Pulse fiber laser with same multi-end output

Abstract

The invention provides a pulse optical fiber laser with same multi-end output. The pulse optical fiber laser comprises a pulse seed source, a plurality of optical splitters, a plurality of optical amplification systems, a plurality of laser output ports and protection devices. One or more optical fiber optical splitters are used for equally splitting the laser into two lasers with the same characteristics, and the two lasers with higher power and the same characteristics are obtained through the same optical amplification system. And the pulse laser with the same multiple ends is realized through multiple times of splitting and amplification. Compared with other multi-end outputs, the multi-end laser has the advantages that the laser characteristics output by all ends are basically consistent, the problem of high cost of a plurality of multi-end lasers is greatly solved, and a scheme is provided for realizing higher-power output by using incoherent beam combination.

Description

Technical Field

[0001] The present application relates to the technical field of optical fiber lasers, and in particular to a pulsed optical fiber laser with identical multi-end outputs. Background Art

[0002] Currently, most multi-end output fiber lasers use fiber gratings to adjust the reflectivity, realize laser oscillation in the cavity, and achieve laser output. The pump light is introduced into the oscillation cavity through a pump combiner. For example, the patent document with application publication number CN108963738A discloses a double-end output linear cavity all-fiber laser oscillator, including a gain fiber, a backward output fiber grating, a forward output fiber grating, a fiber-coupled semiconductor laser, a pump signal combiner, a signal energy transmission fiber, a pump energy transmission fiber, a forward cladding light filter, a forward output fiber end cap, a backward cladding light filter, and a backward output fiber end cap; wherein the backward output fiber grating, the gain fiber, and the forward output fiber grating are sequentially connected through the signal energy transmission fiber to form a fiber laser resonant cavity; the pump light output by the fiber-coupled semiconductor laser is injected into the pump signal combiner through the pump energy transmission fiber, and then injected into the fiber laser resonant cavity through the signal energy transmission fiber; the reflectivity of the forward and backward fiber gratings is not greater than 95%, so that the laser generated by the resonant cavity can be output from both ends of the resonant cavity, and the laser output from both ends of the fiber laser resonant cavity passes through the forward and backward cladding light filters, and is expanded and output by the fiber end caps connected thereto. This type of solution has the following problems: first, there is no modulation device in the cavity, only continuous light, and no pulses can be obtained; second, at most only two-end output can be achieved; third, the cladding light filter directly filters out but does not absorb the remaining pump light.

[0003] Some fiber optic splitter solutions claim that they can split a laser beam into multiple or even N parts, but they do not specify whether the laser characteristics of the split lasers can remain consistent in terms of output power, beam quality, wavelength, etc. The fiber optic splitter they mentioned is a general concept. In practice, a fiber optic splitter cannot be made into an optical device that splits any N parts. The reason is that the fiber optic splitter currently used is formed by tapering multiple optical fibers into one optical fiber. When tapering, multiple optical fibers need to be evenly distributed and have the same structure, such as the common 2*1 combiner, 7*1 combiner, and 19*1 combiner. Otherwise, the optical fiber formed after tapering will have adverse effects such as fiber breakage and structural abnormalities. Therefore, these fiber optic splitters cannot achieve arbitrary multi-channel output. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a multi-end output pulse fiber laser to solve the problems that the above-mentioned prior art fiber lasers cannot obtain pulses, can only achieve dual-end output but not multi-end output, the remaining pump light cannot be absorbed, and cannot be realized with an all-fiber structure, resulting in a large volume.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] A pulsed fiber laser with identical multi-end output comprises a pulse seed source, several levels of splitting devices and a laser output port, each level of splitting device comprises a splitter and two optical amplification systems connected thereto, the pulse seed source realizes pulse output by Q-switching and outputs the pulse to the splitter of the first level of splitting device, the splitter uses a wavelength division multiplexer to completely and evenly split a laser beam into two lasers with identical output characteristics and connects each of the two lasers to the same level of optical amplification system, the output end of the optical amplification system is connected to the input end of the splitter of the next level of splitting device, the optical amplification system of the last level of splitting device is connected to the laser output port to realize laser output, the laser characteristics of the laser output port are identical, and the laser characteristics include but are not limited to output power, beam quality, pulse, and spot diameter.

[0007] Preferably, the laser output from the laser output port is a nanosecond-level pulse laser.

[0008] Preferably, the fiber amplification system includes a pump combiner, a pump source, an active optical fiber, a multimode stripper and a fiber isolator. The pump combiner, the pump source and the active optical fiber form a pump structure which is then sequentially connected to the multimode stripper and the fiber isolator to realize fiber output. The specifications and quantity of the devices used in each level of the fiber amplification system are the same.

[0009] Preferably, the pumping mode of the pumping structure of the optical amplification system is forward pumping, reverse pumping or bidirectional pumping.

[0010] Preferably, the pulse seed source includes an active optical fiber, an active modulator, a high-reflection grating, a pump combiner, a pump source and a low-reflection grating. The pump source is connected to the pump input end of the pump combiner and then connected to the active optical fiber and the active modulator in sequence. The pump light is recovered and finally output through the high-reflection grating.

[0011] Preferably, the active modulator is an acousto-optic modulation device or an electro-optic modulation device.

[0012] Preferably, the high-reflection grating input fiber is connected to the pump input fiber of the pump combiner, and the output end of the active modulator is connected to the pump input fiber of the pump combiner after passing through the low-reflection grating.

[0013] Preferably, the input end of the pump beam combiner is connected to a low-reflection grating and returns to the input end of the pump beam combiner through the other end of the low-reflection grating, and the output end of the active modulator is output through a high-reflection grating.

[0014] Preferably, the laser output ports are all provided with optical path protection devices, and the optical path protection devices are provided with control circuits respectively connected to the control ends of the optical fiber amplification system and the seed source, so as to monitor the status of each output laser in real time and control the simultaneous or individual shutdown of the optical fiber amplification system or the seed source when an abnormality is detected.

[0015] Preferably, the optical path protection device includes a photodiode, a photoelectric signal processing circuit and a control circuit which are connected in sequence and are arranged to bypass the laser output port. The photodiode receives the energy of the bypass scattered light output by the laser output port and sends it to the photoelectric signal processing circuit to determine whether the optical path is correct and control the opening and closing of the optical fiber amplification system or the seed source through the control circuit.

[0016] Compared with the prior art, this solution has the following beneficial effects: by placing the active modulation device in the resonant cavity, a pulsed laser of the order of ns or above is obtained, and by connecting the high-reflection grating to the pump combiner, the residual pump light is processed and reused, while the laser electro-optical conversion efficiency is improved; and by introducing the fiber splitter, the pulsed laser is distributed in a certain proportion and sent to the subsequent optical amplification system to obtain a higher energy pulsed laser, and the step-by-step splitting and amplification of the Q-switched seed laser can obtain a multi-end output pulsed laser. All optical devices in this solution use fiber-coupled optical elements, without reflectors, collimators and other lenses to transmit lasers, realizing an all-fiber structure, such that the laser is more integrated, the volume and weight are reduced, and the cost is reduced; the output double-end or even multi-end laser can be used for synchronous / asynchronous precision processing and other applications, improving work efficiency, and by utilizing the characteristics of the output pulses that are basically consistent in optical properties such as power and beam quality, higher energy laser output can be achieved by combining incoherent light sources. Finally, the optical path protection set at each end of the laser output can identify the abnormality of the optical path at a certain end in the shortest time and protect each optical path to a greater extent to prevent the optical path from being burned all the time or burning on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the composition structure of an embodiment of a pulsed fiber laser;

[0018] Figure 2 This is a schematic diagram of the structure of reverse pump light recovery in a seed source embodiment;

[0019] Figure 3 This is a schematic structural diagram of forward pump light recovery in another embodiment of a seed source;

[0020] Figure 4 It is a schematic structural diagram of forward pumping of an embodiment of an optical amplification system;

[0021] Figure 5 It is a schematic structural diagram of reverse pumping of another embodiment of an optical amplification system;

[0022] Figure 6 It is a structural schematic diagram of bidirectional pumping of another embodiment of an optical amplification system;

[0023] Figure 7 This is a schematic diagram of the structure of an optical path protection device installed in a pulsed fiber laser according to an embodiment of the present invention;

[0024] Among them, 1-seed source, 11a-high reflection grating, 11b-low reflection grating, 12-active modulator, 2-splitter, 2a-first splitter, 2b-second splitter, 2c-third splitter, 3-optical amplification system, 31-multimode stripper, 32-fiber isolator, 3a-first optical amplification system, 3aa-first first optical amplification system, 3ab-second first optical amplification system, 3b-second optical amplification system, 3ba-first second optical amplification system, 3 bb-the second secondary optical amplification system, 3bc-the third secondary optical amplification system, 3bd-the fourth secondary optical amplification system, 5-laser output port, 5a-the first laser output end, 5b-the second laser output end, 5c-the third laser output end, 5d-the fourth laser output end, 5n-the nth laser output end, 6-active optical fiber, 7-pump combiner, 8-pump source, 9-optical path protection device, 91-photodiode, 92-photoelectric signal processing circuit, 93-control circuit. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0026] This embodiment provides a technical solution: a pulse fiber laser with the same multi-end output of the present invention, characterized in that it includes a pulse seed source 1, several levels of splitting devices and a laser output port 5, each level of splitting device includes a splitter 2 and two optical amplification systems 3 connected thereto, the pulse seed source 1 uses Q-switching to achieve pulse output and outputs it to the splitter 2 of the first level splitting device, the splitter 2 uses a wavelength division multiplexer, because ordinary splitters can be divided into 3, 7, 19 channels, etc., but cannot be evenly distributed, and the wavelength division multiplexer type splitter 2 can support one-to-two equal splitting, such as the single-mode coupler greater than 1064nm of Guangku Technology. A laser beam is completely and evenly divided into two lasers with the same output characteristics and each is connected to the optical amplification system 3 of the same level. The output end of the optical amplification system 3 is connected to the input end of the spectrometer 2 of the next level spectrometer. The optical amplification system 3 of the last level spectrometer is connected to the laser output port 5 to realize laser output. In this embodiment, the first level spectrometer includes a first spectrometer 2a and a first level optical amplification system 3a. The first level optical amplification system 3aa includes a first level optical amplification system 3aa and a second level optical amplification system 3ab. The first level optical amplification system 3aa and the second level optical amplification system 3ab are respectively connected to the two spectrometer output ends of the first spectrometer 2a; the second level spectrometer includes a second spectrometer 2b and a first level optical amplification system 3ba and a second level optical amplification system 3b connected thereto. b and the third optical splitter 2c and the third secondary optical amplification system 3bc and the fourth secondary optical amplification system 3bd connected thereto, the first secondary optical amplification system 3ba, the second secondary optical amplification system 3bb, the third secondary optical amplification system 3bc and the fourth secondary optical amplification system 3bd are all secondary optical amplification systems 3b; the laser output port 5 is connected to the last N-level optical amplification system 3, and is divided into the first laser output end 5a, the second laser output end 5b, the third laser output end 5c, the fourth laser output end 5d... the nth laser output end; the laser characteristics output by the first, second... Nth level optical amplification systems 3 are also basically the same, so that the laser characteristics of the laser output port 5 are the same in specifications, and the laser characteristics include but are not limited to output power, beam quality, pulse, and spot diameter. The laser output by all the laser output ports 5 is a nanosecond pulse laser. In a common embodiment of the present scheme, the number of laser output ports 5 is 2 to the power of N, but the embodiment can be modified by not setting an optical amplification system 3 at the front end of the laser output port 5, allowing the laser from the previous stage to be in the optical fiber, using a corrosion process to gradually filter the laser from the optical fiber, and dissipating the heat through a heat sink, or setting an optical amplification system 3 but not supplying power, that is, not driving the optical amplification. Through these modifications, any two-end synchronous output, any three-end synchronous output, and even any N-end synchronous output can be achieved.

[0027] The fiber amplification system 3 includes a pump combiner 7, a pump source 8, an active fiber 6, a multimode stripper 31 and a fiber isolator 32. The pump combiner 7, the pump source 8 and the active fiber 6 form a pump structure which is then sequentially connected to the multimode stripper 31 and the fiber isolator 32 to realize fiber output. The multimode stripper 31 can filter out the remaining pump light of the reverse pump combiner. The specifications and quantity of the devices used in each level of the fiber amplification system 3 are the same.

[0028] The pumping method of the pumping structure of the optical amplification system 3 is as shown in the attached Figure 4-6 It can be forward pumped, reverse pumped or bidirectional pumped.

[0029] In this solution, the seed source structure is realized by the active mode locking principle. The pulse seed source 1 includes an active optical fiber 6, an active modulator 12, a high-reflection grating 11a, a pump combiner 7, a pump source 8 and a low-reflection grating 11b. The pump source 8 is connected to the pump input end of the pump combiner 7 and then connected to the active optical fiber 6 and the active modulator 12 in sequence. The pump light is recovered and finally output through the high-reflection grating 11a. The active modulator 12 can be an acousto-optic modulation device or an electro-optic modulation device.

[0030] One embodiment of this scheme is a reverse pump light recycling method, the high reflection grating 11a input fiber is connected to the pump input fiber of the pump combiner 7, and the output end of the active modulator 12 is connected to the pump input fiber of the pump combiner 7 after passing through the low reflection grating 11b, so that the remaining pump light absorbed in the resonant cavity and a small amount of signal light can be introduced into the resonant cavity again, achieving multiple efficient utilization. The output power of the pulse seed source 1 is further improved, and the pulse width is further reduced.

[0031] In addition to the above-mentioned implementation, a forward pump light recovery method can also be used. The input end of the pump combiner 7 is connected to a low-reflection grating 11b and returns to the input end of the pump combiner 7 through the other end of the low-reflection grating 11b. The output end of the active modulator 12 is output through the high-reflection grating 11a.

[0032] The laser output ports 5 are all provided with optical path protection devices 9, because when the previous optical splitter and optical amplification system are abnormal, they will affect the final output port, so it is sufficient to monitor the output port of each path. The optical path protection device 9 is provided with a control circuit connected to the control end of the optical fiber amplification system 3 and the seed source 1 respectively, to monitor the state of each output laser in real time and control to shut down the optical fiber amplification system 3 or the seed source 1 simultaneously or individually when an abnormality is detected.

[0033] The optical path protection device 9 in this embodiment includes a photodiode 91, a photoelectric signal processing circuit 92 and a control circuit 93 connected in sequence and arranged in a bypass of the laser output port. The photodiode 91 receives the energy of the bypass scattered light output by the laser output port 5 and sends it to the photoelectric signal processing circuit to determine whether the optical path is correct and controls the opening and closing of the optical fiber amplification system 3 or the seed source 1 through the control circuit 93. When there is no laser output or the output energy decreases, the energy detected by the photodiode 91 is greatly attenuated, and the declining laser will be converted into a declining current and sent to the photoelectric signal processing circuit 92 for comparison with the normal electrical signal. When the detected electrical signal is too small, the photoelectric signal processing circuit 92 allows the control circuit 93 to issue an instruction: first turn off the pump drive circuit of the optical amplification system 3, and then turn off the drive circuit of the seed source 1, so that the optical paths at all levels are protected within an extreme time. Thereby avoiding the optical path from being burned all the time or burning on a large scale. In actual use, in order to control costs, the control can only connect the first-stage optical amplification system 3a, and the first stage is turned off. That is, an alarm appears and the overall system is interrupted. Of course, you can also add a photoelectric detection after each stage of amplification, so that you can achieve individual control and shutdown. The effect is good, but the cost is higher.

[0034] There may also be other implementations, such as setting up photoelectric detection and control on the main light path, which can have roughly the same effect, but it has a certain impact on the main light path and is therefore not a better implementation of this solution.

[0035] The above is only a preferred specific implementation method of the present scheme, but the protection scope required by the present scheme is not limited thereto. Any technician familiar with the technical field can make equivalent substitutions or changes according to the technical scheme and inventive concept of the present application within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present application.

Claims

1. A pulsed fiber laser with identical multi-end output, characterized in that: The invention comprises a pulse seed source (1), a plurality of optical splitting devices and a laser output port (5), wherein each optical splitting device comprises an optical splitter (2) and two optical amplification systems (3) connected thereto, wherein the pulse seed source (1) adopts a Q-switching method to realize pulse output and outputs the pulse to the optical splitter (2) of the first optical splitting device, wherein the optical splitter (2) uses a wavelength division multiplexer to completely and evenly split a laser beam into two laser beams with the same output characteristics and connect each of the two laser beams to the optical amplification system (3) of the same level, wherein the output end of the optical amplification system (3) is connected to the input end of the optical splitter (2) of the next optical splitting device, and the optical amplification system (3) of the last optical splitting device is connected to the laser output port (5) to realize laser output, wherein the laser characteristics of the laser output ports (5) are the same, and the laser characteristics include but are not limited to output power, beam quality, pulse, and spot diameter.

2. The same multi-port output pulse fiber laser according to claim 1, characterized in that: The laser output from the laser output port (5) is a nanosecond-level pulse laser.

3. The same multi-port output pulse fiber laser according to claim 1, characterized in that: The optical fiber amplification system (3) comprises a pump combiner (7), a pump source (8), an active optical fiber (6), a multimode stripper (31) and an optical fiber isolator (32); the pump combiner (7), the pump source (8) and the active optical fiber (6) form a pump structure which is then sequentially connected to the multimode stripper (31) and the optical fiber isolator (32) to realize optical fiber output; the specifications and quantities of the devices used in each level of the optical fiber amplification system (3) are the same.

4. The same multi-port output pulse fiber laser according to claim 3, characterized in that: The pumping mode of the pumping structure of the optical amplification system (3) is forward pumping, reverse pumping or bidirectional pumping.

5. The same multi-port output pulse fiber laser according to claim 1, characterized in that: The pulse seed source (1) comprises an active optical fiber (6), an active modulator (12), a high-reflection grating (11a), a pump combiner (7), a pump source (8) and a low-reflection grating (11b); the pump source (8) is connected to a pump input end of the pump combiner (7) and then sequentially connected to the active optical fiber (6) and the active modulator (12); the pump light is recovered and finally output through the high-reflection grating (11a).

6. The same multi-port output pulse fiber laser according to claim 5, characterized in that: The active modulator (12) is an acousto-optic modulation device or an electro-optic modulation device.

7. The same multi-port output pulse fiber laser according to claim 5, characterized in that: The high-reflection grating (11a) input optical fiber is connected to the pump input optical fiber of the pump combiner (7), and the output end of the active modulator (12) is connected to the pump input optical fiber of the pump combiner (7) through the low-reflection grating (11b).

8. The same multi-port output pulse fiber laser according to claim 5, characterized in that: The input end of the pump beam combiner (7) is connected to a low-reflection grating (11b) and returns to the input end of the pump beam combiner (7) through the other end of the low-reflection grating (11b), and the output end of the active modulator (12) is output through the high-reflection grating (11a).

9. The same multi-port output pulse fiber laser according to claim 1, characterized in that: The laser output ports (5) are each provided with an optical path protection device (9), and the optical path protection device (9) is provided with a control circuit respectively connected to the control ends of the optical fiber amplification system (3) and the seed source (1), so as to monitor the status of each output laser in real time and control the optical fiber amplification system (3) or the seed source (1) to be shut down simultaneously or individually when an abnormality is detected.

10. The same multi-port output pulse fiber laser according to claim 9, characterized in that: The optical path protection device (9) comprises a photodiode (91) arranged in a bypass of the laser output port, a photoelectric signal processing circuit (92) and a control circuit (93) connected in sequence, wherein the photodiode (91) receives the energy of the bypass scattered light output by the laser output port (5) and sends it to the photoelectric signal processing circuit to determine whether the optical path is correct and control the opening and closing of the optical fiber amplification system (3) or the seed source (1) through the control circuit (93).

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