High-precision microwave photonic filter based on finite impulse response

Abstract

The invention discloses a high-precision microwave photon filter based on finite impulse response, and relates to the field of filters. The high-precision microwave photonic filter based on the finite impulse response comprises a light source module, a pre-dispersion module, a modulation and delay module, a programmable optical filter and a balanced photoelectric detector, the light source module generates a flat optical frequency comb, and a cascade modulator outputs the optical frequency comb to enter a dispersion element; the optical frequency comb enters the modulation and delay module after passing through the dispersion element, a signal is transmitted to the programmable optical filter through an optical fiber, and the output end of the balanced photoelectric detector directly provides a filtering result. According to the high-precision microwave photonic filter based on finite impulse response, hundreds of flat comb teeth are realized through a cascade modulation architecture, the number of FIR taps is increased by 2-3 orders of magnitude, and THz-level signal processing bandwidth is supported; a pre-dispersion-compensation cooperation mechanism effectively suppresses spurious noise, programmable optical filtering is combined with coherent detection, and arbitrary filtering response reconstruction is realized.

Description

Technical Field

[0001] The invention relates to the technical field of filters, in particular to a high-precision microwave photon filter based on finite impulse response. Background Art

[0002] Photon filters are key devices in the field of optics and photonics. Their core value lies in achieving selective transmission or suppression of signals by manipulating the wavelength characteristics of light.

[0003] The working principle of photon filters is mainly based on the interference, diffraction or absorption characteristics of light. By designing specific medium structures (such as photonic crystals, Fabry-Perot cavities, Mach-Zehnder interferometers, etc.), light of specific wavelengths can be selectively transmitted or reflected / absorbed, thereby achieving filtering functions.

[0004] Traditional electric domain microwave filters face inherent defects in the high frequency band: due to the bandwidth limitation of electronic devices (usually <20GHz), it is difficult to meet the ultra-wideband requirements of 5G millimeter waves (24-40GHz) and radar systems (>100GHz); electromagnetic sensitive structures are susceptible to interference and difficult to integrate; fixed topology structures lack dynamic reconfiguration capabilities.

[0005] With the development of microwave photonics, the use of optical devices to process microwave signals has become a breakthrough direction. Existing technologies mostly use a single modulator to generate sparse optical frequency combs, which results in a limited number of taps, insufficient frequency selectivity, and does not solve the problem of stray interference caused by dispersion mismatch. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a high-precision microwave photonic filter based on finite impulse response, which solves the problem that the prior art mostly uses a single modulator to generate a sparse optical frequency comb, resulting in a limited number of taps and insufficient frequency selectivity, and does not solve the problem of spurious interference caused by dispersion mismatch.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: a high-precision microwave photon filter based on finite impulse response, comprising:

[0008] A light source module, wherein the light source module uses a cascaded electro-optic modulator to generate a flat optical frequency comb;

[0009] A pre-dispersion module, wherein the pre-dispersion module uses a dispersive element, a cascade modulator is connected to the dispersive element via an optical fiber, and the cascade modulator outputs an optical frequency comb that enters the dispersive element;

[0010] A modulation and delay module, wherein the modulation and delay module is connected to a dispersion element through an optical fiber, and the optical frequency comb enters the modulation and delay module after passing through the dispersion element;

[0011] The programmable optical filter and the output end of the modulation and delay module are connected to the programmable optical filter, and the signal compensated by the modulation and delay module is transmitted to the programmable optical filter through an optical fiber;

[0012] The signal after the balanced photoelectric detector and the programmable optical filter are configured is divided into two paths and output to the balanced photoelectric detector. The two paths of optical signals are respectively connected to the balanced photoelectric detector, and the output end of the balanced photoelectric detector directly provides the filtering result.

[0013] Preferably, when the cascaded electro-optic modulator generates a flat optical frequency comb, it is able to provide hundreds of equally spaced comb teeth as multi-tap of a filter, and the comb tooth spacing corresponds to the free spectrum range of the filter.

[0014] Preferably, the dispersion element introduces pre-dispersion into the optical frequency comb to generate a linear phase difference between the comb teeth, thereby suppressing spurious interference generated by the beat frequency of the comb teeth and the signal sidebands in the subsequent modulation process.

[0015] Preferably, the modulation and delay module includes:

[0016] Single sideband modulator, the pre-dispersed optical frequency comb is transmitted to the single sideband modulator through an optical fiber;

[0017] Dispersion compensation element, the modulated signal is transmitted to the dispersion compensation element via the optical fiber.

[0018] Preferably, the single sideband modulator loads the input broadband RF signal onto the optical frequency comb through single sideband modulation, thereby ensuring effective transmission and processing of the signal in the optical domain.

[0019] Preferably, the dispersion compensation element introduces a controllable delay to the modulated signal to compensate for pulse broadening caused by dispersion and ensure the time domain integrity of the signal.

[0020] Preferably, the programmable optical filter performs independent amplitude and phase configuration on each comb tooth of the optical frequency comb to achieve positive and negative tap coefficients and support arbitrary filtering waveform reconstruction.

[0021] Preferably, the balanced photodetector performs coherent detection on the positive and negative tap signals, outputs filtered radio frequency signals, and completes the conversion from the optical domain to the electrical domain.

[0022] The use of finite impulse response high-precision microwave photon filters includes the following:

[0023] Step 1: Frequency Comb Generation

[0024] Light source module: The cascaded electro-optic modulator generates 200+ equally spaced comb teeth through bias voltage control, and the comb tooth spacing is set to FSR = 50GHz, corresponding to a maximum processing bandwidth of 10THz;

[0025] Monitoring feedback: Integrated thermal tuner calibrates comb flatness in real time with fluctuations <0.5dB.

[0026] Step 2: Pre-dispersion treatment

[0027] Dispersion element: A chirped fiber Bragg grating is used to apply second-order dispersion β2 = 10 ps to the optical frequency comb. 2 / km, so that adjacent comb teeth produce a linear phase difference Δφ=β2·Δω2·L, L=1km optical fiber;

[0028] Phase matching: The comb phase distribution is monitored by an optical spectrum analyzer, and the CFBG parameters are optimized to make the phase error <π / 10.

[0029] Step 3: Signal modulation and dispersion compensation

[0030] Single-sideband modulation: Wideband RF signals, such as 5G NR signals with a bandwidth of 400 MHz, are loaded into the optical frequency comb to suppress carrier redundancy.

[0031] Dispersion compensation: using programmable optical delay lines, based on liquid crystal on silicon, to apply reverse dispersion β2 = -10ps 2 / km, compensating for the dispersion broadening in the transmission link and ensuring that the pulse width is compressed to 98% of the original value.

[0032] Step 4: Programmable Filtering

[0033] Amplitude / phase control: 100 comb teeth are independently configured through a silicon-based liquid crystal array to achieve band-stop filtering with a center frequency of 35 GHz and a stop-band attenuation of >40 dB, or arbitrary waveform reconstruction, such as Wi-Fi 6E band selection.

[0034] Dynamic update: The FPGA control unit loads the preset filter template, and the switching speed is <500ns.

[0035] Step 5: Coherent Detection

[0036] Balanced detection: The filtered optical signal is divided into two orthogonal polarization paths and connected to a balanced photodetector to suppress relative intensity noise > 20dB.

[0037] Electrical domain output: Directly output the filtered RF signal for subsequent circuit processing or antenna transmission.

[0038] The present invention discloses a high-precision microwave photon filter based on finite impulse response, which has the following beneficial effects:

[0039] 1. This high-precision microwave photonic filter based on finite impulse response realizes hundreds of flat comb teeth through a cascade modulation architecture, increases the number of FIR taps by 2-3 orders of magnitude, and supports THz-level signal processing bandwidth; the pre-dispersion-compensation synergistic mechanism effectively suppresses stray noise, and programmable optical filtering is combined with coherent detection to realize arbitrary filter response reconstruction, support bandpass / bandstop / multi-band switching, frequency resolution <1MHz, all-optical signal transmission path anti-electromagnetic interference capability, ultra-low latency jitter, and low latency in optical domain processing.

[0040] 2. This high-precision microwave photonic filter based on finite impulse response, the cascaded electro-optic modulator generates 200+ equally spaced comb teeth through bias voltage control, the comb tooth spacing is set to FSR = 50GHz, corresponding to the maximum processing bandwidth of 10THz, the integrated thermal tuner calibrates the comb tooth flatness in real time, the fluctuation is <0.5dB, and a chirped fiber Bragg grating is used to apply second-order dispersion β2 = 10ps to the optical frequency comb 2 / km, so that adjacent comb teeth produce a linear phase difference Δφ=β2·Δω2·L, L=1km of optical fiber, monitor the comb tooth phase distribution through an optical spectrum analyzer, optimize the CFBG parameters to make the phase error <π / 10, load broadband RF signals, such as 5G NR signals, with a bandwidth of 400MHz, into the optical frequency comb, suppress carrier redundancy, and use programmable optical delay lines to apply reverse dispersion β2=-10ps based on silicon-based liquid crystal 2 / km, compensating for the dispersion broadening in the transmission link and ensuring that the pulse width is compressed to 98% of the original value.

[0041] 3. This high-precision microwave photonic filter based on finite impulse response independently configures 100 comb teeth through a silicon-based liquid crystal array to achieve band-stop filtering with a center frequency of 35GHz and a stopband attenuation of >40dB, or arbitrary waveform reconstruction, such as Wi-Fi 6E band selection. The FPGA control unit loads a preset filter template with a switching speed of <500ns. The filtered optical signal is divided into two orthogonal polarization paths, connected to a balanced photodetector, suppressing relative intensity noise >20dB, and directly outputting the filtered RF signal for subsequent circuit processing or antenna transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0044] Figure 2 The present invention uses a flow chart. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] The embodiment of the present application solves the problem that the existing technology mostly uses a single modulator to generate sparse optical frequency combs, resulting in a limited number of taps, insufficient frequency selectivity, and does not solve the problem of spurious interference caused by dispersion mismatch by providing a high-precision microwave photon filter based on finite impulse response. Hundreds of flat comb teeth are realized through a cascade modulation architecture, the number of FIR taps is increased by 2-3 orders of magnitude, and THz-level signal processing bandwidth is supported; the pre-dispersion-compensation synergy mechanism effectively suppresses stray noise, and programmable optical filtering is combined with coherent detection to achieve arbitrary filter response reconstruction, support bandpass / bandstop / multi-band switching, frequency resolution <1MHz, all-optical signal transmission path anti-electromagnetic interference capability, ultra-low latency jitter, and low latency in optical domain processing.

[0047] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0048] The embodiment of the present invention discloses a high-precision microwave photon filter based on finite impulse response.

[0049] According to the attached Figure 1-2 As shown, including:

[0050] A light source module, wherein the light source module uses a cascaded electro-optic modulator to generate a flat optical frequency comb;

[0051] A pre-dispersion module, wherein the pre-dispersion module uses a dispersive element, a cascade modulator is connected to the dispersive element via an optical fiber, and the cascade modulator outputs an optical frequency comb that enters the dispersive element;

[0052] A modulation and delay module, wherein the modulation and delay module is connected to a dispersion element through an optical fiber, and the optical frequency comb enters the modulation and delay module after passing through the dispersion element;

[0053] The programmable optical filter and the output end of the modulation and delay module are connected to the programmable optical filter, and the signal compensated by the modulation and delay module is transmitted to the programmable optical filter through an optical fiber;

[0054] The signal after the balanced photoelectric detector and the programmable optical filter are configured is divided into two paths and output to the balanced photoelectric detector. The two paths of optical signals are respectively connected to the balanced photoelectric detector, and the output end of the balanced photoelectric detector directly provides the filtering result.

[0055] Hundreds of flat comb teeth are realized through the cascade modulation architecture, the number of FIR taps is increased by 2-3 orders of magnitude, and THz-level signal processing bandwidth is supported; the pre-dispersion-compensation synergistic mechanism effectively suppresses stray noise, and the programmable optical filtering is combined with coherent detection to realize arbitrary filter response reconstruction, support bandpass / bandstop / multi-band switching, frequency resolution <1MHz, all-optical signal transmission path anti-electromagnetic interference capability, ultra-low latency jitter, and low latency in optical domain processing.

[0056] Furthermore, when the cascaded electro-optic modulator generates a flat optical frequency comb, it can provide hundreds of equally spaced comb teeth as multi-tap of a filter, and the comb tooth spacing corresponds to the free spectrum range of the filter.

[0057] Furthermore, the dispersion element introduces pre-dispersion into the optical frequency comb, so as to generate a linear phase difference between the comb teeth, thereby suppressing the spurious interference generated by the beat frequency of the comb teeth and the signal sidebands in the subsequent modulation process.

[0058] Particularly disclosed, the modulation and delay module comprises:

[0059] Single sideband modulator, the pre-dispersed optical frequency comb is transmitted to the single sideband modulator through an optical fiber;

[0060] Dispersion compensation element, the modulated signal is transmitted to the dispersion compensation element via the optical fiber.

[0061] The cascaded electro-optic modulator generates 200+ equally spaced comb teeth through bias voltage control. The comb tooth spacing is set to FSR = 50GHz, corresponding to a maximum processing bandwidth of 10THz. The integrated thermal tuner calibrates the comb tooth flatness in real time, with a fluctuation of <0.5dB. A chirped fiber Bragg grating is used to apply second-order dispersion β2 = 10ps to the optical frequency comb. 2 / km, so that adjacent comb teeth produce a linear phase difference Δφ=β2·Δω2·L, L=1km of optical fiber, monitor the comb tooth phase distribution through an optical spectrum analyzer, optimize the CFBG parameters to make the phase error <π / 10, load broadband RF signals, such as 5G NR signals, with a bandwidth of 400MHz, into the optical frequency comb, suppress carrier redundancy, and use programmable optical delay lines to apply reverse dispersion β2=-10ps based on silicon-based liquid crystal 2 / km, compensating for the dispersion broadening in the transmission link and ensuring that the pulse width is compressed to 98% of the original value;

[0062] The 100 comb teeth are independently configured through a silicon-based liquid crystal array to achieve band-stop filtering with a center frequency of 35GHz and a stopband attenuation of >40dB, or arbitrary waveform reconstruction, such as Wi-Fi 6E band selection. The FPGA control unit loads a preset filtering template with a switching speed of <500ns. The filtered optical signal is divided into two orthogonal polarization paths, connected to a balanced photodetector, suppressing relative intensity noise >20dB, and directly outputting the filtered RF signal for subsequent circuit processing or antenna transmission.

[0063] It is particularly disclosed that the single sideband modulator loads the input broadband radio frequency signal onto the optical frequency comb through single sideband modulation, thereby ensuring effective transmission and processing of the signal in the optical domain.

[0064] It is particularly disclosed that the dispersion compensation element introduces a controllable delay to the modulated signal, compensates for the pulse broadening caused by dispersion, and ensures the time domain integrity of the signal.

[0065] Furthermore, the programmable optical filter performs independent amplitude and phase configuration on each comb tooth of the optical frequency comb to achieve positive and negative tap coefficients and support arbitrary filtering waveform reconstruction.

[0066] Furthermore, the balanced photodetector performs coherent detection on the positive and negative tap signals, outputs filtered radio frequency signals, and completes the conversion from the optical domain to the electrical domain.

[0067] The use of finite impulse response high-precision microwave photon filters includes the following:

[0068] Step 1: Frequency Comb Generation

[0069] Light source module: The cascaded electro-optic modulator generates 200+ equally spaced comb teeth through bias voltage control, and the comb tooth spacing is set to FSR = 50GHz, corresponding to a maximum processing bandwidth of 10THz;

[0070] Monitoring feedback: Integrated thermal tuner calibrates comb flatness in real time with fluctuations <0.5dB.

[0071] Step 2: Pre-dispersion treatment

[0072] Dispersion element: A chirped fiber Bragg grating is used to apply second-order dispersion β2 = 10 ps to the optical frequency comb. 2 / km, so that adjacent comb teeth produce a linear phase difference Δφ=β2·Δω2·L, L=1km optical fiber;

[0073] Phase matching: The comb phase distribution is monitored by an optical spectrum analyzer, and the CFBG parameters are optimized to make the phase error <π / 10.

[0074] Step 3: Signal modulation and dispersion compensation

[0075] Single-sideband modulation: Wideband RF signals, such as 5G NR signals with a bandwidth of 400 MHz, are loaded into the optical frequency comb to suppress carrier redundancy.

[0076] Dispersion compensation: using programmable optical delay lines, based on liquid crystal on silicon, to apply reverse dispersion β2 = -10ps 2 / km, compensating for the dispersion broadening in the transmission link and ensuring that the pulse width is compressed to 98% of the original value.

[0077] Step 4: Programmable Filtering

[0078] Amplitude / phase control: 100 comb teeth are independently configured through a silicon-based liquid crystal array to achieve band-stop filtering with a center frequency of 35GHz and a stop-band attenuation of >40dB, or arbitrary waveform reconstruction, such as Wi-Fi 6E band selection.

[0079] Dynamic update: The FPGA control unit loads the preset filter template, and the switching speed is <500ns.

[0080] Step 5: Coherent Detection

[0081] Balanced detection: The filtered optical signal is divided into two orthogonal polarization paths and connected to a balanced photodetector to suppress relative intensity noise > 20dB.

[0082] Electrical domain output: Directly output the filtered RF signal for subsequent circuit processing or antenna transmission.

[0083] Hundreds of flat comb teeth are achieved through the cascade modulation architecture, the number of FIR taps is increased by 2-3 orders of magnitude, and THz-level signal processing bandwidth is supported; the pre-dispersion-compensation synergistic mechanism effectively suppresses stray noise, and the programmable optical filtering is combined with coherent detection to achieve arbitrary filter response reconstruction, support bandpass / bandstop / multi-band switching, frequency resolution <1MHz, all-optical signal transmission path anti-electromagnetic interference capability, ultra-low latency jitter, and low latency in optical domain processing.

[0084] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A high-precision microwave photon filter based on finite impulse response, characterized in that: include: A light source module, wherein the light source module uses a cascaded electro-optic modulator to generate a flat optical frequency comb; A pre-dispersion module, wherein the pre-dispersion module uses a dispersive element, a cascade modulator is connected to the dispersive element via an optical fiber, and the cascade modulator outputs an optical frequency comb that enters the dispersive element; A modulation and delay module, wherein the modulation and delay module is connected to a dispersion element through an optical fiber, and the optical frequency comb enters the modulation and delay module after passing through the dispersion element; The programmable optical filter and the output end of the modulation and delay module are connected to the programmable optical filter, and the signal compensated by the modulation and delay module is transmitted to the programmable optical filter through an optical fiber; The signal after the balanced photoelectric detector and the programmable optical filter are configured is divided into two paths and output to the balanced photoelectric detector. The two paths of optical signals are respectively connected to the balanced photoelectric detector, and the output end of the balanced photoelectric detector directly provides the filtering result.

2. The high-precision microwave photon filter based on finite impulse response according to claim 1, characterized in that: When the cascaded electro-optic modulator generates a flat optical frequency comb, it can provide hundreds of equally spaced comb teeth as multi-tap of a filter, and the comb tooth spacing corresponds to the free spectrum range of the filter.

3. The high-precision microwave photon filter based on finite impulse response according to claim 1, characterized in that: The dispersion element introduces pre-dispersion into the optical frequency comb, so as to generate a linear phase difference between the comb teeth, thereby suppressing the spurious interference generated by the beat frequency of the comb teeth and the signal sidebands in the subsequent modulation process.

4. The high-precision microwave photon filter based on finite impulse response according to claim 1, characterized in that: The modulation and delay module comprises: Single sideband modulator, the pre-dispersed optical frequency comb is transmitted to the single sideband modulator through an optical fiber; Dispersion compensation element, the modulated signal is transmitted to the dispersion compensation element via the optical fiber.

5. The high-precision microwave photon filter based on finite impulse response according to claim 4, characterized in that: The single sideband modulator loads the input broadband radio frequency signal onto the optical frequency comb through single sideband modulation, ensuring effective transmission and processing of the signal in the optical domain.

6. The high-precision microwave photon filter based on finite impulse response according to claim 4, characterized in that: The dispersion compensation element introduces a controllable delay to the modulated signal, compensates for the pulse broadening caused by dispersion, and ensures the time domain integrity of the signal.

7. The high-precision microwave photon filter based on finite impulse response according to claim 1, characterized in that: The programmable optical filter performs independent amplitude and phase configuration on each comb tooth of the optical frequency comb, realizes positive and negative tap coefficients, and supports arbitrary filtering waveform reconstruction.

8. The high-precision microwave photon filter based on finite impulse response according to claim 1, characterized in that: The balanced photodetector performs coherent detection on the positive and negative tap signals, outputs filtered radio frequency signals, and completes the conversion from the optical domain to the electrical domain.

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