CN116435850A - Photo-generated microwave device - Google Patents

Abstract

The specification discloses a photo-generated microwave device, relates to the technical field of microwaves, and aims to solve the problems of high phase noise and low short-term frequency stability of microwave signals generated in the prior art. The device comprises a laser locking loop and an optical oscillation loop; the laser locking loop includes: the device comprises a dual-wavelength laser, an optical coupler, a first photoelectric detector, a branching unit, a mixer and a control unit; the millimeter wave generation link includes: the optical fiber comprises a light filtering unit, a modulation unit, an optical fiber length controller and a second photoelectric detector. The invention can effectively reduce the phase noise of the generated microwave signal, improve the short-term frequency stability and simplify the structure of the device.

Description

A light-generating microwave device

technical field

This document relates to the field of microwave technology, in particular to an optically generated microwave device.

Background technique

Microwave frequency sources with low phase noise and high stability are widely used in radar, communication, aerospace, metrology and basic physics research and other fields. At present, the main ways to obtain the microwave source are: 1. Traditionally, it is obtained by multiplying the frequency of a standard crystal oscillator (5MHz or 10MHz). 2. Obtained by designing the resonant frequency of the dielectric oscillator (DRO) and cooperating with the peripheral circuit. Compared with the above two traditional methods, microwave signal generation technology based on photoelectric conversion has the advantages of low phase noise, high short-term frequency stability, compact structure, long continuous working time, and wide application range.

Optically generated microwave devices mainly include laser components, optical energy storage components, and modulation and demodulation components. Among them, optical energy storage components usually use optical fibers or micro-nano structures. The use of optical fibers has the characteristics of simple structure, but is easily affected by ambient temperature and stress, while the processing and coupling adjustment of micro-nano structures are more complicated.

In view of the application requirements of optically generated microwave devices, improving their phase noise, short-term frequency stability indicators, and simplifying the structure are problems that need to be solved urgently.

Contents of the invention

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 in the prior art. The device includes a laser locked loop and an optical oscillation loop;

The laser locked loop includes: a dual-wavelength laser, an optical coupler, a first photodetector, a branching unit, and a return control device;

The output end of the dual-wavelength laser is connected to the input end of the optical coupler; the first output end of the optical coupler is connected to the input end of the first photodetector; The output terminal is connected to the input terminal of the branching unit; the first output terminal of the branching unit is connected to the first input terminal of the control device; the third output terminal of the branching unit is used to output the The final generated microwave signal of the optical microwave device; the output end of the control device is connected to the input end of the dual-wavelength laser; the control 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 mixer; the optical oscillation The loop is used to modulate and demodulate the microwave signal in combination with the laser signal.

In some preferred embodiments, the control device includes a mixer and a control unit; the output terminal of the mixer is connected to the input terminal of the control unit; the output terminal of the control unit is connected to the dual The input port of the wavelength laser is connected.

In some preferred implementation manners, the first output terminal of the branching unit is used to output the first microwave signal; the second output terminal of the branching unit is used to output the second microwave signal.

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 end of the optical coupler is connected to the filter unit The input end is connected; the output end of the filter 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 mixer; the splitter The second output end of the road unit is connected to the modulation unit;

The filter unit is used to extract a laser signal with a set wavelength;

The modulation unit is configured to modulate the second microwave signal on the laser signal of the set wavelength to generate a modulated laser signal;

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

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

In some preferred embodiments, 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; the output end of the optical fiber length control unit is connected to the second photodetector connected to the input of the device.

In some preferred embodiments, the optical fiber comprises a single mode optical fiber.

In some preferred embodiments, the output frequency of the first photodetector, the output frequency of the second photodetector, the operating frequency of the branching unit, and the operating frequency of the mixer cover the The frequency band of the frequency difference between the two laser beams emitted by the dual-wavelength laser.

In some preferred embodiments, the branching unit is a microwave directional coupler, a microwave power splitter or a microwave splitter.

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

In some preferred embodiments, the filter unit is a wavelength division multiplexer or a filter.

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

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

In the present invention, the two beams of light output by the dual-wavelength laser are photoelectrically converted, and the obtained microwave signal is modulated onto a beam of laser output by the dual-wavelength laser as a modulation signal, and then coupled into an optical fiber, and the optical fiber is used as an energy storage component to demodulate the microwave signal , and perform feedback control on the dual-wavelength laser to obtain high-index microwave signals. Compared with the traditional light-generated microwave technology, the invention uses a dual-wavelength laser without additional microwave modulation signals, has a simple structure, and has the characteristics of excellent phase noise.

Description of drawings

The drawings described here are used to provide a further understanding of the application and constitute a part of the application. The schematic embodiments and descriptions of the application are used to explain the application and do not constitute an improper limitation to the application. In the attached picture:

Fig. 1 is a schematic structural diagram of an optical microwave device provided by an embodiment of this specification;

Reference signs:

1: Dual wavelength laser;

2: Optical coupler;

3: the first photodetector;

4: branching unit;

5: Mixer;

6: Control unit;

7: filter unit;

8: modulation unit;

9: optical fiber;

10: Optical fiber length control unit;

11: Second photodetector.

Detailed ways

In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be clearly and completely described below in conjunction with specific embodiments of the present application and corresponding drawings. Apparently, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

As shown in Figure 1, it is a schematic structural diagram of an optically generated microwave device provided by an embodiment of the present invention, specifically, the device includes a laser locked loop and an optical oscillation loop;

The laser locked loop includes: a dual-wavelength laser, an optical coupler, a first photodetector, a branching unit, and a return control device;

The output end of the dual-wavelength laser is connected to the input end of the optical coupler; the first output end of the optical coupler is connected to the input end of the first photodetector; The output terminal is connected to the input terminal of the branching unit; the first output terminal of the branching unit is connected to the first input terminal of the control device; the third output terminal of the branching unit is used to output the The final generated microwave signal of the optical microwave device; the output end of the control device is connected to the input end of the dual-wavelength laser; the control 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 mixer; the optical oscillation The loop is used to modulate and demodulate the microwave signal in combination with the laser signal.

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

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

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

The output frequency of the first photodetector covers the X-band, and is used to obtain the beat frequency signals of the two laser beams, that is, the X-band microwave signal.

The mixer is used to realize the frequency mixing of two X-band microwave signals, and the working frequency covers the X-band.

The control unit is used to amplify the control signal output by the mixer.

The first output terminal of the branching unit is used to output the first microwave signal; the second output terminal of the branching unit is used to output the second microwave signal.

The optical oscillation loop includes: a filter unit, a modulation unit, an optical fiber processing device and a second photodetector; the second output end of the optical coupler is connected to the input end of the filter unit; the filter unit The output end of the unit is connected to the first input end of the modulation unit; the output end of the second photodetector is connected to the second input end of the mixer; the second output end of the branching unit is connected to the The modulation unit is connected;

The filter unit is used to extract a laser signal with a set wavelength;

The modulation unit is configured to modulate the second microwave signal on the laser signal of the set wavelength to generate a modulated laser signal;

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

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

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; the optical fiber The output terminal of the length control unit is connected with the input terminal of the second photodetector.

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, which is used to adjust the length of the optical fiber and reduce the influence of ambient temperature and stress.

The output frequency of the first photodetector, the output frequency of the second photodetector, the operating frequency of the branching unit, and the operating frequency of the mixer cover the two laser beams emitted by the dual-wavelength laser The frequency band of the frequency difference.

The branching unit is a microwave directional coupler, a microwave power splitter or a microwave splitter.

In this embodiment, the branching unit preferably uses a one-to-three splitter, whose working frequency covers the X-band, and is used to realize the splitting of the X-band microwave signal into three; the branching unit is also used to output the final microwave signal, That is, X-band microwave signals with excellent phase noise and short-term frequency stability indicators.

The control unit is a lock-in amplifier or a PID.

The filter unit is a wavelength division multiplexer or a filter.

In this embodiment, the optical filter unit preferably uses a wavelength division multiplexer for extracting laser light of a certain wavelength.

The above descriptions are only examples of the present application, and are not intended to limit the present application. For those skilled in the art, various modifications and changes may occur in this application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims (10)

1. An optical generating microwave device is characterized by comprising a laser locking loop and an optical oscillating loop;

the laser locking loop includes: the device comprises a dual-wavelength laser, an optical coupler, a first photoelectric detector, a branching unit and a feedback control device;

the output end of the dual-wavelength laser is connected with the input end of the optical coupler; the first output end of the optical coupler is connected with the input end of the first photoelectric detector; the output end of the first photoelectric detector 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 control device; the third output end of the branching unit is used for outputting a finally generated microwave signal of the photo-generated microwave device; the output end of the feedback control device is connected with the input end of the dual-wavelength laser; the feedback control device is used for carrying out feedback control on 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 mixer; the optical oscillation loop is used for modulating and demodulating the microwave signal by combining the laser signal.

2. A photo-generated microwave device as claimed in claim 1, wherein the feedback control device comprises a mixer and a control unit; the output end of the mixer is connected with the input end of the control unit; the output end of the control unit is connected with the input end of the dual-wavelength laser.

3. An optically generated microwave device as defined in claim 1, wherein the first output of the branching unit is configured to output a first microwave signal; the second output end of the branching unit is used for outputting a second microwave signal.

4. A photo-generated microwave device as claimed in claim 3 wherein the optical oscillation loop comprises: the optical filter unit, the modulation unit, the optical fiber processing device and the second photoelectric detector; the second output end of the optical coupler is connected with the input end of the optical filtering unit; the output end of the light filtering unit is connected with the first input end of the modulation unit; the output end of the second photoelectric detector is connected with the second input end of the mixer; the second output end of the branching unit is connected with the modulation unit;

the filtering unit is used for extracting laser signals with set wavelengths;

the modulating unit is used for modulating the second microwave signal on the laser signal with the set wavelength to generate a modulated laser signal;

the optical fiber processing device is used for transmitting the modulated laser signals and adjusting the length of the optical fiber;

the second photodetector is used for demodulating the modulated laser signal.

5. A photo-generated microwave device as claimed in claim 4 wherein the optical fiber processing means comprises an optical fiber and a 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 control unit; and the output end of the optical fiber length control unit is connected with the input end of the second photoelectric detector.

6. A photo-generated microwave device as defined in claim 5 wherein the optical fiber comprises a single mode optical fiber.

7. The apparatus according to claim 4, wherein the output frequency of the first photodetector, the output frequency of the second photodetector, the operating frequency of the branching unit, and the operating frequency of the mixer cover a band in which a frequency difference between two laser beams emitted from the dual wavelength laser is located.

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

9. A photo-generated microwave device as claimed in claim 1, wherein the control unit is a lock-in amplifier or PID.

10. The light-generating microwave device of claim 4, wherein the filter unit is a wavelength division multiplexer or a filter.

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