A Sensitized Temperature Measurement Device and Method Based on a Photoelectric Oscillator

Abstract

This invention provides a sensitivity-enhanced temperature measurement device based on an optoelectronic oscillator, comprising: a laser, an intensity modulator, a delay line interferometer, a sensitive arm fiber optic unit located in the space where the signal to be measured is located, a reference arm fiber optic unit, a photodetector, a microwave amplifier, a bandpass filter, a power divider, and a frequency measurement section. The intensity modulator generates an optical signal containing two frequency components: a carrier wave f0 and a first-order single-sideband wave f1. The delay line interferometer then separates these two frequency components, allowing them to propagate separately along the reference arm and sensitive arm fibers. These components are then returned to the delay line interferometer and combined to output an optical signal whose phase contains the temperature signal to be measured. The phase change of the optical signal caused by the temperature signal to be measured is then converted into a frequency change in the microwave signal output by the optoelectronic oscillator. This invention also provides a sensitivity-enhanced temperature measurement method. The device provided by this invention can effectively improve the sensitivity of temperature detection.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic sensing system technology, and in particular relates to a sensitive temperature measurement device and method based on an optoelectronic oscillator. Background Technology

[0002] Temperature measurement technology has been widely used in various fields of national production and daily life, such as safety monitoring, energy exploration, aerospace, and biomedicine. Initially, electrical sensing technology was used for temperature measurement, but its sensitivity was low and it was susceptible to electromagnetic interference. The development of fiber optic sensing technology has provided a new approach to temperature measurement. Compared with traditional electrical sensors, fiber optic sensors are simple in structure, small in size, lightweight, have low loss, are corrosion-resistant, resistant to electromagnetic interference, and suitable for harsh environments.

[0003] Most current fiber optic temperature measuring devices convert the phase change caused by the measured temperature signal into a change in optical power using an interferometer structure. However, the sensitivity of interferometric temperature measurement systems cannot meet the high sensitivity requirements of certain fields. To improve sensor sensitivity, photoelectric oscillators can be used to convert changes in the optical signal into frequency changes in the electrical signal in the radio frequency domain, which can greatly improve the sensor's sensitivity. However, when the measured temperature signal is very weak, the sensitivity of photoelectric oscillator-based sensing systems will not meet the detection requirements. Therefore, it is necessary to enhance the sensitivity of photoelectric oscillator-based temperature measurement systems to meet the needs of detecting weak temperature signals.

[0004] Patent document CN107084713A discloses a velocity measurement device based on an optoelectronic oscillator, comprising a light source, a first polarization controller, an optoelectronic modulator, a Sagnac interferometer, a photodetector, a bandpass filter, a microwave amplifier, and a power divider. The Sagnac interferometer includes an optical circulator, a second polarization controller, an optical beam splitter, a Sagnac ring, a rotating stage, and a polarizer. The input terminal of the first polarization controller is connected to the light source, and its output terminal is connected to the electro-optic modulator. The electro-optic modulator is connected to the Sagnac interferometer via an optical fiber. The input terminal of the photodetector is connected to the polarizer, and its output terminal is connected to the bandpass filter. The input terminal of the microwave amplifier is connected to the bandpass filter, and its output terminal is connected to the power divider. A portion of the electrical signal output by the power divider is loaded onto the radio frequency terminal of the electro-optic modulator, forming a loop in the optoelectronic oscillator; the other portion serves as the output microwave signal. This device requires polarization operations on the input signal for subsequent signal calculations, but the need for multiple polarization operations can introduce noise into the final signal, affecting the final result.

[0005] Patent document CN108731789B discloses an underwater acoustic detection device based on a photoelectric oscillator, comprising: a laser source circuit, a photoelectric oscillation loop, and a frequency demodulation circuit; the laser source circuit is used to generate a continuous single-frequency laser and output an optical carrier to the photoelectric oscillation loop; the photoelectric oscillation loop is used to convert the underwater acoustic pressure signal into a fiber optic grating pressure signal through a sensing probe, wherein the pressure of the fiber optic grating is related to the resonant wavelength of the fiber optic grating; the device utilizes a laser source, a first polarization controller, a phase modulator, a single-mode fiber, an optical circulator, a sensing probe, and a photodetector to form a micro-structure. The microwave photonic filter, whose center frequency is jointly determined by the laser's center frequency and the resonant wavelength of the fiber optic grating of the sensing probe, modulates the optical carrier into a double-sideband modulated signal, converts the double-sideband modulated signal into an electrical signal, and transmits the electrical signal to the frequency demodulation circuit. The frequency demodulation circuit uses digital signal frequency demodulation technology to demodulate the frequency change information of the electrical signal, obtains the center frequency of the microwave photonic filter, and obtains the intensity of the underwater acoustic pressure signal based on the center frequency of the microwave photonic filter. This method transforms slow, low-resolution optical wavelength measurement into fast, high-precision microwave frequency measurement; however, it still requires signal polarization manipulation, resulting in noise in the final result that affects the final judgment. Summary of the Invention

[0006] The purpose of this invention is to provide a temperature measurement device based on an optoelectronic oscillator to achieve high-sensitivity temperature measurement.

[0007] To achieve the above objectives, the specific technical solution is as follows:

[0008] A temperature measurement device based on an optoelectronic oscillator with enhanced sensitivity includes: a laser, an intensity modulator, a delay line interferometer, a sensitive arm fiber optic unit located in the space where the signal to be measured is located, a reference arm fiber optic unit, a photodetector, a bandpass filter, a microwave amplifier, a power divider, and a frequency measurement section.

[0009] The laser is connected to the optical input terminal of the intensity modulator;

[0010] The intensity modulator outputs a modulated optical signal containing two frequency components: a carrier wave f0 and a first-order single-sideband f1. The output of the intensity modulator is connected to the input of a delay line interferometer, and the polarization state of the modulated optical signal remains unchanged.

[0011] The sensitive arm fiber unit includes a sensitive arm fiber connected to the first interconnection end of the delay line interferometer, and a first reflector connected to the other end of the sensitive arm fiber. The carrier f0 is reflected by the first total reflection mirror after being transmitted in the sensitive arm fiber, and then returns to the interferometer through the first interconnection end.

[0012] The reference arm fiber unit includes a reference arm fiber connected to the second interconnection end of the delay line interferometer, and a second reflector connected to the other end of the reference arm fiber. The first-order single sideband f1 is reflected by the second total reflection mirror after being transmitted through the reference arm fiber, and then returns to the interferometer through the second interconnection end.

[0013] The output of the delay line interferometer is connected to the optical input of the photodetector. The carrier wave f0 and the first-order single-sideband f1 reflected back into the delay line interferometer are combined to obtain a feedback optical signal with the signal to be measured.

[0014] The output end of the photodetector is sequentially connected to a bandpass filter, a microwave amplifier, and a power divider along the photoelectric signal transmission direction, which is used to convert the feedback optical signal into a microwave signal with the signal to be measured.

[0015] The first output terminal of the power divider is connected to the radio frequency terminal of the intensity modulator to form a closed-loop oscillation circuit of the optoelectronic oscillator; the second output terminal of the power divider is connected to the frequency measurement section to obtain the frequency change of the microwave signal output by the closed-loop oscillation circuit of the optoelectronic oscillator.

[0016] This invention utilizes an intensity modulator to generate an optical signal containing two frequency components: a carrier wave f0 and a first-order single-sideband wave f1. Then, a delay line interferometer separates these two frequency components, transmitting them separately along the reference and sensing optical fibers. The signals are then returned to the delay line interferometer and combined to output an optical signal whose phase contains the temperature signal to be measured. The phase change caused by the temperature signal is then converted into a frequency change in the microwave signal output by a photoelectric oscillator. This frequency change is proportional to the temperature signal, and the proportionality coefficient, i.e., the sensing sensitivity, is determined by the optical carrier frequency. This significantly improves the sensitivity of temperature measurement.

[0017] Specifically, the polarization state of the optical signal output by the intensity modulator remains unchanged, and it employs, but is not limited to, a dual parallel Mach-Zehnder intensity modulator, a Mach-Zehnder intensity modulator and its auxiliary devices and apparatuses that can generate single-sideband modulation signals.

[0018] Specifically, the carrier f0 in the modulated optical signal has constructive interference at the first interconnection end of the delay line interferometer, but destructive interference at the second interconnection end of the delay line interferometer. Therefore, the carrier f0 is only transmitted at the first interconnection end.

[0019] Specifically, the first-order single-sideband f1 in the modulated optical signal is constructively interfered at the second interconnection end of the delay line interferometer, but the first-order single-sideband f1 is destructively interfered at the first interconnection end of the delay line interferometer. Therefore, the first-order single-sideband f1 is only transmitted at the second interconnection end.

[0020] Specifically, the sensitive arm fiber is sensitive to the temperature signal to be measured and is used to attach the temperature signal to be measured to the carrier f0, while the reference arm fiber is not sensitive to the temperature signal to be measured.

[0021] The present invention also provides a sensitivity-enhanced temperature measurement method based on a photoelectric oscillator, applied to the aforementioned sensitivity-enhanced temperature measurement device, comprising:

[0022] Step 1: The laser generates an optical signal and transmits the optical signal to the intensity modulator;

[0023] Step 2: The microwave signal output by the photoelectric oscillator is loaded onto the radio frequency terminal of the intensity modulator. The intensity modulator modulates the optical signal to generate a modulated optical signal containing two frequency components: a carrier wave f0 and a first-order single-sideband f1. The polarization state of the modulated optical signal remains unchanged.

[0024] Step 3: The modulated optical signal is split by a delay line interferometer and then output to the sensitive arm fiber unit and the sensitive arm fiber unit respectively.

[0025] When the carrier f0 is transmitted in the optical fiber unit of the sensitive arm, the phase of the temperature signal to be measured changes, and the amount of phase change is proportional to the temperature signal to be measured.

[0026] When the first-order single-sideband f1 is transmitted in the sensitive arm fiber unit, its phase is not changed by the temperature signal to be measured.

[0027] Step 4: The carrier f0 and the first-order single-sideband f1 are combined by the delay line interferometer and output as a feedback optical signal. The phase of the feedback optical signal is proportional to the phase difference between the carrier f0 and the first-order single-sideband f1. Therefore, the phase of the feedback optical signal will be changed by the temperature signal to be measured, and the amount of phase change is proportional to the temperature signal.

[0028] Step 5: The feedback optical signal output by the delay line interferometer is converted into a feedback electrical signal by the photodetector, and after being filtered and amplified by the bandpass filter and the microwave amplifier, it is output to the power divider.

[0029] The power divider splits the electrical signal into two parts. One part is sent to the radio frequency terminal of the intensity modulator to form a loop of the photoelectric oscillator. The other part is used as the microwave signal output by the photoelectric oscillator. The frequency measurement section detects the frequency change. The frequency change is proportional to the temperature signal to be measured. The temperature signal to be measured is obtained by measuring the frequency change.

[0030] Specifically, the phase change of the feedback optical signal is proportional to the measured temperature signal, and the relationship is as follows:

[0031]

[0032]

[0033] in, denoted as phase change, k as proportionality coefficient, ΔT as temperature change, f as laser output optical signal frequency, n as fiber refractive index, c as speed of light, L as fiber length of sensing arm, α as thermo-optic coefficient of fiber, and β as fiber thermal expansion coefficient.

[0034] Specifically, the optical signal output by the delay line interferometer is converted into an electrical signal by a photodetector. After being filtered and amplified by a bandpass filter and a microwave amplifier, it is split into two parts by the power divider. One part is given to the radio frequency terminal of the intensity modulator to form a loop of the photoelectric oscillator. The other part serves as the microwave signal output by the photoelectric oscillator. The frequency measurement section detects the frequency change. The frequency change is proportional to the temperature signal to be measured. Therefore, the temperature signal to be measured can be obtained by measuring the frequency change, thereby realizing temperature measurement.

[0035] The frequency change of the microwave signal is proportional to the signal under test, and the relationship is as follows:

[0036] Δf=(α+β)fΔT

[0037] Where Δf is the frequency change, ΔT is the temperature change, and f is the frequency of the laser output optical signal (10). 14 (on the order of Hz), where α is the thermo-optic coefficient of the optical fiber and β is the coefficient of thermal expansion of the optical fiber.

[0038] The ratio of the frequency change to the measured temperature signal is the sensitivity of the sensor. As can be seen from the above formula, this sensitivity is determined by the frequency of the laser output light signal.

[0039] For temperature measurement methods based on photoelectric oscillators without sensitivity enhancement, the relationship between the frequency change and the measured temperature signal is as follows:

[0040] Δf′=(α+β)f′ΔT

[0041] Where Δf′ is the frequency change, ΔT is the temperature change, and f′ is the oscillation frequency of the photoelectric oscillator (10). 10 (on the order of Hz), α is the thermo-optic coefficient of the optical fiber, and β is the coefficient of thermal expansion of the optical fiber.

[0042] As can be seen from the above formula, the sensitivity of an unsensitized temperature measurement method based on a photoelectric oscillator is determined by the oscillation frequency of the photoelectric oscillator; and the frequency of the optical carrier signal is at least 10 times the frequency of the microwave signal. 4 Therefore, the sensitivity of the photoelectric oscillator-based enhanced temperature measurement method is increased to 10 times. 4 times.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] There is no need to perform polarization processing on the raw data directly, thus avoiding the introduction of excessive noise during data processing and affecting the final detection results. Attached Figure Description

[0045] Figure 1 A schematic diagram of a sensor-enhanced temperature measuring device based on a photoelectric oscillator provided in an embodiment of the present invention;

[0046] Figure 2 A schematic diagram of a method for generating a carrier f0 and a first-order sideband f1 using a Mach-Zehnder intensity modulator, provided in an embodiment of the present invention;

[0047] Figure 3 This is a schematic diagram of a method for generating a carrier f0 and a first-order sideband f1 using a dual parallel Mach-Zehnder intensity modulator, as provided in an embodiment of the present invention. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art based on this application are within the scope of protection of the present invention.

[0049] like Figure 1 As shown in the figure, an embodiment of the present invention provides a structural schematic of a temperature measurement device based on an optoelectronic oscillator. The device includes the following parts: a laser 1, an intensity modulator 2, a delay line interferometer 3, a sensitive arm fiber 4, a reference arm fiber 5, a first total reflection mirror 6, a second total reflection mirror 7, a photodetector 8, a bandpass filter 9, a microwave amplifier 10, a power divider 11, and a frequency measurement section 12.

[0050] The output of laser 1 is connected to the input of intensity modulator 2 to generate an optical signal. This optical signal is modulated by the microwave signal output by photoelectric oscillation processing in modulator 2 to generate a modulated optical signal including a carrier f0 and a first-order single-sideband f1. The polarization state of the modulated optical signal does not change. Intensity modulator 2 includes a dual parallel Mach-Zehnder intensity modulator that generates a single-sideband modulated signal, a Mach-Zehnder intensity modulator and its auxiliary devices and apparatus.

[0051] like Figure 2 The diagram shows a schematic of generating a carrier wave f0 and a first-order single-sideband f1 using a Mach-Zehnder intensity modulator. This is achieved by setting the bias voltage V... biasBy making the Mach-Zehnder modulator 13 operate at its minimum operating point and ignoring higher-order signals, the output modulated optical signal contains only two first-order sidebands. Then, one of the sidebands is filtered out by an optical bandpass filter 14 to obtain the carrier f0 and the first-order single sideband f1 (point C).

[0052] like Figure 3 The diagram illustrates the generation of a single-sideband modulated optical signal, including a carrier wave f0 and a first-order single-sideband wave f1, using a dual-parallel Mach-Zehnder modulator. The dual-parallel Mach-Zehnder intensity modulator 15 consists of two sub-modulators, MZM1 and MZM2, connected in parallel. The microwave signal output from the photoelectric oscillation processing is split into two paths by the power divider 11. One path is modulated onto sub-modulator MZM1 after passing through a 90° phase shifter 16, while the other path is directly modulated onto sub-modulator MZM2. The bias voltage V is adjusted... bias1 V bias2 and V bias3 This ultimately generates a carrier f0 and a first-order single-sideband f1.

[0053] Port 1 of the delay line interferometer 3 is connected to the output of the intensity modulator 2, port 2 of the delay line interferometer 3 is connected to one end of the sensitive arm fiber 4, port 3 of the delay line interferometer 3 is connected to one end of the reference arm fiber 5, the other end of the sensitive arm fiber 4 is connected to the first total reflection mirror 6, and the other end of the reference arm fiber 5 is connected to the second total reflection mirror 7.

[0054] The carrier f0 and the first-order single-sideband f1 are separated using a delay line interferometer 3, where the carrier f0 is output at port 2 and the first-order single-sideband f1 is output at port 3.

[0055] The carrier f0 is transmitted in the sensitive arm fiber 4. The temperature signal to be measured causes a phase change in it, and the amount of phase change is proportional to the temperature signal to be measured. Then the carrier f0 is reflected by the first total reflection mirror 6 and finally returns to port 2.

[0056] The first-order single-sideband f1 is transmitted in the reference arm fiber 5. Its phase is not changed by the temperature signal to be measured. It is then reflected by the second total reflection mirror 7 and finally returns to port 3.

[0057] The carrier wave f0 returning to port 2 and the first-order single-sideband wave f1 returning to port 3 are combined by a delay line interferometer and output at port 4. The phase of the optical signal output from port 4 is changed by the temperature signal to be measured, and the amount of this phase change is proportional to the temperature signal, as shown in the following equation:

[0058]

[0059]

[0060] In the formula, denoted as phase change, k as proportionality coefficient, ΔT as temperature change, f as laser output optical signal frequency, n as fiber refractive index, c as speed of light, L as fiber length of sensing arm, α as thermo-optic coefficient of fiber, and β as fiber thermal expansion coefficient.

[0061] The output of port 4 is connected to the optical input of photodetector 8, thereby converting the optical signal output from port 4 into an electrical signal. The electrical signal is filtered and amplified by bandpass filter 9 and microwave amplifier 10, and then split into two parts by power divider 11. One part is given to the radio frequency terminal of intensity modulator 2 to form the loop of photoelectric oscillator, and the other part is given as the microwave signal output by photoelectric oscillator to frequency measurement section 12 to measure its frequency change.

[0062] The frequency change is proportional to the temperature signal to be measured, and its proportionality coefficient is the sensitivity of the sensor. This sensitivity is determined by the frequency of the laser output light signal. Therefore, the temperature signal to be measured can be obtained by measuring the frequency change, thereby achieving temperature measurement. The relationship is as follows:

[0063] Δf=(α+β)fΔT

[0064] Where Δf is the frequency change, ΔT is the temperature change, and f is the frequency of the laser output optical signal (10). 14 (on the order of Hz), where α is the thermo-optic coefficient of the optical fiber and β is the coefficient of thermal expansion of the optical fiber.

[0065] For temperature measurement methods based on photoelectric oscillators without sensitivity enhancement, the sensitivity is determined by the oscillation frequency of the photoelectric oscillator, as shown in the following formula:

[0066] Δf′=(α+β)f′ΔT

[0067] Where Δf′ is the frequency change, ΔT is the temperature change, and f′ is the oscillation frequency of the photoelectric oscillator (10). 10 (on the order of Hz), where α is the thermo-optic coefficient of the optical fiber and β is the coefficient of thermal expansion of the optical fiber.

[0068] As can be seen from the above formula, the sensitivity of the enhanced temperature measurement method based on photoelectric oscillators will be increased to 10. 4 times.

[0069] In summary, this invention utilizes an intensity modulator to generate an optical modulation signal containing a carrier wave f0 and a first-order single-sideband f1, and then uses a delay line interferometer to separate the signal and transmit it in both arms. This method converts the phase change of the optical signal caused by the temperature signal under test into the frequency change of the microwave signal output by the photoelectric oscillator, greatly improving the sensitivity of temperature measurement.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A photoelectric-oscillator-based enhanced-sensitivity temperature measurement device, characterized by include: Laser, intensity modulator, delay line interferometer, sensitive arm fiber unit located in the space where the signal under test is located, reference arm fiber unit, photodetector, bandpass filter, microwave amplifier, power divider and frequency measurement section; The laser is connected to the optical input terminal of the intensity modulator; The intensity modulator outputs a modulated optical signal containing two frequency components: a carrier wave f0 and a first-order single-sideband f1. The output of the intensity modulator is connected to the input of the delay line interferometer. The delay line interferometer splits the input modulated optical signal and outputs the carrier f0 and the first-order single-sideband f1 obtained by the splitting process through the first and second interconnect ports. The sensitive arm fiber unit includes a sensitive arm fiber connected to the first interconnection end of the delay line interferometer, and a first reflector connected to the other end of the sensitive arm fiber. The carrier f0 is reflected by the first total reflection mirror after being transmitted in the sensitive arm fiber, and then returns to the interferometer through the first interconnection end. The reference arm fiber unit includes a reference arm fiber connected to the second interconnection end of the delay line interferometer, and a second reflector connected to the other end of the reference arm fiber. The first-order single sideband f1 is reflected by the second total reflection mirror after being transmitted through the reference arm fiber, and then returns to the interferometer through the second interconnection end. The output of the delay line interferometer is connected to the optical input of the photodetector. The carrier f0 and the first-order single-sideband f1 reflected back into the delay line interferometer are combined to obtain a feedback optical signal with the signal to be measured. The output end of the photodetector is sequentially connected to a bandpass filter, a microwave amplifier, and a power divider along the photoelectric signal transmission direction, which is used to convert the feedback optical signal into a microwave signal with the signal to be measured. The first output terminal of the power divider is connected to the radio frequency terminal of the intensity modulator to form a closed-loop oscillation circuit of the optoelectronic oscillator; the second output terminal of the power divider is connected to the frequency measurement section to obtain the frequency change of the microwave signal output by the closed-loop oscillation circuit of the optoelectronic oscillator.

2. The opto-electronic oscillator-based enhanced temperature measurement device of claim 1, wherein, The polarization state of the optical signal output by the intensity modulator remains unchanged, and it employs, but is not limited to, a dual parallel Mach-Zehnder intensity modulator, a Mach-Zehnder intensity modulator and its auxiliary devices and apparatuses that can generate single-sideband modulation signals.

3. The opto-electronic oscillator-based enhanced temperature measurement device of claim 1, wherein, The carrier f0 in the modulated optical signal has constructive interference at the first interconnection end of the delay line interferometer, but destructive interference at the second interconnection end of the delay line interferometer. Therefore, the carrier f0 is only transmitted at the first interconnection end.

4. The photosensitive temperature measuring device based on a photoelectric oscillator according to claim 1, characterized in that, The first-order single-sideband f1 in the modulated optical signal is constructively interfered at the second interconnection end of the delay line interferometer, but the first-order single-sideband f1 is destructively interfered at the first interconnection end of the delay line interferometer. Therefore, the first-order single-sideband f1 is only transmitted at the second interconnection end.

5. The photosensitive temperature measuring device based on a photoelectric oscillator according to claim 1, characterized in that, The sensitive arm fiber is sensitive to the temperature signal to be measured and is used to attach the temperature signal to be measured to the carrier f0.

6. A sensitivity-enhanced temperature measurement method based on a photoelectric oscillator, applied to the sensitivity-enhanced temperature measurement device according to any one of claims 1-5, characterized in that, include: Step 1: The laser generates an optical signal and transmits the optical signal to the intensity modulator; Step 2: The microwave signal output by the photoelectric oscillator is loaded onto the radio frequency terminal of the intensity modulator. The intensity modulator modulates the optical signal to generate a modulated optical signal containing two frequency components: a carrier wave f0 and a first-order single-sideband f1. The polarization state of the modulated optical signal remains unchanged. Step 3: The modulated optical signal is split by a delay line interferometer and then output to the sensitive arm fiber unit and the sensitive arm fiber unit respectively. When the carrier f0 is transmitted in the optical fiber unit of the sensitive arm, the phase of the temperature signal to be measured changes, and the amount of phase change is proportional to the temperature signal to be measured. When the first-order single-sideband f1 is transmitted in the sensitive arm fiber unit, its phase is not changed by the temperature signal to be measured. Step 4: The carrier f0 and the first-order single-sideband f1 are combined by the delay line interferometer and output as a feedback optical signal. The phase of the feedback optical signal is proportional to the phase difference between the carrier f0 and the first-order single-sideband f1. Therefore, the phase of the feedback optical signal will be changed by the temperature signal to be measured, and the amount of phase change is proportional to the temperature signal. Step 5: The feedback optical signal output by the delay line interferometer is converted into a feedback electrical signal by the photodetector, and after being filtered and amplified by the bandpass filter and the microwave amplifier, it is output to the power divider. The power divider splits the electrical signal into two parts. One part is sent to the radio frequency terminal of the intensity modulator to form a loop of the photoelectric oscillator. The other part is used as the microwave signal output by the photoelectric oscillator. The frequency measurement section detects the frequency change. The frequency change is proportional to the temperature signal to be measured. The temperature signal to be measured is obtained by measuring the frequency change.

7. The enhanced temperature measurement method based on a photoelectric oscillator according to claim 6, characterized in that, In step 4, the phase change of the feedback optical signal is proportional to the temperature signal to be measured, and the relationship is as follows: in, denoted as phase change, k as proportionality coefficient, ΔT as temperature change, f as the frequency of the laser output optical signal, n as the refractive index of the fiber, c as the speed of light, L as the length of the sensing arm fiber, α as the thermo-optic coefficient of the fiber, and β as the coefficient of thermal expansion of the fiber.

8. The enhanced temperature measurement method based on a photoelectric oscillator according to claim 6, characterized in that, In step 5, the frequency change of the microwave signal is proportional to the signal under test, and the relationship is as follows: Δf=(α+β)fΔT Where Δf is the frequency change, ΔT is the temperature change, f is the frequency of the optical signal output by the laser, α is the thermo-optic coefficient of the optical fiber, and β is the thermal expansion coefficient of the optical fiber.

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