All-fiber laser driven flyer ignition system and method based on cyclotron amplification

Abstract

The purpose of the present invention is to solve the problem of miniaturization caused by the use of solid-state lasers in the existing laser-driven flying chip ignition system and the problem of high ignition failure rate caused by space-fiber coupling, and propose an all-fiber laser-driven flying chip ignition system and method based on cyclotron amplification. The system includes a single-pulse laser signal source, a fiber ring cavity, and an energy transmission fiber, a fiber connector, a transparent window substrate, an acceleration chamber and explosives connected in sequence to the output end of the fiber ring cavity; the fiber ring cavity includes a first optical switch, at least one pump coupler, a second optical switch and at least one gain fiber arranged in sequence along the laser transmission direction; the pump end of the pump coupler is connected to a pump source; the other output end of the second optical switch is connected to the energy transmission fiber, and the energy transmission fiber is connected to the transparent window substrate, the acceleration chamber and the explosive through the fiber connector.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser explosive devices, and in particular relates to an all-fiber laser driven flying chip ignition system and method based on single-pulse laser cyclotron amplification. Background Art

[0002] As a new generation of ignition technology, laser ignition has important application value in the fields of military science and technology, aerospace, etc. due to its strong anti-electromagnetic interference ability, high safety, good ignition consistency and easy multi-point ignition. Laser ignition technology can be roughly divided into three types, namely electrical-optical ignition, laser diode ignition and laser-driven flyer ignition. Among them, laser-driven flyer ignition is recognized as one of the most promising ignition technologies because of its highest time accuracy (nanosecond level), best safety and direct detonation of explosives.

[0003] Laser-driven flyer ignition technology requires that the system can generate a single high-energy laser pulse each time the ignition is started. The pulse energy is generally tens of mJ, and the pulse width is generally between 1 and 100 ns. At present, the ignition laser source of the laser-driven flyer ignition system is usually a solid laser (such as a YAG laser). Its specific working process is as follows: when the system receives the ignition command, the solid laser immediately emits a high-energy laser pulse, which is transmitted into the energy transmission fiber through space-fiber coupling; the energy transmission fiber is connected to the transparent window substrate through an optical fiber connector, and the output surface of the transparent window substrate is coated with a metal film. When the high-energy laser pulse is transmitted to the output surface of the transparent window substrate, the laser will ablate the metal film on its surface and quickly produce gasification to plasma, driving the remaining film layer (flyer) to fly toward the explosive at high speed, and finally achieve impact detonation.

[0004] At present, the laser-driven flyer ignition technology has obvious shortcomings: first, the required high-energy laser pulses are all generated by solid-state lasers, which are difficult to miniaturize, greatly restricting the widespread application of laser-driven flyer ignition technology. Second, when the high-energy laser pulses are spatially coupled with the energy transmission fiber, lenses need to be used for focusing, which is very easy to damage the input end face of the energy transmission fiber, greatly increasing the ignition failure rate.

[0005] Using fiber lasers to replace solid lasers in existing solutions as the ignition laser source of the laser-driven flyer ignition system can avoid the space-fiber coupling process (direct welding) of high-energy laser pulses, thereby perfectly solving the problem of high ignition failure rate. Although X.Shen et al. (X.Shen, H.Zhang, and M.Gong, “High Energy (100mJ) and High Peak Power (8MW) Nanosecond Pulses Delivered by Fiber Lasers and Self-Focusing Analysis Based on a Novel Mode Decomposition Method,” IEEE J.Sel. Top. Quantum Electron. 24 (3), 1–6 (2018)) proposed a technical solution for constructing a high-energy pulse fiber laser based on multi-stage cascade amplification, the number of cascade amplification stages required for this solution is as high as 7, which undoubtedly makes the fiber laser too large, thus losing the advantages of the fiber laser. Therefore, replacing the solid laser in the existing solution with a fiber laser based on cascade amplification still cannot solve the miniaturization problem of the existing laser-driven flyer ignition system. Summary of the invention

[0006] The purpose of the present invention is to solve the miniaturization problem of the existing laser driven flyer ignition system due to the use of solid lasers, as well as the high ignition failure rate due to space-fiber coupling, and propose an all-fiber laser driven flyer ignition system and method based on single-pulse laser cyclotron amplification.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] An all-fiber laser driven flying chip ignition system based on cyclotron amplification is special in that it includes a single pulse laser signal source, a fiber ring cavity connected to the single pulse laser signal source, and an energy transmission fiber, a fiber connector, a transparent window substrate, an acceleration chamber and explosives connected in sequence to the output end of the fiber ring cavity;

[0009] The single-pulse laser signal source is used to emit a single-pulse laser;

[0010] The fiber ring cavity is used to receive a single pulse laser and perform cyclotron amplification several times to output a high-energy single pulse laser; at least one pump source is provided in the fiber ring cavity to generate pump light; the transmission direction of the pump light in the fiber ring cavity is consistent with that of the single pulse laser;

[0011] The input end of the optical fiber ring cavity is provided with a first optical switch for inputting a single pulse laser;

[0012] The output end of the fiber ring cavity is provided with a second optical switch for outputting amplified high-energy single-pulse laser; the second optical switch is connected to the energy transmission fiber, and the energy transmission fiber is connected to the transparent window substrate through an optical fiber connector; after the high-energy single-pulse laser passes through the energy transmission fiber and reaches the output surface of the transparent window substrate, it ablates the metal film on its surface and generates plasma, and then drives the remaining film layer into the acceleration chamber to accelerate and fly towards the explosive at high speed, finally achieving impact detonation.

[0013] Further, the fiber ring cavity includes a first pump coupler and a first gain fiber arranged between the first optical switch output end and the second optical switch input end, and a second pump coupler and a second gain fiber arranged between the second optical switch output end and the first optical switch input end;

[0014] The pump ends of the first pump coupler and the second pump coupler are respectively provided with a first pump source and a second pump source.

[0015] Furthermore, the fiber ring cavity further comprises a first fiber isolator disposed between the first optical switch and the first pump coupler, and a second fiber isolator disposed between the second optical switch and the second pump coupler, both of which are used to control the unidirectional transmission of the pulsed laser in the fiber ring cavity and suppress the self-excited oscillation in the fiber ring cavity;

[0016] And, a first cladding mode stripper and a second cladding mode stripper are respectively arranged before the first optical switch and the second optical switch, and are used to remove the residual pump light not absorbed by the gain optical fiber.

[0017] Furthermore, the first pump source and the second pump source are both high-power multi-mode semiconductor lasers with a central wavelength of 976 nm;

[0018] The first pump coupler and the second pump coupler are side pump couplers prepared by side affinity fusion splicing technology based on the first gain fiber and the second gain fiber respectively; or both are end pump couplers based on fused taper (N+1)×1 type; N≤20.

[0019] Further, the first gain fiber and the second gain fiber are both double-clad gain fibers, the core of the double-clad gain fiber contains rare earth elements, the rare earth elements include ytterbium, erbium, thulium, holmium or neodymium, and the core diameter is greater than 100 μm;

[0020] The first cladding mode stripper and the second cladding mode stripper are prepared by coating a high refractive index glue on the surface of a de-coated double-cladding optical fiber or by chemically etching the surface of the optical fiber.

[0021] Further, the fiber ring cavity comprises a first fiber isolator and a first cladding mode stripper arranged between the first optical switch output end and the second optical switch input end, a second cladding mode stripper arranged between the second optical switch output end and the first optical switch input end, and a first gain fiber;

[0022] The first gain fiber is a GT-wave gain fiber; the signal fiber core of the GT-wave gain fiber contains rare earth elements, and the rare earth elements include ytterbium, erbium, thulium, holmium or neodymium;

[0023] The pump fiber separated at the input end of the first gain fiber is connected to the output end of the first pump coupler; the pump fiber separated before the single pulse laser enters the first cladding mode stripper, after crossing the first cladding mode stripper and the second optical switch, is merged with the signal fiber in the first gain fiber; the pump fiber separated again before the single pulse laser enters the second cladding mode stripper is connected to the input end of the first pump coupler;

[0024] A first pump source is disposed at a pump end of the first pump coupler.

[0025] Furthermore, the first pump source is a high-power multi-mode semiconductor laser with a central wavelength of 976 nm;

[0026] The first pump coupler is a side pump coupler prepared by side affinity fusion splicing technology of the pump fiber separated from the first gain fiber;

[0027] The first cladding mode stripper and the second cladding mode stripper are both prepared by coating the surface of the signal fiber in the GT-wave gain fiber with a high refractive index glue or by chemically etching the surface of the optical fiber.

[0028] Furthermore, the energy transmission optical fiber is a large mode field transmission optical fiber, and its core is not doped with rare earth ions, and the core diameter is equal to or greater than the core diameter of the first gain optical fiber;

[0029] The transparent window substrate is optical glass, and its output surface is plated with a single or multi-layer metal film; the inner diameter of the acceleration chamber is circular, and the inner diameter edge has a knife-like property to facilitate uniform shearing of flying pieces; the explosive is one or more mixed energetic solid materials.

[0030] Furthermore, the single-pulse laser signal source is a nanosecond single-pulse laser signal with a central wavelength of 1064nm and a pulse width of 1 to 100ns;

[0031] The first optical switch and the second optical switch are both 1×2 high-speed all-fiber optical switches, and the switching time is no more than 1 microsecond;

[0032] The total cavity length of the optical fiber ring cavity is 60m, and the first optical switch and the second optical switch divide the gain ring cavity into two half cavities, each of which has a length of 30m.

[0033] The present invention also provides an ignition method using the above-mentioned all-fiber laser driven flying chip ignition system based on cyclotron amplification, that is, when the system receives an ignition command, the pump source switch is turned on, and then the single-pulse laser signal source emits a single-pulse laser signal and injects it into the fiber ring cavity. The single-pulse laser signal will be cyclotronically amplified several times in the fiber ring cavity. When the pulse energy exceeds the ignition threshold, it is coupled out from the fiber ring cavity and injected into the energy transmission fiber for transmission. When the amplified high-energy single-pulse laser reaches the transparent window substrate connected to the energy transmission fiber, it will immediately ablate the metal film on its output surface and quickly generate gasification to plasma, thereby driving the remaining film layer to fly toward the explosive at high speed, and finally achieving impact detonation; its special feature is that it specifically includes the following steps:

[0034] Step 1, placing the first optical switch and the second optical switch in a working state of an annular cavity open or annular cavity closed;

[0035] Step 2: When the system receives the ignition command, it immediately turns on the pump source switch signal, and at the same time or after a delay of t0, turns on the single-pulse laser signal source to emit a single-pulse laser signal. The leading edge of the single-pulse laser signal is injected into the fiber ring cavity through the first optical switch, and will be transmitted unidirectionally along the fiber ring cavity; t0 < 1ms;

[0036] Step 3, after the single pulse laser passes through the second optical switch, the working states of the first optical switch and the second optical switch are immediately switched; when the single pulse laser passes through the first optical switch again, the working states of the first optical switch and the second optical switch are switched again, so that the single pulse laser completes a cyclotron amplification process in the optical fiber ring cavity;

[0037] Step 4, repeat the operation of step 3, so that the single pulse laser completes several cyclotron amplifications in the fiber ring cavity, until the energy of the single pulse laser exceeds the ignition threshold and then the pump source switch is turned off;

[0038] Step 5: Ensure that before the single pulse laser reaches the second optical switch, the second optical switch is placed in an open state of the ring cavity, so that the amplified high-energy single pulse laser is coupled out from the optical fiber ring cavity and then injected into the energy transmission optical fiber;

[0039] Step 6: When a high-energy laser pulse is transmitted to the output surface of the transparent window substrate, the laser will ablate the metal film on its surface and generate gasification to plasma, driving the remaining film layer to accelerate in the acceleration chamber and fly toward the explosive at high speed, ultimately achieving impact detonation.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. The present invention provides an all-fiber laser based on single-pulse laser cyclotron amplification to replace the solid-state laser in the existing solution, which requires fewer devices and can easily miniaturize the ignition system by winding the optical fiber.

[0042] 2. The all-fiber laser-driven flying-chip ignition system based on cyclotron amplification provided by the present invention realizes the reuse of devices in each cyclotron amplification process of the laser pulse, thereby greatly improving the efficiency of the system.

[0043] 3. The present invention realizes full fiberization, and the output fiber of the fiber laser and the energy transmission fiber can be directly fused, avoiding the complexity of space-fiber coupling in the existing solution and greatly reducing the failure rate of ignition. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the structure of an all-fiber laser driven flying chip ignition system based on cyclotron amplification according to the first embodiment of the present invention;

[0045] Figure 2 This is a working timing diagram of the pump switch, the first optical switch and the second optical switch in an ignition process of the all-fiber laser driven flying chip ignition system of Example 1;

[0046] Figure 3 This is a schematic diagram of the structure of an all-fiber laser driven flying chip ignition system based on cyclotron amplification according to the second embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of the structure of an all-fiber laser driven flying chip ignition system based on cyclotron amplification according to the third embodiment of the present invention;

[0048] Reference numerals:

[0049] 1-single pulse laser signal source, 2-first optical switch, 3-first optical fiber isolator, 4-first pump source, 5-first pump coupler, 6-first gain fiber, 7-first cladding mode stripper, 8-second optical switch, 9-second optical fiber isolator, 10-second pump source, 11-second pump coupler, 12-second gain fiber, 13-second cladding mode stripper, 14-energy transfer fiber, 15-optical fiber connector, 16-transparent window substrate, 17-acceleration chamber, 18-explosive. DETAILED DESCRIPTION

[0050] In order to make the purpose, advantages and features of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] Terms such as "input end", "output end", "same direction", "clockwise direction", "before", "after", etc. indicating directions or positional relationships are all directions or positional relationships based on the drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the system or element of the present invention must have a direction or be constructed and operated in a specific direction. The terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention, and are not intended to limit the scope of protection of the present invention.

[0052] The present invention proposes an all-fiber laser driven flying chip ignition system based on cyclotron amplification, which realizes the all-fiber laser driven flying chip ignition process by using a single pulse laser signal source, a fiber ring cavity, an energy transmission fiber, a fiber connector, a transparent window substrate, an acceleration chamber and explosives. The fiber ring cavity includes a first optical switch, a second optical switch, a gain fiber, a pump coupler and a pump source. The pumping mode of the fiber ring cavity is a co-directional pumping mode, that is, the transmission direction of the pump light in the ring cavity is consistent with that of the single pulse laser signal.

[0053] The specific process of all-fiber laser driven flying chip ignition based on single pulse laser cyclotron amplification is as follows: first, the first optical switch and the second optical switch are placed in the ring cavity open state and the ring cavity closed state respectively; second, after the system receives the ignition command, the pump source switch is immediately turned on, and at the same time or after a delay of several microseconds, the single pulse laser signal source emits a single pulse laser signal and injects it into the fiber ring cavity through the first optical switch; each time the single pulse laser signal passes through an optical switch (any optical switch in the cavity) in the fiber ring cavity, the working state of the first optical switch and the second optical switch are switched once; third, after the single pulse laser passes through several cyclotrons in the fiber ring cavity, the pulse energy has exceeded the ignition threshold, and the pump source is turned off at this time; when the single pulse laser is about to pass through the second optical switch again, the second optical switch is placed in the ring cavity open state, so that the single pulse laser is completely coupled out of the fiber ring cavity and injected into the energy transmission fiber for transmission; finally, after the single pulse laser is transmitted to the output surface of the transparent window substrate, the metal film on its surface will be rapidly ablated and gasified to plasma, driving the remaining film layer to fly toward the explosive at high speed, and finally achieving impact detonation.

[0054] Compared with the prior art, the present invention has the advantages of full optical fiber, high reliability and easy miniaturization.

[0055] Among them, the single-pulse laser signal source can be a single-pulse laser signal prepared by a method of directly driving a semiconductor laser diode based on a single-pulse current, or a single-pulse laser signal realized based on a gain switching technology, or a single-pulse laser signal extracted from a laser pulse train using a pulse selector.

[0056] The pump source is a light source with a wavelength at a point where the absorption cross section of the doped rare earth ions is large. It is generally composed of a combination of single-mode or multi-mode semiconductor laser diodes and is output by optical fiber coupling.

[0057] The working state of the optical switch includes the ring cavity open state and the ring cavity closed state. The ring cavity open state refers to the working state of the optical switch that makes the optical fiber ring cavity disconnected at this position; conversely, the ring cavity closed state refers to the working state of the optical switch that makes the optical fiber ring cavity connected at this position.

[0058] The first optical switch and the second optical switch are 1×2 optical switches, that is, the optical switches have three ports, namely, a common port and two output ports. The common port and one of the output ports are connected to the fiber ring cavity, and the other output port is connected to the peripheral input optical path or output optical path. The first optical switch and the second optical switch in the present invention are characterized in that they can withstand high peak power and fast switching speed, and can be used to prepare high-speed all-fiber devices based on electro-optical effect, acousto-optical effect and magneto-optical effect.

[0059] Embodiment 1

[0060] like Figure 1 As shown, the all-fiber laser driven flying chip ignition system based on cyclotron amplification proposed in this embodiment includes a single pulse laser signal source 1, a fiber ring cavity and an energy transmission fiber 14 connected to the output end of the fiber ring cavity, a fiber connector 15, a transparent window substrate 16, an acceleration chamber 17 and explosives 18.

[0061] The fiber ring cavity includes a first optical switch 2, a first optical fiber isolator 3, a first pump coupler 5, a first cladding mode stripper 7, a second optical switch 8, a second optical fiber isolator 9, a second pump coupler 11 and a second cladding mode stripper 13, which are sequentially arranged along the clockwise optical path. The total length of the fiber ring cavity is 60m, and the first optical switch 2 and the second optical switch 8 divide the fiber ring cavity into two half cavities, each of which is 30m long.

[0062] The first pump coupler 5 and the first cladding mode stripper 7 are connected, and the second pump coupler 11 and the second cladding mode stripper 13 are connected respectively by the first gain fiber 6 and the second gain fiber 12; the pump ends of the first pump coupler 5 and the second pump coupler 11 are connected to the first pump source 4 and the second pump source 10 respectively; one output end of the second optical switch 8 is connected to the energy transmission fiber 14, and the energy transmission fiber 14 is connected to the transparent window substrate 16, the acceleration chamber 17 and the explosive 18 through the optical fiber connector 15.

[0063] The single-pulse laser signal source 1 is a nanosecond single-pulse laser signal with a central wavelength of 1064 nm and a pulse width of 50 ns.

[0064] The first optical switch 2 and the second optical switch 8 are both high-speed all-fiber optical switches, and the switching time is 10 ns.

[0065] The first optical fiber isolator 3 and the second optical fiber isolator 9 can control the pulse laser to be transmitted in the optical fiber ring cavity in a clockwise unidirectional manner, and can also suppress the self-excited oscillation generated in the optical fiber ring cavity.

[0066] The first pump coupler 5 and the second pump coupler 11 are both side pump couplers realized based on the side affinity fusion technology of the gain fiber. The first pump source 4 and the second pump source 10 are both high-power multi-mode semiconductor lasers with a central wavelength of 976 nm.

[0067] The first gain optical fiber 6 and the second gain optical fiber 12 are both double-clad ytterbium-doped optical fibers, and the core diameters thereof are greater than 100 μm.

[0068] The first cladding mode stripper 7 and the second cladding mode stripper 13 are both prepared by coating a high refractive index glue on the surface of the uncoated double-clad optical fiber or by chemically etching the surface of the optical fiber.

[0069] The core of the energy transfer optical fiber 14 is not doped with rare earth ions, and its core diameter is equal to or greater than the core diameter of the first gain optical fiber 6 .

[0070] The window substrate 16 is optical glass, including fused quartz glass, K9 glass, etc., and its output surface is plated with a copper film. The inner diameter of the acceleration chamber 17 is circular, and the inner diameter edge should have very good blade properties to facilitate uniform shearing of flying pieces. The explosive 18 is one or more mixed energetic solid materials.

[0071] It may be assumed that when the switch signal levels of the first optical switch 2 and the second optical switch 8 are high, the optical switches are in an annular cavity open state, and conversely, when the switch signal levels are low, the optical switches are in an annular cavity closed state.

[0072] The pump source switch signal controls the first pump source 4 and the second pump source 10 simultaneously, and a high level indicates that the pump source is turned on, and a low level indicates that the pump source is turned off.

[0073] like Figure 2 As shown, the specific working process of this embodiment can be described by the timing diagram of the pump source switch signal, the first optical switch 2 and the second optical switch 8:

[0074] First, the first optical switch 2 is placed in the fiber ring cavity open state, and the second optical switch 8 is placed in the fiber ring cavity closed state. When the system receives the ignition command, the pump source switch signal is immediately turned on. After a delay of 5μs (i.e., time t0 in the figure), the single pulse laser signal is released and the pulse front reaches the first optical switch 2. After 100ns, the time is time t1, at which time the single pulse laser signal has been completely injected into the fiber ring cavity; the working state of the first optical switch 2 and the second optical switch 8 is maintained for 146ns, at which time the single pulse laser signal has completely passed through the second optical switch 8, and the levels of the switch signals of the first optical switch 2 and the second optical switch 8 are switched; after another 146ns, it is time t2, at which time the single pulse laser signal has completely passed through the first optical switch 2, and the levels of the switch signals of the first optical switch 2 and the second optical switch 8 are switched again;

[0075] At this time, the single pulse laser signal completes a cyclotron amplification process in the fiber ring cavity, which takes 292ns. The second cyclotron amplification process is exactly the same as the first one. When the time is t3=t2+292ns, the single pulse laser signal completes the second cyclotron amplification process in the fiber ring cavity. Similarly, when the time is t5=t4+292ns, the single pulse laser signal completes the Nth cyclotron amplification process in the fiber ring cavity, and the single pulse energy has exceeded the ignition threshold.

[0076] After the first optical switch 2 and the second optical switch 8 continue to work for 146 ns, the pump source switch is turned off. At this time, the single pulse laser signal has been completely coupled out of the fiber ring cavity through the second optical switch 8 and injected into the energy transmission fiber 14. When the laser pulse is transmitted to the output end face of the transparent window substrate 16, the incident laser will ablate the surface metal film and generate gasification to plasma, drive the remaining film layer to accelerate in the acceleration chamber 17, and fly to the explosive 18 at a very high speed, finally realizing the impact detonation process.

[0077] Embodiment 2

[0078] like Figure 3 As shown, compared with the all-fiber laser driven flying chip ignition system based on side pump coupling in the first embodiment, the first pump coupler 5 and the second pump coupler 11 of this embodiment adopt end-pump couplers realized based on the traditional fused taper technology.

[0079] The side-pumped coupler based on the side affinity fusion technology of the gain fiber introduces almost no insertion loss for single pulse signal laser, and can also be extended to multi-point distributed pump coupling. Although the end-pumped coupler based on the traditional fused taper technology will introduce a certain amount of insertion loss, the current process is relatively mature and low-cost.

[0080] The specific working process of this embodiment is exactly the same as that of the first embodiment, except that the pump coupling method is different. Figure 2 The timing diagram shown is used to illustrate this.

[0081] Embodiment 3

[0082] like Figure 4 As shown, this embodiment provides an all-fiber laser driven flying chip ignition system based on GT-wave gain fiber, including a single pulse laser signal source 1, a fiber ring cavity and an energy transmission fiber 14 connected to the output end of the fiber ring cavity, a fiber connector 15, a transparent window substrate 16, an acceleration chamber 17 and explosives 18.

[0083] The GT-wave gain fiber contains 1 signal fiber and 1 pump fiber. The pump light is injected from the pump fiber and enters the signal fiber through evanescent wave coupling, providing gain for the laser signal amplification in the signal fiber.

[0084] Based on the structural characteristics of GT-wave gain fiber gain / pump integration, the fiber ring cavity includes a gain ring cavity formed by connecting the signal fiber and a pump ring cavity formed by connecting the pump fiber; the gain ring cavity includes a first optical switch 2, a first optical fiber isolator 3, a first cladding mode stripper 7, a second optical switch 8 and a second cladding mode stripper 13 arranged in sequence along the clockwise optical path. The total length of the gain ring cavity is 60m, and the first optical switch 2 and the second optical switch 8 divide the gain ring cavity into two half cavities, each of which is 30m long. The pump ring cavity is connected to the first pump coupler 5 by the pump fiber separated from the first gain fiber 6, thereby forming a closed loop, such as Figure 4 shown.

[0085] The first gain fiber 6 is a GT-wave gain fiber, and the separated signal fiber is used to connect the first fiber isolator 3, the first cladding mode stripper 7, the second optical switch 8 and the second cladding mode stripper 13. When the single pulse laser is continuously circling in the gain ring cavity, the pump light in the pump ring cavity will continuously enter the gain ring cavity through evanescent wave coupling and provide gain for the amplification of the single pulse laser.

[0086] The pump fiber separated from the input end of the first gain fiber 6 along the clockwise direction is connected to the output end of the first pump coupler 5; the pump fiber separated before the first cladding mode stripper, after crossing the first cladding mode stripper 7 and the second optical switch 8, is merged with the signal fiber in the first gain fiber; the pump fiber separated again before the laser enters the second cladding mode stripper 13 along the clockwise direction is connected to the input end of the first pump coupler 5; the pump end of the first pump coupler 5 is provided with a first pump source 4, which is a high-power multi-mode semiconductor laser with a central wavelength of 976nm. The pump light is injected into the pump ring cavity through the first pump coupler 5 and transmitted in the clockwise direction, so that the pump energy can be effectively stored in the pump ring cavity.

[0087] In this embodiment, the single-pulse laser signal source 1 is a nanosecond single-pulse laser signal with a central wavelength of 1064 nm and a pulse width of 50 ns.

[0088] The first optical switch 2 and the second optical switch 8 are both high-speed all-fiber switches, and the switching time is 10 ns.

[0089] The first optical fiber isolator 3 can control the pulse laser to be transmitted in the optical fiber ring cavity in a clockwise unidirectional manner, and can also suppress the self-excited oscillation generated in the optical fiber ring cavity.

[0090] The first pump coupler 5 is a side pump coupler realized based on the side affinity fusion technology of the separated pump fibers.

[0091] The first cladding mode stripper 7 and the second cladding mode stripper 9 are both prepared by coating the surface of the signal fiber in the GT-wave gain optical fiber with a high refractive index glue.

[0092] The core of the energy transmission optical fiber 14 is not doped with rare earth ions, and its core diameter is equal to or greater than the core diameter of the signal fiber in the first gain optical fiber 6 .

[0093] The output surface of the transparent window substrate 16 is plated with a copper film. The inner diameter of the accelerating chamber 17 is circular, and the inner diameter edge should have very good blade properties to facilitate uniform shearing of flying pieces. The explosive 18 is one or more mixed energetic solid materials.

[0094] Similarly, it is assumed that when the switch signal level of the first optical switch 2 and the second optical switch 8 is high, the optical switch is in the ring cavity open state, and vice versa, when the switch signal level is low, the optical switch is in the ring cavity closed state. A high level of the pump source switch signal indicates that the pump source is turned on, and a low level indicates that the pump source is turned off. The specific working process of this embodiment is also exactly the same as that of the first embodiment, and can also be referred to as Figure 2 The timing diagram shown is used to illustrate this.

[0095] The above embodiments only provide three representative all-fiber laser driven flying chip ignition systems based on single pulse laser cyclotron amplification for three typical pumping methods, and do not describe all possibilities. In fact, as long as the all-fiber laser based on single pulse laser cyclotron amplification is used to replace the solid laser in the existing solution to achieve the miniaturization of all-fiber laser driven flying chip ignition technology, it is within the scope of the present invention.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. An all-fiber laser driven flying chip ignition system based on cyclotron amplification, characterized by: It comprises a single pulse laser signal source (1), an optical fiber ring cavity connected to the single pulse laser signal source (1), and an energy transmission optical fiber (14), an optical fiber connector (15), a transparent window substrate (16), an acceleration chamber (17) and explosives (18) connected in sequence to the output end of the optical fiber ring cavity; The single-pulse laser signal source (1) is used to emit a single-pulse laser; The fiber ring cavity is used to receive a single pulse laser and perform cyclotron amplification several times to output a high-energy single pulse laser; at least one pump source is provided in the fiber ring cavity to generate pump light; the transmission direction of the pump light in the fiber ring cavity is consistent with that of the single pulse laser; The input end of the optical fiber ring cavity is provided with a first optical switch (2) for inputting a single pulse laser, and the output end is provided with a second optical switch (8) for outputting a single pulse laser; the first optical switch (2) and the second optical switch (8) divide the optical fiber ring cavity into two half cavities of equal length; the second optical switch (8) is connected to an energy transmission optical fiber (14), and the energy transmission optical fiber (14) is connected to a transparent window substrate (16) through an optical fiber connector (15); after the high-energy single pulse laser reaches the output surface of the transparent window substrate (16), it ablates the metal film on its surface and generates plasma, driving the remaining film layer to enter the acceleration chamber (17) to accelerate and then fly towards the explosive (18), thereby achieving impact detonation; The fiber ring cavity comprises a first pump coupler (5) and a first gain fiber (6) arranged between an output end of a first optical switch (2) and an input end of a second optical switch (8), and a second pump coupler (11) and a second gain fiber (12) arranged between an output end of the second optical switch (8) and an input end of the first optical switch (2); a first pump source (4) and a second pump source (10) are respectively arranged at the pump ends of the first pump coupler (5) and the second pump coupler (11); The optical fiber ring cavity further comprises a first optical fiber isolator (3) arranged between the first optical switch (2) and the first pump coupler (5), and a second optical fiber isolator (9) arranged between the second optical switch (8) and the second pump coupler (11), both of which are used to control the clockwise unidirectional transmission of pulsed laser in the optical fiber ring cavity and suppress the self-excited oscillation in the optical fiber ring cavity; and a first cladding mode stripper (7) and a second cladding mode stripper (13) respectively arranged before the input ends of the first optical switch (2) and the second optical switch (8), and used to remove residual pump light not absorbed by the gain optical fiber.

2. The all-fiber laser driven flying chip ignition system based on cyclotron amplification according to claim 1 is characterized in that: The first pump source (4) and the second pump source (10) are both high-power multi-mode semiconductor lasers with a central wavelength of 976 nm; The first pump coupler (5) and the second pump coupler (11) are respectively side pump couplers prepared by side affinity fusion splicing of the first gain fiber (6) and the second gain fiber (12), or are both fused taper (N+1)×1 type end-face pump couplers; N≤20.

3. The all-fiber laser driven flying chip ignition system based on cyclotron amplification according to claim 2 is characterized in that: The first gain optical fiber (6) and the second gain optical fiber (12) are both double-clad gain optical fibers, the cores of which contain rare earth elements and the core diameters of which are greater than 100 μm; the rare earth elements include ytterbium, erbium, thulium, holmium or neodymium; The first cladding mode stripper (7) and the second cladding mode stripper (13) are both prepared by coating a high refractive index glue on the surface of a de-coated double-cladding optical fiber or by chemically etching the surface of the optical fiber.

4. The all-fiber laser driven flying chip ignition system based on cyclotron amplification according to any one of claims 1 to 3, characterized in that: The energy transmission optical fiber (14) is a large mode field transmission optical fiber, and its core is not doped with rare earth ions, and the core diameter is equal to or greater than the core diameter of the first gain optical fiber (6); The transparent window substrate (16) is optical glass, and its output surface is coated with a single layer or multiple layers of metal film; the inner diameter of the acceleration chamber (17) is circular, and the inner diameter edge has a knife-like property to facilitate uniform shearing of flying pieces; the explosive (18) is one or more mixed energetic solid materials.

5. The all-fiber laser driven flying chip ignition system based on cyclotron amplification according to claim 4 is characterized in that: The single-pulse laser signal source (1) is a nanosecond single-pulse laser signal with a central wavelength of 1064 nm and a pulse width of 1 to 100 ns; The first optical switch (2) and the second optical switch (8) are both high-speed all-fiber optical switches, and the switching time is no more than 1 microsecond; The total cavity length of the optical fiber ring cavity is 60m, and the first optical switch (2) and the second optical switch (8) divide the gain ring cavity into two half cavities, each of which has a length of 30m.

6. An all-fiber laser driven flying chip ignition system based on cyclotron amplification, characterized in that: It comprises a single pulse laser signal source (1), an optical fiber ring cavity connected to the single pulse laser signal source (1), and an energy transmission optical fiber (14), an optical fiber connector (15), a transparent window substrate (16), an acceleration chamber (17) and explosives (18) connected in sequence to the output end of the optical fiber ring cavity; The single-pulse laser signal source (1) is used to emit a single-pulse laser; The fiber ring cavity is used to receive a single pulse laser and perform cyclotron amplification several times to output a high-energy single pulse laser; at least one pump source is provided in the fiber ring cavity to generate pump light; the transmission direction of the pump light in the fiber ring cavity is consistent with that of the single pulse laser; The input end of the optical fiber ring cavity is provided with a first optical switch (2), and the output end is provided with a second optical switch (8), which are respectively used to input a single pulse laser; the first optical switch (2) and the second optical switch (8) divide the optical fiber ring cavity into two half cavities, and the lengths of the two half cavities are equal; The second optical switch (8) is connected to an energy transmission optical fiber (14), and the energy transmission optical fiber (14) is connected to a transparent window substrate (16) via an optical fiber connector (15); after the high-energy single-pulse laser reaches the output surface of the transparent window substrate (16), it ablates the metal film on its surface and generates plasma, driving the remaining film layer to enter the acceleration chamber (17) and accelerate to fly towards the explosive (18), thereby achieving impact detonation; The optical fiber ring cavity comprises a first optical fiber isolator (3) and a first cladding mode stripper (7) arranged between an output end of a first optical switch (2) and an input end of a second optical switch (8), a second cladding mode stripper (13) arranged between an output end of the second optical switch (8) and an input end of the first optical switch (2), and a first gain optical fiber (6); The first gain optical fiber (6) is a GT-wave gain optical fiber, and the core of the signal fiber thereof contains a rare earth element; the rare earth element includes ytterbium, erbium, thulium, holmium or neodymium; The pump fiber separated at the input end of the first gain optical fiber (6) is connected to the output end of the first pump coupler (5); the pump fiber separated before the laser enters the first cladding mode stripper (7) crosses the first cladding mode stripper (7) and the second optical switch (8), and then merges with the signal fiber in the first gain optical fiber (6); the pump fiber separated again before the laser enters the second cladding mode stripper (13) is connected to the input end of the first pump coupler (5); A first pump source (4) is provided at the pump end of the first pump coupler (5).

7. The all-fiber laser driven flying chip ignition system based on cyclotron amplification according to claim 6 is characterized in that: The first pump source (4) is a high-power multi-mode semiconductor laser with a central wavelength of 976 nm; The first pump coupler (5) is a side pump coupler prepared by side affinity fusion splicing technology of the pump fiber separated from the first gain optical fiber (6); The first cladding mode stripper (7) and the second cladding mode stripper (13) are both prepared by coating the surface of the signal fiber in the GT-wave gain optical fiber with a high refractive index glue or by chemically etching the surface of the optical fiber.

8. The all-fiber laser driven flying chip ignition system based on cyclotron amplification according to claim 6 or 7, characterized in that: The energy transmission optical fiber (14) is a large mode field transmission optical fiber, and its core is not doped with rare earth ions, and the core diameter is equal to or greater than the core diameter of the first gain optical fiber (6); The transparent window substrate (16) is optical glass, and its output surface is coated with a single layer or multiple layers of metal film; the inner diameter of the acceleration chamber (17) is circular, and the inner diameter edge has a knife-like property to facilitate uniform shearing of flying pieces; the explosive (18) is one or more mixed energetic solid materials.

9. The all-fiber laser driven flying chip ignition system based on cyclotron amplification according to claim 8 is characterized in that: The single-pulse laser signal source (1) is a nanosecond single-pulse laser signal with a central wavelength of 1064 nm and a pulse width of 1 to 100 ns; The first optical switch (2) and the second optical switch (8) are both high-speed all-fiber optical switches, and the switching time is no more than 1 microsecond; The total cavity length of the optical fiber ring cavity is 60m, and the first optical switch (2) and the second optical switch (8) divide the gain ring cavity into two half cavities, each of which has a length of 30m.

10. An ignition method using the all-fiber laser driven flyer ignition system based on cyclotron amplification according to claim 1 or 6, characterized in that: The following steps are involved: Step 1, placing the first optical switch (2) and the second optical switch (8) in a working state of an annular cavity being open or annular cavity being closed; Step 2: When the system receives the ignition command, the pump source switch signal is immediately turned on, and at the same time or after a delay of t0, the single pulse laser signal source (1) is turned on to emit a single pulse laser signal, and the leading edge of the single pulse laser signal is injected into the optical fiber ring cavity through the first optical switch (2), and is transmitted in one direction along the optical fiber ring cavity; t0 < 1ms; Step 3: After the single pulse laser passes through the second optical switch (8), the working states of the first optical switch (2) and the second optical switch (8) are immediately switched; when the single pulse laser passes through the first optical switch (2) again, the working states of the first optical switch (2) and the second optical switch (8) are switched again, and the single pulse laser has completed a cyclotron amplification process in the optical fiber ring cavity; Step 4, repeat the operation of step 3, so that the single pulse laser completes several cyclotron amplifications in the fiber ring cavity, until the energy of the single pulse laser exceeds the ignition threshold and then the pump source switch is turned off; Step 5: Ensure that before the single pulse laser reaches the second optical switch (8), the second optical switch (8) is placed in an open state of the ring cavity, so that the amplified high-energy single pulse laser is coupled out from the optical fiber ring cavity and then injected into the energy transmission optical fiber (14); Step 6: When a high-energy laser pulse is transmitted to the output surface of the transparent window substrate (16), the laser will ablate the metal film on its surface and generate gasification to plasma, driving the remaining film layer to accelerate in the acceleration chamber (17) and fly towards the explosive (18) at high speed, finally achieving impact detonation.

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