CN110350392B - Continuous and pulse switchable device and method based on stimulated Brillouin scattering - Google Patents
Continuous and pulse switchable device and method based on stimulated Brillouin scattering Download PDFInfo
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- CN110350392B CN110350392B CN201910713730.9A CN201910713730A CN110350392B CN 110350392 B CN110350392 B CN 110350392B CN 201910713730 A CN201910713730 A CN 201910713730A CN 110350392 B CN110350392 B CN 110350392B
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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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- 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
- H01S3/10—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
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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
- H01S3/30—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
Abstract
The invention discloses a device capable of switching between continuous and pulse based on stimulated Brillouin scattering, which belongs to the technical field of fiber lasers and comprises a laser system, a fiber coupler, a Fabry-Perot interferometer, an optical isolator and a laser state controller. When the number of the reversed particles is accumulated to a threshold value of stimulated Brillouin scattering in the cavity, the reversed particles in the cavity descend and form Q-switched giant pulses in the cavity, and the laser emits a stable Q-switched pulse sequence through the interference effect of the Fabry-Perot interferometer; the laser state controller is connected with the optical isolator; laser output by the laser state controller sequentially enters the cavity through the optical isolator and the optical fiber coupler so as to break gain balance among the multi-stage stimulated Brillouin scattering laser and enable the laser to output a continuous laser state. The invention achieves the technical effects of reducing the complexity of the system and reducing the cost.
Description
Technical Field
The invention belongs to the technical field of fiber lasers, and particularly relates to a device and a method capable of switching between continuous and pulse based on stimulated Brillouin scattering.
Background
The all-fiber laser has the advantages of simple system, strong expansibility, high laser efficiency and the like, and is widely applied to the fields of laser processing, material processing and the like. In some specific fields, mutual conversion of continuous laser and pulse laser energy is required. For example, in general, continuous laser is used for surface cleaning, laser coating, laser remelting, and the like, but characteristics such as high peak power and narrow pulse width of a pulsed laser are required for laser cutting laser drilling.
In the existing fiber laser technology, two lasers, a continuous laser and a pulse laser, are generally used to accomplish the objective together. For example: when continuous laser light is required, providing continuous laser light through a continuous laser; when pulsed laser light is required, pulsed laser light is provided by a pulsed laser. Thus, the working states of the two lasers are switched to respectively provide continuous laser or pulse laser. However, in the process of using two lasers to accomplish the target together, the complexity of the system is increased and the cost is high.
In summary, in the conventional fiber laser technology, there is a technical problem that the complexity and cost of the system are high in the process of switching between the continuous laser and the pulse laser.
Disclosure of Invention
The invention aims to solve the technical problem that in the existing fiber laser technology, the complexity and cost of a system are high in the process of switching continuous laser and pulse laser.
In order to solve the above technical problem, the present invention provides a continuous and pulsed switchable device based on stimulated brillouin scattering, the device comprising: a laser system comprising a semiconductor laser pump source; the wavelength division multiplexer is connected with the pumping source of the semiconductor laser; the gain optical fiber is connected with the wavelength division multiplexer, so that the semiconductor laser pumping source transmits pumping laser to the gain optical fiber through the wavelength division multiplexer; a fiber Bragg grating connected to the gain fiber to provide laser feedback; the optical fiber coupler is connected with the wavelength division multiplexer; the Fabry-Perot interferometer is connected with the optical fiber coupler to form a cavity through the wavelength division multiplexer, the gain optical fiber, the fiber Bragg grating, the optical fiber coupler and the Fabry-Perot interferometer, when the number of reversed particles is accumulated to a threshold value of stimulated Brillouin scattering in the cavity, the reversed particles in the cavity descend and form Q-switched giant pulses in the cavity, and the laser emits a stable Q-switched pulse sequence through the interference effect of the Fabry-Perot interferometer; the optical isolator is connected with the optical fiber coupler; the laser state controller is connected with the optical isolator; laser output by the laser state controller sequentially enters the cavity through the optical isolator and the optical fiber coupler so as to break gain balance among the multi-stage stimulated Brillouin scattering laser and enable the laser to output a continuous laser state.
Further, the model of the wavelength division multiplexer is a 980nm/1550nm three-port wavelength division multiplexer.
Further, the length of the gain fiber is 10m, and the gain fiber is an erbium-doped fiber.
Further, the center wavelength of the fiber bragg grating was 1550.86nm, the peak reflectivity was 99.86%, and the 3dB broadband was 1.67 nm.
Further, the fabry-perot interferometer comprises: the end faces of the two optical fiber jumpers, and the numerical range of the distance between the end faces of the two optical fiber jumpers is 0.005mm to 5 mm.
According to yet another aspect of the present invention, there is also provided a method of continuous and pulsed switchableness based on stimulated brillouin scattering, applied to the apparatus of any one of claims 1 to 5, the method comprising: the laser state controller is closed, pumping laser is transmitted to the gain optical fiber through the wavelength division multiplexer, laser feedback is provided through the fiber Bragg grating, and when the number of the reversed particles is accumulated to a threshold value of stimulated Brillouin scattering in the cavity, the laser output of the laser is in a Q-switched pulse laser state; and starting the laser state controller, wherein laser of the laser state controller enters the cavity through an optical isolator and an optical fiber coupler so as to break gain balance among the multi-stage stimulated Brillouin scattering laser, and the laser output of the laser is in a continuous laser state.
Further, the output wavelength of the laser state controller is 1550 nm.
Further, the maximum output power of the laser state controller is 175 mW.
Further, the central wavelength of the optical isolator is 1550nm, and the bandwidth is ± 20 nm.
Further, the center wavelength of the optical fiber coupler is 1550nm, and the coupling ratio is 5: 95.
Has the advantages that:
the invention provides a device capable of switching between continuous and pulse based on stimulated Brillouin scattering, which is characterized in that a wavelength division multiplexer and a semiconductor laser pumping source in a laser system are connected with each other, a gain optical fiber is connected with the wavelength division multiplexer, and a fiber Bragg grating is connected with the gain optical fiber. Meanwhile, the optical fiber coupler is connected with the Fabry-Perot interferometer, the optical fiber coupler is connected with the wavelength division multiplexer, the optical isolator is connected with the optical fiber coupler, the laser state controller is connected with the optical isolator, a cavity is formed by the wavelength division multiplexer, the gain optical fiber, the fiber Bragg grating, the optical fiber coupler and the Fabry-Perot interferometer, when the reversed particle number is accumulated to a threshold value of stimulated Brillouin scattering in the cavity, the reversed particle number in the cavity descends in an avalanche mode and forms Q-switched giant pulses in the cavity, and the laser emits a stable Q-switched pulse sequence through the interference effect of the Fabry-Perot interferometer. Thus, when the laser state controller is closed, the laser in the Q-switched pulse state is output; when the laser state controller is started, laser in a continuous state is output. And the laser output by the laser state controller sequentially passes through the optical isolator and the optical fiber coupler to enter the cavity so as to break the gain balance among the multi-stage stimulated Brillouin scattering lasers, so that the laser outputs a continuous laser state. And then, the mutual switching between continuous laser and pulse laser can be realized in one laser, the complexity of the system is reduced, and the cost is reduced. Therefore, the technical effects of reducing the complexity of the system and reducing the cost are achieved.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic overall structure diagram of a device that is switchable between continuous and pulse based on stimulated brillouin scattering according to an embodiment of the present invention;
fig. 2 is a time domain diagram of continuous laser output by a device capable of switching between continuous and pulse based on stimulated brillouin scattering provided by an embodiment of the present invention;
fig. 3 is a time domain diagram of a Q-switched pulsed laser output by a device capable of switching between continuous and pulsed based on stimulated brillouin scattering according to an embodiment of the present invention;
fig. 4 is a flowchart of a method for switching between continuous and pulsed based on stimulated brillouin scattering according to an embodiment of the present invention.
Detailed Description
The invention discloses a device capable of switching between continuous and pulse based on stimulated Brillouin scattering, which is characterized in that a wavelength division multiplexer 20 and a semiconductor laser pumping source 10 in a laser system are connected with each other, a gain optical fiber 30 is connected with the wavelength division multiplexer 20, and an optical fiber Bragg grating 40 is connected with the gain optical fiber 30. Meanwhile, the optical fiber coupler 50 is connected with the fabry-perot interferometer 60, the optical fiber coupler 50 is connected with the wavelength division multiplexer 20, the optical isolator 70 is connected with the optical fiber coupler 50, and the laser state controller 80 is connected with the optical isolator 70, so that a cavity is formed by the wavelength division multiplexer 20, the gain optical fiber 30, the fiber bragg grating 40, the optical fiber coupler 50 and the fabry-perot interferometer 60, when the number of reversed particles is accumulated to a threshold value of stimulated brillouin scattering in the cavity, the number of reversed particles in the cavity is lowered in an avalanche mode, Q-switched giant pulses are formed in the cavity, and the laser emits a stable Q-switched pulse sequence through the interference effect of the fabry-perot interferometer 60. Thus, when the laser state controller 80 is turned off, the laser in the Q-switched pulse state is output; when the laser state controller 80 is turned on, laser light in a continuous state is output. And the laser output by the laser state controller 80 sequentially enters the cavity through the optical isolator 70 and the optical fiber coupler 50 to break the gain balance among the multi-stage stimulated brillouin scattering lasers, so that the laser outputs a continuous laser state. And then, the mutual switching between continuous laser and pulse laser can be realized in one laser, the complexity of the system is reduced, and the cost is reduced. Therefore, the technical effects of reducing the complexity of the system and reducing the cost are achieved.
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention belong to the protection scope of the present invention; the "and/or" keyword referred to in this embodiment represents sum or two cases, in other words, a and/or B mentioned in the embodiment of the present invention represents two cases of a and B, A or B, and describes three states where a and B exist, such as a and/or B, which represents: only A does not include B; only B does not include A; including A and B.
Also, in embodiments of the invention where an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or intervening components may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used in the embodiments of the present invention are for illustrative purposes only and are not intended to limit the present invention.
Example one
Referring to fig. 1, fig. 1 is a schematic diagram of an overall structure of a stimulated brillouin scattering-based continuously and pulsed switchable device according to an embodiment of the present invention, where the stimulated brillouin scattering-based continuously and pulsed switchable device includes: a laser system, a fiber coupler 50, a fabry-perot interferometer 60, an optical isolator 70 and a laser state controller 80. The laser system, the fiber coupler 50, the fabry-perot interferometer 60, the optical isolator 70 and the laser state controller 80 will now be described in detail below, respectively:
for a laser system:
the laser system includes a semiconductor laser pump source 10, a wavelength division multiplexer 20, a gain fiber 30, and a fiber bragg grating 40. The wavelength division multiplexer 20 is connected with the semiconductor laser pumping source 10; a gain fiber 30 and the wavelength division multiplexer 20 are connected such that the semiconductor laser pump source 10 transmits pump laser light to the gain fiber 30 through the wavelength division multiplexer 20; a fiber bragg grating 40 is connected to the gain fiber 30 to provide laser feedback. Wherein the wavelength division multiplexer 20 is a 980nm/1550nm three-port wavelength division multiplexer. The length of the gain fiber 30 is 10m, and the gain fiber 30 is an erbium-doped fiber. The fiber bragg grating 40 has a center wavelength of 1550.86nm, a peak reflectivity of 99.86%, and a 3dB broadband of 1.67 nm.
Referring to fig. 1, the stimulated brillouin scattering is mainly due to the fact that the incident light power is high, ultrasonic waves are excited in a substance by an electromagnetic stretching effect generated by light waves, and the incident light is generated by the ultrasonic waves. Brillouin scattering originates from the interaction of the laser electric field with the acoustic field in molecules or solids, i.e. the interaction of photons with phonons, also called phonon scattering. The intense incident laser field induces an intense acoustic wave field in the medium and is scattered by it, a nonlinear optical effect. Unlike spontaneous brillouin scattering, the process of generation of stimulated brillouin scattering is: under the action of an electric field of laser, the medium is subjected to the changes of periodic density and dielectric constant through the electrostriction effect, an acoustic wave field is induced, and a coherent scattering process is generated between incident light and the acoustic wave field. When the strong pumping laser field is injected into the medium, the electrostrictive effect of the light wave field starts to act, so that the acoustic vibration (phonon) of some states in the medium is greatly enhanced, the enhanced acoustic wave field also enhances the scattering effect on the injected laser, and the acoustic wave field, the laser wave field and the scattered light wave field of the laser exist in the medium at the same time and are mutually coupled. When the intensity of the incident laser reaches a threshold value, the enhancement effect of the acoustic wave field and the scattered light wave field in the medium compensates respective loss effect, the stimulated amplification or oscillation effect of the induction acoustic wave field and the Brillouin scattered light wave field is generated, and the scattered light has the characteristics of stimulated emission such as small divergence angle, narrow line width and the like, so that the stimulated Brillouin scattering is realized. The pump source 10 is excited by a laser working substance to pump the excited particles from the ground state to a high energy level to achieve population inversion. Depending on the working substance and the operating conditions of the laser. Different actuation modes and actuation means may be employed. Optical excitation (optical pumping), gas discharge excitation, chemical excitation, and nuclear excitation are common. The fiber bragg grating 40 is a technique of photosensitive glass, and permanent change of refractive index of the photosensitive glass with some special components is caused by a thermal processing effect of ultraviolet light, so that internal refractive index distribution according to a certain rule is formed in the photosensitive glass. It is by this holographic technique that a volume bragg grating is made. The laser state control signal source of the semiconductor laser is a semiconductor laser with the output laser wavelength of 1550nm, and the maximum output power of the laser state control signal source of the semiconductor laser is 175 mW.
It should be noted that the optical state control signal source is first in the off state, passes through the optical isolator 70 with the center wavelength of 1550nm and the bandwidth within the numerical range of ± 20nm, and then is connected to the optical coupler with the center wavelength of 1550nm and the coupling ratio of 5:95, the fiber coupler 50, and the fiber coupler 50 are connected to the laser system. The laser system adopts a semiconductor laser with the highest pumping power of 600mW and the center wavelength of 980nm, and the semiconductor laser emits 500mW laser which is input into an erbium-doped optical fiber with the length of 10m through a wavelength division multiplexer 20 with the wavelength of 980nm/1550 nm. The fiber bragg grating 40 has a center wavelength of 1550.86nm, a peak reflectivity of 99.86%, and a 3dB bandwidth of 1.67 nm. The laser power emitted by the semiconductor laser is 0.1% or more of the power emitted by the semiconductor laser in the pump laser unit. The fiber bragg grating 40 is a high reflectivity grating. The Fabry-Perot interferometer 60 is formed by two end faces of jumpers which are not in contact, and the end face distance of the jumpers is adjusted to enable the laser to emit stable Q-switched pulse laser. Referring to fig. 2, fig. 2 is a time domain diagram of continuous laser output by a device capable of switching between continuous and pulse based on stimulated brillouin scattering according to an embodiment of the present invention, where the laser output state of the system is a Q-switched pulse laser. Referring to fig. 3, fig. 3 is a time domain diagram of a Q-switched pulsed laser output by a device based on stimulated brillouin scattering and switchable between continuous and pulsed output, a semiconductor laser is turned on, the output power is adjusted to 10mW, and the whole system outputs continuous laser.
For the fiber coupler 50 and the fabry-perot interferometer 60:
the optical fiber coupler 50 is connected with the wavelength division multiplexer 20; the fabry-perot interferometer 60 and the fiber coupler 50 are connected to form a cavity through the wavelength division multiplexer 20, the gain fiber 30, the fiber bragg grating 40, the fiber coupler 50 and the fabry-perot interferometer 60, when the number of reversed particles is accumulated to a threshold value of stimulated brillouin scattering in the cavity, the reversed particles in the cavity descend and form a Q-switched giant pulse in the cavity, and the laser emits a stable Q-switched pulse sequence through the interference effect of the fabry-perot interferometer 60. Wherein the fabry-perot interferometer 60 comprises: the end faces of the two optical fiber jumpers, and the numerical range of the distance between the end faces of the two optical fiber jumpers is 0.005mm to 5 mm.
Referring to fig. 1, the optical fiber coupler, also called a splitter, a connector, an adapter, and an optical fiber flange, is an element for splitting/combining optical signals or for extending an optical fiber link, and belongs to the field of optical passive elements. The fabry-perot interferometer 60 is a multi-beam interferometer composed of two parallel glass plates, wherein the opposing inner surfaces of the two glass plates have a high reflectivity. The fiber coupler 50 serves as a connecting device. The fiber coupler 50 is connected to the fabry-perot interferometer 60, the coupling bandwidth of the fiber coupler 50 includes the laser emitted from the laser state control signal source of the semiconductor laser, and the bandwidth and the gain bandwidth of the gain medium (the gain fiber 30 is used as the gain medium) are matched with each other, and the matching of the coupling bandwidth and the gain bandwidth of the fiber coupler means that the laser output by the laser state controller 80 should be close to the center (for example, 1550nm) of the spectral range of the emitted laser in the Q-switched state. The coupling ratio of the fiber coupler 50 can be changed at will without affecting the performance of the laser of the present invention. The end-face spacing of the two hops of the fabry-perot interferometer 60 is between 0.005mm and 5 mm. The free end fiber end face of the fabry-perot interferometer 60 is beveled as the output end of the laser.
For laser state controller 80 and optical isolator 70:
an optical isolator 70 is connected with the optical fiber coupler 50; the laser state controller 80 is connected to the optical isolator 70. The laser output by the laser state controller 80 sequentially passes through the optical isolator 70 and the optical fiber coupler 50 to enter the cavity, so as to break the gain balance among the multi-stage stimulated brillouin scattering lasers, and the laser outputs a continuous laser state.
With continued reference to fig. 1, optical isolator 70 is a passive optical device that allows only one-way light to pass through, and the principle of operation of optical isolator 70 is based on the non-reciprocity of faraday rotation. The light reflected by the optical fiber echo can be well isolated by the optical isolator 70, the optical isolator 70 mainly utilizes the faraday effect of the magneto-optical crystal, and the optical isolator 70 has the characteristics that: the forward insertion loss is low, the reverse isolation degree is high, and the return loss is high. The optical isolator 70 is a passive device which allows light to pass through in one direction and prevents light from passing through in the opposite direction, and has the function of limiting the direction of the light, so that the light can be transmitted only in one direction, and the light reflected by the optical fiber echo can be well isolated by the optical isolator 70, thereby improving the transmission efficiency of light waves. Optical isolator 70 acts as a protection device to isolate the intracavity laser light. The laser state controller 80 refers to a laser state control signal source of the semiconductor laser. The laser control signal source of the semiconductor laser is in a closed state. The semiconductor laser pumping source 10 transmits pumping laser to the gain fiber 30 through the wavelength division multiplexer 20, the fiber bragg grating 40 provides laser feedback, the fabry-perot interferometer 60 has high loss, the population of reversed particles is accumulated in the cavity, and when the threshold value of stimulated brillouin scattering is reached, the population of reversed particles in the cavity is avalanche-decreased and Q-switched giant pulses are formed in the cavity. The laser emits a stable sequence of Q-switched pulses by interference from a fabry-perot interferometer 60. The laser output of the laser is in the Q-switched pulse laser state at this time. And (3) opening a laser state control signal source of the semiconductor laser, enabling the wavelength laser to enter the cavity through the optical isolator 70 and the coupler, breaking the gain balance among the multi-stage stimulated Brillouin scattering lasers, and breaking the stable Q-switching state in the laser. The whole laser loses the Q-switched state, the injected laser is amplified, and the laser is converted into continuous pulse laser. At this time, the laser output of the laser is in a continuous laser state.
It should be noted that the continuous and pulse switchable device based on stimulated brillouin scattering provided by the embodiment of the invention does not need any active modulation medium or additional electric control system in the cavity. The use of an optical signal enables instantaneous transition of the laser continuous/pulsed state. The specific principle is as follows: the operation state can be interfered by injecting the laser with the specific wavelength into a stably-operated Q-switched optical fiber laser based on stimulated Brillouin scattering, the balance state of the laser is broken through changing the gain of multi-stage Stokes light excited by the stimulated Brillouin scattering, so that the normal Q-switched operation of the laser is damaged, the injected light with the specific wavelength is amplified, the output laser state of the laser is changed into a continuous laser state from a Q-switched pulse state, the Q-switched state of the laser can be recovered by stopping inputting the laser with the specific wavelength, and the laser can be injected through the optical fiber coupler 50, so that the control of the output state of the Q-switched pulse laser in a full-fiber mode is realized.
The invention provides a device capable of switching between continuous and pulse based on stimulated Brillouin scattering, which is characterized in that a wavelength division multiplexer 20 and a semiconductor laser pumping source 10 in a laser system are connected with each other, a gain fiber 30 is connected with the wavelength division multiplexer 20, and a fiber Bragg grating 40 is connected with the gain fiber 30. Meanwhile, the optical fiber coupler 50 is connected with the fabry-perot interferometer 60, the optical fiber coupler 50 is connected with the wavelength division multiplexer 20, the optical isolator 70 is connected with the optical fiber coupler 50, and the laser state controller 80 is connected with the optical isolator 70, so that a cavity is formed by the wavelength division multiplexer 20, the gain optical fiber 30, the fiber bragg grating 40, the optical fiber coupler 50 and the fabry-perot interferometer 60, when the number of reversed particles is accumulated to a threshold value of stimulated brillouin scattering in the cavity, the number of reversed particles in the cavity is lowered in an avalanche mode, Q-switched giant pulses are formed in the cavity, and the laser emits a stable Q-switched pulse sequence through the interference effect of the fabry-perot interferometer 60. Thus, when the laser state controller 80 is turned off, the laser in the Q-switched pulse state is output; when the laser state controller 80 is turned on, laser light in a continuous state is output. And the laser output by the laser state controller 80 sequentially enters the cavity through the optical isolator 70 and the optical fiber coupler 50 to break the gain balance among the multi-stage stimulated brillouin scattering lasers, so that the laser outputs a continuous laser state. And then, the mutual switching between continuous laser and pulse laser can be realized in one laser, the complexity of the system is reduced, and the cost is reduced. Therefore, the technical effects of reducing the complexity of the system and reducing the cost are achieved.
Based on the same inventive concept, the application provides a method which is based on the stimulated brillouin scattering and can be switched between continuous mode and pulse mode, and details are shown in an embodiment II.
Example two
As shown in fig. 4, fig. 4 is a flowchart of a method for continuous and pulsed switchable based on stimulated brillouin scattering according to an embodiment of the present invention. The embodiment of the invention provides a continuous and pulse switchable method based on stimulated Brillouin scattering, which comprises the following steps:
step S100, the laser state controller 80 is turned off, the pumping laser is transmitted to the gain fiber 30 through the wavelength division multiplexer 20, and laser feedback is provided through the fiber bragg grating 40, and when the inversion population accumulates in the cavity to reach the threshold of stimulated brillouin scattering, the laser output of the laser is in a Q-switched pulse laser state. Wherein the output wavelength of the laser state controller 80 is 1550 nm. The maximum output power of the laser state controller 80 is 175 mW.
Specifically, the optical state control signal source is first set to an off state, and the optical isolator 70 having a center wavelength of 1550nm and a bandwidth in a numerical range of ± 20nm, and a center wavelength of 1550nm and a coupling ratio of 5:95, the fiber coupler 50, and the fiber coupler 50 are further interconnected to the laser system. The laser system adopts a semiconductor laser with the highest pumping power of 600mW and the center wavelength of 980nm, and the semiconductor laser emits 500mW laser which is input into an erbium-doped optical fiber with the length of 10m through a wavelength division multiplexer 20 with the wavelength of 980nm/1550 nm. The fiber bragg grating 40 has a center wavelength of 1550.86nm, a peak reflectivity of 99.86%, and a 3dB bandwidth of 1.67 nm. The laser power emitted by the semiconductor laser is 0.1% or more of the power emitted by the semiconductor laser in the pump laser unit. The fiber bragg grating 40 is a high reflectivity grating. The Fabry-Perot interferometer 60 is formed by two end faces of jumpers which are not in contact, and the end face distance of the jumpers is adjusted to enable the laser to emit stable Q-switched pulse laser. Thus, when the laser state controller 80 is turned off, a stable Q-switched pulsed laser is emitted.
Step S110, the laser state controller 80 is turned on, laser of the laser state controller 80 enters the cavity through the optical isolator 70 and the optical fiber coupler 50 to break the gain balance between the multi-stage stimulated brillouin scattering lasers, and the laser output of the laser is in a continuous laser state. Wherein the optical isolator 70 has a center wavelength of 1550nm and a bandwidth of ± 20 nm. The fiber coupler 50 has a center wavelength of 1550nm and a coupling ratio of 5: 95.
With continued reference to fig. 4, the laser state controller 80 is a semiconductor laser state control signal source. In actual operation, the output laser wavelength of the semiconductor laser is 1550nm, and the maximum output power is 175 mW. After the semiconductor laser is in a closed state, the semiconductor laser is connected to a light isolator 70 with the center wavelength of 1550nm and the bandwidth of +/-20 nm, the light isolator has the center wavelength of 1550nm and the coupling ratio of 5:95, the fiber coupler 50, and the fiber coupler 50 are connected to the laser system. The laser system adopts a semiconductor laser with the highest pumping power of 600mW and the center wavelength of 980nm, and the semiconductor laser emits 500mW laser which is input into an erbium-doped optical fiber with the length of 10m through a wavelength division multiplexer 20 with the wavelength of 980nm/1550 nm. The fiber bragg grating 40 has a center wavelength of 1550.86nm, a peak reflectivity of 99.86%, and a 3dB bandwidth of 1.67 nm. The Fabry-Perot interferometer 60 is formed by two end faces of jumpers which are not in contact, and the end face distance of the jumpers is adjusted to enable the laser to emit stable Q-switched pulse laser. The laser output state of the system is Q-switched pulse laser. Then the semiconductor laser is turned on, the output power is adjusted to 10mW, namely, the laser with the specific wavelength is injected into a Q-switched fiber laser which stably operates and is based on stimulated Brillouin scattering to generate interference on the operation state, the balance state of the laser is broken through changing the gain of multi-stage Stokes light excited due to the stimulated Brillouin scattering, so that the normal Q-switched operation of the laser is damaged, the injected light with the specific wavelength is amplified, the output laser state of the laser is changed into a continuous laser state from a Q-switched pulse state, the Q-switched state of the laser can be recovered by stopping inputting the laser with the specific wavelength, and the laser can be injected through the optical fiber coupler 50, so that the control of the output state of the Q-switched pulse laser in a full-fiber mode is realized.
The invention provides a method based on stimulated Brillouin scattering, which is characterized in that a laser state controller 80 is closed, pumping laser is transmitted to a gain fiber 30 through a wavelength division multiplexer 20, laser feedback is provided through a fiber Bragg grating 40, and when the number of inversion particles is accumulated to a threshold value of stimulated Brillouin scattering in a cavity, the laser output of a laser is in a Q-switched pulse laser state; and then the laser state controller 80 is started, the laser of the laser state controller 80 enters the cavity through the optical isolator 70 and the optical fiber coupler 50 so as to break the gain balance among the multi-stage stimulated Brillouin scattering lasers, and the laser output of the laser is in a continuous laser state. Thus, when the laser state controller 80 is turned off, the laser in the Q-switched pulse state is output; when the laser state controller 80 is turned on, laser light in a continuous state is output. And the laser output by the laser state controller 80 sequentially enters the cavity through the optical isolator 70 and the optical fiber coupler 50 to break the gain balance among the multi-stage stimulated brillouin scattering lasers, so that the laser outputs a continuous laser state. And then, the mutual switching between continuous laser and pulse laser can be realized in one laser, the complexity of the system is reduced, and the cost is reduced. Therefore, the technical effects of reducing the complexity of the system and reducing the cost are achieved.
Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (10)
1. A device switchable between continuous and pulsed based on stimulated brillouin scattering, the device comprising:
a laser system, the laser system comprising:
a semiconductor laser pumping source;
the wavelength division multiplexer is connected with the pumping source of the semiconductor laser;
the gain optical fiber is connected with the wavelength division multiplexer, so that the semiconductor laser pumping source transmits pumping laser to the gain optical fiber through the wavelength division multiplexer;
a fiber Bragg grating connected to the gain fiber to provide laser feedback;
the optical fiber coupler is connected with the wavelength division multiplexer;
the Fabry-Perot interferometer is connected with the optical fiber coupler to form a cavity through the wavelength division multiplexer, the gain optical fiber, the fiber Bragg grating, the optical fiber coupler and the Fabry-Perot interferometer, when the number of reversed particles is accumulated to a threshold value of stimulated Brillouin scattering in the cavity, the reversed particles in the cavity descend and form Q-switched giant pulses in the cavity, and the laser emits a stable Q-switched pulse sequence through the interference effect of the Fabry-Perot interferometer;
the optical isolator is connected with the optical fiber coupler;
the laser state controller is connected with the optical isolator; when the laser state controller is started, laser output by the laser state controller sequentially passes through the optical isolator and the optical fiber coupler to enter the cavity so as to break gain balance among the multi-stage stimulated Brillouin scattering laser and enable the laser to output a continuous laser state; when the laser state controller is closed, pumping laser is transmitted to the gain fiber through the wavelength division multiplexer, laser feedback is provided through the fiber Bragg grating, and when the number of the reversed particles is accumulated to a threshold value of stimulated Brillouin scattering in the cavity, the laser output of the laser is in a Q-switched pulse laser state.
2. The stimulated brillouin scattering-based continuously and impulsively switchable apparatus of claim 1, wherein:
the wavelength division multiplexer is a 980nm/1550nm three-port wavelength division multiplexer.
3. The stimulated brillouin scattering-based continuously and impulsively switchable apparatus of claim 2, wherein:
the length of the gain fiber is 10m, and the gain fiber is an erbium-doped fiber.
4. The stimulated brillouin scattering-based continuously and impulsively switchable apparatus according to claim 3, wherein:
the center wavelength of the fiber Bragg grating is 1550.86nm, the peak reflectivity is 99.86%, and the 3dB broadband is 1.67 nm.
5. The stimulated brillouin scattering-based continuously and impulsively switchable apparatus of claim 4, wherein:
the fabry-perot interferometer comprises: the end faces of the two optical fiber jumpers, and the numerical range of the distance between the end faces of the two optical fiber jumpers is 0.005mm to 5 mm.
6. A method based on continuous and pulse switchability of stimulated Brillouin scattering, applied to the apparatus of any one of claims 1-5, wherein the method comprises:
the laser state controller is closed, pumping laser is transmitted to the gain optical fiber through the wavelength division multiplexer, laser feedback is provided through the fiber Bragg grating, and when the number of the reversed particles is accumulated to a threshold value of stimulated Brillouin scattering in the cavity, the laser output of the laser is in a Q-switched pulse laser state;
and starting the laser state controller, wherein laser of the laser state controller enters the cavity through an optical isolator and an optical fiber coupler so as to break gain balance among the multi-stage stimulated Brillouin scattering laser, and the laser output of the laser is in a continuous laser state.
7. The method of continuous and pulsed switchablebased on stimulated brillouin scattering according to claim 6, characterized in that:
the output wavelength of the laser state controller is 1550 nm.
8. The method of continuous and pulsed switchablebased on stimulated brillouin scattering according to claim 7, characterized in that:
the maximum output power of the laser state controller is 175 mW.
9. The method of continuous and pulsed switchablebased on stimulated brillouin scattering according to claim 8, characterized in that:
the central wavelength of the optical isolator is 1550nm, and the bandwidth is +/-20 nm.
10. The method of continuous and pulsed switchablebased on stimulated brillouin scattering according to claim 9, characterized in that:
the center wavelength of the optical fiber coupler is 1550nm, and the coupling ratio is 5: 95.
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