal using the spectrum analyzer.

7. A device for determining refractive index and temperature, characterized in that, The device includes: a light source, a phase modulator, a first optical fiber, a second optical fiber, a photodetector, a microwave coupler, and a spectrum analyzer; the wavelength of the light beam passing through the first optical fiber is linearly related to the refractive index and temperature; the wavelength of the light beam passing through the second optical fiber is linearly related to the refractive index. The light source device is communicatively connected to the phase modulator; The phase modulator is connected to the first optical fiber for communication. The first optical fiber and the second optical fiber are cascaded together; The first optical fiber is communicatively connected to the photodetector; The photodetector is communicatively connected to the microwave coupler; The microwave coupler is communicatively connected to the phase modulator; The microwave coupler is communicatively connected to the spectrum analyzer; The light source device is configured to send a coupled optical signal to the phase modulator; The phase modulator is configured to: receive the coupled optical signal; modulate the third microwave signal and the fifth microwave signal with the coupled optical signal respectively to obtain a first target optical signal; and transmit the first target optical signal to the first optical fiber. The first optical fiber is configured to: receive the first target optical signal; and transmit a first optical fiber signal to the second optical fiber. The second optical fiber is configured to: receive the first optical fiber signal; and transmit the second optical fiber signal to the first optical fiber. The first optical fiber is configured to: receive the second optical fiber signal from the second optical fiber; and transmit the second optical fiber signal to the photodetector. The photodetector is configured to: receive the second fiber optic signal; convert the second fiber optic signal into a first microwave signal and a second microwave signal; and transmit the first microwave signal and the second microwave signal to the microwave coupler. The microwave coupler is configured to: separate the first microwave signal into a third microwave signal and a fourth microwave signal; separate the second microwave signal into a fifth microwave signal and a sixth microwave signal; transmit the third microwave signal and the fifth microwave signal to the phase modulator; and transmit the fourth microwave signal and the sixth microwave signal to the spectrum analyzer. The spectrum analyzer is configured to: receive the fourth microwave signal and the sixth microwave signal; monitor the fourth microwave signal to determine a first oscillation frequency; and monitor the sixth microwave signal to determine a second oscillation frequency.

8. The apparatus according to claim 7, characterized in that, The light source device includes a first laser, a second laser, and an optical coupler; The first laser is communicatively connected to the optical coupler; the second laser is communicatively connected to the optical coupler; the optical coupler is communicatively connected to the phase modulator. The first laser is configured to send a first optical signal to the optical coupler; The second laser is configured to send a second optical signal to the optical coupler; The optical coupler is configured to receive the first optical signal and the second optical signal; The first optical signal and the second optical signal are coupled together to obtain the coupled optical signal.

9. The apparatus according to claim 8, characterized in that, The light source device further includes a first polarization controller and a second polarization controller; The first terminal of the first polarization controller is connected to the first laser; the first terminal of the second polarization controller is connected to the second laser.

10. The apparatus according to claim 7, characterized in that, The device for determining the refractive index and temperature also includes an optical circulator, an erbium-doped fiber amplifier, and a microwave amplifier. The optical circulator is communicatively connected to the phase modulator; The optical circulator is connected to the first optical fiber for communication. The optical circulator is communicatively connected to the erbium-doped fiber amplifier. The erbium-doped fiber amplifier is communicatively connected to the photodetector; The microwave amplifier is communicatively connected to the photodetector; The microwave amplifier is communicatively connected to the microwave coupler; The optical circulator is configured to: receive a first target optical signal from the phase modulator; transmit the first target optical signal to the first optical fiber; receive the first fiber optical signal from the first optical fiber; and transmit the first fiber optical signal to the erbium-doped fiber amplifier. The erbium-doped fiber amplifier is configured to: receive the first fiber optical signal; amplify the signal power of the first fiber optical signal; and transmit the first fiber optical signal to the photodetector. The microwave amplifier is configured to: receive a first microwave signal and a second microwave signal from the microwave amplifier; amplify the signal power of the first microwave signal and the second microwave signal; and transmit the first microwave signal and the second microwave signal to the microwave coupler.

11. A device for determining refractive index and temperature, characterized in that, The device includes: a communication unit and a processing unit; The communication unit is used to determine the first oscillation frequency corresponding to the first target optical signal passing through the first optical fiber and the second oscillation frequency corresponding to the second optical fiber; the wavelength of the light beam passing through the first optical fiber is linearly related to the refractive index and temperature; the wavelength of the light beam passing through the second optical fiber is linearly related to the refractive index. The processing unit is used to determine the third oscillation frequency of the second target optical signal corresponding to the first optical fiber and the fourth oscillation frequency after passing through the second optical fiber; The processing unit is further configured to determine a first frequency shift based on the difference between the first oscillation frequency and the third oscillation frequency; The processing unit is further configured to determine a second frequency shift based on the difference between the second oscillation frequency and the fourth oscillation frequency; The processing unit is further configured to determine the refractive index and temperature of the environment where the second target optical signal is located based on the first frequency shift, the second frequency shift, and the refractive index and temperature of the environment where the first target optical signal is located; The first target optical signal passes through a photodetector in sequence, and the first target optical signal is converted into a first microwave signal and a second microwave signal; the first microwave signal includes the first oscillation frequency; the second microwave signal includes the second oscillation frequency. The first microwave signal is separated into a third microwave signal and a fourth microwave signal by a microwave coupler; the frequencies of the third microwave signal and the fourth microwave signal are both the first oscillation frequency; the power of the third microwave signal is greater than the power of the fourth microwave signal. The second microwave signal is separated into a fifth microwave signal and a sixth microwave signal by the microwave coupler; the frequencies of the fifth microwave signal and the sixth microwave signal are both the second oscillation frequency; the power of the fifth microwave signal is greater than the power of the sixth microwave signal. A first optical signal is coupled with a second optical signal to obtain a coupled optical signal; the coupled optical signal includes the frequency of the first optical signal and the frequency of the second optical signal. The third microwave signal and the fifth microwave signal are respectively modulated with the coupled optical signal by a phase modulator to obtain the first target optical signal; The first target optical signal includes a first optical signal frequency, a first double-sideband frequency, a second optical signal frequency, and a second double-sideband frequency.

12. A device for determining refractive index and temperature, characterized in that, include: A processor and a communication interface; the communication interface is coupled to the processor, the processor being used to run computer programs or instructions to implement the method for determining the refractive index and temperature as described in any one of claims 1-6.

13. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores instructions that, when executed by a computer, perform the method for determining the refractive index and temperature as described in any one of claims 1-6.

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