Photoelectric oscillation injection locking frequency division method and system

Abstract

The invention provides a photoelectric oscillation injection locking frequency division method and system. The system comprises an oscillation loop and a frequency division loop connected with 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 on-light frequency multiplication on an oscillation signal output by the oscillation loop based on the input optical signal to obtain a frequency multiplication signal, performs frequency mixing on the frequency multiplication signal and the reference signal, outputs a feedback signal, and transmits the feedback signal to the oscillation loop; and 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 a locked state is used as a final output frequency division signal. According to the invention, high-order frequency division of an electric signal can be realized and phase noise can be reduced.

Description

Technical Field

[0001] The present invention relates to the field of microwave photon technology, and in particular to a photoelectric oscillation injection locking frequency division method and system. Background Art

[0002] The frequency division system is used to lock the fractional frequency of the input reference signal. It can be used to process analog or digital signals and is a key component in systems such as frequency synthesizers and phase-locked loops (PLLs). Frequency division plays a vital role in applications such as telecommunication systems, radar, and optical frequency tracking. The additive phase noise of the frequency division system directly affects the phase noise of the output signal and largely determines the highest level of performance that can be achieved by the entire system. For example, in Doppler radar, lower phase noise close to the carrier increases the sensitivity to slow-moving objects. Therefore, in fields such as radar and other sensing and detection applications, frequency division systems with lower phase noise are needed to support the continued development of technology. Therefore, it is very important to develop frequency division systems with lower additive phase noise. At present, frequency division is mainly achieved in two forms: digital frequency division and analog frequency division. Among them, analog frequency division has been proven to work in a higher frequency range with relatively good phase noise performance.

[0003] Since optoelectronic oscillators have the advantages of low phase noise performance and easy tuning of the oscillation frequency, optoelectronic oscillators can also be applied to frequency division systems. For example, there is a low phase noise 2-way divider based on an injection-locked optoelectronic oscillator (OEO), whose output signal frequency is 10GHz and the phase noise is -130dBc / Hz at a 10KHz offset. However, for the study of this 2-way divider, the additive phase noise is not analyzed separately, and its frequency division factor cannot be higher.

[0004] The existing frequency division system can only achieve two-way frequency division through light frequency division. The frequency division coefficient is fixed and cannot be adjusted. It cannot meet common requirements such as phase-locked loops and clock synchronization. In addition, the additional phase noise is high, which will introduce additional noise in specific applications and affect system performance. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides an optoelectronic oscillation injection locked 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 an optoelectronic 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, optically frequency-multiplies 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 with 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, and 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 oscillation 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 a 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 further used to amplify the starting 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 transmit the adjusted oscillating electrical signal to the first filter;

[0016] The first filter is also used to filter the adjusted 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 compensate the power loss generated during the oscillation process of the filtered oscillating electrical signal, and transmit the oscillating electrical signal after the power loss is compensated 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 multiplication module, a photodetector, a second filter, a second low noise amplifier, and a mixer;

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

[0020] The photodetector is used to perform frequency mixing and photoelectric conversion on the frequency-doubled optical 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-doubled 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 multiplication module is a Mach-Zehnder modulator or an electrical frequency multiplier.

[0025] In some embodiments of the present invention, the difference between the frequency division coefficient and the frequency multiplication 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 method for photoelectric oscillation injection locking frequency division, which is implemented by a photoelectric oscillation injection locking frequency division system, wherein the system includes 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, optically frequency-multiplies 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 with 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, and 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 to generate 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 a 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 starting 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 by the frequency division loop, and transmits 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;

[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 the power loss generated during the oscillation process for the filtered oscillating electrical signal, and transmits the oscillating electrical signal after the power loss is compensated to the combiner.

[0041] In some embodiments of the present invention, the reference signal is a reference electrical signal, the frequency division loop includes a frequency multiplication 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, optically multiplies the oscillation signal output by the oscillation loop based on the input optical signal to obtain a frequency multiplication signal, mixes the frequency multiplication signal with the reference signal, outputs a feedback signal, and transmits the feedback signal to the oscillation loop, including:

[0042] The frequency doubling module receives an input optical signal from a laser and an oscillation signal output by the oscillation loop, optically frequency-doubles the oscillation signal based on the input optical signal, outputs a 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-doubled electrical signal and the reference electrical signal, outputs a feedback electrical signal, and transmits the feedback electrical signal to the oscillation loop.

[0047] The photoelectric oscillation injection locking frequency division method and system of the present invention generates a baseband signal (oscillation signal) through photoelectric oscillation, modulates the baseband signal onto light first, and then multiplies the frequency. The multiplication process adopts the method of multiplying the frequency on light. The down-converted signal output after the multiplied signal is mixed with the reference signal to be divided is then injected back into the oscillation loop. When the frequency is approximately equal to or completely the same as the baseband signal, locking is achieved, thereby achieving the purpose of frequency division and reducing phase noise. The system divides the frequency by light, effectively utilizing the advantages of the bandwidth of Guangda, and the available frequency is very high. Its frequency division coefficient is determined by the frequency multiplication coefficient, which can not only realize low-order frequency division coefficients, but also high-order frequency division coefficients, and the frequency division coefficient is adjustable.

[0048] Additional advantages, purposes, and features of the present invention will be described in part in the following description, and will become apparent to those skilled in the art after studying the following, or may be learned from the practice of the present invention. The purposes and other advantages of the present invention may be achieved and obtained by the structures specifically indicated in the specification and the accompanying drawings.

[0049] Those skilled in the art will appreciate that the objectives and advantages that can be achieved with the present invention are not limited to the above specific description, and the above and other objectives that can be achieved by the present invention will be more clearly understood from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of this application, and do not constitute a limitation of the present invention.

[0051] Figure 1 It is a structural schematic diagram of a photoelectric oscillation injection locking frequency division system in one embodiment of the present invention;

[0052] Figure 2 It is a schematic structural diagram of a photoelectric oscillation injection locking frequency division system in another embodiment of the present invention;

[0053] Figure 3 The figure is a flow chart of a photoelectric oscillation injection locked frequency division method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

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

[0056] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, elements, steps or components, 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” herein may refer not only to a direct connection but also to an indirect connection involving an intermediate.

[0058] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

[0059] Since the existing frequency division system can only achieve two-way frequency division through light, the frequency division coefficient is fixed and cannot be adjusted, and the additional phase noise is high, which makes it impossible to meet the common requirements of phase-locked loops, clock synchronization, etc., and additional noise will be introduced in specific applications, and the performance of the system is not good. Therefore, in order to overcome the above defects, the embodiment of the present invention provides a method and system for frequency division by injection locking of photoelectric oscillation, which performs feedback locking based on photoelectric oscillation to achieve frequency division. In addition, the oscillation frequency and frequency division coefficient of the photoelectric oscillation can be adjusted, and the phase noise of the frequency division signal and the system is effectively suppressed.

[0060] Figure 1 FIG. 1 is a schematic diagram of the structure of an optoelectronic oscillation injection locked frequency division system in one 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, optically frequency-multiplies 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 with 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, and 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 directly any electrical signal to be divided, such as the radio frequency electrical signal. At this time, the input optical signal of the input frequency division loop only serves as a carrier for modulating the oscillation signal onto light, providing a carrier frequency. Both the oscillation signal and the input optical signal are input into the frequency division loop, and the oscillation signal is modulated onto the input optical signal (optical carrier) through the frequency division loop, and the frequency doubling of the oscillation signal is achieved.

[0065] When the frequency division loop outputs a feedback signal for the first time and the feedback signal can be locked with the oscillation signal initially generated by the oscillation loop (the frequencies of the two are the same, substantially the same or close), the feedback signal is used as the final frequency division signal and output to achieve frequency division. When the frequency division loop outputs a feedback signal for the first time and the feedback signal cannot be locked with the oscillation signal initially generated by the oscillation loop, the oscillation loop adjusts the initially generated oscillation signal according to the feedback signal output for the first time, and outputs the adjusted oscillation signal (the oscillation signal output for the second time) after the oscillation signal oscillates inside the oscillation loop for one circle and transmits it to the frequency division loop, and then after one circle of the frequency division loop, the frequency division loop outputs the corresponding feedback signal for the second time. If the frequency of the feedback signal output for the second time is the same, substantially the same or close to the frequency of the adjusted oscillation signal, locking is achieved. Otherwise, the oscillation loop adjusts and outputs the oscillation signal multiple times according to the above process, and the frequency division loop outputs the corresponding feedback signal each time until the feedback signal output each time and the corresponding adjusted oscillation signal are locked. While achieving locking, the system can effectively suppress additional phase noise.

[0066] That is to say, the optoelectronic oscillation injection locking frequency division system of this embodiment generates a baseband signal (oscillation signal) through optoelectronic oscillation, modulates the baseband signal onto light first, and then multiplies the frequency. The multiplication process adopts the method of multiplying the frequency on light. The down-converted signal output after mixing the multiplied signal with the reference signal to be divided is then injected back into the oscillation loop. When the frequency is approximately equal or completely the same as the baseband signal, locking is achieved, thereby achieving the purpose of frequency division and reducing phase noise. The system divides the frequency by light, effectively utilizing the advantages of Guangda's bandwidth, and the available frequency is very high. Its frequency division coefficient is determined by the frequency multiplication coefficient and satisfies the relationship that the difference between the two is 1. Not only low-order frequency division coefficients can be achieved, but also high-order frequency division coefficients can be achieved, and the frequency division coefficients are adjustable.

[0067] In one embodiment of the present invention, 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 a 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 further used to amplify the starting 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 transmit the adjusted oscillating electrical signal to the first filter;

[0073] The first filter is also used to filter the adjusted 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 compensate the power loss generated during the oscillation process of the filtered oscillating electrical signal, and transmit the oscillating electrical signal after the power loss is compensated to the combiner.

[0075] In this embodiment, specifically, Figure 2 As shown, the passband range of the first filter is the target starting frequency range, that is, the oscillation range of the oscillation loop. The center frequency and bandwidth of the first filter can be adjusted according to the known approximate frequency of the signal to be divided and the preset frequency division coefficient, so as to select and use different first filters, and the first filter can control the starting frequency range of the oscillation loop. The oscillation loop is mainly started by noise through the first low-noise amplifier (which can ensure the signal oscillation) and the first filter, and a stable oscillation signal is formed through oscillation. The combiner has two input ends and three outputs, one of which receives the oscillation signal output by the first low-noise amplifier, and the first output transmits the oscillation signal to the frequency multiplication module; the other input end is the feedback input end, which receives the feedback signal injected by the mixing module in the frequency division loop, and the second output transmits the oscillation signal and the feedback signal to the phase shifter, and the phase shifter can adjust the cavity length or cavity delay (referring to the duration of one oscillation in the oscillation loop) by controlling the phase according to the feedback signal within the filter passband range, thereby adjusting the oscillation frequency of the oscillation signal. The adjusted oscillation signal passes through the first filter and the first low-noise amplifier and is transmitted to the frequency division loop by the first output of the combiner. The output feedback signal is injected into the oscillation loop multiple times through multiple oscillations of the oscillation loop and the frequency division loop. 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 paths of the combiner are: Among them, |x osc | represents the amplitude of the oscillation signal, represents phase noise, and fosc represents the oscillation frequency. The oscillation signal of the second output of the combiner is transmitted inside the oscillation loop. After a complete transmission cycle or oscillation cycle (one oscillation), the gain g1 and delay τ are obtained. The expression of the oscillation signal at this time becomes: The photoelectric oscillation equation is simplified as follows:

[0077] Figure 2 FIG. 2 is a schematic diagram of the structure of an optoelectronic oscillation injection locked frequency division system in 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 multiplication module, a photodetector, a second filter, a second low noise amplifier and a mixer;

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

[0079] The photodetector is used to perform frequency mixing and photoelectric conversion on the frequency-doubled optical 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-doubled 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 locking frequency division system of the above structure realizes the frequency division of the electrical signal to be divided. The frequency multiplication module adopts Mach-Zehnder modulator (MZM), and the frequency mixing module adopts a mixer. The photodetector used in this embodiment has both the function of frequency mixing and the function of photoelectric conversion. 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 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, the frequency multiplication coefficient 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, and the frequency multiplication optical signal output by the Mach-Zehnder modulator includes separated optical signals with signal frequencies of f, f+fosc, f+2fosc, ..., and f+Kfosc, and the input optical signal only provides a carrier frequency for modulating the oscillating electrical signal onto the optical carrier. The photodetector performs photoelectric conversion and mixing on the frequency-doubled optical signal with the signal frequencies of f, f+fosc, f+2fosc, ..., and f+Kfosc, and outputs a frequency-doubled electrical signal with the signal frequencies of fosc, 2fosc, ..., and Kfosc. The frequency-doubled electrical signal output by the photodetector passes through a second filter to filter out clutter, and the second filter filters out the frequency-doubled electrical signal with the signal frequencies of fosc, 2fosc, ..., and (K-1)fosc, and outputs a frequency-doubled electrical signal with the signal frequency of Kfosc and transmits it to a second low-noise amplifier for amplification. Then, the amplified signal frequency Kfosc and the RF reference signal to be divided with a frequency of f0 are input into the mixer for mixing, and the mixer outputs a feedback signal with a frequency of f0-Kfosc. The frequencies of the oscillating signal and the feedback signal are adjusted to satisfy the relationship: f0-Kfosc=fosc, thus obtaining f0=(K+1)fosc. In this way, the signal to be divided with a frequency of (K+1)fosc is divided, and finally a divided signal with a frequency of fosc is output, that is, K+1 division (division coefficient is K+1) of the signal to be divided is achieved.

[0084] It can be seen that the difference between the frequency division coefficient K+1 and the frequency multiplication coefficient K of the optoelectronic oscillation injection locked frequency division system in this embodiment is 1. In addition, the system can generate an adjustable frequency division coefficient of any order, which can not only achieve frequency division by two, but also achieve a frequency division coefficient of a higher order than frequency division by two. This is mainly because the system divides the frequency through light, and since the bandwidth of light is large, the available frequency is very high, the frequency multiplication coefficient can be very large, and the frequency division coefficient is determined by the frequency multiplication coefficient, so the frequency division coefficient can also be high.

[0085] The optoelectronic oscillation injection locked frequency division system of this embodiment has been verified by experiments. The reference electrical signal to be divided with a phase noise of -135.9dBc / Hz and a frequency of 9GHz is locked and divided through a 1GHz oscillation loop and a frequency division loop, and finally outputs a 1GHz frequency division signal. The phase noise of the frequency division signal is -152dBc / Hz at a 10KHz offset, and the additional phase noise of the system is -155dBc / Hz, that is, nine-frequency division is achieved, and the phase noise of the frequency division signal is reduced, and the additional phase noise of the system is effectively suppressed. At the same time, compared with the existing low-phase noise binary divider based on injection locking OEO, which outputs a binary signal with a phase noise of -130dBc / Hz at a 10KHz offset, the performance of this system is more advantageous.

[0086] In summary, the optoelectronic oscillation injection locked frequency division system of this embodiment realizes the frequency division of the reference electrical signal, the frequency division coefficient can be high and adjustable, and at the same time, the additional phase noise of the system can be effectively suppressed, and the performance is good.

[0087] In one embodiment of the present invention, the frequency multiplication module is a Mach-Zehnder modulator or an electrical frequency multiplier. That is, the frequency multiplication 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 FIG. 1 is a flow chart of a method for photoelectric oscillation injection locking frequency division in one embodiment of the present invention. Figure 3 As shown, the method is implemented by the above-mentioned optoelectronic oscillation injection locking 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 an input optical signal and a reference signal, optically frequency-multiplies 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 with 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, and 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 by a photoelectric oscillation injection locked frequency division system, the system includes an oscillation loop and a frequency division loop connected to the oscillation loop, wherein the frequency division loop includes a frequency multiplication module, a photodetector, a second filter, a second low noise amplifier and a mixing module. The reference signal is a reference electrical signal, and the method includes the following steps:

[0093] Step S410, the oscillation loop generates an oscillating electrical signal, and transmits the oscillating electrical signal to the frequency multiplication module;

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

[0095] Step S430, the photodetector performs 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-doubled 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 oscillating electrical signal in the oscillation loop based on the feedback electrical signal output by the mixing module until the oscillation electrical signal output by the oscillation loop and the feedback electrical signal output by the mixing module are locked, and the feedback electrical 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; in step S410, the oscillation loop generates an oscillating electrical signal and transmits the oscillating electrical signal to the frequency multiplication module, including the following steps:

[0101] The first low noise amplifier receives the natural thermal noise in the oscillation loop, amplifies the natural thermal noise to generate 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 a 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 starting 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 multiplication module.

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

[0106] The combiner receives the feedback electrical signal output by the frequency mixing module or the photodetector, and transmits the oscillating electrical signal output by the first low noise amplifier and the feedback electrical signal output by the frequency 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 mixing 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 the power loss generated during the oscillation process for the filtered oscillating electrical signal, and transmits the oscillating electrical signal after the power loss is compensated to the combiner.

[0110] It should be clear that the present invention is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known method is 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, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present invention.

[0111] In the present 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 features of other embodiments or replace features of other embodiments.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An optoelectronic oscillation injection locked frequency division system, characterized in that: The system comprises: an oscillating loop and a frequency dividing loop connected to the oscillating 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, optically frequency-multiplies 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 with 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.

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 a 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 further used to amplify the starting 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 transmit the adjusted oscillating electrical signal to the first filter; The first filter is also used to filter the adjusted 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 compensate the power loss generated during the oscillation process of the filtered oscillating electrical signal, and transmit the oscillating electrical signal after the power loss is compensated 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 multiplication module, a photodetector, a second filter, a second low noise amplifier and a mixer; The frequency doubling module is used to receive an input optical signal from a laser and an oscillation signal output by the oscillation loop, optically frequency-double the oscillation signal based on the input optical signal, output a frequency-doubled optical signal, and transmit the frequency-doubled optical signal to the photodetector; The photodetector is used to perform frequency mixing and photoelectric conversion on the frequency-doubled optical 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-doubled 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 multiplication module is a Mach-Zehnder modulator or an electrical 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 method for frequency division by injection locking of photoelectric oscillation, characterized in that: The method is implemented by an optoelectronic oscillation injection-locked frequency division system, wherein the system comprises an oscillation loop and a frequency division loop connected to the oscillation loop; the method comprises: 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, optically frequency-multiplies 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 with 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.

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 to generate 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 a 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 starting 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.

9. The method according to claim 8, characterized in that 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 by the frequency division loop, and transmits 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; 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 the power loss generated during the oscillation process for the filtered oscillating electrical signal, and transmits the oscillating electrical signal after the power loss is compensated to the combiner.

10. The method according to claim 7, characterized in that The reference signal is a reference electrical signal, and the frequency division loop includes a frequency multiplication 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, optically multiplies the oscillation signal output by the oscillation loop based on the input optical signal to obtain a frequency multiplication signal, mixes the frequency multiplication signal with the reference signal, outputs a feedback signal, and transmits the feedback signal to the oscillation loop, including: The frequency doubling module receives an input optical signal from a laser and an oscillation signal output by the oscillation loop, optically frequency-doubles the oscillation signal based on the input optical signal, outputs a 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-doubled electrical signal and the reference electrical signal, outputs a feedback electrical signal, and transmits the feedback electrical signal to the oscillation loop.

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