Optoelectronic injection-locked frequency division method and system

Abstract

This invention provides a photoelectric oscillation injection locking frequency division method and system. The system includes: an oscillation loop and a frequency division loop connected to the oscillation loop; the oscillation loop generates an oscillation signal and transmits the oscillation signal to the frequency division loop; the frequency division loop receives an input optical signal and a reference signal, performs optical up-frequency multiplication on the oscillation signal output by the oscillation loop based on the input optical signal to obtain a frequency-multiplied signal, mixes the frequency-multiplied signal and the reference signal, outputs a feedback signal, and transmits the feedback signal to the oscillation loop; the oscillation loop adjusts the oscillation signal in the oscillation loop based on the feedback signal output by the frequency division loop until the oscillation signal output by the oscillation loop and the feedback signal output by the frequency division loop are locked, and the feedback signal in the locked state is used as the final output frequency division signal. This invention can achieve high-order frequency division of electrical signals and reduce phase noise.

Description

Technical Field

[0001] This invention relates to the field of microwave photonics technology, and in particular to a photoelectric oscillation injection locking frequency division method and system. Background Technology

[0002] Frequency division systems are used to lock onto a fractional frequency of an input reference signal. They can be used to process analog or digital signals and are key components in systems such as frequency synthesizers and phase-locked loops (PLLs). Frequency division plays a crucial role in applications such as telecommunications systems, radar, and optical frequency tracking. The added phase noise of a frequency division system directly affects the phase noise of the output signal, largely determining the highest performance level achievable by the entire system. For example, in Doppler radar, lower phase noise near the carrier increases sensitivity to slow-moving objects. Therefore, frequency division systems with low phase noise are needed in radar and other sensing and detection applications to support the continuous development of technology. Thus, developing frequency division systems with low added phase noise is very important. Currently, frequency division is mainly implemented through digital and analog frequency division. Analog frequency division has proven to operate relatively well in higher frequency ranges with relatively good phase noise performance.

[0003] Due to their low phase noise performance and ease of frequency tuning, optoelectronic oscillators can also be used in frequency division systems. For example, there is a low phase noise divider based on an injection-locked optoelectronic oscillator (OEO) with an output signal frequency of 10 GHz and a phase noise of -130 dBc / Hz at a 10 kHz offset. However, studies on this divider have not separately analyzed the additive phase noise, and its division factor cannot be higher.

[0004] Existing frequency division systems use light for frequency division, which can only achieve a 2-fold division. The division coefficient is fixed and cannot be adjusted, which cannot meet common requirements such as phase-locked loops and clock synchronization. In addition, the added phase noise is relatively high, which will introduce additional noise in specific applications and thus affect the system performance. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a photoelectric oscillation injection locking frequency division method and system to eliminate or improve one or more defects existing in the prior art.

[0006] One aspect of the present invention provides a photoelectric oscillation injection locked frequency division system, the system comprising: an oscillation loop and a frequency division loop connected to the oscillation loop;

[0007] The oscillation loop generates an oscillation signal and transmits the oscillation signal to the frequency division loop;

[0008] The frequency division loop receives an input optical signal and a reference signal, performs optical up-frequency multiplication on the oscillation signal output by the oscillation loop based on the input optical signal to obtain a frequency multiplied signal, mixes the frequency multiplied signal and the reference signal, outputs a feedback signal, and transmits the feedback signal to the oscillation loop.

[0009] The oscillation loop adjusts the oscillation signal in the oscillation loop based on the feedback signal output by the frequency division loop until the oscillation signal output by the oscillation loop and the feedback signal output by the frequency division loop are locked together. The feedback signal in the locked state is used as the final output frequency division signal.

[0010] In some embodiments of the present invention, the oscillating loop includes a combiner, a phase shifter, a first filter, and a first low-noise amplifier;

[0011] The first low-noise amplifier is used to receive the natural thermal noise in the oscillation loop, amplify the natural thermal noise, generate a noise signal, and transmit the noise signal to the first filter through the combiner and the phase shifter;

[0012] The first filter is used to select an oscillation noise signal within the target oscillation frequency range from the noise signal and transmit the oscillation noise signal to the first low-noise amplifier;

[0013] The first low-noise amplifier is also used to amplify the oscillation noise signal and provide loop gain, generate an oscillating electrical signal, and transmit the oscillating electrical signal to the combiner;

[0014] The combiner is used to transmit the oscillating electrical signal output by the first low-noise amplifier to the frequency division loop; it is also used to receive the feedback signal output by the frequency division loop, and transmit the oscillating electrical signal output by the first low-noise amplifier and the feedback signal output by the frequency division loop to the phase shifter; and it is also used to finally output the feedback signal as the frequency division signal.

[0015] The phase shifter is used to adjust the oscillating electrical signal output by the first low-noise amplifier based on the feedback signal output by the frequency division loop, and transmits the adjusted oscillating electrical signal to the first filter;

[0016] The first filter is also used to filter the regulated oscillating electrical signal and transmit the filtered oscillating electrical signal to the first low-noise amplifier;

[0017] The first low-noise amplifier is also used to supplement the power loss generated during the oscillation process of the filtered oscillating electrical signal, and to transmit the oscillating electrical signal after supplementing the power loss to the combiner.

[0018] In some embodiments of the present invention, the reference signal is a reference electrical signal, and the frequency division loop includes a frequency multiplier module, a photodetector, a second filter, a second low-noise amplifier, and a mixer;

[0019] The frequency doubling module is used to receive the input optical signal from the laser and the oscillation signal output by the oscillation loop, perform optical up-frequency doubling on the oscillation signal based on the input optical signal, output the frequency-doubled optical signal, and transmit the frequency-doubled optical signal to the photodetector;

[0020] The photodetector is used to mix and convert the frequency-doubled optical signal into a photoelectric signal, output a frequency-doubled electrical signal, and transmit the frequency-doubled electrical signal to the second filter;

[0021] The second filter is used to filter the frequency-doubled electrical signal and transmit the filtered frequency-doubled electrical signal to the second low-noise amplifier;

[0022] The second low-noise amplifier is used to amplify the filtered frequency-doubled electrical signal and transmit the amplified frequency-doubled electrical signal to the mixing module;

[0023] The mixing module is used to receive the reference electrical signal, mix the amplified frequency-multiplied electrical signal and the reference electrical signal, output a feedback electrical signal, and transmit the feedback electrical signal to the oscillation loop.

[0024] In some embodiments of the present invention, the frequency multiplier module is a Mach-Zehnder modulator or an electric frequency multiplier.

[0025] In some embodiments of the present invention, the difference between the frequency division coefficient and the frequency harmonic coefficient of the system is 1.

[0026] In some embodiments of the present invention, the frequency division coefficient is an adjustable frequency division coefficient of any order.

[0027] Another aspect of the present invention provides a photoelectric oscillation injection locking frequency division method, which is implemented by a photoelectric oscillation injection locking frequency division system, the system including an oscillation loop and a frequency division loop connected to the oscillation loop; the method includes the following steps:

[0028] The oscillation loop generates an oscillation signal and transmits the oscillation signal to the frequency division loop;

[0029] The frequency division loop receives an input optical signal and a reference signal, performs optical up-frequency multiplication on the oscillation signal output by the oscillation loop based on the input optical signal to obtain a frequency multiplied signal, mixes the frequency multiplied signal and the reference signal, outputs a feedback signal, and transmits the feedback signal to the oscillation loop.

[0030] The oscillation loop adjusts the oscillation signal in the oscillation loop based on the feedback signal output by the frequency division loop until the oscillation signal output by the oscillation loop and the feedback signal output by the frequency division loop are locked together. The feedback signal in the locked state is used as the final output frequency division signal.

[0031] In some embodiments of the present invention, the oscillation loop includes a combiner, a phase shifter, a first filter, and a first low-noise amplifier; the oscillation loop generates an oscillation signal and transmits the oscillation signal to the frequency division loop, including:

[0032] The first low-noise amplifier receives the natural thermal noise in the oscillation loop, amplifies the natural thermal noise, generates a noise signal, and transmits the noise signal to the first filter through the combiner and the phase shifter;

[0033] The first filter selects an oscillation noise signal within the target oscillation frequency range from the noise signal and transmits the oscillation noise signal to the first low-noise amplifier.

[0034] The first low-noise amplifier amplifies the oscillation noise signal and provides loop gain to generate an oscillating electrical signal, and transmits the oscillating electrical signal to the combiner;

[0035] The combiner transmits the oscillating electrical signal to the frequency division loop.

[0036] In some embodiments of the present invention, the oscillation loop adjusts the oscillation signal in the oscillation loop based on the feedback signal output by the frequency division loop, including:

[0037] The combiner receives the feedback signal output from the frequency divider loop and transmits the oscillation signal output from the first low-noise amplifier and the feedback signal output from the frequency divider loop to the phase shifter.

[0038] The phase shifter adjusts the oscillating electrical signal output by the first low-noise amplifier based on the feedback signal output by the frequency division loop, and transmits the adjusted oscillating electrical signal to the first filter;

[0039] The first filter filters the adjusted oscillating electrical signal and transmits the filtered oscillating electrical signal to the first low-noise amplifier;

[0040] The first low-noise amplifier compensates for the power loss generated during the oscillation process of the filtered oscillating electrical signal, and transmits the oscillating electrical signal after power loss compensation to the combiner.

[0041] In some embodiments of the present invention, the reference signal is a reference electrical signal, and the frequency division loop includes a frequency multiplier module, a photodetector, a second filter, a second low-noise amplifier, and a mixer; the frequency division loop receives an input optical signal and a reference signal, performs optical up-frequency multiplication on the oscillation signal output by the oscillation loop based on the input optical signal to obtain a frequency-multiplied signal, mixes the frequency-multiplied signal and the reference signal, outputs a feedback signal, and transmits the feedback signal to the oscillation loop, including:

[0042] The frequency doubling module receives the input optical signal from the laser and the oscillation signal output from the oscillation loop, performs optical up-frequency doubling on the oscillation signal based on the input optical signal, outputs the frequency-doubled optical signal, and transmits the frequency-doubled optical signal to the photodetector;

[0043] The photodetector performs frequency mixing and photoelectric conversion on the frequency-doubled optical signal, outputs a frequency-doubled electrical signal, and transmits the frequency-doubled electrical signal to the second filter;

[0044] The second filter filters the frequency-doubled electrical signal and transmits the filtered frequency-doubled electrical signal to the second low-noise amplifier;

[0045] The second low-noise amplifier amplifies the filtered frequency-doubled electrical signal and transmits the amplified frequency-doubled electrical signal to the mixing module;

[0046] The mixing module receives the reference electrical signal, mixes the amplified frequency-multiplied electrical signal and the reference electrical signal, outputs a feedback electrical signal, and transmits the feedback electrical signal to the oscillation loop.

[0047] The present invention discloses a photoelectric oscillation injection-locked frequency division method and system. This system generates a fundamental frequency signal (oscillation signal) through photoelectric oscillation. The fundamental frequency signal is first modulated onto light and then frequency-multiplied. The frequency multiplication process is performed on the light itself. The multiplied signal is mixed with a reference signal to be divided, and the resulting down-converted signal is injected back into the oscillation loop. Locking is achieved when the frequency of the down-converted signal is approximately equal to or exactly the same as the fundamental frequency signal, thereby achieving frequency division and reducing phase noise. This system uses light for frequency division, effectively utilizing the advantage of the large bandwidth of light, resulting in a high usable frequency. Its frequency division coefficient is determined by the frequency multiplication coefficient, enabling not only low-order but also high-order frequency division coefficients, and the frequency division coefficient is adjustable.

[0048] Additional advantages, objects, and features of the invention will be set forth in part in the description which follows, and will also become apparent in part to those skilled in the art upon studying the description, or may be learned by practice of the invention. The objects and other advantages of the invention can be realized and obtained by means of the structures specifically pointed out in the description and drawings.

[0049] Those skilled in the art will understand that the objectives and advantages achievable with the present invention are not limited to those specifically described above, and that the above and other objectives achievable with the present invention will become clearer from the following detailed description. Attached Figure Description

[0050] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, are not intended to limit the scope of the invention.

[0051] Figure 1 This is a schematic diagram of a photoelectric oscillation injection locking frequency division system according to an embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram of a photoelectric oscillation injection locking frequency division system according to another embodiment of the present invention;

[0053] Figure 3 This is a schematic flowchart of a photoelectric oscillation injection locking frequency division method according to an embodiment of the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. Here, the illustrative embodiments and descriptions of this invention are used to explain the invention, but are not intended to limit the invention.

[0055] It should also be noted that, in order to avoid obscuring the invention with unnecessary details, only the structures and / or processing steps closely related to the solution according to the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0056] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, element, step, or component, but does not exclude the presence or addition of one or more other features, elements, steps, or components.

[0057] It should also be noted that, unless otherwise specified, the term "connection" in this article can refer not only to a direct connection, but also to an indirect connection involving an intermediary.

[0058] In the following description, embodiments of the invention will be illustrated with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same or similar parts, or the same or similar steps.

[0059] Existing frequency division systems, which use light for frequency division, can only achieve a 2:2 division, with a fixed and unadjustable division coefficient, and suffer from high added phase noise. This makes them unsuitable for common requirements such as phase-locked loops (PLLs) and clock synchronization. Furthermore, they introduce additional noise in practical applications, resulting in poor system performance. Therefore, to overcome these shortcomings, this invention provides a photoelectric oscillation injection-locked frequency division method and system. This method uses photoelectric oscillation for feedback locking to achieve frequency division. Moreover, both the oscillation frequency and the division coefficient of the photoelectric oscillation are adjustable, while the phase noise of the divided signal and the system is effectively suppressed.

[0060] Figure 1 This is a schematic diagram of a photoelectric oscillation injection locking frequency division system according to an embodiment of the present invention. Figure 1 As shown, the system includes: an oscillation loop and a frequency division loop connected to the oscillation loop;

[0061] The oscillation loop generates an oscillation signal and transmits the oscillation signal to the frequency division loop;

[0062] The frequency division loop receives an input optical signal and a reference signal, performs optical up-frequency multiplication on the oscillation signal output by the oscillation loop based on the input optical signal to obtain a frequency multiplied signal, mixes the frequency multiplied signal and the reference signal, outputs a feedback signal, and transmits the feedback signal to the oscillation loop.

[0063] The oscillation loop adjusts the oscillation signal in the oscillation loop based on the feedback signal output by the frequency division loop until the oscillation signal output by the oscillation loop and the feedback signal output by the frequency division loop are locked together. The feedback signal in the locked state is used as the final output frequency division signal.

[0064] Specifically, the reference signal of the input frequency division loop can be any electrical signal to be divided, such as the radio frequency signal to be divided. In this case, the input optical signal of the input frequency division loop only serves as a carrier to modulate the oscillation signal onto the light, providing a carrier frequency. Both the oscillation signal and the input optical signal are input into the frequency division loop. The frequency division loop modulates the oscillation signal onto the input optical signal (optical carrier) and achieves frequency multiplication of the oscillation signal.

[0065] If the frequency divider loop outputs a feedback signal for the first time, and this feedback signal can lock with the oscillation signal initially generated by the oscillation loop (their frequencies are the same, essentially the same, or close), then this feedback signal is used as the final frequency divider signal and output, thus achieving frequency division. If the frequency divider loop outputs a feedback signal for the first time, and this feedback signal cannot lock with the oscillation signal initially generated by the oscillation loop, then the oscillation loop adjusts the initially generated oscillation signal according to the first output feedback signal. After oscillating this oscillation signal once within the oscillation loop, the adjusted oscillation signal is output (the second output oscillation signal) and transmitted to the frequency divider loop. After another cycle through the frequency divider loop, the frequency divider loop outputs a corresponding feedback signal for the second time. If the frequency of this second output feedback signal is the same, essentially the same, or close to the frequency of the adjusted oscillation signal, then locking is achieved. Otherwise, the oscillation loop adjusts and outputs the oscillation signal multiple times according to the above process, with the frequency divider loop outputting a corresponding feedback signal each time, until each output feedback signal locks with the corresponding adjusted oscillation signal. While achieving locking, the system can effectively suppress additional phase noise.

[0066] In other words, the photoelectric oscillation injection locking frequency division system of this embodiment generates a fundamental frequency signal (oscillation signal) through photoelectric oscillation. This fundamental frequency signal is first modulated onto light and then frequency-multiplied. The frequency multiplication process is performed on the light itself. The multiplied signal is mixed with the reference signal to be divided, and the resulting down-converted signal is injected back into the oscillation loop. Locking is achieved when the frequency of the down-converted signal is approximately equal to or exactly the same as the fundamental frequency signal, thus achieving frequency division and reducing phase noise. This system uses light for frequency division, effectively utilizing the advantage of the large bandwidth of light, resulting in a high usable frequency. Its frequency division coefficient is determined by the frequency multiplication coefficient and satisfies a relationship where the difference between the two is 1. It can achieve not only low-order frequency division coefficients but also high-order frequency division coefficients, and the frequency division coefficients are adjustable.

[0067] In one embodiment of the present invention, as Figure 2 As shown, the oscillation loop includes a combiner, a phase shifter, a first filter, and a first low-noise amplifier;

[0068] The first low-noise amplifier is used to receive the natural thermal noise in the oscillation loop, amplify the natural thermal noise, generate a noise signal, and transmit the noise signal to the first filter through the combiner and the phase shifter;

[0069] The first filter is used to select an oscillation noise signal within the target oscillation frequency range from the noise signal and transmit the oscillation noise signal to the first low-noise amplifier;

[0070] The first low-noise amplifier is also used to amplify the oscillation noise signal and provide loop gain, generate an oscillating electrical signal, and transmit the oscillating electrical signal to the combiner;

[0071] The combiner is used to transmit the oscillating electrical signal output by the first low-noise amplifier to the frequency division loop; it is also used to receive the feedback signal output by the frequency division loop, and transmit the oscillating electrical signal output by the first low-noise amplifier and the feedback signal output by the frequency division loop to the phase shifter; and it is also used to finally output the feedback signal as the frequency division signal.

[0072] The phase shifter is used to adjust the oscillating electrical signal output by the first low-noise amplifier based on the feedback signal output by the frequency division loop, and transmits the adjusted oscillating electrical signal to the first filter;

[0073] The first filter is also used to filter the regulated oscillating electrical signal and transmit the filtered oscillating electrical signal to the first low-noise amplifier;

[0074] The first low-noise amplifier is also used to supplement the power loss generated during the oscillation process of the filtered oscillating electrical signal, and to transmit the oscillating electrical signal after supplementing the power loss to the combiner.

[0075] In this embodiment, specifically, as follows: Figure 2 As shown, the passband range of the first filter is the target oscillation frequency range, i.e., the oscillation range of the oscillation loop. The center frequency and bandwidth of the first filter can be adjusted according to the approximate frequency of the signal to be divided and the preset division coefficients, thus allowing the selection of different first filters. The first filter controls the oscillation frequency range of the oscillation loop. The oscillation loop mainly starts oscillating from noise through the first low-noise amplifier (ensuring signal oscillation) and the first filter, forming a stable oscillation signal. The combiner has two inputs and three outputs. One input receives the oscillation signal output from the first low-noise amplifier, and the first output transmits the oscillation signal to the frequency multiplier module. The other input is a feedback input, receiving the feedback signal injected by the mixer module in the frequency division loop. The second output transmits the oscillation signal and the feedback signal to the phase shifter. The phase shifter can adjust the oscillation frequency of the oscillation signal by controlling the phase within the filter passband based on the feedback signal, adjusting the cavity length or cavity delay (referring to the duration of one oscillation cycle in the oscillation loop). The regulated oscillation signal passes through the first filter and the first low-noise amplifier, and is then transmitted to the frequency division loop by the first output of the combiner. Through multiple oscillations of the oscillation loop and the frequency division loop, the output feedback signal is injected into the oscillation loop multiple times. The third output of the combiner is connected to the phase noise analyzer, and the final output frequency division signal after locking is transmitted to the phase noise analyzer for phase noise analysis.

[0076] For example, the oscillation signals output by the first and second channels of the combiner are Where, |x osc | indicates the amplitude of the oscillation signal. denoted by phase noise, fosc represents the oscillation frequency. The oscillation signal from the second output of the combiner propagates within the oscillation loop, obtaining a gain g1 and a delay τ after one complete propagation cycle or oscillation cycle (one oscillation rotation). The expression for the oscillation signal at this point becomes: The simplified photoelectric oscillation equation is:

[0077] Figure 2 This is a schematic diagram of a photoelectric oscillation injection locking frequency division system according to another embodiment of the present invention. Figure 2 As shown, the reference signal is a reference electrical signal, and the frequency division loop includes a frequency multiplier module, a photodetector, a second filter, a second low-noise amplifier, and a mixer;

[0078] The frequency doubling module is used to receive the input optical signal from the laser and the oscillation signal output by the oscillation loop, perform optical up-frequency doubling on the oscillation signal based on the input optical signal, output the frequency-doubled optical signal, and transmit the frequency-doubled optical signal to the photodetector;

[0079] The photodetector is used to mix and convert the frequency-doubled optical signal into a photoelectric signal, output a frequency-doubled electrical signal, and transmit the frequency-doubled electrical signal to the second filter;

[0080] The second filter is used to filter the frequency-doubled electrical signal and transmit the filtered frequency-doubled electrical signal to the second low-noise amplifier;

[0081] The second low-noise amplifier is used to amplify the filtered frequency-doubled electrical signal and transmit the amplified frequency-doubled electrical signal to the mixing module;

[0082] The mixing module is used to receive the reference electrical signal, mix the amplified frequency-multiplied electrical signal and the reference electrical signal, output a feedback electrical signal, and transmit the feedback electrical signal to the oscillation loop.

[0083] In this embodiment, the photoelectric oscillation injection-locked frequency division system described above achieves frequency division of the electrical signal to be divided. The frequency multiplication module uses a Mach-Zehnder modulator (MZM), and the mixing module uses a mixer. The photodetector used in this embodiment has both mixing and photoelectric conversion functions. Specifically, the oscillation loop outputs an oscillating electrical signal with a frequency of fosc through its own oscillation and transmits it to the Mach-Zehnder modulator, which serves as the frequency multiplication module. Assuming that the frequency of the input optical signal emitted by the laser to the Mach-Zehnder modulator is f and the frequency multiplication factor is K, the oscillating electrical signal with a frequency of fosc and the input optical signal with a frequency of f pass through the Mach-Zehnder modulator. The frequency-multiplied optical signal output by the Mach-Zehnder modulator includes separate optical signals with signal frequencies of f, f+fosc, f+2fosc, ..., and f+Kfosc. This input optical signal only provides the carrier frequency for modulating the oscillating electrical signal onto the optical carrier. Optical signals with frequencies of f, f+fosc, f+2fosc, ..., and f+Kfosc are passed through a photodetector. The photodetector then performs photoelectric conversion and mixing on these signals, outputting harmonic electrical signals with frequencies of fosc, 2fosc, ..., and Kfosc. The harmonic electrical signals output by the photodetector are then filtered by a second filter to remove noise. The second filter removes harmonic electrical signals with frequencies of fosc, 2fosc, ..., and (K-1)fosc, outputting a harmonic electrical signal with a frequency of Kfosc, which is then amplified by a second low-noise amplifier. Then, the amplified frequency-multiplied electrical signal with a frequency of Kfosc and the RF reference signal to be divided with a frequency of f0 are input together into a mixer for mixing. The mixer outputs a feedback electrical signal with a frequency of f0-Kfosc. By adjusting the frequencies of the oscillation signal and the feedback signal, the relationship f0-Kfosc=fosc is satisfied, thus obtaining f0=(K+1)fosc. In this way, the frequency of the electrical signal to be divided with a frequency of (K+1)fosc is divided, and the final output is a divided electrical signal with a frequency of fosc, that is, the K+1 frequency division of the electrical signal to be divided is achieved (the division coefficient is K+1).

[0084] Therefore, the difference between the division coefficient K+1 and the multiplication coefficient K in the photoelectric oscillation injection locked frequency division system of this embodiment is 1. Furthermore, this system can generate adjustable frequency division coefficients of any order, achieving not only division by two but also higher-order division coefficients. This is mainly because the system performs frequency division using light. Due to the large bandwidth of light and its high usable frequency, the multiplication coefficient can be very large, and since the division coefficient is determined by the multiplication coefficient, it can also be relatively high.

[0085] The optoelectronic oscillation injection-locked frequency divider system of this embodiment has been experimentally verified. A reference electrical signal to be divided, with a phase noise of -135.9 dBc / Hz and a frequency of 9 GHz, is locked and divided through a 1 GHz oscillation loop and a frequency division loop, ultimately outputting a 1 GHz divided signal. The phase noise of the divided signal is -152 dBc / Hz at a 10 kHz offset, and the system's additional phase noise is -155 dBc / Hz, achieving a nine-way division and reducing the phase noise of the divided signal. The system's additional phase noise is effectively suppressed. Furthermore, compared to the existing low-phase-noise frequency divider based on injection-locked OEO, whose output frequency-divided signal has a phase noise of -130 dBc / Hz at a 10 kHz offset, this system exhibits superior performance.

[0086] In summary, the photoelectric oscillation injection locking frequency division system of this embodiment achieves frequency division of the reference electrical signal, with a high and adjustable division coefficient, while effectively suppressing the additional phase noise of the system, exhibiting good performance.

[0087] In one embodiment of the present invention, the frequency multiplier module is a Mach-Zehnder modulator or an electrical frequency multiplier. That is, the frequency multiplier module can be an MZM or an electrical frequency multiplier. In other embodiments, the Mach-Zehnder modulator in the above embodiments can be replaced by an integrated electrical frequency multiplier.

[0088] Figure 3 This is a schematic flowchart of a photoelectric oscillation injection locking frequency division method according to an embodiment of the present invention. Figure 3 As shown, this method is implemented through the aforementioned photoelectric oscillation injection-locked frequency division system, which includes an oscillation loop and a frequency division loop connected to the oscillation loop. The method includes the following steps:

[0089] Step S310: The oscillation loop generates an oscillation signal and transmits the oscillation signal to the frequency division loop;

[0090] Step S320: The frequency division loop receives the input optical signal and the reference signal, performs optical up-frequency doubling on the oscillation signal output by the oscillation loop based on the input optical signal to obtain a frequency-doubled signal, mixes the frequency-doubled signal and the reference signal, outputs a feedback signal, and transmits the feedback signal to the oscillation loop.

[0091] In step S330, the oscillation loop adjusts the oscillation signal in the oscillation loop based on the feedback signal output by the frequency division loop until the oscillation signal output by the oscillation loop and the feedback signal output by the frequency division loop are locked together. The feedback signal in the locked state is used as the final output frequency division signal.

[0092] In another embodiment of the present invention, a photoelectric oscillation injection-locked frequency division method is implemented through a photoelectric oscillation injection-locked frequency division system. This system includes an oscillation loop and a frequency division loop connected to the oscillation loop. The frequency division loop includes a frequency multiplier module, a photodetector, a second filter, a second low-noise amplifier, and a mixer module. The reference signal is a reference electrical signal. The method includes the following steps:

[0093] Step S410: The oscillation loop generates an oscillation electrical signal and transmits the oscillation electrical signal to the frequency multiplier module;

[0094] Step S420: The frequency doubling module receives the input optical signal from the laser, performs optical up-frequency doubling on the oscillating electrical signal output by the oscillating loop based on the input optical signal, outputs a frequency-doubled optical signal, and transmits the frequency-doubled optical signal to the photodetector;

[0095] In step S430, the photodetector performs frequency mixing and photoelectric conversion on the frequency-doubled optical signal, outputs a frequency-doubled electrical signal, and transmits the frequency-doubled electrical signal to the second filter;

[0096] Step S440: The second filter filters the frequency-doubled electrical signal and transmits the filtered frequency-doubled electrical signal to the second low-noise amplifier;

[0097] Step S450: The second low-noise amplifier amplifies the filtered frequency-doubled electrical signal and transmits the amplified frequency-doubled electrical signal to the mixing module.

[0098] Step S460: The mixing module receives the reference electrical signal, mixes the amplified frequency-multiplied electrical signal and the reference electrical signal, outputs a feedback electrical signal, and transmits the feedback electrical signal to the oscillation loop.

[0099] In step S470, the oscillation loop adjusts the oscillation signal in the oscillation loop based on the feedback signal output by the mixer module until the oscillation signal output by the oscillation loop and the feedback signal output by the mixer module are locked together. The feedback signal in the locked state is used as the final output frequency division signal.

[0100] In one embodiment of the present invention, the oscillation loop includes a combiner, a phase shifter, a first filter, and a first low-noise amplifier; step S410, in which the oscillation loop generates an oscillating electrical signal and transmits the oscillating electrical signal to the frequency multiplier module, includes the following steps:

[0101] The first low-noise amplifier receives the natural thermal noise in the oscillation loop, amplifies the natural thermal noise, generates a noise signal, and transmits the noise signal to the first filter through the combiner and the phase shifter;

[0102] The first filter selects an oscillation noise signal within the target oscillation frequency range from the noise signal and transmits the oscillation noise signal to the first low-noise amplifier.

[0103] The first low-noise amplifier amplifies the oscillation noise signal and provides loop gain to generate an oscillating electrical signal, and transmits the oscillating electrical signal to the combiner;

[0104] The combiner transmits the oscillating electrical signal to the frequency multiplier module.

[0105] In one embodiment of the present invention, the oscillation loop in step S470 adjusts the oscillation signal in the oscillation loop based on the feedback electrical signal output by the mixer module or the photodetector, including the following steps:

[0106] The combiner receives the feedback electrical signal output by the mixing module or the photodetector, and transmits the oscillation electrical signal output by the first low-noise amplifier and the feedback electrical signal output by the mixing module or the photodetector to the phase shifter.

[0107] The phase shifter adjusts the oscillating electrical signal output by the first low-noise amplifier based on the feedback electrical signal output by the mixer module or the photodetector, and transmits the adjusted oscillating electrical signal to the first filter.

[0108] The first filter filters the adjusted oscillating electrical signal and transmits the filtered oscillating electrical signal to the first low-noise amplifier;

[0109] The first low-noise amplifier compensates for the power loss generated during the oscillation process of the filtered oscillating electrical signal, and transmits the oscillating electrical signal after power loss compensation to the combiner.

[0110] It should be clarified that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of the present invention.

[0111] In this invention, features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with or in place of features of other embodiments.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations of the embodiments of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A photoelectric oscillation injection locking frequency division system, characterized in that, The system includes: an oscillation loop and a frequency division loop connected to the oscillation loop; the oscillation loop includes a combiner, a phase shifter, a first filter, and a first low-noise amplifier connected in sequence, with the output of the first low-noise amplifier connected to one input of the combiner; the frequency division loop includes a frequency multiplier module, a photodetector, a second filter, a second low-noise amplifier, and a mixer module connected in sequence, with the output of the mixer module connected to the other input of the combiner, and one input of the frequency multiplier module connected to one output of the combiner; The oscillation loop generates an oscillation signal and transmits the oscillation signal to the frequency division loop; The frequency division loop receives an input optical signal and a reference signal, performs optical up-frequency multiplication on the oscillation signal output by the oscillation loop based on the input optical signal to obtain a frequency multiplied signal, mixes the frequency multiplied signal and the reference signal, outputs a feedback signal, and transmits the feedback signal to the oscillation loop. The oscillation loop adjusts the oscillation signal in the oscillation loop based on the feedback signal output by the frequency division loop until the oscillation signal output by the oscillation loop and the feedback signal output by the frequency division loop are locked together. The feedback signal in the locked state is used as the final output frequency division signal.

2. The system according to claim 1, characterized in that, The oscillation loop includes a combiner, a phase shifter, a first filter, and a first low-noise amplifier; The first low-noise amplifier is used to receive the natural thermal noise in the oscillation loop, amplify the natural thermal noise, generate a noise signal, and transmit the noise signal to the first filter through the combiner and the phase shifter; The first filter is used to select an oscillation noise signal within the target oscillation frequency range from the noise signal and transmit the oscillation noise signal to the first low-noise amplifier; The first low-noise amplifier is also used to amplify the oscillation noise signal and provide loop gain, generate an oscillating electrical signal, and transmit the oscillating electrical signal to the combiner; The combiner is used to transmit the oscillating electrical signal output by the first low-noise amplifier to the frequency division loop; it is also used to receive the feedback signal output by the frequency division loop, and transmit the oscillating electrical signal output by the first low-noise amplifier and the feedback signal output by the frequency division loop to the phase shifter; and it is also used to finally output the feedback signal as the frequency division signal. The phase shifter is used to adjust the oscillating electrical signal output by the first low-noise amplifier based on the feedback signal output by the frequency division loop, and transmits the adjusted oscillating electrical signal to the first filter; The first filter is also used to filter the regulated oscillating electrical signal and transmit the filtered oscillating electrical signal to the first low-noise amplifier; The first low-noise amplifier is also used to supplement the power loss generated during the oscillation process of the filtered oscillating electrical signal, and to transmit the oscillating electrical signal after supplementing the power loss to the combiner.

3. The system according to claim 1, characterized in that, The reference signal is a reference electrical signal, and the frequency division loop includes a frequency multiplier module, a photodetector, a second filter, a second low-noise amplifier, and a mixer module; The frequency doubling module is used to receive the input optical signal from the laser and the oscillation signal output by the oscillation loop, perform optical up-frequency doubling on the oscillation signal based on the input optical signal, output the frequency-doubled optical signal, and transmit the frequency-doubled optical signal to the photodetector; The photodetector is used to mix and convert the frequency-doubled optical signal into a photoelectric signal, output a frequency-doubled electrical signal, and transmit the frequency-doubled electrical signal to the second filter; The second filter is used to filter the frequency-doubled electrical signal and transmit the filtered frequency-doubled electrical signal to the second low-noise amplifier; The second low-noise amplifier is used to amplify the filtered frequency-doubled electrical signal and transmit the amplified frequency-doubled electrical signal to the mixing module; The mixing module is used to receive the reference electrical signal, mix the amplified frequency-multiplied electrical signal and the reference electrical signal, output a feedback electrical signal, and transmit the feedback electrical signal to the oscillation loop.

4. The system according to claim 3, characterized in that, The frequency multiplier module is a Mach-Zehnder modulator or an electric frequency multiplier.

5. The system according to any one of claims 1 to 4, characterized in that, The difference between the frequency division coefficient and the frequency multiplication coefficient of the system is 1.

6. The system according to claim 5, characterized in that, The frequency division coefficient is an adjustable frequency division coefficient of any order.

7. A photoelectric oscillation injection locking frequency division method, characterized in that, The method is implemented through a photoelectric oscillation injection locked frequency division system. The system includes an oscillation loop and a frequency division loop connected to the oscillation loop. The oscillation loop includes a combiner, a phase shifter, a first filter, and a first low-noise amplifier connected in sequence, with the output of the first low-noise amplifier connected to one input of the combiner. The frequency division loop includes a frequency multiplier module, a photodetector, a second filter, a second low-noise amplifier, and a mixer module connected in sequence, with the output of the mixer module connected to the other input of the combiner, and one input of the frequency multiplier module connected to one output of the combiner. The method includes: The oscillation loop generates an oscillation signal and transmits the oscillation signal to the frequency division loop; The frequency division loop receives an input optical signal and a reference signal, performs optical up-frequency multiplication on the oscillation signal output by the oscillation loop based on the input optical signal to obtain a frequency multiplied signal, mixes the frequency multiplied signal and the reference signal, outputs a feedback signal, and transmits the feedback signal to the oscillation loop. The oscillation loop adjusts the oscillation signal in the oscillation loop based on the feedback signal output by the frequency division loop until the oscillation signal output by the oscillation loop and the feedback signal output by the frequency division loop are locked together. The feedback signal in the locked state is used as the final output frequency division signal.

8. The method according to claim 7, characterized in that, The oscillation loop includes a combiner, a phase shifter, a first filter, and a first low-noise amplifier; the oscillation loop generates an oscillation signal and transmits the oscillation signal to the frequency division loop, including: The first low-noise amplifier receives the natural thermal noise in the oscillation loop, amplifies the natural thermal noise, generates a noise signal, and transmits the noise signal to the first filter through the combiner and the phase shifter; The first filter selects an oscillation noise signal within the target oscillation frequency range from the noise signal and transmits the oscillation noise signal to the first low-noise amplifier. The first low-noise amplifier amplifies the oscillation noise signal and provides loop gain to generate an oscillating electrical signal, and transmits the oscillating electrical signal to the combiner; The combiner transmits the oscillating electrical signal to the frequency division loop; The oscillation loop adjusts the oscillation signal in the oscillation loop based on the feedback signal output by the frequency division loop, including: The combiner receives the feedback signal output from the frequency divider loop and transmits the oscillation signal output from the first low-noise amplifier and the feedback signal output from the frequency divider loop to the phase shifter. The phase shifter adjusts the oscillating electrical signal output by the first low-noise amplifier based on the feedback signal output by the frequency division loop, and transmits the adjusted oscillating electrical signal to the first filter; The first filter filters the adjusted oscillating electrical signal and transmits the filtered oscillating electrical signal to the first low-noise amplifier; The first low-noise amplifier compensates for the power loss generated during the oscillation process of the filtered oscillating electrical signal, and transmits the oscillating electrical signal after power loss compensation to the combiner.

9. The method according to claim 7, characterized in that, The reference signal is a reference electrical signal. The frequency division loop includes a frequency multiplier module, a photodetector, a second filter, a second low-noise amplifier, and a mixer module. The frequency division loop receives an input optical signal and a reference signal, performs optical up-frequency multiplication on the oscillation signal output by the oscillation loop based on the input optical signal to obtain a frequency-multiplied signal, mixes the frequency-multiplied signal and the reference signal, outputs a feedback signal, and transmits the feedback signal to the oscillation loop, including: The frequency doubling module receives the input optical signal from the laser and the oscillation signal output from the oscillation loop, performs optical up-frequency doubling on the oscillation signal based on the input optical signal, outputs the frequency-doubled optical signal, and transmits the frequency-doubled optical signal to the photodetector; The photodetector performs frequency mixing and photoelectric conversion on the frequency-doubled optical signal, outputs a frequency-doubled electrical signal, and transmits the frequency-doubled electrical signal to the second filter; The second filter filters the frequency-doubled electrical signal and transmits the filtered frequency-doubled electrical signal to the second low-noise amplifier; The second low-noise amplifier amplifies the filtered frequency-doubled electrical signal and transmits the amplified frequency-doubled electrical signal to the mixing module; The mixing module receives the reference electrical signal, mixes the amplified frequency-multiplied electrical signal and the reference electrical signal, outputs a feedback electrical signal, and transmits the feedback electrical signal to the oscillation loop.

10. The method according to any one of claims 7 to 9, characterized in that, The difference between the frequency division coefficient and the frequency multiplication coefficient of the system is 1.

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