CN114976836A - High-coherence frequency-sweeping light source based on Brillouin random fiber laser oscillation - Google Patents

High-coherence frequency-sweeping light source based on Brillouin random fiber laser oscillation Download PDF

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CN114976836A
CN114976836A CN202210416613.8A CN202210416613A CN114976836A CN 114976836 A CN114976836 A CN 114976836A CN 202210416613 A CN202210416613 A CN 202210416613A CN 114976836 A CN114976836 A CN 114976836A
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brillouin
frequency
optical fiber
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张亮
蒋义坤
裘增欢
庞拂飞
张吉临
谢浩然
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University of Shanghai for Science and Technology
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06791—Fibre ring lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/08—Construction or shape of optical resonators or components thereof
    • H01S3/08018—Mode suppression
    • H01S3/08022—Longitudinal modes
    • H01S3/08031—Single-mode emission
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094003—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094042—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a fibre laser
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094076—Pulsed or modulated pumping
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/30—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range using scattering effects, e.g. stimulated Brillouin or Raman effects
    • H01S3/302—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range using scattering effects, e.g. stimulated Brillouin or Raman effects in an optical fibre

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Abstract

The invention discloses a high-coherence frequency sweep light source based on Brillouin random fiber laser oscillation, which structurally comprises an initial frequency sweep pump light module combined with a semi-open Brillouin fiber annular cavity. The initial sweep frequency pumping optical module is a resonant cavity formed by a gain medium, an optical tunable filter, an optical coupler and an optical isolator, and wide-spectrum laser output with different wavelengths can be realized by adjusting the optical filter. The semi-open Brillouin optical fiber ring cavity realizes narrow-band gain of Stokes (Stokes) light by using stimulated Brillouin scattering effect in the optical fiber, and realizes ultra-narrow linewidth frequency-sweeping laser output by introducing a distributed random feedback mechanism to form random laser oscillation and deeply compress linewidth. The sweep frequency light source not only realizes the stable output of sweep frequency laser, but also has the characteristics of controllable sweep frequency rate, convenient operation and narrow output laser line width, and further expands the application range of the sweep frequency laser in the aspects of optical fiber sensing, biological imaging, optical fiber communication and the like.

Description

High-coherence frequency-sweeping light source based on Brillouin random fiber laser oscillation
Technical Field
The invention relates to the field of fiber lasers, in particular to a high-coherence frequency-sweeping light source based on Brillouin random fiber laser oscillation. By utilizing the advantages of the ultra-narrow gain bandwidth and any working wavelength of the Brillouin random fiber laser, and combining the special stimulated Brillouin laser line width compression characteristic of the laser, the responsivity and line width index of the sweep frequency light source are effectively enhanced, and the method has important practical application value in the fields of optical fiber sensing, biomedical imaging, optical fiber communication and the like.
Background
In practical application, the fiber swept-frequency laser not only needs to have a large enough swept-frequency range, but also has high requirements on the line width of output laser and the swept-frequency speed. At present, the main types of fiber swept-frequency lasers studied at home and abroad comprise a swept-frequency fiber laser based on an acousto-optic tunable filter, a swept-frequency light source based on an F-P filter, a swept-frequency laser based on intracavity dispersion modulation and a swept-frequency light source based on a radio-frequency signal modulation intracavity polarization state. The fiber sweep lasers can realize a large sweep range, but because fine frequency selection is not carried out, multi-longitudinal mode laser output exists mostly, the time Coherence of the output laser is poor, and the linewidth is wide, so that the critical performances of the fiber sweep lasers on high sensitivity, detection distance and the like in the biomedical imaging Optical Coherence Tomography (OCT) technology and fiber sensing are severely limited.
The random fiber laser has important application prospect in the aspects of fiber communication, fiber sensing and the like due to the unique noise and coherence characteristics. Compared with the traditional resonant cavity fiber laser, the random fiber laser does not have a fixed mirror feedback type optical resonant cavity for mode selection, adopts distributed random feedback to realize laser oscillation, and has the advantages of simple structure, low cost and the like. The Brillouin random fiber laser adopts the Brillouin scattering effect in the optical fiber as laser gain, can realize ultra-narrow linewidth single-frequency random laser of dozens of hertz, realizes compression of two orders of magnitude of the linewidth of the pump optical fiber, effectively inhibits and eliminates a multi-longitudinal-mode cavity mode in a fixed cavity structure by Rayleigh random feedback in the structure, and does not need to precisely regulate and control the frequency of the pump optical fiber. In addition, the random feedback adopts a distributed feedback mechanism such as Rayleigh scattering in the optical fiber, has the advantage of any working wavelength, and is applicable to ultra-wideband wavelength tuning and frequency sweeping.
Disclosure of Invention
The invention mainly aims at the defects of poor coherence of the current sweep frequency light source and the like, and provides a high-coherence sweep frequency light source based on Brillouin random fiber laser oscillation. The broadband frequency-sweep laser output is realized by combining the Brillouin random fiber laser oscillation scheme under the tunable frequency-sweep pumping, and the time coherence performance of the frequency-sweep light source can be effectively improved while the large-range wavelength tuning is realized. The sweep frequency light source not only realizes the stable output of sweep frequency laser, but also has the characteristics of controllable sweep frequency speed, convenient operation and narrow output laser line width.
In order to achieve the purpose of the invention, the invention adopts the following inventive concept:
the basic idea of the invention is to utilize the ultra-narrow gain bandwidth and any tuning characteristic of the Brillouin optical fiber laser, and combine Rayleigh random feedback in the optical fiber to eliminate multi-longitudinal mode oscillation of a traditional laser cavity mode, and meanwhile, the random feedback can work at any wavelength to optimize the laser coherence and the sweep frequency range of the sweep frequency laser. The basic structure of the optical fiber cavity comprises a frequency sweeping pumping optical module and a Brillouin semi-open annular random optical fiber cavity. The frequency sweeping pumping optical module consists of a gain medium, a high-speed tunable optical filter, an optical isolator and a coupler; and a semi-open ring cavity consisting of an optical circulator, an optical fiber and an optical isolator.
The semi-open ring cavity structure comprises a section of long optical fiber as a Brillouin gain medium, wherein the pumped light injected into the semi-open ring cavity structure generates a stimulated Brillouin scattering effect after reaching a Brillouin threshold value, Stokes (Stokes) light with the propagation direction opposite to that of the pumped light is generated and amplified, a fixed Brillouin frequency shift amount exists between the pumped light and the Stokes, a random feedback structure with a certain length is introduced into the output end of the Stokes, backward distributed random feedback is provided, the pumped light is injected again and returns to the Brillouin gain optical fiber to form a cycle, finally, the power of the pumped light is increased, the Stokes light forms laser oscillation after the Brillouin gain is overcome, and single longitudinal mode laser output can be achieved. The semi-open cavity structure provided by the invention utilizes the characteristic that Stokes light is reversely transmitted relative to pump light in the stimulated Brillouin effect, the optical circulator is used for controlling the propagation direction of the Stokes laser in the cavity and automatically separating the Stokes laser from the input pump light, meanwhile, the pump light has no resonance and can be randomly tuned without meeting the requirement of precise frequency regulation, the requirement of frequency sweep is met, an additional filter device is not needed for filtering residual pump light after the Stokes laser is output, and the device is simple and easy to operate.
According to the conception, the invention adopts the following technical scheme:
a high-coherence frequency sweep light source based on Brillouin random fiber laser oscillation comprises an initial frequency sweep pumping light module and a semi-open Brillouin fiber annular cavity; the initial frequency sweep pumping optical module comprises a gain medium, an optical tunable filter, a first optical isolator and an optical coupler; the semi-open Brillouin optical fiber annular cavity comprises a first optical circulator, a gain optical fiber, a second optical circulator, a Rayleigh feedback structure and a second optical isolator.
Further, an optical tunable filter in the initial frequency sweep pumping optical module comprises a high-speed tunable optical filter and a driver, and controls laser outputs with different wavelengths; the gain medium realizes wide-spectrum laser, the output end of the gain medium is connected with a high-speed tunable optical filter, the output end of the high-speed tunable optical filter is connected with the input end of a first optical isolator, one output end of the first optical isolator is connected back to the gain medium to form a closed loop, and the other output end of the first optical isolator is connected with the input end of a semi-open Brillouin optical fiber annular cavity.
Furthermore, the semi-open Brillouin optical fiber annular cavity comprises a first optical circulator and a second optical circulator, and due to the characteristics of the circulators, transmitted light can only pass through one way from the port I to the port II and from the port II to the port III, so that Stokes laser in the semi-open Brillouin optical fiber annular cavity cannot pass through the port III to the port I of the second optical circulator and cannot pass through the port III to the port II of the first optical circulator to form a traditional closed annular resonant cavity.
Further, the semi-open brillouin fiber ring cavity includes a section of fiber as a gain fiber, the pump light injected into the fiber generates a stimulated brillouin scattering effect after reaching a brillouin threshold, and generates Stokes light transmitted in the same direction as the original pump light, and the frequency difference between the two is described as brillouin frequency shift and satisfies the relation:
Figure BDA0003604991260000021
wherein n is p Is the effective refractive index, ν, of the brillouin gain fiber A Is the propagation velocity of the acoustic wave, λ P Is the wavelength of the brillouin pump light, and c is the propagation speed of light in vacuum.
Furthermore, the output end of the semi-open Brillouin optical fiber ring cavity comprises a Rayleigh feedback structure, backward random feedback is provided, and the backward random feedback enters the semi-open Brillouin optical fiber ring cavity through the ports from the second port to the third port of the second optical circulator, so that laser oscillation is realized.
Further, the output end of the semi-open Brillouin optical fiber ring cavity comprises a second optical isolator, so that interference of Fresnel reflection of the end face of the output optical fiber on random laser is reduced.
The performance of the swept-frequency light source is optimized by optimizing the length and the type of the gain fiber in the semi-open Brillouin fiber annular cavity, the type of the filter and the type of the Rayleigh feedback structure.
Compared with the prior art, the invention has the following obvious and prominent substantive characteristics and remarkable advantages:
1. the stimulated Brillouin scattering effect in the optical fiber is adopted as laser gain, the ultra-narrow line width compression effect can be realized, the pumping light frequency can work at any wavelength, the output Stokes spectrum meets the requirement that the pumping light frequency shifts down the Brillouin frequency shift amount of the optical fiber material, and the output Stokes frequency-sweeping laser has excellent coherence performance.
2. The invention adopts random laser oscillation of distributed random feedback, can eliminate the longitudinal mode of the fixed cavity to realize single longitudinal mode laser output, and the distributed random feedback such as Rayleigh scattering can work on the characteristics of any wavelength, thereby realizing the output of the sweep frequency laser in a large range.
3. The invention adopts the structure that the optical fiber builds the semi-open annular random cavity, the structure fully utilizes the reverse transmission characteristic of Stokes light and pump light, the frequency of the pump light realizes a large sweep frequency range through a tunable filter, the pump light is excited to generate reverse transmission high-coherence Stokes random laser, no additional narrow-band filter is needed for residual pump light filtering operation, the structure is simple, and the cost is low.
Drawings
Fig. 1 is a schematic diagram of a high-coherence swept-frequency light source based on brillouin random fiber laser oscillation according to an embodiment of the present invention.
Fig. 2 shows a typical structure of an optically tunable filter employed in the present invention.
Wherein, 1 is gain medium, 2 is the tunable optical filter of optics, 3 is first optical isolator, 4 are optical coupler, 5 are first optical circulator, 6 are gain optic fibre, 7 are second optical circulator, 8 are rayleigh feedback structure, 9 are second optical isolator, 10 are the drive, 11 are high-speed tunable optical filter.
Detailed Description
The technical contents of the preferred embodiments of the present invention will be more clearly understood and appreciated by referring to the accompanying drawings described below. While the present invention may be embodied in many different forms of embodiments, it should be understood that the embodiments described herein are illustrative only and that the scope of the invention is not limited to the embodiments described herein.
The wide-spectrum sweep laser is combined as the pumping light Brillouin random fiber cavity to excite the output of the high-coherence Stokes sweep laser, so that the narrow line width and the stability of the output spectrum are ensured. The performance of the power, the threshold value, the efficiency, the line width, the noise and the like of the output laser of the sweep frequency light source is optimized by optimizing the length of the gain optical fiber, the type of the optical fiber and the type of a feedback mechanism in the Brillouin random cavity structure.
The above scheme is further illustrated below with reference to specific examples, in which preferred embodiments of the invention are detailed below:
example 1
In this embodiment, referring to fig. 1, a high-coherence swept-frequency light source based on brillouin random fiber laser oscillation includes an initial swept-frequency pumping optical module and a semi-open brillouin fiber annular cavity; the initial frequency sweep pumping optical module comprises a gain medium 1, an optical tunable filter 2, a first optical isolator 3 and an optical coupler 4; the semi-open Brillouin optical fiber annular cavity comprises a first optical circulator 5, a gain optical fiber 6, a second optical circulator 7, a Rayleigh feedback structure 8 and a second optical isolator 9. In the embodiment, the line width compression of the sweep frequency Stokes laser is realized through Brillouin random oscillation in a semi-open Brillouin optical fiber annular cavity.
Example 2
This embodiment is substantially the same as embodiment 1, and is characterized in that:
in an embodiment, the optical tunable filter 2 in the initial frequency sweep pumping optical module includes a high-speed tunable optical filter 11 and a driver 10, and controls laser outputs with different wavelengths; the gain medium 1 realizes wide-spectrum laser, the output end of the gain medium 1 is connected with the high-speed tunable optical filter 11, the output end of the high-speed tunable optical filter 11 is connected with the input end of the first optical isolator 3, one output end of the first optical isolator 3 is connected back to the gain medium 1 to form a closed loop, and the other output end of the first optical isolator 3 is connected with the input end of the semi-open Brillouin optical fiber annular cavity. The adopted pump light provides laser gain through a gain medium 1, and then is filtered by an optical tunable filter 2 to form original sweep frequency laser output with any wavelength. Then enters the semi-open Brillouin optical fiber annular cavity from the first port to the second port of the first optical circulator 5, and the first optical isolator 3 controls the light propagation direction in the cavity.
In this embodiment, the semi-open brillouin fiber ring cavity includes a first optical circulator 5 and a second optical circulator 7, and due to the characteristics of the circulators, light transmitted in the semi-open brillouin fiber ring cavity can only pass through one way from the port i to the port ii and from the port ii to the port iii, so Stokes laser in the semi-open brillouin fiber ring cavity cannot pass through the port iii to the port i of the second optical circulator 7 and cannot pass through the port iii to the port iii of the first optical circulator 5 to form a traditional closed ring resonator.
In this embodiment, the semi-open brillouin fiber ring cavity includes a section of fiber as a gain fiber 6, the pump light injected into the fiber generates a stimulated brillouin scattering effect after reaching a brillouin threshold, and generates Stokes light transmitted in the same direction as the original pump light, and a frequency difference between the two is described as brillouin frequency shift, and satisfies a relation:
Figure BDA0003604991260000041
wherein n is p Is the effective refractive index, v, of the Brillouin gain fiber A Is the propagation velocity of the acoustic wave, λ P Is the wavelength of the brillouin pump light, and c is the propagation speed of light in vacuum.
In this embodiment, the output end of the semi-open brillouin fiber ring cavity includes a rayleigh feedback structure 8, which provides backward random feedback and enters the semi-open brillouin fiber ring cavity through ports two to three of the second optical circulator 7, so as to realize Stokes laser random oscillation and output high-coherence swept laser.
In this embodiment, the output end of the semi-open brillouin fiber ring cavity includes a second optical isolator 9, which reduces interference of fresnel reflection on the end face of the output fiber to the random laser light, and forms multi-longitudinal mode laser light.
Example 3
This embodiment is substantially the same as the above embodiment, and is characterized in that:
in this embodiment, the structure of the whole swept-source is shown in fig. 1. The adopted gain medium 1 is generated by erbium-doped fiber (EDF), and then enters a semi-open Brillouin fiber annular cavity through a port I to a port II of a first optical circulator 5 after being filtered by an optical tunable filter 2. The semi-open Brillouin optical fiber annular cavity comprises a section of 10km long single-mode optical fiber as a gain optical fiber 6, the injected pump light generates a stimulated Brillouin scattering effect after reaching a Brillouin threshold value, Stokes light which is transmitted in the direction of the original pump light is generated, and the Stokes light is output from a first port to a second port of a second optical circulator 7. Meanwhile, the output end comprises a section of 20km single-mode optical fiber serving as a Rayleigh feedback structure 8, backward random feedback is provided, and the single-mode optical fiber enters a semi-open Brillouin optical fiber annular cavity through ports (II) to (III) of a second optical circulator 7, so that Stokes random laser oscillation is realized. Due to the one-way conduction characteristic of the circulator, Stokes light transmitted in the cavity cannot pass through the port III to the port I of the second optical circulator 7 and the port III to the port II of the first optical circulator 5 to form a traditional closed ring-shaped resonant cavity, so that multi-longitudinal-mode oscillation is avoided, meanwhile, pump light cannot form closed-loop resonance, and the laser is suitable for large-range frequency-sweeping optical pumping. Finally, the output end of the laser comprises a second optical isolator 9, so that the influence of Fresnel reflection on the output end face on the random cavity is reduced, and multi-longitudinal-mode laser oscillation is avoided.
A typical structure of the optically tunable filter 2 used is shown in fig. 2. The wide-spectrum light source amplified by the gain medium 1 is filtered by the optical tunable filter 2, and the two ends of the optical tunable filter 2 are loaded with driving signals, so that the central wavelength of the filter periodically changes along with the driving signals, and continuous frequency-sweeping laser output is realized.
The high-coherence frequency sweep light source based on Brillouin random fiber laser oscillation structurally comprises an initial frequency sweep pump light module and a semi-open Brillouin fiber annular cavity. The initial sweep frequency pumping optical module is a resonant cavity formed by a gain medium, an optical tunable filter, an optical coupler and an optical isolator, and wide-spectrum laser output with different wavelengths can be realized by adjusting the optical filter. The semi-open Brillouin optical fiber ring cavity utilizes stimulated Brillouin scattering effect in the optical fiber to realize narrow-band gain of Stokes light, random laser oscillation is formed by introducing a distributed random feedback mechanism, the line width is deeply compressed, and ultra-narrow line width frequency sweep laser output is realized. The sweep frequency light source of the embodiment of the invention not only realizes the stable output of the sweep frequency laser, but also has the characteristics of controllable sweep frequency rate, convenient operation and narrow output laser line width, and further expands the application range of the sweep frequency laser in the aspects of optical fiber sensing, biological imaging, optical fiber communication and the like.
The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made according to the purpose of the invention, and any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention should be replaced with equivalents as long as the object of the present invention is met, without departing from the technical principle and the inventive concept of the present invention.

Claims (6)

1. A high-coherence frequency sweep light source based on Brillouin random fiber laser oscillation is characterized in that: the optical fiber scanning device comprises an initial frequency scanning pumping optical module and a semi-open Brillouin optical fiber annular cavity; the initial frequency sweep pumping optical module comprises a gain medium (1), an optical tunable filter (2), a first optical isolator (3) and an optical coupler (4); the semi-open Brillouin optical fiber annular cavity comprises a first optical circulator (5), a gain optical fiber (6), a second optical circulator (7), a Rayleigh feedback structure (8) and a second optical isolator (9).
2. A highly coherent swept-frequency light source based on brillouin random fiber laser oscillation according to claim 1, wherein: the optical tunable filter (2) in the initial sweep frequency pumping optical module comprises a high-speed tunable optical filter (11) and a driver (10) and is used for controlling laser output with different wavelengths; the gain medium (1) realizes wide-spectrum laser, the output end of the gain medium is connected with the high-speed tunable optical filter (11), the output end of the high-speed tunable optical filter (11) is connected with the input end of the first optical isolator (3), one output end of the first optical isolator (3) is connected back to the gain medium (1) to form a closed loop, and the other output end of the first optical isolator (3) is connected with the input end of the semi-open Brillouin optical fiber annular cavity.
3. A highly coherent swept-frequency light source based on brillouin random fiber laser oscillation according to claim 1, wherein: the semi-open Brillouin optical fiber ring cavity comprises a first optical circulator (5) and a second optical circulator (7), and due to the characteristics of the circulators, light transmitted in the semi-open Brillouin optical fiber ring cavity can only pass through from the first port to the second port and from the second port to the third port in a one-way mode, so that Stokes (Stokes) laser in the semi-open Brillouin optical fiber ring cavity cannot pass through from the third port to the first port of the second optical circulator (7) and cannot pass through from the third port to the second port of the first optical circulator (5) to form a traditional closed ring resonant cavity.
4. A highly coherent swept-frequency light source based on brillouin random fiber laser oscillation according to claim 1, wherein: the semi-open Brillouin optical fiber annular cavity comprises a section of optical fiber as a gain optical fiber (6), the pumped light injected into the semi-open Brillouin optical fiber annular cavity generates a stimulated Brillouin scattering effect after reaching a Brillouin threshold value, Stokes light transmitted in the direction opposite to the original pumped light is generated, the frequency difference between the two is described as Brillouin frequency shift, and the relation is satisfied:
Figure FDA0003604991250000011
wherein n is p Is the effective refractive index, ν, of the brillouin gain fiber A Is the propagation velocity of the acoustic wave, λ P Is the wavelength of the brillouin pump light, and c is the propagation speed of light in vacuum.
5. A highly coherent swept-frequency light source based on brillouin random fiber laser oscillation according to claim 1, wherein: the output end of the semi-open Brillouin optical fiber annular cavity comprises a Rayleigh feedback structure (8) which provides backward random feedback and enters the semi-open Brillouin optical fiber annular cavity from the second port to the third port of the second optical circulator (7) to realize laser oscillation.
6. A highly coherent swept-frequency light source based on brillouin random fiber laser oscillation according to claim 1, wherein: the output end of the semi-open Brillouin optical fiber annular cavity comprises a second optical isolator (9) which reduces the interference of Fresnel reflection of the end face of the output optical fiber on random laser.
CN202210416613.8A 2022-04-20 2022-04-20 High-coherence frequency-sweeping light source based on Brillouin random fiber laser oscillation Pending CN114976836A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116231435A (en) * 2023-05-08 2023-06-06 山东省科学院激光研究所 Laser and sensing system based on sparse frequency sequence pulse optical time domain reflection technology

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116231435A (en) * 2023-05-08 2023-06-06 山东省科学院激光研究所 Laser and sensing system based on sparse frequency sequence pulse optical time domain reflection technology

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