A light-to-microwave device

Abstract

The present specification discloses a kind of photo generation microwave device, it is related to microwave technical field, it aims at solving the problem of high microwave signal phase noise, low short-term frequency stability generated by prior art.The device of the present application includes laser locking loop and optical oscillation loop;The laser locking loop includes: dual-wavelength laser, optical coupler, first photodetector, shunt unit, frequency mixer and control unit;The millimeter wave generation link includes: optical filter unit, modulation unit, optical fiber, optical fiber length controller and second photodetector.The present application can effectively reduce the phase noise of generated microwave signal, improve short-term frequency stability and simplify device structure.

Description

Technical Field

[0001] This document relates to the field of microwave technology, and in particular to a photogenerated microwave device. Background Technology

[0002] Low-phase-noise, high-stability microwave frequency sources are widely used in radar, communications, aerospace, metrology, and fundamental physics research. Currently, microwave sources are mainly obtained in two ways: 1. Traditionally, by frequency doubling a standard crystal oscillator (5MHz or 10MHz). 2. By designing the resonant frequency of a dielectric oscillator (DRO) and using external circuitry. Compared to these two traditional methods, photoelectric conversion-based microwave signal generation technology offers advantages such as low phase noise, high short-term frequency stability, compact structure, long continuous operating time, and a wider range of applications.

[0003] Optical microwave devices mainly include laser components, optical energy storage components, and modulation / demodulation components. Among them, optical energy storage components typically use optical fibers or micro / nano structures. Using optical fibers has the advantages of simple structure, but it is easily affected by environmental temperature, stress, etc., while the fabrication and coupling adjustment of micro / nano structures are more complex.

[0004] To meet the application requirements of photogenerated microwave devices, improving their phase noise and short-term frequency stability, and simplifying their structure are urgent problems that need to be solved. Summary of the Invention

[0005] This specification provides an optically generated microwave device to solve the problems of high phase noise and low short-term frequency stability of microwave signals generated by existing technologies. The device includes a laser-locked loop and an optical oscillation loop.

[0006] The laser locking loop includes: a dual-wavelength laser, an optical coupler, a first photodetector, a splitter unit, and a return control device;

[0007] The output of the dual-wavelength laser is connected to the input of the optical coupler; the first output of the optical coupler is connected to the input of the first photodetector; the output of the first photodetector is connected to the input of the splitter unit; the first output of the splitter unit is connected to the first input of the feedback control device; the third output of the splitter unit is used to output the final microwave signal generated by the photogenerated microwave device; the output of the feedback control device is connected to the input of the dual-wavelength laser; the feedback control device is used for feedback control of the wavelength laser.

[0008] The input terminal of the optical oscillation loop is connected to the second output terminal of the optical coupler, the second output terminal of the splitter unit, and the second input terminal of the mixer; the optical oscillation loop is used to modulate and demodulate the microwave signal in conjunction with the laser signal.

[0009] In some preferred embodiments, the control device includes a mixer and a control unit; the output of the mixer is connected to the input of the control unit; and the output of the control unit is connected to the input of the dual-wavelength laser.

[0010] In some preferred embodiments, the first output terminal of the splitter unit is used to output a first microwave signal; the second output terminal of the splitter unit is used to output a second microwave signal.

[0011] In some preferred embodiments, the optical oscillation loop includes: a filter unit, a modulation unit, an optical fiber processing device, and a second photodetector; the second output terminal of the optical coupler is connected to the input terminal of the filter unit; the output terminal of the filter unit is connected to the first input terminal of the modulation unit; the output terminal of the second photodetector is connected to the second input terminal of the mixer; and the second output terminal of the splitter unit is connected to the modulation unit.

[0012] The filtering unit is used to extract laser signals of a set wavelength;

[0013] The modulation unit is used to modulate the second microwave signal onto the laser signal of the set wavelength to generate a modulated laser signal;

[0014] The optical fiber processing device is used to transmit the modulated laser signal and adjust the length of the optical fiber;

[0015] The second photodetector is used to demodulate the modulated laser signal.

[0016] In some preferred embodiments, the optical fiber processing device includes an optical fiber and an optical fiber length controller;

[0017] The output of the modulation unit is connected to the input of the optical fiber; the output of the optical fiber is connected to the input of the optical fiber length control unit; and the output of the optical fiber length control unit is connected to the input of the second photodetector.

[0018] In some preferred embodiments, the optical fiber comprises a single-mode optical fiber.

[0019] In some preferred embodiments, the output frequency of the first photodetector, the output frequency of the second photodetector, the operating frequency of the splitter unit, and the operating frequency of the mixer cover the band in which the frequency difference between the two laser beams emitted by the dual-wavelength laser is located.

[0020] In some preferred embodiments, the splitting unit is a microwave directional coupler, a microwave power divider, or a microwave splitter.

[0021] In some preferred embodiments, the control unit is a lock-in amplifier or a PID controller.

[0022] In some preferred embodiments, the filtering unit is a wavelength division multiplexer or a filter.

[0023] The above-described at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0024] This invention can effectively reduce the phase noise of the generated microwave signal, improve short-term frequency stability, and simplify the device structure.

[0025] This invention achieves high-performance microwave signals by photoelectric conversion of the two beams output from a dual-wavelength laser. The resulting microwave signal is modulated onto one of the laser beams output from the dual-wavelength laser and coupled into an optical fiber. The optical fiber acts as an energy storage component, demodulating the microwave signal and providing feedback control for the dual-wavelength laser. Compared to traditional photogenerated microwave technology, this invention utilizes a dual-wavelength laser, eliminates the need for an additional microwave modulation signal, has a simple structure, and exhibits excellent phase noise reduction. Attached Figure Description

[0026] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0027] Figure 1 This is a schematic diagram of the structure of a photogenerated microwave device provided in one embodiment of this specification;

[0028] Figure label:

[0029] 1: Dual-wavelength laser;

[0030] 2: Optical coupler;

[0031] 3: First photodetector;

[0032] 4: Branching unit;

[0033] 5: Mixer;

[0034] 6: Control unit;

[0035] 7: Filter unit;

[0036] 8: Modulation unit;

[0037] 9: Fiber optic cable;

[0038] 10: Fiber optic length control unit;

[0039] 11: Second photodetector. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] like Figure 1 The diagram shown is a schematic diagram of the structure of a photogenerated microwave device provided in an embodiment of the present invention. Specifically, the device includes a laser locking loop and an optical oscillation loop.

[0042] The laser locking loop includes: a dual-wavelength laser, an optical coupler, a first photodetector, a splitter unit, and a return control device;

[0043] The output of the dual-wavelength laser is connected to the input of the optical coupler; the first output of the optical coupler is connected to the input of the first photodetector; the output of the first photodetector is connected to the input of the splitter unit; the first output of the splitter unit is connected to the first input of the feedback control device; the third output of the splitter unit is used to output the final microwave signal generated by the photogenerated microwave device; the output of the feedback control device is connected to the input of the dual-wavelength laser; the feedback control device is used for feedback control of the wavelength laser.

[0044] The input terminal of the optical oscillation loop is connected to the second output terminal of the optical coupler, the second output terminal of the splitter unit, and the second input terminal of the mixer; the optical oscillation loop is used to modulate and demodulate the microwave signal in conjunction with the laser signal.

[0045] The control device includes a mixer and a control unit; the output of the mixer is connected to the input of the control unit; the output of the control unit is connected to the input of the dual-wavelength laser.

[0046] In this embodiment, the output optical signal wavelength of the dual-wavelength laser is preferably 1550nm or 1300nm, the frequency difference between the two laser beams is preferably in the X-band, and the cavity length of the dual-wavelength laser is adjustable and controlled by the output signal of the control unit.

[0047] The optical coupler preferably operates at a wavelength of 1550nm or 1300nm and has a splitting ratio of 50:50 or 40:60, which is used to split the optical signal into two beams with the same or different power.

[0048] The output frequency of the first photodetector covers the X-band and is used to obtain the beat frequency signal of the two laser beams, i.e., the X-band microwave signal.

[0049] The mixer is used to mix two X-band microwave signals, and its operating frequency covers the X-band.

[0050] The control unit is used to amplify and process the feedback signal output by the mixer.

[0051] The first output terminal of the splitter unit is used to output a first microwave signal; the second output terminal of the splitter unit is used to output a second microwave signal.

[0052] The optical oscillation loop includes: a filter unit, a modulation unit, an optical fiber processing device, and a second photodetector; the second output terminal of the optical coupler is connected to the input terminal of the filter unit; the output terminal of the filter unit is connected to the first input terminal of the modulation unit; the output terminal of the second photodetector is connected to the second input terminal of the mixer; and the second output terminal of the splitter unit is connected to the modulation unit.

[0053] The filtering unit is used to extract laser signals of a set wavelength;

[0054] The modulation unit is used to modulate the second microwave signal onto the laser signal of the set wavelength to generate a modulated laser signal;

[0055] The optical fiber processing device is used to transmit the modulated laser signal and adjust the length of the optical fiber;

[0056] The second photodetector is used to demodulate the modulated laser signal.

[0057] The optical fiber processing device includes an optical fiber and an optical fiber length controller; the output end of the modulation unit is connected to the input end of the optical fiber; the output end of the optical fiber is connected to the input end of the optical fiber length control unit; and the output end of the optical fiber length control unit is connected to the input end of the second photodetector.

[0058] In this embodiment, the optical fiber is preferably a single-mode optical fiber; the optical fiber length controller is preferably a PZT piezoelectric ceramic tube, used to adjust the optical fiber length and reduce the influence of ambient temperature, stress, etc.

[0059] The output frequency of the first photodetector, the output frequency of the second photodetector, the operating frequency of the splitter unit, and the operating frequency of the mixer cover the band in which the frequency difference of the two laser beams emitted by the dual-wavelength laser is located.

[0060] The splitting unit is a microwave directional coupler, a microwave power divider, or a microwave splitter.

[0061] In this embodiment, the splitting unit preferably uses a one-to-three splitter with an operating frequency covering the X-band, used to achieve the splitting of the X-band microwave signal into three; the splitting unit is also used to output the final microwave signal, namely the X-band microwave signal with excellent phase noise and short-term frequency stability.

[0062] The control unit is a lock-in amplifier or a PID controller.

[0063] The filtering unit is a wavelength division multiplexer or a filter.

[0064] In this embodiment, the filtering unit preferably uses a wavelength division multiplexer to extract laser light of a certain wavelength.

[0065] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A light-to-microwave device, characterized by, The laser locking loop and the optical oscillation loop are included; The laser locking loop includes a dual-wavelength laser, an optical coupler, a first photodetector, a branching unit and a feedback device; The output end of the dual-wavelength laser is connected with the input end of the optical coupler, the output optical signal has a wavelength of 1550 nm or 1300 nm, and the frequency difference between the two laser beams is in the X band; the first output end of the optical coupler is connected with the input end of the first photodetector; the output end of the first photodetector is connected with the input end of the branching unit; the first output end of the branching unit is connected with the first input end of the feedback device; the third output end of the branching unit is used for outputting the finally generated microwave signal of the optical microwave device; the output end of the feedback device is connected with the input end of the dual-wavelength laser, the feedback device includes a frequency mixer and a control unit; the output end of the frequency mixer is connected with the input end of the control unit, the frequency mixer is used for mixing two X band microwave signals, and the working frequency covers the X band; the output end of the control unit is connected with the input end of the dual-wavelength laser, and the feedback device is used for feedback control of the wavelength laser; The input end of the optical oscillation loop is connected with the second output end of the optical coupler, the second output end of the branching unit and the second input end of the frequency mixer, and the second output end of the branching unit is used for outputting a second microwave signal; the optical oscillation loop is used for modulating and demodulating the microwave signal in combination with the laser signal; The optical oscillation loop includes a filtering unit, a modulation unit, a fiber processing device and a second photodetector; the second output end of the optical coupler is connected with the input end of the filtering unit; the output end of the filtering unit is connected with the first input end of the modulation unit; the output end of the second photodetector is connected with the second input end of the frequency mixer; and the second output end of the branching unit is connected with the modulation unit; The filtering unit is used for extracting a laser signal of a set wavelength; The modulation unit is used for modulating the second microwave signal on the laser signal of the set wavelength to generate a modulated laser signal; The fiber processing device is used for transmitting the modulated laser signal and adjusting the length of the optical fiber; The second photodetector is used for demodulating the modulated laser signal.

2. A light-to-microwave device according to claim 1, wherein The first output end of the branching unit is used for outputting a first microwave signal.

3. A light-to-microwave device according to claim 1, wherein The fiber processing device includes an optical fiber and an optical fiber length controller; The output end of the modulation unit is connected with the input end of the optical fiber; the output end of the optical fiber is connected with the input end of the optical fiber length controller; and the output end of the optical fiber length controller is connected with the input end of the second photodetector.

4. A light-to-microwave device according to claim 3, wherein The optical fiber includes a single-mode optical fiber.

5. The light-to-microwave device of claim 1, wherein The output frequency of the first photodetector, the output frequency of the second photodetector, the working frequency of the branching unit and the working frequency of the frequency mixer cover the frequency difference between the two laser beams emitted by the dual-wavelength laser.

6. The light-to-microwave device of claim 1, wherein The branching unit is a microwave directional coupler, a microwave power divider or a microwave branching unit.

7. The light-to-microwave device of claim 1, wherein The control unit is a phase-locked amplifier or a PID.

8. The light-to-microwave device of claim 1, wherein The filter unit is a wavelength division multiplexer or a filter. The filter unit is a wavelength division multiplexer or a filter.

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