Miniaturized high-stable low-phase-noise photoelectric oscillator

Abstract

The present application relates to the field of photoelectric technology, specifically to a miniaturized high-stability low-phase-noise photoelectric oscillator, a signal laser outputs an optical signal, the optical signal enters an electro-optic modulator and is modulated and output, the output optical signal is divided into two optical signals with orthogonal polarization states by a polarization beam splitter, the two optical signals enter adjustable high-Q value resonant microcavities respectively, the signals after microcavity oscillation are combined into one signal by a polarization combiner and enter a photodetector, the output microwave signal composed of multiple frequency components is output after photoelectric conversion, the microwave signal enters a filter and obtains a 10GHz single-frequency signal, the 1A signal enters a low-noise amplifier for amplification and is then divided into two signals by a second power divider, one of the two signals is used as a signal output, and the other is used as an oscillation signal to inject into the electro-optic modulator, the B signal enters a frequency locking module, and a reference frequency is compared to complete a phase locking process, thereby solving the problem of reduced stability caused by the large structure of the existing photoelectric oscillator.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, and in particular to a miniaturized, highly stable, low-phase-noise optoelectronic oscillator. Background Technology

[0002] Optoelectronic oscillators achieve feedback oscillation of microwave signals through optoelectronic loops and output high-frequency microwave signals. Traditional optoelectronic oscillator schemes, which use single-loop oscillation structures, cannot meet the system's requirements for low phase noise and high stability microwave signals.

[0003] To address this issue, subsequent research, based on the fundamental theory of optoelectronic oscillators, proposed dual-optical-path structures, master-slave structures under all-optical gain, injection-locked-loop structures, optoelectronic oscillator coupling, and mode-locked laser structures to obtain high-quality microwave signals.

[0004] However, most of these structures are quite complex. For example, although the dual-loop structure can improve side-mode suppression and reduce phase noise, the use of two optical fibers as its delay energy storage elements increases the size and weight, which in turn leads to a decrease in stability. Summary of the Invention

[0005] The purpose of this invention is to provide a miniaturized, highly stable, and low-phase-noise optoelectronic oscillator, which aims to solve the problem of reduced stability caused by the large structure of existing optoelectronic oscillators.

[0006] To achieve the above objectives, the present invention provides a miniaturized, highly stable, low-phase-noise optoelectronic oscillator, comprising a signal laser, an electro-optic modulator, a polarization beamsplitter, a resonator microcavity, a polarization combiner, a photodetector, a filter, a first power divider, a frequency stabilization module, a low-noise amplifier, and a second power divider. The signal laser, the electro-optic modulator, the polarization beamsplitter, the polarization combiner, the photodetector, the filter, the first power divider, and the frequency stabilization module are connected sequentially. The low-noise amplifier is connected to the first power divider, the second power divider is connected to the low-noise amplifier and to the electro-optic modulator, and the resonator microcavity is connected to the frequency stabilization module.

[0007] The signal laser is used to output optical signals;

[0008] The electro-optic modulator is used to modulate the optical signal;

[0009] The polarization beam splitter is used to split the modulated optical signal into two optical signals with orthogonal polarization states.

[0010] The resonator microcavity is used to resonate the two optical signals and adjust the resonant wavelength.

[0011] The polarization combiner is used to combine the two control signals into one signal;

[0012] The photodetector is used to transform the signal into a microwave signal.

[0013] The filter is used to filter the microwave signal to obtain a single-frequency signal;

[0014] The first power divider is used to divide the single-frequency signal into a first signal and a second signal;

[0015] The frequency stabilization module uses the second signal to compare with the reference frequency to complete the phase-locking process;

[0016] The low-noise amplifier is used to amplify the first signal to obtain an amplified signal.

[0017] The second power divider is used to divide the amplified signal into an output signal and an oscillation signal.

[0018] The resonator microcavity includes a first microcavity and a second microcavity. The first microcavity is connected to the polarization beamsplitter, the polarization combiner, and the frequency stabilization module. The second microcavity is connected to the polarization beamsplitter, the polarization combiner, and the frequency stabilization module.

[0019] The first microcavity and the second microcavity have a first longitudinal mode spacing and a second longitudinal mode spacing, the first longitudinal mode spacing and the second longitudinal mode spacing being in the range of 1nm to 20nm.

[0020] Wherein, the first longitudinal module interval is equal to an integer multiple of the second longitudinal module interval.

[0021] The frequency stabilization module includes a phase detector, a loop filter, a voltage-controlled oscillator, and a frequency divider. The phase detector, the loop filter, the voltage-controlled oscillator, and the frequency divider are connected in sequence, and the frequency divider is connected to the phase detector.

[0022] The phase detector is used to output an error signal;

[0023] The loop filter is used to filter out error signals;

[0024] The voltage-controlled oscillator is used to output signals and generate comparison signals;

[0025] The frequency divider is used to feed back the comparison signal to the phase detector in a proportional manner.

[0026] This invention discloses a miniaturized, highly stable, low-phase-noise optoelectronic oscillator. The signal laser outputs an optical signal, which is modulated by an electro-optic modulator and then output. The output optical signal is split into two orthogonally polarized optical signals by a polarization beamsplitter. A resonant microcavity is used, and a polarization combiner synthesizes the two signals into a single signal, which then enters a photodetector. After photoelectric conversion, a microwave signal composed of multiple frequency components is output. This microwave signal enters a filter to obtain a 10GHz single-frequency signal. The 10GHz single-frequency signal is split into two paths, A and B, by a power divider. Path A is amplified by a low-noise amplifier and then split into two paths, A1 and A2, by a second power divider. Path A1 is used as the signal output, and path A2 is used as the oscillation signal injected into the electro-optic modulator. Path B enters a frequency-locking module, where it is compared with a reference frequency to further complete the phase-locking process. The proposed solution uses an adjustable resonant microcavity instead of an optical fiber ring, achieving miniaturization while maintaining stability control, thus solving the problem of reduced stability caused by the large structure of existing optoelectronic oscillators. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the structure of a miniaturized, highly stable, low-phase-noise optoelectronic oscillator provided by the present invention.

[0029] Figure 2 This is a schematic diagram of the frequency stabilization module.

[0030] 1-Signal laser, 2-Electro-optic modulator, 3-Polarization beam splitter, 4-Resonator microcavity, 5-Polarization combiner, 6-Photodetector, 7-Filter, 8-First power divider, 9-Frequency stabilization module, 10-Low noise amplifier, 11-Second power divider, 41-First microcavity, 42-Second microcavity, 91-Phase detector, 92-Loop filter, 93-Voltage controlled oscillator, 94-Frequency divider. Detailed Implementation

[0031] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] In the description of this invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0033] Please see Figures 1 to 2 This invention provides a miniaturized, highly stable, low-phase-noise optoelectronic oscillator, comprising a signal laser 1, an electro-optic modulator 2, a polarization beam splitter 3, a resonator microcavity 4, a polarization combiner 5, a photodetector 6, a filter 7, a first power divider 8, a frequency stabilization module 9, a low-noise amplifier 10, and a second power divider 11. The signal laser 1, the electro-optic modulator 2, the polarization beam splitter 3, the polarization combiner 5, the photodetector 6, the filter 7, the first power divider 8, and the frequency stabilization module 9 are connected sequentially. The low-noise amplifier 10 is connected to the first power divider 8, the second power divider 11 is connected to the low-noise amplifier 10, and is also connected to the electro-optic modulator 2. The resonator microcavity 4 is connected to the frequency stabilization module 9.

[0034] The signal laser 1 is used to output optical signals;

[0035] The electro-optic modulator 2 is used to modulate the optical signal;

[0036] The polarization beam splitter 3 is used to split the modulated optical signal into two optical signals with orthogonal polarization states.

[0037] The resonator microcavity 4 is used to resonate the two optical signals and adjust the resonant wavelength.

[0038] The polarization combiner 5 is used to combine the two control signals into one signal;

[0039] The photodetector 6 is used to transform the signal to form a microwave signal;

[0040] The filter 7 is used to filter the microwave signal to obtain a single-frequency signal;

[0041] The first power divider 8 is used to divide the single-frequency signal into a first signal and a second signal;

[0042] The frequency stabilization module 9 uses the second signal to compare with the reference frequency to complete the phase-locking process;

[0043] The low-noise amplifier 10 is used to amplify the first signal to obtain an amplified signal.

[0044] The second power divider 11 is used to divide the amplified signal into an output signal and an oscillation signal.

[0045] In this embodiment, a laser with a relative intensity noise RIN ≤ -160dBc / Hz and an output optical power of 100mW is selected, along with a lithium niobate intensity modulator with a half-wave voltage of 4V and an insertion loss of 5dB, a detector with a responsivity of 0.8A / W, a bandpass filter with a center frequency of 10GHz, a power divider with a bandwidth of 12GHz, a low-noise amplifier with a noise figure of 1.2dB, and a Q value of 10. 7 A SiN resonator with a single-ring structure and an insertion loss of 5dB was used as the experimental device in this scheme, ultimately outputting a 10GHz microwave signal. The signal laser 1 outputs an optical signal, which enters the electro-optic modulator 2 and is modulated before being output. The output optical signal is split into two orthogonally polarized optical signals by the polarization beam splitter 3. The resonator microcavity 4 is combined into a single signal by the polarization combiner 5 and enters the photodetector 6. After photoelectric conversion, a microwave signal composed of multiple frequency components is output. The microwave signal enters the filter 7 to obtain a 10GHz single-frequency signal. The 10GHz single-frequency signal is split into two paths, A and B, by the power divider. Path A is amplified by the low-noise amplifier 10 and then split into two paths, A1 and A2, by the second power divider 11. Path A1 is used as the signal output, and path A2 is used as the oscillation signal injected into the electro-optic modulator 2. Path B signal enters the frequency locking module and is compared with the reference frequency to further complete the phase-locking process. The proposed solution uses an adjustable resonant microcavity instead of an optical fiber ring to achieve miniaturization while maintaining stability control, thus solving the problem of reduced stability caused by the large structure of existing optoelectronic oscillators.

[0046] Furthermore, the resonator microcavity 4 includes a first microcavity 41 and a second microcavity 42. The first microcavity 41 is connected to the polarization beam splitter 3, the polarization combiner 5, and the frequency stabilization module 9. The second microcavity 42 is connected to the polarization beam splitter 3, the polarization combiner 5, and the frequency stabilization module 9.

[0047] The first microcavity 41 and the second microcavity 42 have a first longitudinal mode spacing and a second longitudinal mode spacing, the range of the first longitudinal mode spacing and the second longitudinal mode spacing being 1nm to 20nm;

[0048] The first longitudinal module interval is equal to an integer multiple of the second longitudinal module interval;

[0049] Furthermore, the frequency stabilization module 9 includes a phase detector 91, a loop filter 92, a voltage-controlled oscillator 93, and a frequency divider 94. The phase detector 91, the loop filter 92, the voltage-controlled oscillator 93, and the frequency divider 94 are connected in sequence, and the frequency divider 94 is connected to the phase detector 91.

[0050] The phase detector 91 is used to output an error signal;

[0051] The loop filter 92 is used to filter out error signals;

[0052] The voltage-controlled oscillator 93 is used to output signals and generate comparison signals;

[0053] The frequency divider 94 is used to feed back the comparison signal proportionally to the phase detector.

[0054] In this embodiment, the frequency stabilization module 9 uses a phase-locked loop (PLL) for frequency locking. The PLL mainly consists of a phase detector 91 (PFD), a loop filter 92 (LPF), a voltage-controlled oscillator 93 (VCO), and a frequency divider 94. When the loop starts working, it is initially assumed that the VCO output is 0. At this time, the phase difference between the two signals input to the PFD (VCO output signal and reference signal) is large, and the error signal output by the PFD reaches its maximum. After the high-frequency components are filtered out by the LPF, the VCO output is controlled to maximize the VCO frequency. Through multiple cycles, the frequencies of the reference signal and the VCO output signal eventually become the same, with a fixed phase difference, and the loop enters a "locked" state.

[0055] When a phase-locked loop is in the locked state, the instantaneous phase difference is a fixed value, so the differential is equal to zero, U. C The value of (t) remains unchanged; when in the unlocked state, the differential is not equal to zero, U C The value of (t) will change. At this time, the error signal obtained is processed by a certain algorithm and then outputs a feedback signal to control the resonator of the SiN resonant single-ring structure, thus completing the phase-locked loop process.

[0056] The present invention uses a polarization beam splitter 3 and a polarization combiner 5 to ensure the polarization orthogonality of the optical field in the double ring, thereby greatly reducing the phase noise effect introduced by the interference beat frequency.

[0057] The frequency stabilization module 9 of this invention uses a phase-locked loop (PLL) to achieve frequency locking. The PLL adjusts the resonant wavelength of the resonator through an output feedback signal, ultimately ensuring frequency stability. The PLL mainly consists of a phase detector 91 (PFD), a loop filter 92 (LPF), a voltage-controlled oscillator 93 (VCO), and a frequency divider 94.

[0058] This invention uses resonant microrings or microcavities as resonators to replace traditional optical fibers. By increasing the resonator's resonant structure length, optimizing the resonator coupling method, and improving the manufacturing process to increase the intrinsic Q-value of the materials, a Q-value of up to 10⁸ can be achieved. A high Q-value reduces link noise. Compared to traditional fiber optic rings, the resonators with microring or microcavity structures are significantly smaller and lighter.

[0059] The resonant wavelength of the resonant microring or microcavity used in this invention can be adjusted by voltage or temperature. Specifically, the temperature control method, which heats the electrodes of the resonator with current, allows for continuous adjustment of the resonant wavelength with an accuracy of 0.05 nm.

[0060] The above-disclosed embodiments are merely preferred embodiments of a miniaturized, highly stable, low-phase-noise optoelectronic oscillator of the present invention, and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that all or part of the processes for implementing the above embodiments, and equivalent variations made in accordance with the claims of the present invention, still fall within the scope of the invention.

Claims

1. A miniaturized, highly stable, low-phase-noise optoelectronic oscillator, characterized in that, The system includes a signal laser, an electro-optic modulator, a polarization beamsplitter, a resonator microcavity, a polarization combiner, a photodetector, a filter, a first power divider, a frequency stabilization module, a low-noise amplifier, and a second power divider. The signal laser, the electro-optic modulator, the polarization beamsplitter, the polarization combiner, the photodetector, the filter, the first power divider, and the frequency stabilization module are connected in sequence. The low-noise amplifier is connected to the first power divider, the second power divider is connected to the low-noise amplifier and to the electro-optic modulator, and the resonator microcavity is connected to the frequency stabilization module. The signal laser is used to output optical signals; The electro-optic modulator is used to modulate the optical signal; The polarization beam splitter is used to split the modulated optical signal into two optical signals with orthogonal polarization states. The resonator microcavity is used to resonate the two optical signals and adjust the resonant wavelength. The polarization combiner is used to combine the two optical signals into one signal; The photodetector is used to transform the signal into a microwave signal. The filter is used to filter the microwave signal to obtain a single-frequency signal; The first power divider is used to divide the single-frequency signal into a first signal and a second signal; The frequency stabilization module uses the second signal to compare with the reference frequency to complete the phase-locking process; The low-noise amplifier is used to amplify the first signal to obtain an amplified signal. The second power divider is used to divide the amplified signal into an output signal and an oscillation signal.

2. The miniaturized, highly stable, low-phase-noise optoelectronic oscillator as described in claim 1, characterized in that, The resonator microcavity includes a first microcavity and a second microcavity. The first microcavity is connected to the polarization beam splitter, the polarization combiner, and the frequency stabilization module. The second microcavity is connected to the polarization beam splitter, the polarization combiner, and the frequency stabilization module.

3. The miniaturized, highly stable, low-phase-noise optoelectronic oscillator as described in claim 2, characterized in that, The first microcavity and the second microcavity have a first longitudinal mode spacing and a second longitudinal mode spacing, the first longitudinal mode spacing and the second longitudinal mode spacing being in the range of 1 nm to 20 nm.

4. The miniaturized, highly stable, low-phase-noise optoelectronic oscillator as described in claim 3, characterized in that, The first longitudinal module interval is equal to an integer multiple of the second longitudinal module interval.

5. A miniaturized, highly stable, low-phase-noise optoelectronic oscillator as described in claim 4, characterized in that, The frequency stabilization module includes a phase detector, a loop filter, a voltage-controlled oscillator, and a frequency divider. The phase detector, the loop filter, the voltage-controlled oscillator, and the frequency divider are connected in sequence, and the frequency divider is connected to the phase detector. The phase detector is used to output an error signal; The loop filter is used to filter out error signals; The voltage-controlled oscillator is used to output signals and generate comparison signals; The frequency divider is used to feed back the comparison signal to the phase detector in a proportional manner.

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