Microwave photon channelized receiving method and device based on double-vernier effect

Abstract

The invention discloses a microwave photon channelized receiving method based on a double-vernier effect. The method comprises the following steps: S1, generating two paths of coherent optical frequency comb signals of which the initial frequency and the free spectral range are slightly different; s2, performing single side band modulation on the two paths of optical frequency comb signals by using the original radio frequency signal; s3, respectively carrying out wavelength division multiplexing on the two paths of modulated optical signals, separating out each comb tooth and radio-over-fiber signal components at the same frequency with each comb tooth in the other path of modulated optical signals, and then forming a local oscillator / signal pair by the comb teeth at the same frequency and the radio-over-fiber signal components; and S4, performing dual-output image frequency suppression mixing on each group of local oscillator / signal pairs. The invention further discloses a microwave photon channelization receiving device based on the double-vernier effect. Compared with the prior art, the channelization efficiency and the image frequency suppression effect can be greatly improved.

Description

Technical Field

[0001] The invention relates to a microwave photon channelized receiving method, belonging to the technical field of microwave photons. Background Art

[0002] In modern electronic information systems such as communications, radar, and electronic warfare, RF channelization is a typical approach for achieving broadband RF signal reception. The basic concept is to divide the received RF signal into several narrowband parallel channels, which are then acquired and processed by a series of low-speed electronic analog-to-digital converters. Traditional electrical channelization approaches suffer from insufficient bandwidth and excessive equipment requirements in resource-constrained scenarios. Due to the wide operating bandwidth and parallel processing capabilities introduced by photonics, photonics-assisted RF channelization has been widely studied. To achieve RF channelization based on microwave photonics, one approach is to modulate the RF signal onto an optical carrier and then use a set of optical filters to separate it into multiple channels. Alternatively, the RF signal can be replicated onto a set of optical carriers, using periodic optical filters with different free spectral ranges (FSRs) to select different frequency components. However, these approaches are often limited by the performance of the optical filters in terms of channel bandwidth control and crosstalk suppression.

[0003] To address this challenge, researchers have investigated coherent optical channelization schemes based on a pair of optical frequency combs (OFCs). The RF signal is modulated onto the comb lines of one OFC, while another OFC with a vernier frequency acts as an optical local oscillator (LO) signal to downconvert the different RF components. Because the OFCs effectively separate these RF components in the optical domain, low-cost optical filters are sufficient to separate them into a series of distinct channels. For this type of approach, the number of output channels is typically equal to the number of OFC comb teeth. Therefore, a large number of high-quality optical comb teeth are required to achieve broadband channelization. A typical approach uses microring resonators, but this faces challenges with dual OFC locking and thermal instability. Furthermore, the complexity of the RF channelization system increases rapidly with the number of output channels. To halve the number of comb teeth and system complexity, researchers have proposed a microwave photonic dual-output image-rejected mixing method. By further applying optical polarization multiplexing, the requirement for the number of optical comb teeth can be further reduced. However, in these proposed microwave photonic channelization methods, the two OFCs serve as the signal and LO OFCs, respectively, and the optical comb teeth are not fully utilized. Therefore, new approaches are needed to improve system efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiency of the existing microwave photon channelization technology based on dual optical frequency combs that the optical comb teeth are not fully utilized, and to provide a microwave photon channelization receiving method based on the dual vernier effect, which adopts the dual vernier effect of two optical frequency combs serving as vernier optical frequency combs for each other, thereby greatly improving the channelization efficiency.

[0005] The present invention specifically adopts the following technical solutions to solve the above technical problems:

[0006] A microwave photon channelized receiving method based on a double vernier effect comprises the following steps:

[0007] S1, generating two coherent optical frequency comb signals with slightly different starting frequencies and free spectral ranges;

[0008] S2. Use the original RF signal to perform single-sideband modulation on the two optical frequency comb signals to obtain two modulated optical signals;

[0009] S3. De-wavelength-division-multiplex the two modulated optical signals, respectively, to separate each comb tooth and the optically carried radio frequency signal component at the same frequency as each comb tooth in the other modulated optical signal. Then, the comb teeth at the same frequency and the optically carried radio frequency signal component are combined into a pair of local oscillator / signal pairs, thereby obtaining 2m-1 pairs of local oscillator / signal pairs, where m is the number of comb teeth in each optical frequency comb signal.

[0010] S4. Dual-output image rejection mixing is performed on each LO / signal pair. The resulting 4m-2 intermediate frequency signals constitute the 4m-2 channels divided by the original RF signal.

[0011] Preferably, the two coherent optical frequency comb signals are generated using the following method: dividing the optical carrier into two paths; performing double-sideband modulation on the first optical carrier using the radio frequency signal f1 to generate the first optical frequency comb signal; first frequency-shifting the second optical carrier, and then performing double-sideband modulation on the frequency-shifted second optical carrier using the radio frequency signal f2 to generate the second optical frequency comb signal.

[0012] Preferably, the de-wavelength division multiplexing is achieved using a multi-channel optical filter.

[0013] Preferably, the dual-output image frequency suppression mixing method is specifically as follows: the local oscillator / signal pair is input into a 90-degree optical mixer, and then the two in-phase optical signals and the two orthogonal optical signals output are respectively subjected to balanced photoelectric detection, and then the two generated electrical signals are input into a 90-degree orthogonal bridge, and finally the two output electrical signals are respectively subjected to electrical filtering.

[0014] Preferably, the single sideband modulation is implemented using a dual-drive Mach-Zehnder modulator.

[0015] Based on the same inventive concept, the following technical solutions can also be obtained:

[0016] A microwave photon channelized receiving device based on a double vernier effect, comprising:

[0017] A dual optical comb generation module, used to generate two coherent optical frequency comb signals with slightly different starting frequencies and free spectral ranges;

[0018] The spectrum replication module is used to perform single-sideband modulation on the two optical frequency comb signals using the original RF signal to obtain two modulated optical signals;

[0019] The wavelength division demultiplexing module is used to demultiplex the two modulated optical signals, separate each comb tooth and the optical radio frequency signal component at the same frequency as each comb tooth in the other modulated optical signal, and then form a local oscillator / signal pair with the comb teeth at the same frequency and the optical radio frequency signal component, thereby obtaining 2m-1 local oscillator / signal pairs, where m is the number of comb teeth in each optical frequency comb signal;

[0020] The 2m-1 dual-output image rejection mixing modules are used to perform dual-output image rejection mixing on each local oscillator / signal pair. The resulting 4m-2 intermediate frequency signals constitute the 4m-2 channels divided by the original RF signal.

[0021] Preferably, the dual optical comb generation module comprises:

[0022] Optical coupler, used to split the optical carrier into two paths;

[0023] A first intensity modulator is configured to perform double-sideband modulation on the first optical carrier using the radio frequency signal f1 to generate a first optical frequency comb signal;

[0024] A frequency shift module, used to first shift the frequency of the second optical carrier;

[0025] The second intensity modulator is used to perform double-sideband modulation on the frequency-shifted second optical carrier using the radio frequency signal f2 to generate a second optical frequency comb signal.

[0026] Preferably, the wavelength division demultiplexing module is composed of two multi-channel optical filters.

[0027] Preferably, the dual optical comb generation module includes a 90-degree optical mixer, two balanced photodetectors, a 90-degree orthogonal bridge, and two electrical filters connected in sequence.

[0028] Preferably, the spectrum replication module includes two dual-drive Mach-Zehnder modulators operating in a single-sideband modulation state.

[0029] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0030] The present invention adopts the dual vernier effect of two optical frequency combs serving as each other's vernier optical frequency combs, which can greatly improve the channelization efficiency compared with the existing photon-assisted channelization technology. When the number of comb teeth of the two optical frequency combs is m, 4m-2 narrowband sub-channels can be output; the present invention further adopts a dual-output image frequency suppression mixing structure to effectively improve the image frequency suppression effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the principle of the microwave photon channelized receiving method based on the double vernier effect of the present invention;

[0032] Figure 2 The figure is a schematic structural diagram of a specific embodiment of a microwave photon channelized receiving device based on the double vernier effect of the present invention. DETAILED DESCRIPTION

[0033] To address the problem that the optical comb teeth of the existing microwave photonic channelization technology based on dual optical frequency combs are not fully utilized, the solution of the present invention is to use the dual vernier effect of two optical frequency combs as each other's vernier optical frequency combs, thereby greatly improving the channelization efficiency, and combining it with a dual-output image frequency suppression mixing structure to improve the image frequency suppression effect.

[0034] The microwave photon channelized receiving method based on the double vernier effect proposed in the present invention comprises the following steps:

[0035] S1, generating two coherent optical frequency comb signals with slightly different starting frequencies and free spectral ranges;

[0036] S2. Use the original RF signal to perform single-sideband modulation on the two optical frequency comb signals to obtain two modulated optical signals;

[0037] S3. De-wavelength-division-multiplex the two modulated optical signals, respectively, to separate each comb tooth and the optically carried radio frequency signal component at the same frequency as each comb tooth in the other modulated optical signal. Then, the comb teeth at the same frequency and the optically carried radio frequency signal component are combined into a pair of local oscillator / signal pairs, thereby obtaining 2m-1 pairs of local oscillator / signal pairs, where m is the number of comb teeth in each optical frequency comb signal.

[0038] S4. Dual-output image rejection mixing is performed on each LO / signal pair. The resulting 4m-2 intermediate frequency signals constitute the 4m-2 channels divided by the original RF signal.

[0039] The microwave photon channelized receiving device based on the double vernier effect proposed in the present invention includes:

[0040] A dual optical comb generation module, used to generate two coherent optical frequency comb signals with slightly different starting frequencies and free spectral ranges;

[0041] The spectrum replication module is used to perform single-sideband modulation on the two optical frequency comb signals using the original RF signal to obtain two modulated optical signals;

[0042] The wavelength division demultiplexing module is used to demultiplex the two modulated optical signals, separate each comb tooth and the optical radio frequency signal component at the same frequency as each comb tooth in the other modulated optical signal, and then form a local oscillator / signal pair with the comb teeth at the same frequency and the optical radio frequency signal component, thereby obtaining 2m-1 local oscillator / signal pairs, where m is the number of comb teeth in each optical frequency comb signal;

[0043] The 2m-1 dual-output image rejection mixing modules are used to perform dual-output image rejection mixing on each local oscillator / signal pair. The resulting 4m-2 intermediate frequency signals constitute the 4m-2 channels divided by the original RF signal.

[0044] The technical solution of the present invention is described in detail below with reference to the accompanying drawings:

[0045] The basic principle of the present invention is as follows Figure 1 As shown, first, two coherent optical frequency comb signals with slightly different starting frequencies and free spectral ranges are generated. The spectra of the generated two coherent optical frequency combs are shown in (a) and (b), respectively, and their free spectral ranges are denoted as f rep1 and f rep2 ; Then, the original RF signal is used to perform single-sideband modulation on the two optical frequency comb signals respectively. The spectra of the two modulated optical signals are shown in Figures (c) and (d) respectively. It can be seen that the optical frequency comb teeth in each modulated optical signal correspond to the optical radio frequency signals of different frequency components in the other modulated optical signal; the two modulated optical signals are de-wavelength-division-multiplexed respectively, and each comb tooth and the optical radio frequency signal components at the same frequency as the comb teeth in the other modulated optical signal are separated. Then, the comb teeth at the same frequency and the optical radio frequency signal components are combined into a pair of local oscillator / signal pairs. Assuming that the number of comb teeth of the two optical frequency combs is m, 2m-1 pairs of local oscillator / signal pairs can be obtained; then these local oscillator / signal pairs are mixed using the existing dual-output mirror frequency suppression mixing structure, as shown in FIG. Figure 1 As shown in (e), 4m-2 intermediate frequency signals can be obtained, and each intermediate frequency signal is a signal channel of the original RF signal.

[0046] Figure 2 The figure shows a specific implementation structure of the microwave photon channelized receiving device of the present invention. Figure 2 As shown, the microwave photon channelized receiving device includes:

[0047] A dual optical comb generation module, used to generate two coherent optical frequency comb signals with slightly different starting frequencies and free spectral ranges;

[0048] The spectrum replication module is used to perform single-sideband modulation on the two optical frequency comb signals using the original RF signal to obtain two modulated optical signals;

[0049] The wavelength division demultiplexing module is used to demultiplex the two modulated optical signals, separate each comb tooth and the optical radio frequency signal component at the same frequency as each comb tooth in the other modulated optical signal, and then form a local oscillator / signal pair with the comb teeth at the same frequency and the optical radio frequency signal component, thereby obtaining 2m-1 local oscillator / signal pairs, where m is the number of comb teeth in each optical frequency comb signal;

[0050] The 2m-1 dual-output image rejection mixing modules are used to perform dual-output image rejection mixing on each local oscillator / signal pair. The resulting 4m-2 intermediate frequency signals constitute the 4m-2 channels divided by the original RF signal.

[0051] The optical frequency comb generation module consists of a laser, a 3dB optical coupler, an intensity modulator 1, an intensity modulator 2, an optical filter 1, and an intensity modulator 3. The optical carrier generated by the laser is divided into two paths through the 3dB optical coupler. One path passes through the intensity modulator 1 modulated by the radio frequency signal f1 to generate the optical frequency comb 1, and the other path passes through the intensity modulator 1 modulated by the radio frequency signal f1 to generate the optical frequency comb 1. s The optical carrier is frequency-shifted by the intensity modulator 2, and the +1-order sideband is filtered out by the optical filter 1. Then, the frequency-shifted optical carrier passes through the intensity modulator 3 modulated by the RF signal f2 to generate the optical frequency comb 2. The FSR of the optical frequency comb 1 and the optical frequency comb 2 are equal to the frequencies of the RF signals f1 and f2, respectively. There is a slight difference between f1 and f2, and the frequency difference between the two is equal to the bandwidth of the output sub-channel intermediate frequency signal. All three intensity modulators operate in the double-sideband modulation state. The spectra of the optical frequency comb 1 and the optical frequency comb 2 can be expressed by E ofc1 (t) and E ofc2 (t) is expressed as:

[0052]

[0053] In formula (1), A1, A2 and f c1 、f c2 Represent the amplitude and starting frequency of the two optical frequency combs respectively. rep1 and f rep2 These are the FSRs of frequency comb 1 and frequency comb 2, respectively.

[0054] The spectrum replication module consists of dual-driven Mach-Zehnder modulators 1 and 2. The optical frequency combs 1 and 2 output by the optical frequency comb generation module are modulated by the broadband RF signal through dual-driven Mach-Zehnder modulators 1 and 2, respectively, to replicate the spectrum of the broadband RF signal. Both dual-driven Mach-Zehnder modulators in the spectrum replication module operate in a single-sideband modulation state that retains the carrier. The single-sideband modulated signal can be expressed as:

[0055]

[0056] The demultiplexing module uses two identical multi-channel optical filters: optical filter 2 and optical filter 3. The optical filters demultiplex the two modulated optical signals, separating each comb tooth and the optically carried RF signal component at the same frequency as the comb teeth in the other modulated optical signal. The comb teeth at the same frequency and the optically carried RF signal component are then combined into a pair of local oscillator / signal pairs, resulting in 2m-1 pairs of local oscillator / signal pairs. The expression for the local oscillator / signal pair can be written as:

[0057]

[0058] In formula (3), f ver1 (n) = f c1 +(n+1)f rep1 -f c2 -nf rep2 , which represents the corresponding vernier beat frequency when OFC1 is used as the photon LOs. When OFC2 is used as the photon LOs, the corresponding vernier beat frequency can be expressed as f ver2 (n) = f c2 +nf rep2 -f c1 -nf rep1 .f RL and f RR are the RF signals on the left and right sides of the optical comb teeth, γ RL and γ RR Respectively represent f RL and f RR electro-optical conversion loss.

[0059] The dual-output image rejection mixer module is an existing technology and consists of a 90-degree optical mixer, balanced photodetector 1, balanced photodetector 2, a 90-degree quadrature bridge, electrical filter 1, and electrical filter 2. The local oscillator / signal pairs selected by two multi-channel optical filters are input into the 90-degree optical mixer, which outputs two in-phase (I1, I2) and two quadrature (Q1, Q2) optical signals:

[0060]

[0061] The signal output by the 90-degree optical mixer is converted into photoelectricity by balanced photodetector 1 and balanced photodetector 2:

[0062]

[0063] The electrical signal then passes through a 90-degree orthogonal bridge and electrical filters 1 and 2 to achieve dual-output image rejection mixing and output two intermediate frequency signals, completing coherent dual-optical frequency comb RF channelized reception based on the dual vernier effect. The output intermediate frequency signal can be expressed as:

[0064]

[0065] It can be found that it simultaneously outputs the intermediate frequency signals on both sides of the local oscillator optical comb teeth and has excellent image frequency suppression capability. When the number of comb teeth of the two optical frequency combs is m, 4m-2 narrowband sub-channels can be output, such as Figure 1 Dual optical frequency combs, each with three teeth, can output 10 narrowband sub-channels. This approach leverages both the optical dual-vernier effect and a dual-output image rejection mixing structure, achieving high channelization efficiency and high image rejection ratio in RF channelization.

Claims

1. A microwave photon channelized receiving method based on a double vernier effect, characterized in that: The following steps are involved: S1, generating two coherent optical frequency comb signals with slightly different starting frequencies and free spectral ranges; S2. Use the original RF signal to perform single-sideband modulation on the two optical frequency comb signals to obtain two modulated optical signals; S3. De-wavelength-division-multiplex the two modulated optical signals, respectively, to separate each comb tooth and the optically carried radio frequency signal component at the same frequency as each comb tooth in the other modulated optical signal. Then, the comb teeth at the same frequency and the optically carried radio frequency signal component are combined into a pair of local oscillator / signal pairs, thereby obtaining 2m-1 pairs of local oscillator / signal pairs, where m is the number of comb teeth in each optical frequency comb signal. S4. Dual-output image rejection mixing is performed on each LO / signal pair. The resulting 4m-2 intermediate frequency signals constitute the 4m-2 channels divided by the original RF signal.

2. The microwave photon channelized receiving method based on the double vernier effect according to claim 1, characterized in that: The two coherent optical frequency comb signals are generated using the following method: dividing an optical carrier into two channels; performing double-sideband modulation on the first optical carrier using a radio frequency signal f1 to generate a first optical frequency comb signal; first frequency-shifting the second optical carrier, and then performing double-sideband modulation on the frequency-shifted second optical carrier using a radio frequency signal f2 to generate a second optical frequency comb signal.

3. The microwave photon channelized receiving method based on the double vernier effect according to claim 1, characterized in that: The de-wavelength division multiplexing is achieved using a multi-channel optical filter.

4. The microwave photon channelized receiving method based on the double vernier effect according to claim 1, characterized in that: The dual-output image suppression mixing method is specifically as follows: a local oscillator / signal pair is input into a 90-degree optical mixer, and then the two in-phase optical signals and two orthogonal optical signals output are subjected to balanced photoelectric detection, and then the two generated electrical signals are input into a 90-degree orthogonal bridge, and finally the two output electrical signals are subjected to electrical filtering.

5. The microwave photon channelized receiving method based on the double vernier effect according to claim 1, characterized in that: The single sideband modulation is achieved using a dual-drive Mach-Zehnder modulator.

6. A microwave photon channelized receiving device based on the double vernier effect, characterized in that: include: A dual optical comb generation module, used to generate two coherent optical frequency comb signals with slightly different starting frequencies and free spectral ranges; The spectrum replication module is used to perform single-sideband modulation on the two optical frequency comb signals using the original RF signal to obtain two modulated optical signals; The wavelength division demultiplexing module is used to demultiplex the two modulated optical signals, separate each comb tooth and the optical radio frequency signal component at the same frequency as each comb tooth in the other modulated optical signal, and then form a local oscillator / signal pair with the comb teeth at the same frequency and the optical radio frequency signal component, thereby obtaining 2m-1 local oscillator / signal pairs, where m is the number of comb teeth in each optical frequency comb signal; The 2m-1 dual-output image rejection mixing modules are used to perform dual-output image rejection mixing on each local oscillator / signal pair. The resulting 4m-2 intermediate frequency signals constitute the 4m-2 channels divided by the original RF signal.

7. The microwave photon channelized receiving device based on the double vernier effect according to claim 6, characterized in that: The dual optical comb generation module comprises: Optical coupler, used to split the optical carrier into two paths; A first intensity modulator is configured to perform double-sideband modulation on the first optical carrier using the radio frequency signal f1 to generate a first optical frequency comb signal; A frequency shift module, used to first shift the frequency of the second optical carrier; The second intensity modulator is used to perform double-sideband modulation on the frequency-shifted second optical carrier using the radio frequency signal f2 to generate a second optical frequency comb signal.

8. The microwave photon channelized receiving device based on the double vernier effect as claimed in claim 6, characterized in that: The de-wavelength division multiplexing module is composed of two multi-channel optical filters.

9. The microwave photon channelized receiving device based on the double vernier effect as claimed in claim 6, characterized in that: The dual optical comb generation module includes a 90-degree optical mixer, two balanced photodetectors, a 90-degree orthogonal bridge, and two electrical filters connected in sequence.

10. The microwave photon channelized receiving device based on the double vernier effect according to claim 6, characterized in that: The spectrum replication module includes two dual-drive Mach-Zehnder modulators operating in a single-sideband modulation state.

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