CN109244801B

CN109244801B - Tunable photoelectric oscillator based on random Brillouin fiber laser and method

Info

Publication number: CN109244801B
Application number: CN201811195238.9A
Authority: CN
Inventors: 李明; 王光强; 郝腾飞; 祝宁华
Original assignee: Institute of Semiconductors of CAS
Current assignee: Institute of Semiconductors of CAS
Priority date: 2018-08-29
Filing date: 2018-10-12
Publication date: 2020-01-31
Anticipated expiration: 2038-10-12
Also published as: CN109244801A

Abstract

The disclosure provides tunable ultra-narrow linewidth optoelectronic oscillators based on random Brillouin fiber lasers, which comprise tunable lasers (1), second tunable lasers (2), couplers (3), beam splitters (4), intensity modulators (5), erbium-doped fiber amplifiers (6), circulators (7), high nonlinear fibers (8), second circulators (9), single mode fibers (10), photodetectors (11), power dividers (12) and phase-locked loop systems (13), wherein instant feedback systems are formed, so that two beams of laser emitted by the two tunable lasers have fixed and stable phase difference.

Description

Tunable photoelectric oscillator based on random Brillouin fiber laser and method

Technical Field

The disclosure relates to the technical field of microwave photonics, in particular to tunable ultra-narrow linewidth photoelectric oscillators based on random Brillouin fiber lasers and a method.

Background

The microwave source with high quality has quite extensive applications in many fields, such as in the communication industry, phased array radar systems, remote distributed antennas, etc., wherein, the method for generating microwave signals by microwave photonics has the advantages of large bandwidth, low phase noise, etc., wherein methods for directly generating microwave signals are the optical heterodyne method, two laser beats with the frequency difference required by us are used for generating microwave signals, the problems of the line width and the frequency drift of the two lasers are directly reflected on the generated microwave signals, in addition, methods are provided for generating microwave signals by using an optoelectronic oscillator, the optoelectronic oscillator can generate high-quality signals with high frequency, high Q value and low phase noise, which are very ideal signal generating devices, methods for generating microwave signals based on random Brillouin optical fiber lasers have been proposed, which can generate microwave signals with extremely narrow line width (3dB bandwidth is less than 10Hz), but based on the instability of stimulated Brillouin scattering, the generated microwave signals also have extremely unstable characteristics, and specific application is difficult to obtain.

In order to realize an extremely narrow, stable and tunable microwave source, the invention provides tunable ultra-narrow linewidth photoelectric oscillators based on random Brillouin fiber lasers.

Disclosure of Invention

() problems to be solved

The present disclosure provides tunable ultra-narrow linewidth optoelectronic oscillators based on random brillouin fiber lasers and methods to at least partially solve the above-presented technical problems.

(II) technical scheme

According to aspects of the disclosure, tunable ultra-narrow linewidth optoelectronic oscillators based on random Brillouin fiber lasers are provided, which comprise a tunable laser, a second tunable laser, a coupler, a beam splitter, an intensity modulator, an erbium-doped fiber amplifier, a circulator, a high nonlinear fiber, a second circulator, a single-mode fiber, a photoelectric detector, a power splitter and a phase-locked loop system, wherein instant feedback systems are formed, so that two beams of laser emitted by the two tunable lasers have a fixed and stable phase difference;

the th tunable laser is connected to the th input end of the coupler, the output end of the second tunable laser is connected to the second input end of the coupler, the output end of the coupler is connected to the input end of the beam splitter, the th output end of the beam splitter is connected to the input end of the phase-locked loop system, the output end of the phase-locked loop system is connected to the second tunable laser, the second output end of the beam splitter is connected to the input end of the intensity modulator, the output end of the intensity modulator is connected to the input end of the erbium-doped fiber amplifier, the output end of the erbium-doped fiber amplifier is connected to the input end of the th circulator, the th output end of the st circulator is connected to the th input end of the second circulator, the second output end of the high nonlinear fiber is connected to the th end, the second end of the high nonlinear fiber is connected to the second input end of the second circulator, the output end of the second circulator is connected to the th end of the single-mode fiber, the second end of the photodetector, the output.

In , by adjusting the wavelength difference between the tunable laser and the second tunable laser, the optoelectronic oscillator system can generate a microwave signal with extremely narrow line width and good stability.

In , the tunable laser, the second tunable laser, the coupler, the beam splitter, the intensity modulator, the erbium-doped fiber amplifier, the th circulator, the second circulator, the high nonlinear light, the single mode fiber, and the photodetector are connected by fiber, the beam splitter is connected by fiber to the phase-locked loop system, the photodetector, the power splitter, and the intensity modulator are connected by cable, and the phase-locked loop system is connected by cable to the tunable laser.

In , tunable laser, second tunable laser, coupler, intensity modulator, erbium-doped fiber amplifier, circulator, second circulator, highly nonlinear fiber, and single-mode fiber constitute random brillouin fiber lasers, the central wavelength of the lasers is determined by the central wavelengths of tunable laser and second tunable laser, and the lasers can emit laser light with extremely narrow line width.

In , the tunable laser and the second tunable laser are semiconductor lasers with wavelength capable of being tuned in a rapid and continuous mode.

In , the high-nonlinearity fiber is a high-Q microwave energy storage device with optical nonlinearity, and the length of the high-Q microwave energy storage device is hundreds of meters to tens of kilometers.

In , the single mode fiber is a low loss feedback element with a length of thousands of meters to tens of kilometers.

In , the dispersion of the opto-oscillator loop is controlled to zero so that signals of different frequencies have the same delay in the loop.

In , the phase-locked loop system is used to control the optical signals emitted from the th tunable laser and the second tunable laser to have stable phase differences.

According to another aspects of the present disclosure, methods for using the tunable ultra-narrow linewidth optoelectronic oscillator based on the random brillouin fiber laser are provided, which includes that the tunable laser and the second tunable laser emit two laser beams with a specific frequency difference, which are coupled via a coupler into path, and then split into two paths via a beam splitter , wherein path enters a phase-locked loop system and feeds back to the second tunable laser in real time, so that there is a fixed phase difference between the laser beams emitted by the tunable laser and the second tunable laser, and the path enters an intensity modulator and is modulated by a microwave signal generated by beat frequency, generating two positive orders with a frequency difference equal to the frequency difference of the two laser beams, the two modulated optical carriers enter an erbium-doped fiber amplifier and are amplified to a threshold value higher than the stimulated brillouin scattering, and then enter a high nonlinear optical fiber through a second ring circulator, where they are scattered in the high nonlinear optical fiber, and then enter a second fiber 632, and then enter a second fiber bragg grating optical fiber amplifier, and the high-frequency-spectrum-fiber amplifier, and the two optical fiber-ring nonlinear optical fiber amplifier outputs two rayleigh signals, which are amplified and fed back to form a narrow-line-wavelength-scattering optical-line-scattering amplifier, and fed back to a narrow-line-wavelength optical fiber-spectrum-based nonlinear fiber bragg-based fiber nonlinear optical fiber bragg-optical fiber spectrometer, so that the target optical fiber-optical fiber.

(III) advantageous effects

From the technical scheme, the tunable ultra-narrow linewidth photoelectric oscillator based on the random Brillouin fiber laser and the method have at least of the following beneficial effects:

(1) generating a microwave signal with adjustable center frequency and extremely narrow stable linewidth by utilizing the modulation characteristic of an intensity modulator, the nonlinear characteristic of a high nonlinear optical fiber, the feedback characteristic of a single-mode optical fiber, the quick wavelength adjustable characteristic of a tunable laser and the microwave generation performance of a photoelectric oscillator;

(2) because the system does not need optical and electrical filters, and the frequency of the microwave signal generated by the photoelectric oscillator loop is determined by the frequency difference between two lasers emitted by the tunable laser, the broadband tuning of the microwave signal can be realized by adjusting the wavelength difference of the two tunable lasers.

Drawings

Fig. 1 is a schematic structural diagram of a tunable ultra-narrow linewidth optoelectronic oscillator based on a random brillouin fiber laser according to an embodiment of the present disclosure.

Fig. 2 is a spectral line diagram of a tunable ultra-narrow linewidth optoelectronic oscillator based on a random brillouin fiber laser according to an embodiment of the present disclosure.

[ description of main reference numerals in the drawings ] of the embodiments of the present disclosure

1. th tunable laser, 2 nd tunable laser

3. A coupler; 4. beam splitter

5. Intensity modulator 6, erbium-doped fiber amplifier

7. th circulator 8, high nonlinear optical fiber

9. Second circulator 10 single mode optical fibre

11. Photoelectric detector 12 and power divider

13. A phase-locked loop system.

Detailed Description

The modulating characteristic of an intensity modulator, the nonlinear characteristic of a high nonlinear optical fiber, the feedback characteristic of a single mode optical fiber, the quick wavelength adjustable characteristic of the tunable laser and the microwave generating performance of the photoelectric oscillator are utilized to generate a microwave signal with adjustable center frequency and extremely narrow stable line width.

For purposes of promoting a better understanding of the objects, aspects and advantages of the disclosure, reference is made to the following detailed description, taken in conjunction with the accompanying drawings, at .

Indeed, various embodiments of the disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, which are provided so that this disclosure will satisfy applicable legal requirements.

In exemplary embodiments of the present disclosure, tunable ultra-narrow linewidth optoelectronic oscillators based on random brillouin fiber lasers are provided, fig. 1 is a schematic structural diagram of the tunable ultra-narrow linewidth optoelectronic oscillator based on random brillouin fiber lasers in the embodiments of the present disclosure, as shown in fig. 1, the tunable ultra-narrow linewidth optoelectronic oscillator based on random brillouin fiber lasers includes a tunable laser 1, a second tunable laser 2, a coupler 3, a beam splitter 4, an intensity modulator 5, an erbium-doped fiber amplifier 6, a circulator 7, a high nonlinear fiber 8, a second circulator 9, a single mode fiber 10, a photodetector 11, a power divider 12 and a phase-locked loop system 13, which constitute instant feedback systems, so that two lasers emitted by the two tunable lasers have a fixed and stable phase difference.

The -th tunable laser 1 is connected to the -th input end of the coupler 3, the output end of the second tunable laser 2 is connected to the second input end of the coupler 3, the output end of the coupler 3 is connected to the input end of the beam splitter 4, the -th output end of the beam splitter 4 is connected to the input end of the phase-locked loop system 13, the output end of the phase-locked loop system 13 is connected to the second tunable laser 2, the second output end of the beam splitter 4 is connected to the input end of the intensity modulator 5, the output end of the intensity modulator 5 is connected to the input end of the erbium-doped fiber amplifier 6, the output end of the erbium-doped fiber amplifier 6 is connected to the input end of the circulator 7, the -th output end of the -th circulator 7 is connected to the -th input end of the second circulator 9, the second output end is connected to the -th end of the high nonlinear fiber 8, the second end of the second circulator 9, the output end of the second circulator 9 is connected to the -th end of the single-mode fiber 10, the second end of the single-mode fiber is connected to the input end of the.

The tunable laser device comprises an -th tunable laser device 1, a second tunable laser device 2, 1

coupler

3, 1

beam splitter

4, 1

intensity modulator

5, 1 erbium-doped fiber amplifier 6, a -th circulator 7, a second circulator 9, 1 high-

nonlinearity light

8, 1 single-

mode fiber

10, 1 photoelectric detector 11 connected through an optical fiber, the beam splitter 4 connected with a phase-locked loop system 13 through an optical fiber, 1

photoelectric detector

11, 1

power divider

12, 1 intensity modulator 5 connected through a cable, and 1 phase-locked loop system 13 connected with 1 tunable laser device 2 through a cable.

tunable laser 1, second tunable laser 2, coupler 3, intensity modulator 5, erbium-doped fiber amplifier 6, circulator 7, second circulator 9, high nonlinear fiber 8, single mode fiber 10 constitute random brillouin fiber lasers, the center wavelength of the lasers is determined by the center wavelength of tunable laser 1 and second tunable laser 2, and the lasers with extremely narrow line width can be emitted.

Specifically, the th tunable laser 1 and the th tunable laser 2 are semiconductor lasers whose wavelengths can be tuned rapidly and continuously.

The high nonlinear optical fiber 8 is an optically nonlinear high-Q microwave energy storage element, and has a length of several hundreds of meters to several tens of kilometers.

The single mode optical fibre 10 is a feedback element with low loss, ranging from several kilometres to tens of kilometres in length.

Further , the chromatic dispersion of the opto-oscillator loop should be controlled to zero so that signals of different frequencies have the same delay in the loop.

The phase-locked loop system 13 is used for controlling and ensuring that the th tunable laser 1 and the second tunable laser 2 emit optical signals with stable phase difference.

When the system works, the tunable laser 1 and the second tunable laser 2 emit two lasers with a specific frequency difference, the two lasers are coupled into paths through the coupler 3, the optical spectra are as shown in (a) of fig. 2 and are divided into two paths through the beam splitter 4 , paths enter the phase-locked loop system 13 and feed back to the tunable laser 2 instantly, so that the lasers emitted from the tunable laser 1 and the second tunable laser 2 have a fixed phase difference, in addition, paths enter the intensity modulator 5 and are modulated by a microwave signal generated by beat frequency, two positive sidebands with a frequency difference equal to the frequency difference of the two lasers are generated (in the discussed range, small signal modulation is adopted, so that other high-order sidebands are ignored), the two modulated optical carriers enter the erbium-doped optical fiber amplifier and are amplified to a threshold value higher than that of stimulated ring scattering, the two optical carriers enter the high-nonlinear optical fiber amplifier, as shown in (b) of fig. 2, enter the high-nonlinear optical fiber amplifier, the high-frequency-fiber-amplifier, the high-frequency-fiber-amplifier is used for forming a narrow-frequency-fiber-amplifier, the narrow-fiber-amplifier-fiber-amplifier, the microwave-fiber-amplifier-fiber-amplifier-fiber-amplifier-fiber-amplifier-fiber-amplifier-fiber-amplifier can form a narrow-.

In addition, as can be seen from (d) in fig. 2, the spectrum shown in the figure also generates other noise waves due to beat frequency, but shows that the optical power of the optical signals is small, the generated noise wave power is small, and secondly, when the random laser power generated by the random brillouin fiber laser is large enough, the random laser can inhibit other generated microwave signals, so the quality of the generated signals cannot be influenced.

Furthermore, the above definitions of the various elements and methods are not limited to the specific structures, shapes or modes mentioned in the embodiments, and those skilled in the art may simply well-know substitutions for their structures, such as: an electric amplifier can be added in the system to amplify the signal; phase-locked loop systems that may take any other form and may be phase-locked, and the like. Also, the attached drawings are simplified and are for illustration purposes. The number, shape, and size of the devices shown in the drawings may be modified depending on the actual situation, and the arrangement of the devices may be more complicated.

So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It is to be noted that, in the attached drawings or in the description, the implementation modes not shown or described are all the modes known by the ordinary skilled person in the field of technology, and are not described in detail. Further, the above definitions of the various elements and methods are not limited to the various specific structures, shapes or arrangements of parts mentioned in the examples, which may be easily modified or substituted by those of ordinary skill in the art.

It should also be noted that directional terms, such as "upper", "lower", "front", "rear", "left", "right", and the like, used in the embodiments are only directions referring to the drawings, and are not intended to limit the scope of the present disclosure. Throughout the drawings, like elements are represented by like or similar reference numerals. Conventional structures or constructions will be omitted when they may obscure the understanding of the present disclosure.

And the shapes and sizes of the respective components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure. Furthermore, in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

In particular, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". is intended to be interpreted to mean the inclusion of a particular number of changes from + -10% in the embodiments, + -5% in the embodiments, + -1% in the embodiments, and + -0.5% in the embodiments, unless otherwise indicated.

The word "" or "" preceding an element does not exclude the presence of a plurality of such elements.

The use of ordinal numbers such as "", "second", "third", etc., in the specification and claims to modify a corresponding element does not by itself connote any ordinal number of the element or imply a sequence between and elements or a sequence in a method of manufacture, and is used merely to distinguish a designated element from a designated element with clarity.

In addition, unless steps are specifically described or must occur in sequence, the order of the steps is not limited to that listed above and may be changed or rearranged as desired by the desired design. The embodiments described above may be mixed and matched with each other or with other embodiments based on design and reliability considerations, i.e., technical features in different embodiments may be freely combined to form further embodiments.

Except where at least of such features and/or processes or units are mutually exclusive, all features disclosed in this specification (including any accompanying claims, abstract and drawings) may be combined in any combination, except where expressly stated otherwise, each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose.

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the disclosure, various features of the disclosure are sometimes grouped together by in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of the same or more of the various disclosed aspects.

The above-mentioned embodiments, objects, technical solutions and advantages of the present disclosure have been described in further , it should be understood that the above-mentioned embodiments are only illustrative of the embodiments of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.

Claims

The tunable ultra-narrow linewidth photoelectric oscillator based on the random Brillouin fiber laser comprises tunable lasers (1), second tunable lasers (2), a coupler (3), a beam splitter (4), an intensity modulator (5), an erbium-doped fiber amplifier (6), a circulator (7), high-nonlinearity fibers (8), a second circulator (9), a single-mode fiber (10), a photoelectric detector (11), a power divider (12) and a phase-locked loop system (13), wherein instant feedback systems are formed, so that two beams of laser emitted by the two tunable lasers have a fixed and stable phase difference;

wherein, the tunable laser (1) is connected to the input end of the coupler (3), the output end of the second tunable laser (2) is connected to the second input end of the coupler (3), the output end of the coupler (3) is connected to the input end of the beam splitter (4), the output end of the beam splitter (4) is connected to the input end of the phase-locked loop system (13), the output end of the phase-locked loop system (13) is connected to the second tunable laser (2), the second output end of the beam splitter (4) is connected to the input end of the intensity modulator (5), the output end of the intensity modulator (5) is connected to the input end of the erbium-doped fiber amplifier (6), the output end of the erbium-doped fiber amplifier (6) is connected to the input end of the circulator (7), the output end of the circulator (7) is connected to the second input end of the of the second circulator (9), the second output end is connected to the end of the high nonlinearity fiber (8), the second end of the high nonlinearity fiber (8) is connected to the second input end of the second circulator (9), the output end of the second circulator (9) is connected to the second input end 7312, the output end of the single-mode optical fiber (49311) is connected to the photoelectric detector (3), the single-mode optical fiber detector (3) is connected to the single-loop system, the single-mode.
2. The tunable ultra-narrow linewidth optoelectronic oscillator of claim 1, wherein the optoelectronic oscillator system can generate a microwave signal with extremely narrow linewidth and good stability by adjusting the wavelength difference between the th tunable laser (1) and the second tunable laser (2).
3. The tunable ultra-narrow linewidth optoelectronic oscillator according to claim 1, wherein the th tunable laser (1), the second tunable laser (2), the coupler (3), the beam splitter (4), the intensity modulator (5), the erbium-doped fiber amplifier (6), the th circulator (7), the second circulator (9), the high nonlinear optical fiber (8) and the single-mode optical fiber (10), the photodetectors (11) are connected with each other through optical fibers, the beam splitter (4) and the phase-locked loop system (13) are connected with each other through optical fibers, the photodetectors (11), the power splitter (12), the intensity modulator (5) are connected with each other through cables, and the phase-locked loop system (13) and the tunable laser (2) are connected with each other through cables.
4. The tunable ultra-narrow linewidth optoelectronic oscillator according to claim 1, wherein the th tunable laser (1), the second tunable laser (2), the coupler (3), the intensity modulator (5), the erbium-doped fiber amplifier (6), the th circulator (7), the second circulator (9), the highly nonlinear fiber (8) and the single-mode fiber (10) constitute random brillouin fiber lasers, and the center wavelengths of the lasers are determined by the center wavelengths of the th tunable laser (1) and the second tunable laser (2), and can emit laser light with an extremely narrow linewidth.
5. The tunable ultra-narrow linewidth optoelectronic oscillator of claim 1, wherein the th tunable laser (1) and the second tunable laser (2) are semiconductor lasers with the wavelength capable of being tuned rapidly and continuously.
6. The tunable ultra-narrow linewidth optoelectronic oscillator of claim 1, wherein the high nonlinear optical fiber (8) is a high Q microwave energy storage element with optical nonlinearity, with a length of hundreds of meters to tens of kilometers.
7. The tunable ultra-narrow linewidth optoelectronic oscillator of claim 1, wherein the single-mode fiber (10) is a low loss feedback element having a length of several kilometers to tens of kilometers.
8. The tunable ultra-narrow linewidth optoelectronic oscillator of claim 1, wherein the dispersion of the optoelectronic oscillator loop is controlled to zero so that signals of different frequencies have the same delay in the loop.
9. The tunable ultra-narrow linewidth optoelectronic oscillator according to claim 1, wherein the phase-locked loop system (13) is used for controlling and ensuring that the th tunable laser (1) and the second tunable laser (2) emit optical signals with stable phase difference.
10, method of tunable ultra-narrow linewidth optoelectronic oscillator based on random Brillouin optical fiber laser as claimed in claim 1, comprising that a second tunable laser (1) and a second tunable laser (2) emit two lasers with specific frequency difference, which are coupled to via a coupler (3), and split into two via a beam splitter (4) , wherein enters a phase-locked loop system (13) and instantly feeds back to the second tunable laser (2), so that there is a fixed phase difference between the lasers emitted from tunable laser (1) and the second tunable laser (2), and enters an intensity modulator (8655) to be modulated by microwave signal generated by beat frequency, two positive orders with frequency difference equal to frequency difference of the laser frequency difference are generated, two optical carriers after sideband enter a ring erbium-doped ring fiber amplifier to be amplified to be higher than scattering threshold value, enter a high linear nonlinear optical fiber (8) via a circulator (7), and enter a second nonlinear optical fiber (9) as a narrow-linewidth optical fiber oscillator, and a narrow-line-width optical fiber oscillator, wherein the two lasers enter a second multimode fiber (9) and a narrow-frequency-scattering fiber spectrometer (9) to be amplified as narrow-line-width optical fiber-scattering optical fiber oscillator, and a narrow-frequency-fiber-based nonlinear optical fiber laser-fiber-based on-fiber laser-Raman-fiber laser-fiber optical-fiber-.