Reconfigurable microwave photonic filter and filtering method

Abstract

The invention discloses a reconfigurable microwave photonic filter, which comprises a laser source, an electro-optical modulator, an adjustable feedback type array waveguide grating, a filtering module and a photoelectric detector, and is characterized in that the laser source generates an optical signal and transmits the optical signal to the electro-optical modulator, and the electro-optical modulator modulates the optical signal after receiving the optical signal to form a corresponding sideband; the adjustable feedback type array waveguide grating divides the frequency spectrum of an optical signal into different wavelengths and carries out independent amplitude and phase adjustment on the optical signal with different wavelengths, then the filtering module filters out periodically repeated signals, and the photoelectric detector converts the filtered optical signal into an electric signal, so that optical-electric conversion is completed. The reconfigurable microwave photonic filter and the filtering method have the advantages of being simple in structure, highly programmable in frequency spectrum shape, rapid and reconfigurable in response and high in integration level, and have great attraction to the field of high-frequency signal processing. The application obtains the Young Science Foundation project (62204156) of the National Natural Science Foundation.

Description

Technical Field

[0001] The invention relates to the field of microwave optoelectronic signal processing, and in particular to a reconfigurable microwave photon filter and a filtering method. Background Art

[0002] With the deepening integration of microwave photonics with radio frequency engineering and optoelectronic technology, this interdisciplinary field has become a hot topic of research. Microwave photonics uses optical devices to process radio frequency signals to achieve multiple functions such as filtering, frequency multiplication / conversion, arbitrary waveform generation, phase shifting and pulse shaping, which is crucial for applications such as radar, wireless communications and sensing. However, traditional electronic microwave filters face challenges in meeting the exponential growth demand for capacity in next-generation RF systems due to electronic bottlenecks. Photonics, with its advantages of wide bandwidth, parallelism and adaptability, provides a promising alternative. Microwave photonic filters perform filtering operations in the optical domain, providing not only broadband tunability, but also high stability, low latency and strong immunity to electromagnetic interference.

[0003] Although microwave photonic systems are becoming increasingly powerful, their complexity is also increasing, resulting in bulky systems that are difficult to meet the requirements of lightweight, miniaturization, low power consumption and long-term stability. Integrated photonics provides a solution to this problem, achieving compactness and miniaturization of the system by integrating multiple high-speed, wide-bandwidth optical devices on a single chip. Photonic integration platforms, such as III-V semiconductors, silicon photonics, SiN / SiO2 photonic integration and hybrid integration of multiple materials, provide diverse options for RF signal processing. Silicon photonic integration, in particular, has the advantages of high compactness and small chip size due to its high refractive index. In addition, the application of CMOS-compatible processes enables the integration of electronic and optical devices on one chip, reducing costs and enabling large-scale production.

[0004] In microwave photonic devices, photon-assisted RF filters play a fundamental role, using optical devices to process RF signals. Microwave photonic filters are mainly divided into three categories: those based on stimulated Brillouin scattering effect, those that directly map the light domain to the frequency domain, and those synthesized using multi-tap delay lines. These filters each have their own advantages and applicable scenarios: filters based on stimulated Brillouin scattering effect require precise structures to improve performance; the filtering performance of direct mapping schemes is limited by optical filters, and the wavelength separation and signal processing structures are complex; although multi-tap filters are flexible, the dispersion structure increases the complexity of the system. Summary of the invention

[0005] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is that the existing microwave photon filter and filtering method have the problems of large system volume, high requirements on structural precision, complex wavelength separation and signal processing structure, and high system complexity. Therefore, the present invention provides a reconfigurable microwave photon filter and filtering method, which utilizes a feedback array waveguide grating structure and combines the direct mapping technology from the optical domain to the frequency domain to realize a microwave photon filter with a simple structure, highly programmable spectrum shape, fast and reconfigurable response, and high integration. This innovative combination will show significant technical advantages and application potential in the field of radio frequency signal processing.

[0006] To achieve the above-mentioned purpose, the present invention provides a reconfigurable microwave photon filter, comprising a laser source, an electro-optic modulator, an adjustable feedback arrayed waveguide grating, a filtering module and a photodetector. The laser source generates an optical signal and transmits it to the electro-optic modulator. After receiving the optical signal, the electro-optic modulator modulates the optical signal to form a corresponding sideband. The adjustable feedback arrayed waveguide grating divides the spectrum of the formed sideband signal into different wavelengths, and independently adjusts the amplitude and phase of the optical signals of different wavelengths. The filtering module then filters out the periodically repeated signal. The photodetector converts the filtered optical signal into an electrical signal, thereby completing the optical-electrical conversion.

[0007] Furthermore, the adjustable feedback array waveguide grating and the filter module are configured as an on-chip integrated structure.

[0008] Furthermore, the laser source, electro-optic modulator, and photodetector are all configured as one or more of on-chip full integration, on-chip semi-integration, and off-chip structures.

[0009] Furthermore, the configuration of the electro-optic modulator and the adjustable feedback arrayed waveguide grating is based on a method of directly mapping the optical domain to the frequency domain.

[0010] Furthermore, the filtering module is configured to use a broadband high extinction ratio filtering structure.

[0011] Furthermore, the filtering module is configured to use a dual micro-ring assisted Mach-Zehnder filtering structure.

[0012] Furthermore, the filtering module includes two output waveguides, two multimode interference couplers and two microring resonators, wherein the two microring resonators are respectively integrated on two arms of the Mach-Zehnder interferometer, and the phases of the two microring resonators are adjustable, and the resonance conditions of the microring resonators are used to dynamically adjust the interference effect of the Mach-Zehnder interferometer.

[0013] In a preferred embodiment of the present invention, the present invention provides a filtering method of the above-mentioned reconfigurable microwave photon filter, comprising the following steps:

[0014] Generate an optical signal of a specific frequency through a laser source, modulate the optical signal using an electro-optical modulator, and encode information by changing the phase or intensity of the optical signal;

[0015] The adjustable feedback array waveguide grating divides the spectrum of the modulated optical signal into multiple different wavelength components;

[0016] Using filtering modules, specific wavelength components can be selectively retained or suppressed;

[0017] The photodetector converts the filtered optical signal into an electrical signal, thereby completing the optical-electrical conversion.

[0018] Furthermore, the filtering shape is reconstructed by adjusting the amplitude phase regulator on the feedback loop of the feedback array waveguide grating.

[0019] Technical Effects

[0020] The present invention provides a reconfigurable microwave photon filter and filtering method, which have the following technical effects:

[0021] 1. Innovative combination of feedback arrayed waveguide grating and frequency domain mapping scheme: The present invention combines the direct mapping technology from the optical domain to the frequency domain with the integrated design of the feedback arrayed waveguide grating to create a new type of microwave photonic filter. This combination fully utilizes the advantages of arrayed waveguide grating in wavelength selectivity, and through the mapping technology from the optical domain to the frequency domain, it realizes efficient and accurate filtering of RF signals. Each output port of the arrayed waveguide grating corresponds to a specific wavelength, which corresponds to the specific frequency of the RF signal through the frequency mapping scheme. This combination not only improves the selectivity of the filter, but also realizes accurate filtering of RF signals by accurately adjusting the amplitude and phase of signals of different wavelengths independently, which is difficult to achieve with traditional microwave filters.

[0022] 2. High flexibility and tunability: The reconfigurable microwave photonic filter of the present invention adopts an adjustable feedback array waveguide grating structure, which significantly improves the flexibility and tunability of the filter, supports structural reconstruction and parameter adjustment, and enables the filter to provide programmable spectrum shape and fast response reconstruction, meeting the needs of modern RF signal processing for fast adaptability.

[0023] 3. High-efficiency performance and compact design: The reconfigurable microwave photonic filter of the present invention realizes the reduction of chip size, the improvement of integration, the reduction of power consumption and the enhancement of stability. The feedback array waveguide grating adopted by the reconfigurable microwave photonic filter of the present invention not only has the function of wavelength division and regulation, but can also be used as a multi-wavelength filter and dispersion element. The device has the characteristics of more compact size, lower loss and greater dispersion. While reducing the physical size of the device and the complexity of the system, it maintains high-efficiency performance, which is particularly suitable for space-constrained application scenarios. In addition, this design also allows the performance of the filter to be adjusted by changing the number and configuration of wavelength channels to adapt to different application requirements, and is compatible with CMOS technology, further improving the flexibility and cost-effectiveness of production.

[0024] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of a reconfigurable microwave photon filter according to a preferred embodiment of the present invention;

[0026] Figure 2 It is a structural schematic diagram of a reconfigurable microwave photon filter according to a preferred embodiment of the present invention;

[0027] Figure 3 It is a structural schematic diagram of a feedback arrayed waveguide grating module of a reconfigurable microwave photon filter according to a preferred embodiment of the present invention;

[0028] Figure 4 The figure is a schematic structural diagram of a filter module of a reconfigurable microwave photon filter according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] In the following description, specific details such as specific internal procedures and techniques are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0031] like Figure 1and 2 As shown, an embodiment of the present invention provides a reconfigurable microwave photon filter, including a laser source 1, an electro-optical modulator 2, an adjustable feedback array waveguide grating 3, a filtering module 4 and a photodetector 5. The laser source generates an optical signal and transmits it to the electro-optical modulator. After receiving the optical signal, the electro-optical modulator modulates the optical signal to form a corresponding sideband. The sideband signal will be further processed by the subsequent adjustable feedback array waveguide grating. The adjustable feedback array waveguide grating divides the spectrum of the optical signal into different wavelengths, and independently adjusts the amplitude and phase of the optical signals of different wavelengths. The periodically repeated signal is then filtered out by the filtering module. The photodetector converts the filtered optical signal into an electrical signal, thereby completing the optical-electrical conversion. In this embodiment, the laser source 1 is a continuously adjustable single-frequency light source, and the electro-optical modulator 2 is a phase modulator. Specifically, the continuously adjustable single-frequency light source 1 generates an optical signal, which is a single-frequency signal λ c , input to the electro-optic modulator 2, the RF input terminal of the electro-optic modulator 2 inputs the RF signal, generates two sidebands, and the sideband signal will be further processed by the subsequent adjustable feedback array waveguide grating, wherein the sideband includes an upper sideband and a lower sideband, and the phase difference between the two sidebands is 180 degrees. If no other filtering processing is performed, this will cause the optical signals of the upper sideband and the lower sideband to cancel each other in the beat frequency signal at the photodetector 5, forming suppression in the RF domain.

[0032] The optical signal then passes through the adjustable feedback array waveguide grating 3, which divides the spectrum into N different wavelengths. These N signals repeat periodically in the frequency domain. After passing through the filter module 4 (a wide spectrum filter structure in this embodiment), the periodically repeated signal is filtered out, leaving λ1, λ2 to λ N The amplitude and phase of each wavelength signal can be adjusted individually by the regulator of the adjustable feedback array waveguide grating 3. Assuming that all N groups of wavelengths are located in the upper sideband, at the photodetector 5, the N signals generate beat frequency signals with the carrier respectively, and finally output N frequencies of λ1-λ C ,λ2-λ C To N -λ C Each RF signal can be adjusted independently to achieve reconfigurable microwave photonic filtering.

[0033] Furthermore, the adjustable feedback array waveguide grating and the filter module are set as an on-chip integrated structure. The laser source, electro-optic modulator, and photodetector are all set as one or more of on-chip full integration, on-chip semi-integration, and off-chip structure. This embodiment adopts CMOS integration technology, including on-chip full integration, on-chip semi-integration, and optimized combination with off-chip structure of key optoelectronic devices in microwave photon filters. This integration method not only improves the integration and performance of the system, but also significantly reduces the cost and power consumption. Using CMOS technology, combined with photon integration technology, it is possible to realize complex optoelectronic systems on a single chip, including laser sources, electro-optic modulators, and photodetectors. The models and parameters of these modules are specially designed to meet the requirements of high-performance microwave photon filters. Compared with traditional technologies, this innovative integration method enables the filter to achieve a smaller chip size while maintaining high bandwidth, low loss, and high integration, thereby showing excellent versatility, adaptability, and flexibility in a variety of application scenarios.

[0034] The configuration of the electro-optic modulator and the tunable feedback arrayed waveguide grating is set based on the method of directly mapping the optical domain into the frequency domain.

[0035] like Figure 3 As shown, the adjustable feedback arrayed waveguide grating module includes an input module 31, an arrayed waveguide module 32, an output module 33 and a feedback loop 34. The input module 1 includes N+1 strip waveguides connected to an input flat waveguide, wherein the N+1 strip waveguides include 1 input waveguide and N feedback waveguides; both ends of the arrayed waveguide module 2 are connected to the flat waveguides of the input and output parts to form an arrayed waveguide grating; the output module 33 includes N+1 strip waveguides connected to an output flat waveguide, wherein the N+1 strip waveguides include 1 output waveguide and N feedback waveguides; the feedback loop 34 includes N feedback waveguides, each waveguide is equipped with an independent amplitude and phase regulator to adjust the amplitude and phase of signals of different wavelengths. Each output port of the arrayed waveguide grating corresponds to a specific wavelength, and these wavelengths correspond to the specific frequencies of the radio frequency signal through a frequency mapping scheme, which not only improves the selectivity of the filter, but also realizes accurate filtering of the radio frequency signal by precisely controlling the wavelength. The reconfigurable microwave photonic filter provided in the embodiment of the present invention adopts an adjustable feedback array waveguide grating structure, which gives the filter higher flexibility and tunability, supports structural reconstruction and parameter adjustment, and enables the filter to provide programmable spectrum shape and fast response reconstruction, meeting the requirements of modern RF signal processing for fast adaptability.

[0036] The filter module is configured to use a broadband high extinction ratio filter structure to filter out periodically repeated interference signals, and any filter module that implements a broadband high extinction ratio filter function can be applied here. The filter module of the embodiment of the present invention functions to filter out periodically repeated signals output by the arrayed waveguide grating, and the filter module meets the high extinction ratio broadband filtering requirements.

[0037] like Figure 4 As shown, in this embodiment, the filter module is configured to use a Mach-Zehnder filter structure assisted by a double microring. The filter module includes two output waveguides 41, two multimode interference couplers 42 and two microring resonators 43, wherein the two microring resonators are respectively integrated on the two arms of the Mach-Zehnder interferometer, and the phases of the two microring resonators are adjustable, and the resonance conditions of the microring resonators are used to dynamically adjust the interference effect of the Mach-Zehnder interferometer. When the double microring-assisted Mach-Zehnder filter structure is working, the two microring resonators and the coupled waveguide are in an over-coupling state. In this scheme, the phase of the coupled waveguide changes dramatically near the resonant wavelength of the microring, so that the Mach-Zehnder interferometer does not need to rely on increasing the arm length to introduce a π phase shift, thereby achieving a smaller size and a higher filter extinction ratio, and the working wavelength can be selected at the middle point of the two microring resonance peaks and can be dynamically adjusted. Among them, the double microring-assisted Mach-Zehnder filter structure is represented by the following transfer matrix:

[0038]

[0039] Where E bar and E cross represent the electric field E at the through port and the cross port of the Mach-Zehnder interferometer respectively. in is the electric field at the input port. κ and τ are the coupling coefficient and transmission coefficient of the input and output multimode interference (MMI) couplers. For an ideal 3dB coupler, κ 2 =τ 2 =0.5, at this time (i=1,2) is the electric field transmitted through the two arms of the Mach-Zehnder interferometer coupled to the microring. The increase in bandwidth can be achieved by adjusting the resonance condition of the microring. In the dual microring-assisted Mach-Zehnder filter structure, the resonance condition of the microring directly affects the amplitude and phase response of the two arms of the Mach-Zehnder interferometer, thereby affecting the frequency response of the entire system. Amplitude and phase response T i and It is given by the following formula:

[0040]

[0041] Where t is the field transmission coefficient, θ i(i=1,2) is the round-trip phase in the microring, and a is the ring loss factor. By adjusting these parameters, the amplitude and phase response of the two arms of the Mach-Zehnder interferometer can be changed, thereby affecting the frequency response of the entire system and achieving bandwidth adjustment.

[0042] The extinction ratio is defined as the ratio of the maximum transmittance to the minimum transmittance. The input normalized output power at the transverse port and the cross port is thus expressed as:

[0043]

[0044] By adjusting the resonance condition of the microring, the interference effect of the Mach-Zehnder interferometer can be controlled to achieve modulation and routing of optical signals. By adjusting the resonance condition of the microring, the transmittance P of the cross port can be adjusted to a certain frequency. x The transmittance P at the transverse port reaches its maximum b Close to 0, thus achieving a high extinction ratio. The dual-microring-assisted Mach-Zehnder filter structure optimizes the amplitude and phase response of the two arms of the Mach-Zehnder interferometer by adjusting the resonance conditions of the microring, thereby achieving a larger extinction ratio and a larger bandwidth. This design provides an effective method to control the transmission characteristics of optical signals, which is of great significance for optical communications and other photonics applications. By adjusting the resonance conditions of the microring, the dual-microring-assisted Mach-Zehnder filter structure makes the phase change of the coupled waveguide more drastic near the resonant wavelength of the microring, thereby achieving a larger bandwidth and a higher extinction ratio without increasing the arm length.

[0045] In another preferred embodiment of the present invention, a cascaded Mach-Zehnder filter structure is provided. The structure cascades two Mach-Zehnder interferometer structures, and the double-arm phases of the two Mach-Zehnder interferometers are adjustable. In the cascaded Mach-Zehnder interferometer structure, the key to improving the extinction ratio and bandwidth is to utilize the cascade effect of multiple Mach-Zehnder interferometers.

[0046] The increase in bandwidth can be achieved by adjusting the phase difference of each Mach-Zehnder interferometer. In a cascaded Mach-Zehnder interferometer, the phase difference of each Mach-Zehnder interferometer unit can be adjusted independently, which allows the designer to control the frequency response of the entire system by finely adjusting the phase difference. Specifically, the transfer function of the cascaded Mach-Zehnder interferometer involves the product of multiple cosine functions, which results in a more complex frequency response, thereby providing effective filtering over a wider frequency range.

[0047] For the cascaded Mach-Zehnder interferometer, the overall transfer function is expressed as:

[0048]

[0049] Where N is the number of cascaded Mach-Zehnder interferometers, φ i is the phase difference of the i-th Mach-Zehnder interferometer, Δφ(f) is the frequency-dependent phase difference, and this structure is a 2-stage cascaded Mach-Zehnder interferometer, with N being 2. This expression shows that the overall transfer function is a complex function of frequency, providing the desired filtering characteristics over a wider frequency range, thereby increasing the bandwidth.

[0050] The input normalized output power is described by the following formula:

[0051]

[0052] Among them, T i and (i=1,2) are the amplitude and phase responses of the i-th Mach-Zehnder interferometer, respectively. By cascading Mach-Zehnder interferometers, the phase modulation effect of each Mach-Zehnder interferometer is accumulated, thereby achieving deeper attenuation at certain frequencies, that is, higher extinction ratio.

[0053] The cascaded Mach-Zehnder interferometer structure improves the extinction ratio by cascading multiple Mach-Zehnder interferometers and utilizing the phase modulation effect of each unit. At the same time, by independently adjusting the phase difference of each Mach-Zehnder interferometer, the frequency response of the entire system is controlled to increase the bandwidth. This design is of great significance in optical communications and other photonics applications because it allows for more precise control of the transmission characteristics of optical signals. Through the design of cascaded Mach-Zehnder interferometers, optical filters with higher extinction ratios and wider bandwidths can be achieved without increasing the physical size.

[0054] The filtering structure selects an integrated broadband high extinction ratio structure, which, together with the feedback array waveguide grating, can achieve fine control of microwave filtering, meet the requirements of integration, and make the microwave filtering system more compact.

[0055] In a preferred embodiment of the present invention, the present invention provides a filtering method of the above-mentioned reconfigurable microwave photon filter, comprising the following steps:

[0056] Generate an optical signal of a specific frequency through a laser source, modulate the optical signal using an electro-optical modulator, and encode information by changing the phase or intensity of the optical signal;

[0057] The adjustable feedback array waveguide grating divides the spectrum of the modulated optical signal into multiple different wavelength components;

[0058] Using filtering modules, specific wavelength components can be selectively retained or suppressed;

[0059] The photodetector converts the filtered optical signal into an electrical signal, thereby completing the optical-electrical conversion.

[0060] Furthermore, the filtering shape is reconstructed by adjusting the amplitude phase regulator on the feedback loop of the feedback array waveguide grating.

[0061] Specifically, optical signals of specific frequencies are generated by a laser source, and these signals are modulated by an electro-optical modulator to form upper and lower sidebands.

[0062] The adjustable feedback array waveguide grating divides the spectrum of the modulated optical signal into multiple different wavelength components and finely controls the intensity of these optical signals.

[0063] Specific wavelength components are selectively retained or suppressed through the filtering module.

[0064] The photodetector converts the filtered optical signal into an electrical signal, realizing the optical-electrical conversion process.

[0065] Since the optical domain to frequency domain mapping scheme is used for microwave filtering, the spectrum of the optical signal can be mapped to the frequency domain. Therefore, the characteristics of the microwave spectrum are mainly affected by the feedback array waveguide grating and the filter module. In order to describe this filtering process in detail, the corresponding formula is constructed to mathematically deduce the feedback array waveguide grating and the filter module.

[0066] For a feedback array waveguide grating, the transmission spectrum of each channel can be represented by a Gaussian function. Now there are N such channels, the peak of each channel is controlled by an amplitude and phase modulator, and the transmission spectrum of all channels is the superposition of these Gaussian functions. The mth channel at wavelength λ m The transmission spectrum at can be expressed as:

[0067]

[0068] Among them, λ m is the central wavelength of the mth channel, T 0m is the wavelength λ of the mth channel m The normalized peak transmittance at , controlled by the amplitude and phase modulators of each channel, can be adjusted independently, while Δλ m is the wavelength λ of the mth channel m The full width at half maximum (FWHM) at λ is the full width at half maximum (FWHM) at λ. Affected by the characteristics of the arrayed waveguide grating, each channel has a fixed period FSR interval and a repetitive wavelength signal. For the mth channel in the arrayed waveguide grating, its transmission spectrum is at wavelength λ m The peak value T 0m , and the transmission spectrum λ of each channel m +k·FSR (where k is an integer) will also reach the same peak value T 0mSpecifically, FSR represents the interval between periodic repetitive wavelengths at the same output port, which is affected by the inherent characteristics of the arrayed waveguide grating, such as the diffraction order, the length difference of the arrayed waveguide, the effective refractive index of the waveguide, etc. k is an integer representing the distance from the center wavelength λ m The number of FSR shifts. A positive number indicates a FSR shift above the center wavelength, and a negative number indicates a FSR shift below the center wavelength. Affected by the periodically repeated wavelength signal, the transmission spectra of all periodically repeated wavelengths of the mth channel are superimposed as follows:

[0069]

[0070] The feedback arrayed waveguide grating can realize the superposition of the transmission spectra of all N channels, so after the feedback arrayed waveguide grating, the transmission spectra of N channels are superimposed as follows:

[0071]

[0072] Above T total (λ) is the transmission spectrum of the feedback array waveguide grating. After the signal passes through the filtering module, the periodic repetitive signal is filtered out, leaving only λ1, λ2 to λ n Because the filter module has the characteristics of broadband and high extinction ratio, after filtering out the periodic repetitive signal, it can be approximately regarded as adding an amplitude coefficient T to the transmission spectrum system. f , then the transmission spectrum is:

[0073]

[0074] After the optical domain to frequency domain conversion, the transmission spectrum is mapped to the frequency domain to complete the microwave filtering.

[0075] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A reconfigurable microwave photonic filter, characterized in that: It includes a laser source, an electro-optic modulator, an adjustable feedback array waveguide grating, a filtering module and a photodetector. The laser source generates an optical signal and transmits it to the electro-optic modulator. After receiving the optical signal, the electro-optic modulator modulates the optical signal to form a corresponding sideband and transmits it to the adjustable feedback array waveguide grating. The adjustable feedback array waveguide grating divides the spectrum of the formed sideband signal into different wavelengths, and independently adjusts the amplitude and phase of the optical signals of different wavelengths. The filtering module then filters out the periodically repeated signal. The photodetector converts the filtered optical signal into an electrical signal, thereby completing the optical-electrical conversion. Each output port of the arrayed waveguide grating corresponds to a specific wavelength, and these wavelengths correspond to specific frequencies of the radio frequency signal through frequency mapping.

2. A reconfigurable microwave photonic filter as claimed in claim 1, characterized in that: The adjustable feedback arrayed waveguide grating includes an input module, an arrayed waveguide module, an output module and a feedback loop. Specifically, the input module includes N+1 first strip waveguides connected to an input slab waveguide, wherein the N+1 first strip waveguides include 1 input waveguide and N first feedback waveguides; The two ends of the arrayed waveguide module are connected to the slab waveguide of the input and output parts to form an arrayed waveguide grating; The output module includes N+1 second strip waveguides connected to the output slab waveguide, wherein the N+1 second strip waveguides include 1 output waveguide and N second feedback waveguides; The feedback loop includes N third waveguides, each waveguide integrating a set of independently adjustable amplitude and phase regulators.

3. A reconfigurable microwave photonic filter as claimed in claim 1, characterized in that: The adjustable feedback array waveguide grating and the filter module are configured as an on-chip integrated structure.

4. A reconfigurable microwave photonic filter as claimed in claim 1, characterized in that: The laser source, the electro-optic modulator, and the photodetector are all configured to be one or more of on-chip full integration, on-chip semi-integration, and off-chip structures.

5. The reconfigurable microwave photonic filter according to claim 1, characterized in that: The configuration of the electro-optic modulator and the adjustable feedback arrayed waveguide grating is based on a method of directly mapping the optical domain to the frequency domain.

6. The reconfigurable microwave photonic filter according to claim 1, characterized in that: The filtering module is configured to use a broadband high extinction ratio filtering structure.

7. A reconfigurable microwave photonic filter as claimed in claim 6, characterized in that: The filtering module is configured to use a dual micro-ring assisted Mach-Zehnder filtering structure.

8. The reconfigurable microwave photonic filter according to claim 6, characterized in that: The filtering module includes two output waveguides, two multimode interference couplers and two microring resonators; wherein the two microring resonators are respectively integrated on two arms of a Mach-Zehnder interferometer, and the phases of the two microring resonators are adjustable, and the resonance conditions of the microring resonators are used to dynamically adjust the interference effect of the Mach-Zehnder interferometer.

9. A filtering method based on the reconfigurable microwave photonic filter according to any one of claims 1 to 8, characterized in that: The following steps are involved: Generate an optical signal of a specific frequency through a laser source, modulate the optical signal using an electro-optical modulator, and encode information by changing the phase or intensity of the optical signal; The adjustable feedback array waveguide grating divides the spectrum of the modulated optical signal into multiple different wavelength components; Using filtering modules, specific wavelength components can be selectively retained or suppressed; The photodetector converts the filtered optical signal into an electrical signal, thereby completing the optical-electrical conversion.

10. A reconfigurable microwave photon filtering method as claimed in claim 9, characterized in that: The filtering shape is reconstructed by adjusting the amplitude and phase regulator on the feedback loop of the feedback array waveguide grating.

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