A microwave photon frequency hopping signal generation device and method based on an optical switch

Abstract

The application discloses a microwave photon frequency hopping signal generation device and method based on an optical switch and belongs to the technical field of optical communication. The application is composed of a light source, a beam splitter, an optical frequency comb generator, an electro-optical frequency shifter, an acousto-optic modulator, a digital frequency synthesizer, a filter array, a signal control unit, an electrically controlled high-speed optical switch, a beam combiner and a photoelectric detector. The application separates optical frequency comb teeth by using an ultra-narrow bandwidth optical filter, selects and opens the frequency hopping signal generated by the local light beat frequency through the optical switch, and can generate a high-speed high-order high-stability frequency hopping signal compared with the prior art.

Description

Technical Field

[0001] This invention belongs to the field of optical communication technology, specifically relating to a microwave photonic frequency hopping signal generation device and method based on an optical switch. Background Technology

[0002] With the increasing threat of electronic warfare, the risk of interception and jamming in military communications is constantly rising. High-speed frequency-hopping communication has excellent security and anti-jamming performance, and has been rapidly developed, especially in the field of military communications. Currently, the vast majority of military communication systems use frequency-hopping communication to increase their anti-jamming and anti-interception capabilities. However, current major frequency-hopping communication systems are limited by the electronic components themselves; the frequency-hopping speed can only reach the millisecond level, and the frequency-hopping bandwidth is difficult to reach the GHz level, making it difficult to meet application requirements.

[0003] Microwave photonics combines the advantages of photonics, such as high speed, large bandwidth, low loss, and strong resistance to electromagnetic interference, thus compensating for the shortcomings of electronic technology to some extent. Therefore, in recent years, frequency-hopping signal generation schemes based on microwave photonics technology have attracted increasing attention from researchers. Optical frequency-hopping signal generation methods mainly include electro-optic modulator methods, direct-modulated laser heterodyne methods, and tunable filter methods. The first type uses baseband encoded signals to control an electro-optic modulator to achieve a switching function, allowing the baseband signal to correspond to different output frequencies. This scheme is simple but can only generate second-order frequency-hopping signals. The second type uses baseband signals to control the phase region of a DBR laser, changing the laser's output frequency, and obtains multi-order frequency-hopping signals through heterodyne detection. In practice, the wavelength tuning speed of DBR lasers is slow, making high-speed frequency hopping difficult, and the stability during tuning is poor. In the third type, the filter's center frequency is easily affected by the environment, resulting in poor frequency stability of the generated frequency-hopping signal. Summary of the Invention

[0004] To overcome the shortcomings of the above-mentioned technologies, the present invention provides a microwave photonic frequency hopping signal generation device and method based on optical switches. The device uses a narrowband filter to separate the teeth of a low repetition frequency optical frequency comb, and uses an optical switch to select different comb teeth to beat with the local oscillator to generate a high-speed frequency hopping signal.

[0005] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0006] A microwave photonic frequency hopping signal generation device based on an optical switch includes a light source 1, a beam splitter 2, an optical comb generator 3, an electro-optic frequency shifter 4, an acousto-optic modulator 5, a clock frequency source 6, a digital frequency synthesizer 7, a filter array 8, a signal control unit 9, an electrically controlled high-speed optical switch 10, a beam combiner 11, and a photodetector 12.

[0007] In this system, the optical signal generated by the light source 1 is split into an upper branch and a lower branch by the beam splitter 2. The clock frequency source 6 generates a clock signal and a frequency signal. The lower branch changes the optical frequency as the local oscillator by the electro-optic frequency shifter 4. The upper branch generates an optical frequency comb by the optical frequency comb generator 3. The baseband signal generated by the digital frequency synthesizer 7 is loaded onto each optical comb tooth by the acousto-optic modulator 5. The filter array 8 separates the optical comb teeth and inputs them into the electronically controlled high-speed optical switch 10. The signal control unit 9 controls the optical switch to select the input channel according to the frequency hopping pattern. The optical signal is then combined with the local oscillator light by the beam combiner 11 and enters the photodetector 12 to beat the frequency and generate a frequency hopping signal.

[0008] A method for generating microwave photonic frequency-hopping signals based on an optical switch includes the following steps:

[0009] The optical signal generated by light source 1 is split into an upper branch and a lower branch by beam splitter 2;

[0010] Clock and frequency signals are generated by clock frequency source 6;

[0011] The lower branch circuit changes the optical frequency via electro-optic frequency shifter 4 to serve as the local oscillator;

[0012] The upper branch path generates an optical frequency comb via optical frequency comb generator 3;

[0013] The baseband signal generated by the digital frequency synthesizer 7 is loaded onto each optical comb tooth via the acousto-optic modulator 5.

[0014] The filter array 8 separates the optical comb teeth and inputs them into the electronically controlled high-speed optical switch 10;

[0015] The signal control unit 9 controls the optical switch to select the input channel according to the frequency hopping pattern, and after being combined with the local oscillator light by the beam combiner 11, it enters the photodetector 12 to beat the frequency and generate a frequency hopping signal.

[0016] The present invention has the following beneficial effects:

[0017] 1. This invention generates an optical frequency comb with a low repetition frequency, uses an optical filter with an ultra-narrow bandwidth to separate the comb teeth, and then uses an electronically controlled high-speed optical switch to select the beat frequency with the local oscillator to generate a high-speed frequency hopping signal.

[0018] 2. This invention utilizes an optical frequency comb to generate multiple optical frequency signals, which can realize high-order frequency hopping signals. The high-speed electronically controlled optical switch has a faster response than a directly modulated laser, thus enabling the generation of high-speed, high-order, and highly stable frequency hopping signals. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a microwave photonic frequency hopping signal generation device based on an optical switch, according to an embodiment of the present invention.

[0020] Figure 2This is a schematic diagram illustrating the frequency hopping signal generation principle of an embodiment of the present invention.

[0021] Figure 3 The short-time Fourier transform diagram of the fourth-order frequency hopping signal is generated in an embodiment of the present invention. Implementation

[0022] To enable those skilled in the art to better understand this invention, the invention will be further described in detail below with reference to the accompanying drawings and examples.

[0023] like Figure 1 As shown, a microwave photonic frequency hopping signal generation device based on an optical switch includes a light source 1, a beam splitter 2, an optical comb generator 3, an electro-optic frequency shifter 4, an acousto-optic modulator 5, a clock frequency source 6, a digital frequency synthesizer 7, a filter array 8, a signal control unit 9, an electrically controlled high-speed optical switch 10, a beam combiner 11, and a photodetector 12.

[0024] like Figure 2 As shown, the steps for generating microwave photon frequency-hopping signals using the above-described device are as follows:

[0025] Light source 1 is split into two beams by beam splitter 2. One beam goes directly into optical frequency comb generator 3 to generate an optical frequency comb, and the other beam goes into electro-optic frequency shifter 4 to be used as a local oscillator. The baseband signal generated by digital frequency synthesizer 7 is loaded onto each tooth of the optical frequency comb by acousto-optic modulator 5. Each tooth is separated by filter array 8 and input into electronically controlled high-speed optical switch 10. Signal control unit 9 generates control signals according to the frequency hopping pattern to control the optical switch. The output frequency-hopping optical signal and the local oscillator light are combined by beam combiner 11 and input into photodetector 12 to generate a frequency hopping signal.

[0026] Here is a more specific example:

[0027] See Figure 1 A microwave photonic frequency hopping signal generation device based on an optical switch is mainly composed of a light source 1, a beam splitter 2, an optical comb generator 3, an electro-optic frequency shifter 4, an acousto-optic modulator 5, a clock frequency source 6, a digital frequency synthesizer 7, a filter array 8, a signal control unit 9, an electrically controlled high-speed optical switch 10, a beam combiner 11, and a photodetector 12.

[0028] The light source is a laser with a stable output carrier of 193400 GHz, which is split into two paths. A clock frequency source generates frequency signals of 7 GHz and 3 GHz to produce an optical frequency comb with a repetition rate of 7 GHz and an electro-optic frequency shifter. Four ultra-narrow optical filters with bandwidths less than 2 GHz separate signals with frequencies of 193414 GHz, 193407 GHz, 193393 GHz, and 193386 GHz. A 4×1 high-speed optical switch switches between the four channels to beat the frequency of the frequency-shifted 193403 GHz signal, outputting a fourth-order frequency-hopping signal. Figure 3 To generate the short-time Fourier transform of the frequency-hopping signal, the frequency-hopping signal jumps sequentially between 17 GHz, 10 GHz, 4 GHz, and 11 GHz, with each frequency lasting for 10 μs and a jumping rate of up to 100,000 jumps per second.

[0029] In summary, this invention utilizes an ultra-narrow bandwidth optical filter to separate the optical frequency comb teeth, and generates a frequency-hopping signal by selecting and beating the local oscillator light through an optical switch. Compared with existing technologies, this invention can generate high-speed, high-order, and highly stable frequency-hopping signals.

[0030] The above description is merely a specific implementation of the present invention in the embodiments, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A microwave photonic frequency hopping signal generation device based on an optical switch, characterized in that, Includes light source (1), beam splitter (2), optical comb generator (3), electro-optic frequency shifter (4), acousto-optic modulator (5), clock frequency source (6), digital frequency synthesizer (7), filter array (8), signal control unit (9), electrically controlled high-speed optical switch (10), beam combiner (11), and photodetector (12). Among them, the light signal generated by the light source (1) is divided into an upper branch and a lower branch by the beam splitter (2), the clock frequency source (6) generates a clock signal and a frequency signal, the lower branch changes the optical frequency as the local oscillator by the electro-optic frequency shifter (4), and the upper branch generates an optical frequency comb by the optical frequency comb generator (3); the baseband signal generated by the digital frequency synthesizer (7) is loaded onto each optical comb tooth by the acousto-optic modulator (5), the filter array (8) separates the optical comb teeth and inputs them into the electronically controlled high-speed optical switch (10); the signal control unit (9) controls the optical switch to select the input channel according to the frequency hopping pattern, and after being combined with the local oscillator light by the beam combiner (11), it enters the photodetector (12) to beat the frequency and generate a frequency hopping signal.

2. A method for generating microwave photonic frequency hopping signals based on an optical switch, characterized in that, Includes the following steps: The light signal generated by the light source (1) is split into an upper branch and a lower branch by a beam splitter (2); A clock signal and a frequency signal are generated by a clock frequency source (6); The lower branch passes through an electro-optic frequency shifter (4) to change the optical frequency as the local oscillator; The upper branch path generates an optical frequency comb via the optical frequency comb generator (3); The baseband signal generated by the digital frequency synthesizer (7) is loaded onto each optical comb tooth by the acousto-optic modulator (5); The filter array (8) separates the optical comb teeth and inputs them into the electronically controlled high-speed optical switch (10); The signal control unit (9) controls the optical switch to select the input channel according to the frequency hopping pattern, and after being combined with the local oscillator light through the beam combiner (11), it enters the photodetector (12) to beat the frequency and generate a frequency hopping signal.

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