CN110729623B - Microwave source - Google Patents

Abstract

The invention discloses a microwave source, which comprises a semiconductor laser, a photoelectric modulator, a polarization controller, an annular resonant cavity module, a photoelectric conversion module, a filter, a directional coupler and a potential regulator, wherein the semiconductor laser is connected with the photoelectric modulator through a power line; the annular resonant cavity module comprises an input waveguide, a plurality of annular waveguides with different radiuses and a plurality of output waveguides matched with the annular waveguides, and electrodes are arranged on the annular waveguides; the semiconductor laser, the photoelectric modulator and the polarization controller are sequentially connected along a light path; the input waveguide of the annular resonant cavity module is connected with the output end of the polarization controller; the electrode is connected with the potential adjuster; the plurality of output waveguides are connected with the photoelectric conversion module; the photoelectric conversion module, the filter and the directional coupler are sequentially connected; the directional coupler is connected with the photoelectric modulator.

Description

Microwave source

Technical Field

The invention relates to a microwave source. And more particularly to a microwave source capable of substantially suppressing the amplitude of spurious signals.

Background

The microwave frequency source with low phase noise and high stability is widely applied to the fields of radar, communication measurement and the like, and is a core component of modern electronic devices.

There are generally three ways in which microwave sources can be obtained:

firstly, a frequency doubling mode of a standard crystal oscillator;

designing a medium resonant cavity with a high Q value by utilizing the low loss of a medium, constructing a positive feedback amplifying circuit, controlling the phase and the amplitude and improving the stability of an output signal; as ZL201510357893. X; "Ultra-low vibration pulse-tube crystallized nutritional sapphire tissue with 10-16fractional frequency stability", IEEE TRANS. ON MICROWAVE THEORY AND TECHNIQUES, VOL.10, NO.1, 2010;

thirdly, adopting a photoproduction microwave mode;

there are two main categories: 1. the ultrastable laser is locked on a high-stability optical resonant cavity and is converted to the required frequency through an optical comb; "Generation of ultrastable microwave visual optical frequency division", Nature Photonics, DOI 10.1038/NPHOTON.2011.121;

2. a method of a photoelectric oscillator; the light is filtered by using an optical fiber or an optical filter, the optical signal is converted into an electric signal, and the electric signal is amplified and loaded to a modulator of a laser to form an oscillation loop. The first method among the above methods is the most mature method at present, but the phase noise index and stability index are poor. The second method has extremely high stability index and phase noise index, but has large equipment volume and weight and small application occasion. In the third method, the method for locking the ultrastable laser on the optical resonant cavity can obtain extremely high stability and phase noise indexes, but due to wavelength drift and aging of the laser, the continuous operation time is short, the optical path structure is complex and high in cost, the method for the photoelectric oscillator can obtain better phase noise indexes, the structure is compact, the continuous operation time is long, the application range is wide, and the main components of the photoelectric oscillator comprise the laser, an optical filter cavity (generally comprising an optical fiber or a micro-nano structure optical filter cavity), an optical detector, an electric amplifier, an optical modulator and the like. According to the main working principle, different devices are selected to construct various photoelectric oscillators for generating high-quality microwave signals; for example, ZL201010102017.X forms a laser microwave source with low phase noise, narrow line width and capable of accurately tuning fiber by using active BRAGG fiber, a wavelength division multiplexer, a laser and the like; ZL201410299327.3 utilizes the semiconductor double-mode laser to set up the high-quality tunable microwave source, has got rid of the demand of the external microwave source; ZL201510212059.1 employs a laser injection phase lock module and pilot control to compensate for the optical-to-electrical loop delay ripple. The optical fiber is used as an optical energy storage device, and is easily influenced by temperature and pressure, so that the performance of the whole machine and the frequency stability of output microwave signals are influenced; and the optical energy storage device with the micro-nano structure is complex to process and high in cost, and the coupling adjustment of the laser and the micro-nano structure is complex.

In the invention, two or more microstructure ring-shaped resonant cavities with different cavity lengths and capable of controlling delay time by voltage are provided to construct an optical filtering loop, so that the amplitude of a stray signal is suppressed. The invention can obtain extremely low phase noise, and has the advantages of good stray wave suppression level, low cost and simple optical path adjustment.

Disclosure of Invention

The invention aims to provide a microwave source to solve the problems of high spurious level and high phase noise of microwave output signals in a photoelectric oscillator in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a microwave source, which comprises a semiconductor laser, a photoelectric modulator, a polarization controller, an annular resonant cavity module, a photoelectric conversion module, a filter, a directional coupler and a potential regulator, wherein the semiconductor laser is connected with the photoelectric modulator through the polarization controller;

the annular resonant cavity module comprises an input waveguide, a plurality of annular waveguides with different radiuses and a plurality of output waveguides matched with the annular waveguides, and electrodes are arranged on the annular waveguides;

wherein,

the semiconductor laser, the photoelectric modulator and the polarization controller are sequentially connected along a light path;

the input waveguide of the annular resonant cavity module is connected with the output end of the polarization controller;

the electrode is connected with the potential adjuster;

the plurality of output waveguides are connected with the photoelectric conversion module;

the photoelectric conversion module, the filter and the directional coupler are sequentially connected;

the directional coupler is connected with the photoelectric modulator.

Optionally, the microwave source further comprises a signal amplifier disposed between the filter and the directional coupler for amplifying the strength of the filtered signal.

Optionally, the photoelectric conversion module includes a plurality of photodetectors having the same number as the output waveguides, input ends of the photodetectors are respectively connected with the plurality of output waveguides in a paired manner, and output ends of the photodetectors are respectively connected with the filter.

Optionally, the center frequency of the filter is less than the modulation frequency of the electro-optic modulator.

Optionally, the semiconductor laser is a VCSEL laser or a DFB laser.

Optionally, the semiconductor laser is a semiconductor laser with a center wavelength of 850nm, 1330nm or 1550nm, and a line width of the semiconductor laser is less than or equal to 20 MHz.

Optionally, the ring resonator module is made of a GaAs-based material or an InP-based material,

when the central wavelength of the semiconductor laser is 850nm, the annular resonant cavity module is made of a GaAs-based material;

and when the central wavelength of the semiconductor laser is 1330nm or 1550nm, the annular resonant cavity module is made of an InP-based material.

The invention has the following beneficial effects:

according to the invention, two or more microstructure ring-shaped resonant cavities with different cavity lengths and capable of controlling the delay time by voltage are provided to construct an optical filtering loop, so that the amplitude of a stray signal is suppressed.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 shows a schematic diagram of the structure of the microwave source of the present invention.

Detailed Description

In order to make the technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

A microwave source as shown in fig. 1, comprising a semiconductor laser, a photoelectric modulator, a polarization controller, a ring resonator module, a photoelectric conversion module, a filter, a directional coupler and a potential adjuster;

the annular resonant cavity module comprises an input waveguide, a plurality of annular waveguides with different radiuses and a plurality of output waveguides matched with the annular waveguides, and electrodes are arranged on the annular waveguides;

wherein,

the semiconductor laser, the photoelectric modulator and the polarization controller are sequentially connected along a light path;

the input waveguide of the annular resonant cavity module is connected with the output end of the polarization controller;

the electrode is connected with the potential adjuster;

the plurality of output waveguides are connected with the photoelectric conversion module;

the photoelectric conversion module, the filter and the directional coupler are sequentially connected;

the directional coupler is connected with the photoelectric modulator.

In particular, the microwave source further comprises a signal amplifier arranged between the filter and the directional coupler for amplifying the strength of the filtered signal.

Specifically, the photoelectric conversion module includes a plurality of photodetectors having the same number as the output waveguides, input ends of the photodetectors are respectively connected in a pair with the output waveguides, and output ends of the photodetectors are respectively connected with the filter.

In particular, the center frequency of the filter is smaller than the modulation frequency of the electro-optical modulator.

Specifically, the semiconductor laser is a VCSEL laser or a DFB laser.

Specifically, the semiconductor laser is a semiconductor laser with a central wavelength of 850nm, 1330nm or 1550nm, and the line width of the semiconductor laser is less than or equal to 20 MHz.

Specifically, the ring-shaped resonant cavity module is made of GaAs-based material or InP-based material,

when the central wavelength of the semiconductor laser is 850nm, the annular resonant cavity module is made of a GaAs-based material;

and when the central wavelength of the semiconductor laser is 1330nm or 1550nm, the annular resonant cavity module is made of an InP-based material.

It should be noted that the number of the ring waveguides with different radii is not limited in the present invention, and only two ring waveguides with different radii are illustrated in the present embodiment.

When the device is used, light path assembly is carried out as shown in fig. 1, light emitted by a semiconductor laser is modulated by a photoelectric modulator, the modulated light enters a polarization controller to be subjected to polarization state control, the polarized light enters an annular resonant cavity unit, voltage loaded on an annular waveguide is controlled by the adjustment of the polarization controller to adjust the propagation time of an optical signal in the annular waveguide, an extremely narrow free spectrum is filtered and screened by the annular waveguide with different peak wavelengths to filter out optical signals with high stray and high phase noise, the screened optical signals are converted into electric signals by an optical detector, the electric signals are filtered by a filter and enter a directional coupling unit after passing through a signal amplifier, one path of the amplified electric signals is output as a microwave output signal, and the other path of the amplified electric signals is loaded to the photoelectric modulation unit to form an oscillation loop.

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.

Claims (7)

1. A microwave source is characterized by comprising

The device comprises a semiconductor laser, a photoelectric modulator, a polarization controller, an annular resonant cavity module, a photoelectric conversion module, a filter, a directional coupler and a potential regulator;

the annular resonant cavity module comprises an input waveguide, a plurality of annular waveguides with different radiuses and a plurality of output waveguides matched with the annular waveguides, and electrodes are arranged on the annular waveguides;

wherein,

the semiconductor laser, the photoelectric modulator and the polarization controller are sequentially connected along a light path;

the input waveguide of the annular resonant cavity module is connected with the output end of the polarization controller;

the electrode is connected with the potential adjuster;

the plurality of output waveguides are connected with the photoelectric conversion module;

the photoelectric conversion module, the filter and the directional coupler are sequentially connected;

the directional coupler is connected with the photoelectric modulator.

2. The microwave source of claim 1 further comprising a signal amplifier disposed between the filter and the directional coupler for amplifying the strength of the filtered signal.

3. The microwave source of claim 1 wherein the photoelectric conversion module includes a plurality of photodetectors equal in number to the number of output waveguides, wherein input ends of the photodetectors are respectively coupled in pairs with the plurality of output waveguides, and wherein output ends of the photodetectors are respectively coupled to the filter.

4. The microwave source of claim 1 wherein the center frequency of the filter is less than the modulation frequency of the electro-optic modulator.

5. The microwave source of claim 1 wherein the semiconductor laser is a VCSEL laser or a DFB laser.

6. The microwave source of claim 3 wherein the semiconductor laser is a semiconductor laser having a center wavelength of 850nm, 1330nm, or 1550nm, and the linewidth of the semiconductor laser is less than or equal to 20 MHz.

7. The microwave source of claim 4 wherein the ring cavity module is fabricated from a GaAs based material or an InP based material,

when the central wavelength of the semiconductor laser is 850nm, the annular resonant cavity module is made of a GaAs-based material;

and when the central wavelength of the semiconductor laser is 1330nm or 1550nm, the annular resonant cavity module is made of an InP-based material.

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