A high-stability adjustable photoelectric oscillator and its oscillation frequency stabilization method

Abstract

The present invention discloses a high-stability adjustable optoelectronic oscillator and an oscillation frequency stabilization method thereof, comprising an oscillation loop and a feedback compensation loop, wherein the oscillation loop is used to generate a microwave signal, and the feedback compensation loop is used to compensate for the influence of external environmental factors on the output frequency of the oscillation loop. The present invention stabilizes the oscillation frequency of the optoelectronic oscillator while ensuring that the frequency of the optoelectronic oscillator based on a phase-shifted fiber grating is adjustable, so that the optoelectronic oscillator can work stably for a long time in a temperature-changing environment.

Description

Technical Field

[0001] The invention relates to the technical field of microwave photonics, and in particular to a high-stability adjustable photoelectric oscillator and an oscillation frequency stabilization method thereof. Background Art

[0002] With the rapid development of high-frequency electronic systems and modern wireless communications, these electronic and communication systems have increasingly higher requirements for the frequency range, frequency stability, phase noise, etc. of the signals generated by oscillators. Optoelectronic oscillators use optoelectronic hybrid feedback closed-loop technology to convert laser energy into microwave signal energy. They can generate high-frequency, broadband, low-phase-noise high-quality signals and are tunable, making them ideal signal source devices for high-frequency electronic and communication systems.

[0003] In an optoelectronic oscillator, the optoelectronic resonant cavity formed by a long optical fiber is easily affected by ambient temperature and vibration, which causes length changes, leading to deterioration of the proximal phase noise of the optoelectronic oscillator, output frequency drift, and even mode hopping. As a microwave source, the frequency stability and phase noise performance of the optoelectronic oscillator are crucial.

[0004] Therefore, there is an urgent need for a high-stability adjustable optoelectronic oscillator that can stabilize the oscillation frequency of the optoelectronic oscillator while ensuring that the frequency of the optoelectronic oscillator based on phase-shifted fiber grating is adjustable, so that the optoelectronic oscillator can work stably for a long time in a temperature-changing environment. Summary of the invention

[0005] The purpose of the present invention is to provide a high-stability adjustable optoelectronic oscillator and an oscillation frequency stabilization method thereof, so as to solve the problems existing in the above-mentioned prior art. While ensuring that the frequency of the optoelectronic oscillator based on phase-shifted fiber grating is adjustable, the oscillation frequency of the optoelectronic oscillator is stabilized, so that the optoelectronic oscillator can work stably for a long time in a temperature-changing environment.

[0006] To achieve the above-mentioned purpose, the present invention provides the following solution: The present invention provides a high-stability adjustable optoelectronic oscillator, comprising an oscillation loop and a feedback compensation loop, wherein the oscillation loop is used to generate a microwave signal, and the feedback compensation loop is used to compensate for the influence of external environmental factors on the output frequency of the oscillation loop.

[0007] Optionally, the oscillation loop includes a laser source, which is connected to a polarization controller and a first optical coupler in sequence; one output end of the first optical coupler is connected to an input end of an optical phase shifter; another output end of the first optical coupler is connected to a phase modulator, a Mach-Zehnder modulator, a long optical fiber, a second optical coupler, an optical isolator, and a phase-shifting fiber grating in sequence; the output end of the optical phase shifter and the output end of the phase-shifting fiber grating are both connected to an input end of a third optical coupler; the output end of the third optical coupler, a first photodetector, a first microwave amplifier, and a microwave power divider are connected in sequence; one output end of the microwave power divider is connected to a radio frequency input end of the phase modulator; and the other output end of the microwave power divider is a microwave signal output end of the optoelectronic oscillator.

[0008] Optionally, the feedback compensation loop includes an external reference source, one output end of the external reference source is connected to the RF input end of the Mach-Zehnder modulator, the optical output end of the Mach-Zehnder modulator is connected to the input end of a second optical coupler through a long optical fiber, the output end of the second optical coupler is connected to the input end of a second photodetector, the output end of the second photodetector is connected to the input end of a second microwave amplifier, the output end of the second microwave amplifier is connected to the local oscillator input end of a phase detection module, the other output end of the external reference source is connected to the RF input end of the phase detection module, and the output end of the phase detection module is connected to the optical phase shifter through a controller.

[0009] Optionally, the phase detector module includes a phase detector and a low-pass filter, the phase detector is used to compare the output signal of the external reference source with the output signal of the second microwave amplifier, and the output signal of the phase detector is filtered by the low-pass filter to output a voltage error signal.

[0010] Optionally, the controller includes an analog-to-digital conversion module and a control unit, the analog-to-digital conversion module converts the output voltage error signal of the phase detection module into a digital signal, and the control unit processes the digital signal and controls the phase shift of the optical phase shifter.

[0011] Optionally, the control unit adopts FPGA or single-chip microcomputer.

[0012] Optionally, the laser source is a tunable laser source.

[0013] A method for stabilizing the oscillation frequency of a high-stability adjustable optoelectronic oscillator is also provided, comprising:

[0014] The output light of the laser source is modulated by a phase modulator and a Mach-Zehnder modulator to form a modulated optical signal including phase modulation and intensity modulation; the modulated optical signal is photon filtered by a phase-shifted fiber grating, and the modulated optical signal filtered by the photon and the optical carrier passing through the optical phase shifter are optically coupled by a third optical coupler to achieve adjustable oscillation frequency of the optoelectronic oscillator;

[0015] Injecting a first output signal of an external reference source into a radio frequency input terminal of a Mach-Zehnder modulator, modulating a reference signal far from an output frequency of an optoelectronic oscillator through the Mach-Zehnder modulator, the reference signal passing through a long optical fiber and a second optical coupler and then inputting into a second photodetector, the second photodetector performing beat frequency recovery on the reference signal and outputting a radio frequency signal, the radio frequency signal passing through a second microwave amplifier and inputting into a phase detection module, and the second output signal of the external reference source is input into the phase detection module;

[0016] The phase detection module compares the phase of the second output signal and the radio frequency signal to obtain a voltage error signal. The controller processes the voltage error signal and controls the optical phase shifter to change the phase according to the processing result to compensate for the phase change of the optoelectronic oscillator caused by external environmental factors and keep the oscillation frequency stable.

[0017] The present invention discloses the following technical effects:

[0018] The present invention provides a high-stability adjustable optoelectronic oscillator and an oscillation frequency stabilization method thereof. The optoelectronic oscillator comprises an oscillation loop and a feedback compensation loop. A third optical coupler is used in the oscillation loop to optically couple a transmitted light signal of a phase-shifted fiber grating and an output optical carrier of an optical phase shifter. The output optical signal comprises an upper or lower sideband and a phase-shifted optical carrier. Thus, the wavelength of the output light of a laser source can be changed to change the frequency of the transmitted light signal of the phase-shifted fiber grating, thereby realizing adjustable oscillation frequency of the optoelectronic oscillator. A phase detector module in the feedback compensation loop compares the phase of an output signal of an external reference source with the phase of an output signal of a second photodetector to obtain a voltage error signal. A controller controls the optical phase shifter to change the phase after processing the voltage error signal, thereby compensating for the phase changed due to changes in external environmental factors. By continuously detecting the voltage error signal, the optical phase shifter is feedback-controlled to maintain long-term stable operation of the optoelectronic oscillator. Thus, while ensuring that the frequency of the optoelectronic oscillator based on the phase-shifted fiber grating is adjustable, the oscillation frequency of the optoelectronic oscillator is stabilized, so that the optoelectronic oscillator can work stably for a long time in a temperature-changing environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 This is a schematic diagram of the structure of a high stability adjustable optoelectronic oscillator in an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the structure of the phase detection module in the embodiment of the present invention;

[0022] Figure 3 A schematic diagram of the structure of a controller in an embodiment of the present invention;

[0023] Figure 4 This is a spectrum processing diagram of a high stability adjustable optoelectronic oscillator within the range of 0 GHz-10 GHz in an embodiment of the present invention;

[0024] Figure 5 This is a spectrum processing diagram of a high stability adjustable optoelectronic oscillator within the range of 10 GHz-20 GHz in an embodiment of the present invention;

[0025] Figure 6 This is a spectrum processing diagram of a high-stability adjustable optoelectronic oscillator without feedback compensation in an embodiment of the present invention.

[0026] Figure 7 This is a spectrum processing diagram of a high stability adjustable optoelectronic oscillator under feedback compensation in an embodiment of the present invention.

[0027] Among them, 1 is a laser source, 2 is a polarization controller, 3 is a first optical coupler, 4 is a phase modulator, 5 is a Mach-Zehnder modulator, 6 is a long optical fiber, 7 is a second optical coupler, 8 is an optical isolator, 9 is a phase-shifted fiber grating, 10 is an optical phase shifter, 11 is a third optical coupler, 12 is a first photodetector, 13 is a first microwave amplifier, 14 is a microwave power divider, 15 is an external reference source, 16 is a second photodetector, 17 is a second microwave amplifier, 18 is a phase detector module, 19 is a controller, 20 is a phase detector, 21 is a low-pass filter, 22 is an analog-to-digital conversion module, and 23 is a single-chip microcomputer. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] The present invention provides a highly stable and adjustable optoelectronic oscillator, such as Figure 1 The optoelectronic oscillator comprises an oscillation loop and a feedback compensation loop, wherein the oscillation loop is used to generate a microwave signal, and the feedback compensation loop is used to compensate for the influence of external environmental factors on the output frequency of the oscillation loop.

[0031] The oscillation loop includes a laser source 1, a polarization controller 2, a first optical coupler 3, a phase modulator 4, a Mach-Zehnder modulator 5, a long optical fiber 6, a second optical coupler 7, an optical isolator 8, a phase-shifted fiber grating 9, an optical phase shifter 10, a third optical coupler 11, a first photodetector 12, a first microwave amplifier 13, and a microwave power divider 14. Specifically, the output end of the laser source 1 is connected to the input end of the polarization controller 2, the output end of the polarization controller 2 is connected to the input end of the first optical coupler 3, one output end of the first optical coupler 3 is connected to the input end of the optical phase shifter 10, the other output end of the first optical coupler 3 is connected to the optical input end of the phase modulator 4, the optical output end of the phase modulator 4 is connected to the optical input end of the Mach-Zehnder modulator 5, the optical output end of the Mach-Zehnder modulator 5 is connected to the input end of the long optical fiber 6, the output end of the long optical fiber 6 is connected to the input end of the second optical coupler 7, and the One output end of the optical coupler 7 is connected to the input end of the second photodetector 16, the output end of the second photodetector 16 is connected to the input end of the second microwave amplifier 17, the other output end of the second optical coupler 7 is connected to the input end of the optical isolator 8, the output end of the optical isolator 8 is connected to the input end of the phase-shifted fiber Bragg grating 9, the output end of the optical phase shifter 10 and the output end of the phase-shifted fiber Bragg grating 9 are respectively connected to two input ends of the third optical coupler 11, the output end of the third optical coupler 11 is connected to the input end of the first photodetector 12, the output end of the first photodetector 12 is connected to the input end of the first microwave amplifier 13, the output end of the first microwave amplifier 13 is connected to the input end of the microwave power divider 14, one output end of the microwave power divider 14 is connected to the radio frequency input end of the phase modulator 4, and the other output end of the microwave power divider 14 is the microwave signal output end of the phase-shifted fiber Bragg grating optical oscillator.

[0032] The feedback compensation loop includes an external reference source 15, a Mach-Zehnder modulator 5, a second photodetector 16, a second microwave amplifier 17, a phase detector module 18, a controller 19 and an optical phase shifter 10. Specifically, the external reference source is a highly stable signal source far away from the oscillation frequency of the optoelectronic oscillator, which serves as a detection signal of the optoelectronic oscillator to obtain interference information of external environmental factors on the optoelectronic oscillation loop. An output end of the external reference source 15 is connected to the RF input end of the Mach-Zehnder modulator 5. The optical output end of the Mach-Zehnder modulator 5 is connected to the second optical coupler 7 through a long optical fiber 6. The input end of the second optical coupler 7 is connected to the input end of the second photodetector 16, the output end of the second photodetector 16 is connected to the input end of the second microwave amplifier 17, the other output end of the external reference source 15 and the output end of the second microwave amplifier 17 are respectively connected to the RF input end and the local oscillator input end of the phase detection module 18, and the voltage error signal at the output end of the phase detection module 18 is transmitted to the controller 19, and the controller 19 controls the phase shifter 10 to shift the phase to compensate for the influence of external environmental factors on the output frequency of the phase-shifted fiber Bragg grating optical oscillator.

[0033] Further optimization scheme, such as Figure 2 As shown, the phase detector module 18 includes a phase detector 20 and a low-pass filter 21. The phase detector 20 is used to compare the output signal of the external reference source 15 with the output signal of the second microwave amplifier 17. The output signal of the phase detector 20 is filtered by the low-pass filter 21 to output a voltage error signal.

[0034] Further optimization scheme, such as Figure 3 As shown, the controller 19 includes an analog-to-digital conversion module 22 and a control unit. The analog-to-digital conversion module 22 converts the output voltage error signal of the phase detection module 18 into a digital signal. The control unit processes the digital signal and controls the phase shift of the optical phase shifter 10. The control unit adopts an FPGA or a single-chip microcomputer 23.

[0035] According to a further optimization scheme, the laser source 1 is a tunable laser source.

[0036] This embodiment also provides a method for stabilizing the oscillation frequency of an adjustable optoelectronic oscillator, comprising:

[0037] Assuming that the wavelength of the output light of the laser source 1 is stable, and ignoring the high-order sidebands of the phase modulator 4 and the Mach-Zehnder modulator 5, the optical signal at the output end of the third optical coupler 11 is expressed as shown in formula (1):

[0038]

[0039] Where, E0 is the intensity of the light output by laser source 1; T(ω c +ω RF) is the transmission coefficient of the phase-shifted fiber Bragg grating 9, ω c is the angular frequency of the output light of laser source 1, ω RF is the angular frequency of the oscillation signal of the optoelectronic oscillator; J0(·) is the first-order Bessel function of the first kind; J1(·) is the first-order Bessel function of the first kind; α=πV RF / V π1 , V RF is the amplitude of the photoelectric oscillator oscillation signal, V π1 is the half-wave voltage of the phase modulator 4; β=πV ref / V π2 , V ref is the amplitude of the output signal of the external reference source 15, V π2 is the half-wave voltage of the Mach-Zehnder modulator 5; τ is the delay time caused by the long optical fiber 6; is the phase change caused by the optical phase shifter 10;

[0040] The transmission coefficient T(ω) of the phase-shifted fiber Bragg grating 9 can be expressed as shown in formula (2):

[0041]

[0042] Wherein, κ=ωΔn / (2c), ω is the angular frequency of the incident light signal of the phase-shifted fiber grating 9, Δn is the refractive index change of the phase-shifted fiber grating 9, and c is the speed of light in vacuum; δ=n eff (ω-ω B ) / c,n eff is the effective refractive index of the phase-shifted fiber Bragg grating 9, ω B is the angular frequency of the Bragg wavelength; γ 2 =κ 2 -δ 2 ; κ is the AC coupling coefficient; δ is the DC self-coupling coefficient; L is the length of the phase-shifted fiber grating 9; sinh is the hyperbolic sine function.

[0043] From the analysis of equations (1) and (2), it can be known that by changing the wavelength of the output light of the laser source 1, the frequency of the optical signal transmitted through the phase-shifted fiber grating 9 can be controlled. The third optical coupler 11 optically couples the transmitted optical signal of the phase-shifted fiber grating 9 and the output optical carrier of the optical phase shifter 10 to complete the conversion from phase modulation to intensity modulation, that is, the optical signal at the output end of the third optical coupler 11 contains the upper or lower sideband and the phase-shifted optical carrier. Therefore, the oscillation frequency of the optoelectronic oscillator can be adjusted by changing the wavelength of the output light of the laser source 1. When the center wavelength of the notch of the phase-shifted fiber grating 9 is 1549.983nm, the 3dB bandwidth is about 20MHz, the length of the long optical fiber 6 is 38m, and the refractive index of the long optical fiber 6 is 1.46, the wavelength of the output light of the laser source 1 is adjusted to 1549.955nm to 1550.002nm, the output microwave signal frequency of the optoelectronic oscillator is 2.12GHz-7.99GHz, and the tuning step is about 2GHz. Figure 4 As shown; the wavelength of the output light of the laser source 1 is adjusted to 1550.033nm to 1550.083nm, the output microwave signal frequency of the optoelectronic oscillator is 11.90GHz-18.10GHz, and the tuning step is about 2GHz, such as Figure 5 As shown. Figure 4 , Figure 5 It can be seen that the optoelectronic oscillator can be tuned by adjusting the wavelength of the light output by the laser source 1, and the tuning range is 2.12 GHz-18.10 GHz.

[0044] When the system is working normally, the phase of the output signal of the external reference source 15 and the output signal of the second photodetector 16 are consistent; when the output frequency of the optoelectronic oscillator drifts due to changes in external environmental factors, the RF signal at the output end of the first photodetector 12 is expressed as shown in formula (3):

[0045]

[0046] Among them, V PD1 (t) is the radio frequency signal output by the first photodetector 12; R1 is the responsiveness of the first photodetector 12; τ is the delay time caused by the long optical fiber 6, and Δτ is the delay jitter caused by the long optical fiber 6 due to changes in external environmental factors; ω c is the angular frequency of the output light of laser source 1, ω RF is the angular frequency of the oscillation signal of the optoelectronic oscillator; J0(·) is the first-order Bessel function of the first kind; J1(·) is the first-order Bessel function of the first kind;

[0047] The first output signal of the external reference source 15 is injected into the RF input end of the Mach-Zehnder modulator 5, and a reference signal far away from the output frequency of the optoelectronic oscillator is modulated by the Mach-Zehnder modulator 5. The reference signal passes through the long optical fiber 6 and the second optical coupler 7 and then is restored by the beat frequency of the second photodetector 16. The RF signal at the output end of the second photodetector 16 is expressed as shown in formula (4):

[0048] V ref (t)∝R2J0 2 (α)J0(β)J1(β)cos[ω ref (t+τ+Δτ)] (4)

[0049] Among them, V ref (t) is the radio frequency signal output by the second photodetector 16; R2 is the responsivity of the second photodetector 16; J0(·) is the first-order Bessel function of the first kind; J1(·) is the first-order Bessel function of the first kind; τ is the delay time caused by the long optical fiber 6, and Δτ is the delay jitter caused by the change of the long optical fiber 6 due to the external environmental factors; ω ref is the angular frequency of the output signal of the external reference source 15.

[0050] It can be seen from equations (3) and (4) that the RF signal at the output end of the second photodetector 16 will carry the delay jitter information caused by the long optical fiber 6 changing with the external environmental factors. The phase detector module 18 obtains the voltage error signal by comparing the output signal of the external reference source 15 with the phase of the output signal of the second photodetector 16. The controller 19 processes the voltage error signal and controls the optical phase shifter 10 to change the phase to compensate for the phase change due to the change of the external environmental factors. By continuously detecting the voltage error signal, the optical phase shifter 10 is feedback-controlled to maintain the long-term stable operation of the optoelectronic oscillator.

[0051] like Figure 6 As shown, the wavelength of the output light of the laser source 1 is set to 1550.000nm, the center wavelength of the phase-shifted fiber grating 9 is 1549.983nm, the 3dB bandwidth is about 20MHz, the length of the long optical fiber 6 is 38m, and the refractive index of the long optical fiber 6 is 1.46. Therefore, the output signal frequency of the parameter optoelectronic oscillator is 7.376GHz. Taking the ambient temperature of 0℃ as the reference temperature, when the ambient temperature changes by -10℃, +25℃, and +50℃, the delay time caused by the long optical fiber 6 will change, causing the oscillation frequency of the optoelectronic oscillator to jump or drift. When the ambient temperature changes by -10℃, the oscillation frequency shifts by 0.59MHz, when the temperature changes by +25℃, the oscillation frequency shifts by 1.24MHz, and when the temperature changes by +50℃, the oscillation frequency shifts by 2.48MHz.

[0052] like Figure 7As shown, when the output frequency of the optoelectronic oscillator drifts due to changes in the external temperature, the phase detector module 18 obtains a voltage error signal by comparing the phase of the output signal of the external reference source 15 and the output signal of the second photodetector 16. The controller 19 processes the voltage error signal and controls the optical phase shifter 10 to change the phase, thereby compensating for the phase changed due to changes in external environmental factors. Through phase compensation, when the external ambient temperature changes by -10°C, +25°C, and +50°C, the oscillation frequency offset is less than 0.5kHz, that is, the technical solution provided by the present invention can achieve the stabilization of the oscillation frequency of the optoelectronic oscillator based on the phase-shifted fiber Bragg grating when the frequency is adjustable.

[0053] It should be noted that similar numbers and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and are not to be understood as indicating or implying relative importance.

[0054] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, those skilled in the art should understand that any person skilled in the art can still modify the technical solutions described in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or perform equivalent replacements on some of the technical features thereof; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. They should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A high stability adjustable optoelectronic oscillator, characterized in that: It comprises an oscillation loop and a feedback compensation loop, wherein the oscillation loop is used to generate a microwave signal, and the feedback compensation loop is used to compensate for the influence of external environmental factors on the output frequency of the oscillation loop; The oscillation loop comprises a laser source (1), the laser source (1) is connected to a polarization controller (2) and a first optical coupler (3) in sequence, one output end of the first optical coupler (3) is connected to an input end of an optical phase shifter (10), the other output end of the first optical coupler (3) is connected to a phase modulator (4), a Mach-Zehnder modulator (5), a long optical fiber (6), a second optical coupler (7), an optical isolator (8), and a phase-shifting fiber grating (9) in sequence, the output end of the optical phase shifter (10) and the output end of the phase-shifting fiber grating (9) are both connected to an input end of a third optical coupler (11), the output end of the third optical coupler (11), a first photodetector (12), a first microwave amplifier (13), and a microwave power divider (14) are connected in sequence, one output end of the microwave power divider (14) is connected to a radio frequency input end of the phase modulator (4), and the other output end of the microwave power divider (14) is a microwave signal output end of the photoelectric oscillator; The feedback compensation loop comprises an external reference source (15), one output end of the external reference source (15) is connected to the radio frequency input end of the Mach-Zehnder modulator (5), the optical output end of the Mach-Zehnder modulator (5) is connected to the input end of a second optical coupler (7) via a long optical fiber (6), the output end of the second optical coupler (7) is connected to the input end of a second photodetector (16), the output end of the second photodetector (16) is connected to the input end of a second microwave amplifier (17), the output end of the second microwave amplifier (17) is connected to the local oscillator input end of a phase detector module (18), the other output end of the external reference source (15) is connected to the radio frequency input end of the phase detector module (18), and the output end of the phase detector module (18) is connected to the optical phase shifter (10) via a controller (19).

2. The high stability adjustable optoelectronic oscillator according to claim 1, characterized in that: The phase detector module (18) comprises a phase detector (20) and a low-pass filter (21); the phase detector (20) is used to compare the output end signal of the external reference source (15) and the output end signal of the second microwave amplifier (17); the output end signal of the phase detector (20) is filtered by the low-pass filter (21) and then outputs a voltage error signal.

3. The high stability adjustable optoelectronic oscillator according to claim 1, characterized in that: The controller (19) comprises an analog-to-digital conversion module (22) and a control unit, wherein the analog-to-digital conversion module (22) converts the output voltage error signal of the phase detection module (18) into a digital signal, and the control unit processes the digital signal and controls the phase shift of the optical phase shifter (10).

4. The high stability adjustable optoelectronic oscillator according to claim 3, characterized in that: The control unit adopts FPGA or single chip microcomputer (23).

5. The high stability adjustable optoelectronic oscillator according to claim 1, characterized in that: The laser source (1) is a tunable laser source.

6. A method for stabilizing the oscillation frequency of a high-stability adjustable optoelectronic oscillator, wherein: The method is implemented by using the high stability adjustable optoelectronic oscillator according to any one of claims 1 to 5, and is characterized by comprising: The output light of the laser source (1) is modulated by a phase modulator (4) and a Mach-Zehnder modulator (5) to form a modulated optical signal including phase modulation and intensity modulation; the modulated optical signal is photon filtered by a phase-shifted fiber grating (9), and the modulated optical signal after photon filtering and the optical carrier after passing through the optical phase shifter (10) are optically coupled by a third optical coupler (11) to achieve adjustable oscillation frequency of the photoelectric oscillator; The first output signal of the external reference source (15) is injected into the radio frequency input end of the Mach-Zehnder modulator (5), and a reference signal far away from the output frequency of the photoelectric oscillator is modulated by the Mach-Zehnder modulator (5). The reference signal is input into the second photodetector (16) after passing through the long optical fiber (6) and the second optical coupler (7). The second photodetector (16) performs beat frequency recovery on the reference signal and outputs a radio frequency signal. The radio frequency signal is input into the phase detection module (18) through the second microwave amplifier (17). The second output signal of the external reference source (15) is input into the phase detection module (18); The phase detection module (18) compares the phases of the second output signal and the radio frequency signal to obtain a voltage error signal. The controller (19) processes the voltage error signal and controls the optical phase shifter (10) to change the phase according to the processing result, thereby compensating for the phase change of the optoelectronic oscillator caused by external environmental factors and maintaining the stability of the oscillation frequency.

Images