CN116780318B - Brillouin laser and method for generating Brillouin laser - Google Patents
Brillouin laser and method for generating Brillouin laser Download PDFInfo
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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
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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
- H01S3/0675—Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
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- 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
- H01S3/06754—Fibre amplifiers
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- H—ELECTRICITY
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- 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
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/106—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity
- H01S3/108—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering
- H01S3/1086—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering using scattering effects, e.g. Raman or Brillouin effect
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
- H01S3/1106—Mode locking
- H01S3/1112—Passive mode locking
- H01S3/1115—Passive mode locking using intracavity saturable absorbers
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Abstract
本申请提供一种布里渊激光器及布里渊激光的产生方法。所述布里渊激光器包括：光纤、泵浦源、环形腔和动态光栅单元；所述泵浦源被配置为提供第一频率的泵浦光；所述环形腔被配置为将所述泵浦光通过所述光纤激发为第二频率的斯托克斯光；所述动态光栅单元，被配置为进行滤波以保证所述布里渊激光器的单模状态。本申请的方案，改善了传统布里渊激光器的跳模现象和瞬态多模现象，实现较长时间内单频的稳定激光。
The present application provides a Brillouin laser and a method for generating a Brillouin laser. The Brillouin laser includes: an optical fiber, a pump source, a ring cavity, and a dynamic grating unit; the pump source is configured to provide pump light of a first frequency; the ring cavity is configured to excite the pump light through the optical fiber into Stokes light of a second frequency; the dynamic grating unit is configured to perform filtering to ensure the single-mode state of the Brillouin laser. The solution of the present application improves the mode hopping phenomenon and transient multi-mode phenomenon of the traditional Brillouin laser, and realizes a single-frequency stable laser for a long time.
Description
Technical Field
The application relates to the technical field of laser, in particular to a Brillouin laser and a Brillouin laser generating method.
Background
Brillouin lasers based on the Stimulated Brillouin Scattering (SBS) effect are considered as a technical approach to obtain narrow linewidth, low noise lasers. However, with the brillouin laser in the related art, transient multimode and mode jump phenomena are liable to occur over a long period of time.
Disclosure of Invention
In view of the above, an object of the present application is to provide a brillouin laser and a brillouin laser generating method, which solve or partially solve the above problems.
In a first aspect of the application, there is provided a brillouin laser comprising:
the optical fiber, the pumping source, the annular cavity and the dynamic grating unit;
The pump source is configured to provide pump light at a first frequency;
The annular cavity is configured to excite the pump light through the optical fiber to stokes light of a second frequency;
the dynamic grating unit is configured to filter to ensure a single mode state of the brillouin laser.
Optionally, the annular cavity includes:
the optical fiber amplifier comprises a first circulator, a second circulator, a first coupler and an optical fiber amplifying unit;
the first circulator and the second circulator are configured to ensure unidirectional transmission of light within the annular cavity;
the first end of the first circulator is connected with the pump source, the second end of the first circulator is connected with the optical fiber amplifying unit, and the third end of the first circulator is connected with the first end of the second circulator;
the second end of the second circulator is connected with the dynamic grating unit, and the third end of the second circulator is connected with the first coupler.
Optionally, the brillouin laser further comprises a second coupler and a third coupler;
The second and third couplers are configured to form a feedback loop and re-inject a portion of the stokes light into the annular cavity through the first coupler to reduce the linewidth of the brillouin laser.
Optionally, the dynamic grating unit comprises a saturated absorber and a uniform Bragg grating;
The uniform Bragg grating is configured to reflect light entering from the second circulator and passing through the saturated absorber;
the saturated absorber is configured to form standing waves and saturated absorption effects for filtering based on light entering from the second circulator and light reflected by the uniform Bragg grating.
Optionally, the second coupler is further configured to output a portion of the stokes light.
Optionally, the third coupler is further configured to filter the re-injected stokes light.
Optionally, the optical fiber amplifying unit is configured to amplify the pump light and comprises a wavelength division multiplexer, a semiconductor laser and an erbium-doped optical fiber;
The first end of the wavelength division multiplexer is connected with the second end of the first circulator, and the second end of the wavelength division multiplexer is respectively connected with the semiconductor laser and the erbium-doped fiber.
In a second aspect of the present application, there is provided a brillouin laser generating method, applied to a brillouin laser according to the first aspect, the method comprising:
Providing pump light with a first frequency by using a pump source;
Exciting the pump light into Stokes light with a second frequency through an optical fiber by using an annular cavity;
and filtering by using a dynamic grating unit to ensure the single-mode state of the Brillouin laser.
Optionally, the annular cavity includes a first coupler;
The method further comprises forming a feedback loop with a second coupler and a third coupler and re-injecting a portion of the stokes light into the annular cavity through the first coupler to reduce a linewidth of the brillouin laser.
From the above, it can be seen that the brillouin laser and the brillouin laser generating method provided by the application obtain stokes light based on the optical fiber, the pumping source and the annular cavity, and ensure the single-mode state of the brillouin laser by using the dynamic grating unit. The mode-jump phenomenon and the transient multimode phenomenon of the traditional Brillouin laser are improved, and the single-frequency stable laser in a longer time is realized.
Drawings
In order to more clearly illustrate the technical solutions of the present application or related art, the drawings that are required to be used in the description of the embodiments or related art will be briefly described below, and it is apparent that the drawings in the following description are only embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort to those of ordinary skill in the art.
FIG. 1 is a schematic diagram of an exemplary Brillouin laser;
FIG. 2 is a schematic diagram of another exemplary Brillouin laser;
Fig. 3 is a schematic structural diagram of a brillouin laser according to an embodiment of the present application;
Fig. 4 is a flow chart of a brillouin laser generating method according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present application more apparent, embodiments of the present application will be described in detail below with reference to the accompanying drawings.
It should be noted that unless otherwise defined, technical or scientific terms used in the embodiments of the present application should be given the ordinary meaning as understood by one of ordinary skill in the art to which the present application belongs. The terms "first," "second," and the like, as used in embodiments of the present application, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, which may also be changed when the absolute position of the object to be described is changed.
Fig. 1 shows a schematic diagram of an exemplary brillouin laser 100. As shown in fig. 1, the brillouin laser 100 includes a pump laser source (DFB) 101, a circulator (CIR 1) 102, a band-pass filter (TOF) 103, 980nm optical source pump (LD) 104, a Wavelength Division Multiplexer (WDM) 105, an erbium-doped fiber (EDF) 106, and a coupler (OC) 107. The main working principle of the brillouin laser 100 is that a brillouin pump laser with a longer linewidth is injected into an a' port of a circulator 102 based on a pump laser source 101, and backward-propagating stokes light is generated by a brillouin effect in an erbium-doped optical fiber 106 pumped by a 980nm light source 104 based on a wavelength division multiplexer 105. The backward stokes light enters the band-pass filter 103 through the b 'port and the c' port of the circulator 102 and is output through the 50:50 coupler 107.
In the brillouin laser 100, the erbium-doped fiber is used as the gain medium, and the erbium-doped fiber laser is essentially the erbium-doped fiber laser when the brillouin pump light is not injected, after the pump light is injected, the stokes light gradually increases under the competition of gain to occupy the dominant position, but since the single-mode state is ensured to be mainly through the narrow-band brillouin gain bandwidth in the whole cavity, and the erbium-doped fiber is easily interfered by the outside, transient multimode and mode jump phenomena are easily generated in a longer time. And the main mode and the rest modes are restrained relatively little, and if the output power is too large, the side mode can also have larger power.
Fig. 2 shows a schematic diagram of another exemplary brillouin laser 200. As shown in fig. 2, the brillouin laser 200 includes a pump laser source 201, an Isolator (ISO) 202, an Erbium Doped Fiber Amplifier (EDFA) 203, an attenuator (VOA) 204, a first circulator 205, a Polarization Controller (PC) 206, double couplers 207 and 208, a first single mode fiber 209 (SMF 1), a second circulator 210, and a second single mode fiber 211 (SMF 2). The principle of the main operation of the brillouin laser 200 is that based on a pumping laser source 201, after brillouin pumping light is amplified by an isolator 202 and an erbium-doped fiber amplifier 203, the brillouin pumping light is injected into a single mode fiber 209 with a thousand meters through an adjusting attenuator 204, a stokes light is generated by exciting the brillouin effect, then the double couplers 207 and 208 form the function of an optical filter to filter, redundant modes are reduced, a second single mode fiber 211 is used as a medium of Rayleigh scattering, and the noise of the laser is further reduced by using the effect of weak distributed feedback of the stokes light on the basis of the stokes light.
In the brillouin laser 200, a single-mode fiber is used as a gain medium, and filtering is performed by the double couplers 207 and 208, so that the mode-jump phenomenon can be reduced to a certain extent, but the mode-jump itself is difficult to completely avoid due to the overlong cavity length, and the effect is poor.
In view of this, the embodiment of the application provides a brillouin laser and a brillouin laser generating method, which obtain stokes light based on an optical fiber, a pumping source and a ring cavity, and ensure a single-mode state of the brillouin laser by using a dynamic grating unit. The mode-jump phenomenon and the transient multimode phenomenon of the traditional Brillouin laser are improved, and the single-frequency stable laser in a longer time is realized.
Referring to fig. 3, a schematic structure of a brillouin laser 300 according to an embodiment of the present application is shown. As shown in fig. 3, the brillouin laser 300 according to the embodiment of the present application may include an optical fiber, a pumping source 301, a ring cavity, and a dynamic grating unit.
Specifically, the pump source 301 is configured to provide pump light with a first frequency, the annular cavity is configured to excite the pump light into stokes light with a second frequency through the optical fiber, and the dynamic grating unit is configured to perform filtering to ensure a single-mode state of the brillouin laser.
In this embodiment, pump light of a first frequency is injected into the annular cavity based on the pump source 301. For example, the wavelength of the pump light may be 1550nm.
It will be appreciated that when no pump light is injected, the annular cavity is essentially a free-standing laser and there is a certain frequency (wavelength) of light within the annular cavity, i.e. there is a corresponding resonant mode within the annular cavity. After the pump light is injected, under the competition of gain, stokes light gradually increases to occupy the dominant position.
In some embodiments, as shown in FIG. 3, the annular cavity may include a first circulator 302, a second circulator 306, a first coupler 309, and a fiber amplification unit.
Specifically, a first end a1 of the first circulator 302 is connected to the pump source 301, a second end b1 of the first circulator 302 is connected to the optical fiber amplifying unit, a third end c1 of the first circulator 302 is connected to a first end a2 of the second circulator 306, a second end b2 of the second circulator 306 is connected to the dynamic grating unit, and a third end b3 of the second circulator 306 is connected to the first coupler 309.
In some embodiments, the first circulator 302 and the second circulator 306 are configured to ensure unidirectional transmission of light within the annular cavity. Taking the first circulator 302 as an example, the order of light transmission through the first circulator 302 can only be from the first end a1 to the second end b1 to the third end c1.
In some embodiments, the first circulator 302 and the second circulator 306 may also be configured to filter. Since the first circulator 302 and the second circulator 306 themselves also have a certain bandwidth, only light of a certain wavelength band (e.g., 1530-1560 nm) is allowed to pass through.
In some embodiments, pump light of a first frequency is injected into the annular cavity based on the pump source 301. Specifically, as shown in fig. 3, the pump light is injected at the first end a1 of the first circulator 302.
Additionally, as an alternative embodiment, the first circulator 302 may be replaced with a coupler. However, if the coupler is provided, the power loss is larger than that of the first circulator 302.
In some embodiments, the optical fiber amplification unit is configured to amplify the pump light.
In some alternative embodiments, as shown in FIG. 3, the fiber amplification unit may further include a wavelength division multiplexer 303, a semiconductor laser 304, and an erbium doped fiber 305. Specifically, a first end of the wavelength division multiplexer 303 is connected to the second end b1 of the first circulator 302, and a second end of the wavelength division multiplexer 303 is connected to the semiconductor laser 304 and the erbium-doped fiber 305, respectively.
In some alternative embodiments, the semiconductor laser 304 is configured to provide pumping to the erbium doped fiber 305 to provide gain for laser formation.
In the related art, a single mode fiber is used to excite the brillouin effect, which requires a length of several kilometers. In the embodiment of the application, the erbium-doped optical fiber is used as a medium of Brillouin gain, the Brillouin effect can be excited only by the length smaller than 10 meters, and compared with the single-mode optical fiber, the cavity length can be obviously reduced, so that the single-mode state can be realized more favorably.
In some alternative embodiments, the semiconductor laser 304 has an exit wavelength of 900-980nm. For example, the semiconductor laser 304 may be 980nm light source pumped.
In alternative embodiments, the erbium doped fiber 305 may be replaced by an optical fiber doped with other rare earth elements, as long as the optical fiber doped with other rare earth elements can perform the optical amplification function of the optical fiber amplifying unit.
It will be appreciated that when pump light of the first frequency provided by the pump source 301 is not injected, the semiconductor laser 304 provides amplified energy that is absorbed by the erbium doped fiber 305, generating the same photons as in the annular cavity, thereby amplifying the light in the annular cavity, i.e. the light propagating in the fiber undergoes an optical gain process. The gain of the semiconductor laser 304 is robbed in response to the pump light injected at the first frequency.
As an alternative embodiment, the power of the pump source 301 and the semiconductor laser 304 needs to be controlled within a certain range.
It will be appreciated that in response to the pump source 301 being too low in power, the resonant modes within the annular cavity are not sufficiently suppressed such that stokes light cannot dominate, and in response to the pump source being too high in power, the pump light will rob the gain of the erbium doped fibre 305 such that the brillouin gain effect cannot occur such that stokes light cannot be generated.
Further, for the semiconductor laser 304, the appropriate power is such that the gain provided within the erbium doped fiber 305 can amplify the stokes light.
Accordingly, a preliminary experiment may be performed, and a control instruction may be set to control the power of the pump source 301 and the semiconductor laser 304 based on the composition of the output light of the preliminary experiment. Specifically, in the preliminary experiment, the composition of the output light can be determined by externally connecting a spectrometer and by observing the spectral image.
Thus, in response to the power of the pump source 301 and the semiconductor laser 304 reaching the power threshold, respectively, the generated backward stokes light enters from the second end b1 of the first circulator 302 and is output from the third end c1 of the first circulator 302, and then enters the dynamic grating unit through the first end a2 and the second end b2 of the second circulator 306.
It should be appreciated that stokes light cannot be generated in response to the power of the pump source 301 or the semiconductor laser 304 not reaching the power threshold. In addition, in the case where the power does not reach the threshold value, due to the unidirectional transmission effect of the first circulator 302 and the second circulator 306 on the light in the annular cavity, the pump light injected from the pump source 301 cannot pass through the first circulator 302 and cannot be output, resulting in the finally output light of only the resonant mode in the annular cavity.
Specifically, the power threshold may be calculated by the following formula:
Wherein R is the power reflectivity of the annular cavity, G is the linear gain, A eff is the effective mode field area of the erbium-doped optical fiber, G B is the Brillouin gain coefficient of the optical fiber, and L eff is the effective optical fiber length.
In addition, although stokes light is dominant in gain competition and light of other wavelengths than light closer to the wavelength of the pump light (1550 nm) is hardly robbed to the gain of the semiconductor laser 304, other modes of output light than stokes light are possible. Therefore, it is necessary to further increase the suppression ratio between the main mode (stokes light) and the side mode (resonance mode in the annular cavity and other light than stokes light) to avoid the occurrence of multimode phenomenon.
As an alternative embodiment, the dynamic grating unit may comprise a saturated absorber 307 and a uniform bragg grating 308, as shown in fig. 3.
Specifically, the uniform Bragg grating 308 is an all-fiber device formed by periodically modulating its refractive index. The uniform bragg grating 308 is configured to reflect light entering from the second circulator 306 and passing through the saturated absorber 307.
Further, in some embodiments, the uniform Bragg grating 308 may also have a precise wavelength selection function. The uniform Bragg grating 308 is a small length of optical fiber of several mm length, the fundamental characteristic of which is a narrow band optical filter centered at the resonant wavelength, with a bandwidth on the order of nm. Thus, based on the bandwidth of the uniform Bragg grating 308, only the pump light and Stokes light are within their bandwidths, while light generated by the semiconductor laser 304 (e.g., 980nm light) is filtered out. However, since the bandwidth of the uniform bragg grating 308 is relatively wide, only the coarse filtering effect is achieved, and the light of the resonant mode in the annular cavity cannot be filtered, and a multimode phenomenon may still occur.
Further, in some embodiments, the saturated absorber 307 is configured to form standing waves and saturated absorption effects for filtering based on light entering from the second circulator 306 and light reflected by the uniform Bragg grating 308. The light of the other modes in the annular cavity is further filtered on the basis that the light generated by the semiconductor laser 304 is filtered out.
In this way, the incident light (light entering from the second circulator 306) and the reflected light (light of which the incident light passes through the saturation absorber 307 and is then reflected by the uniform bragg grating 308) form a stable standing wave in the saturation absorber 307, thereby producing a complex refractive index spatially modulated grating by the saturation absorption effect. And the resulting grating has a narrower bandwidth than the uniform bragg grating 308. Specifically, since standing wave interference occurs, the absorption coefficient of the saturated absorber 307 changes periodically, the absorption at the peak of the standing wave light field is weak, and the absorption at the trough is strong, thereby forming a periodic refractive index grating.
In some alternative embodiments, a length of un-pumped erbium doped fiber can be inserted as the saturated absorber 307. For example, the low concentration erbium doped fiber has an absorption coefficient at 1530nm of not more than 20dB/m.
In this way, the dynamic grating unit formed by the saturated absorber 307 and the uniform bragg grating 308 can filter the light of the modes other than stokes light in the annular cavity to suppress the mode jump and avoid the generation of multimode phenomenon.
In addition, in some alternative embodiments, the length of the erbium doped fiber 305 for the fiber amplification unit, as well as the low concentration erbium doped fiber of the dynamic grating unit forming the saturated absorber 307, affects the power required to be achieved by the pump source 301 and the semiconductor laser 304. For example, the length may be 2m, 4m, 6m, etc.
Furthermore, in some embodiments, as shown in FIG. 3, the Brillouin laser 300 may further include a second coupler 310 and a third coupler 311. Specifically, after filtering and noise reduction by the dynamic grating unit, the second coupler 310 and the third coupler 311 are configured to form a feedback loop and re-inject a portion of the stokes light into the annular cavity through the first coupler 309 to reduce the linewidth of the brillouin laser.
It will be appreciated that re-injecting a portion of the light into the annular cavity can significantly reduce the noise performance of the intracavity excitation light, thereby further reducing the linewidth of the brillouin laser 300.
In this embodiment, the second coupler 310 is further configured to output a portion of the stokes light. Specifically, as shown in fig. 3, a part of stokes light is output from the arrow mark.
In this embodiment, the third coupler 311 is further configured to filter the re-injected stokes light, thereby further increasing the rejection ratio of the main mode and the side mode.
Furthermore, in some alternative embodiments, the coupling ratios for the first coupler 309, the second coupler 310, and the third coupler 311 may be specifically set according to the application requirements, respectively. For example, the coupling ratios of the first coupler 309, the second coupler 310, and the third coupler 311 may each be 50:50. Or the coupling ratio of the first coupler 309 is 90:10, and the coupling ratio of the second coupler 310 and the third coupler 311 is 50:50. Thus, based on the fact that the light of 309,90% remains in the annular cavity, 10% of the light is distributed through 50% of the second coupler 310 and then through 50% of the redistribution of the third coupler 311, resulting in feedback light for the feedback loop. It will be appreciated that the coupling ratio for the first coupler 309 cannot be too great to avoid too much light output resulting in less light in the annular cavity and thus an increase in the lasing threshold.
In some alternative embodiments, the transmission function calculated by the port connection of the dual coupler (the second coupler 310 and the third coupler 311) is calculated by the transmission matrix of the coupler, and the obtained transmission function of the optical fiber filter is a periodic function, and the transmittance bandwidth is changed by changing the length of the connection optical fiber and the coupler ratio, so that the narrow-band filtering performance is realized.
In some alternative embodiments, the F-P cavity structure or the medium of weak distributed feedback such as random grating, high Rayleigh scattering fiber and the like can be used, and filtering and improving the single-mode performance of the laser can also be realized.
In this way, the brillouin laser 300 according to the embodiment of the present application improves the function of maintaining a single frequency of the brillouin laser in the related art by simply relying on the brillouin narrow-band gain spectrum, and can improve the phenomenon of transient mode-jump of the laser to some extent within a long time.
Based on the same technical concept, the application also provides a brillouin laser generating method 400.
As shown in fig. 4, the method 400 may include the steps of:
Step S401, providing pump light with a first frequency by using a pump source 301;
step S402, exciting the pump light into Stokes light with a second frequency through an optical fiber by utilizing a ring cavity;
step S403, filtering by using a dynamic grating unit to ensure a single mode state of the brillouin laser.
In some embodiments, the annular cavity includes a first coupler 309. The method further comprises forming a feedback loop with a second coupler 310 and a third coupler 311 and re-injecting part of the stokes light into the annular cavity through the first coupler 309 to reduce the linewidth of the brillouin laser.
In some alternative embodiments, the annular cavity further comprises a first circulator 302 and a second circulator 306. The method further includes ensuring unidirectional transmission of light within the annular cavity using the first circulator 302 and the second circulator 306.
In some alternative embodiments, the dynamic grating unit includes a saturated absorber 307 and a uniform Bragg grating 308. The method further comprises the steps of:
The light entering from the second circulator 306 and passing through the saturation absorber 307 is reflected by the uniform bragg grating 308, and a standing wave and a saturation absorption effect are formed for filtering based on the light entering from the second circulator 306 and the light reflected by the uniform bragg grating 308 by the saturation absorber 307.
In some alternative embodiments, the method further comprises outputting a portion of the Stokes light using a second coupler 310.
It should be noted that the foregoing describes some embodiments of the present application. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments described above and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.
The method of the above embodiment is applied to the corresponding brillouin laser in any of the foregoing embodiments, and has the beneficial effects of the corresponding embodiments, which are not described herein.
It will be appreciated by persons skilled in the art that the above discussion of any embodiment is merely exemplary and is not intended to imply that the scope of the application (including the claims) is limited to these examples, that combinations of technical features in the above embodiments or in different embodiments may be also possible within the spirit of the application, and that many other variations of the different aspects of the embodiments of the application as described above exist, which are not provided in detail for the sake of brevity.
While the application has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations of those embodiments will be apparent to those skilled in the art in light of the foregoing description.
The present embodiments are intended to embrace all such alternatives, modifications and variances which fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, and the like, which are within the spirit and principles of the embodiments of the application, are intended to be included within the scope of the application.
Claims (8)
1. The Brillouin laser is characterized by comprising an optical fiber, a pumping source, an annular cavity and a dynamic grating unit;
The pump source is configured to provide pump light at a first frequency;
The annular cavity is configured to excite the pump light through the optical fiber to stokes light of a second frequency;
the dynamic grating unit is configured to perform filtering to ensure a single-mode state of the Brillouin laser;
wherein the annular cavity comprises:
the optical fiber amplifier comprises a first circulator, a second circulator, a first coupler and an optical fiber amplifying unit;
the first circulator and the second circulator are configured to ensure unidirectional transmission of light within the annular cavity;
the first end of the first circulator is connected with the pump source, the second end of the first circulator is connected with the optical fiber amplifying unit, and the third end of the first circulator is connected with the first end of the second circulator;
The second end of the second circulator is connected with the dynamic grating unit, and the third end of the second circulator is connected with the first coupler;
And after the pump light is injected, the Stokes light gradually increases to occupy the dominant position under the competition of gain.
2. The brillouin laser according to claim 1, further comprising a second coupler and a third coupler;
The second and third couplers are configured to form a feedback loop and re-inject a portion of the stokes light into the annular cavity through the first coupler to reduce the linewidth of the brillouin laser.
3. The brillouin laser according to claim 1, wherein the dynamic grating unit includes a saturated absorber and a uniform bragg grating;
The uniform Bragg grating is configured to reflect light entering from the second circulator and passing through the saturated absorber;
the saturated absorber is configured to form standing waves and saturated absorption effects for filtering based on light entering from the second circulator and light reflected by the uniform Bragg grating.
4. The brillouin laser according to claim 2, wherein the second coupler is further configured to output a portion of the stokes light.
5. The brillouin laser of claim 2, wherein the third coupler is further configured to filter the re-injected stokes light.
6. The brillouin laser according to claim 1, wherein the optical fiber amplifying unit is configured to amplify the pump light, and comprises a wavelength division multiplexer, a semiconductor laser, and an erbium-doped optical fiber;
The first end of the wavelength division multiplexer is connected with the second end of the first circulator, and the second end of the wavelength division multiplexer is respectively connected with the semiconductor laser and the erbium-doped fiber.
7. A brillouin laser generation method, which is applied to the brillouin laser according to any one of claims 1 to 6, and which includes:
Providing pump light with a first frequency by using a pump source;
Exciting the pump light into Stokes light with a second frequency through an optical fiber by using an annular cavity;
and filtering by using a dynamic grating unit to ensure the single-mode state of the Brillouin laser.
8. The method of claim 7, wherein the annular cavity comprises a first coupler;
The method further comprises forming a feedback loop with a second coupler and a third coupler and re-injecting a portion of the stokes light into the annular cavity through the first coupler to reduce a linewidth of the brillouin laser.
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