A multi-pass laser amplifier

Abstract

The present invention relates to the field of laser amplifier equipment, and in particular to a multi-pass laser amplifier, comprising a laser amplifier and a laser oscillator that cooperate with each other, wherein the laser amplifier and the laser oscillator are both placed in a functional chamber, the functional chamber is a rectangular parallelepiped structure, a movable guide rail is arranged on the lower bottom surface of the functional chamber, the laser amplifier and the laser oscillator are arranged on the movable guide rail in sequence, and both can move back and forth on the movable guide rail along the length direction of the movable guide rail, thereby solving the technical problem that the front and rear end glass windows of the existing laser amplifier undergo local high temperature denaturation after long-term laser irradiation during use, thereby reducing the service life and the light transmittance.

Description

Technical Field

[0001] The invention relates to the field of laser amplifier equipment, and in particular to a multi-pass laser amplifier. Background Art

[0002] In many practical occasions, a high-quality laser beam is required, that is, a single transverse mode and single longitudinal mode laser beam. However, the output power or energy of a laser working in a single mode is not very large because of the large cavity loss and small mode volume. In order to increase the power or energy, a laser amplifier is needed.

[0003] Laser amplifiers are devices that use stimulated radiation of light to amplify the energy (power) of light. By using laser amplifiers, it is possible to obtain high laser energy or power while maintaining the quality of the laser (including pulse width, line width, polarization characteristics, etc.). They are often used in high-power laser systems in major technologies such as controlled nuclear fusion, nuclear explosion simulation, and ultra-long laser ranging. The characteristics of laser amplifiers are that they can obtain extremely high output energy and power, maintain the beam quality of the oscillator, and reduce the destruction and damage of optical components.

[0004] In actual use of the laser amplifier, the signal laser source and the pump light pass through the glass window on one side of the laser amplifier and the working medium in the same direction, and then are emitted from the glass window on the other side. In this process, the pump light power is very high, and the signal laser source power is relatively low. Therefore, the pump light amplifies the signal laser source, accelerates it, and obtains greater energy.

[0005] In the above process, since the glass window in the equipment is always in a static state, accompanied by the heating effect of the high-power pump light on the glass window, after working for a period of time, the glass window will quickly reach a high temperature state and even burn. This will damage the internal structure of the glass window, reduce its service life, reduce the transmittance and quality of the laser after transmission. At the same time, during the laser amplification process, only by ensuring that the gain of the amplifier lags behind the oscillator for a certain period of time can the amplified laser beam maintain the maximum gain effect when passing through.

[0006] The invention patent with Chinese patent application number 201810735336.0 discloses a laser amplifier, including a laser amplifier body, a glass window and a sealing gland; the laser amplifier body is provided with a through working medium flow channel, and the working medium flow channel is filled with flowing working medium; cooling cavities are symmetrically provided on both sides of the working medium flow channel, and a gap is provided between each cooling cavity and the working medium flow channel; one end of the glass window is sealed and placed in the gap, and the other end of the glass window is sealed and pressed by a sealing gland; the sealing gland is installed on the laser amplifier body; the symmetrical cooling cavities are connected through through holes; a coolant inlet and a coolant outlet are provided on the laser amplifier body, and the coolant inlet is connected to one cooling cavity, and the coolant outlet is connected to another cooling cavity. The present invention can cool the glass window by injecting coolant, greatly improve the heat exchange rate, and enhance the cooling effect. The glass windows are placed in the cooling cavity in a ring-shaped arrangement, with a simple structure and easy processing. The technical solution proposed in the above invention solves the heating problem of glass windows in the background technology. However, in the process of adding coolant to the glass window, firstly, the glass window body is still subjected to the high temperature from the laser, and the irradiation effect does not change at the same position, and high temperature is still generated locally. Under the action of high temperature, it is difficult to ensure that the liquid coolant will not chemically react with the solid glass window. At the same time, the coolant is still stationary after being added and no circulation occurs, so the cooling effect is not good. Summary of the invention

[0007] Therefore, in order to solve the above problems, the present invention proposes a multi-pass laser amplifier, which solves the technical problem that the front and rear end glass windows of the existing laser amplifier will undergo local high-temperature denaturation after long-term laser irradiation during use, thereby reducing the service life and the light transmittance.

[0008] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a multi-pass laser amplifier, comprising a laser amplifier and a laser oscillator that cooperate with each other, wherein the laser amplifier and the laser oscillator are both placed in a functional chamber, the functional chamber is a rectangular parallelepiped structure, a movable guide rail is arranged on the lower bottom surface of the functional chamber, the laser amplifier and the laser oscillator are arranged on the movable guide rail in sequence, and both can move back and forth on the movable guide rail along the length direction of the movable guide rail;

[0009] The laser oscillator comprises a first receiving plate, an optical resonant cavity, a pump source and a gain medium. The optical resonant cavity, the pump source and the gain medium interact with each other and are all arranged on the first receiving plate to form a closed-loop system. When the pump source provides sufficient energy, atoms or molecules in the gain medium are excited and release photons, which form a resonance effect in the optical resonant cavity and form laser output when a preset threshold is reached.

[0010] The laser amplifier comprises a second receiving plate, a total reflection mirror, a double-clad optical fiber and an output reflection mirror, and the laser amplifier is used to receive the laser light and pump light generated by the laser oscillator;

[0011] The laser amplifier also includes an automatic control device for controlling the total reflection mirror and the output reflection mirror, and the automatic control device enables the total reflection mirror and the output reflection mirror to move in a rotational manner.

[0012] Furthermore, the double-clad optical fiber includes a core, an inner cladding, an outer cladding and a protective layer.

[0013] Furthermore, the core is a single-mode optical waveguide doped with rare earth elements, the inner cladding is a multi-mode optical waveguide, the lateral size of the inner cladding is larger than that of the core, and the refractive index of the inner cladding is smaller than that of the core.

[0014] Furthermore, the refractive index of the outer cladding is smaller than that of the inner cladding, and the pump light propagates in the inner cladding.

[0015] Furthermore, the automatic control device includes a front-end support frame, a rear-end support frame, a first transmission roller, a second transmission roller and a central drive motor, the front-end support frame and the rear-end support frame are respectively arranged at the front, back, left and right ends of the second supporting plate, the total reflection mirror is arranged on the front-end support frame, the output reflection mirror is arranged on the rear-end support frame, the first transmission roller and the second transmission roller are both meshed and connected with the output end of the central drive motor, the first transmission roller connects the front-end support frame and the central drive motor, and the second transmission roller connects the rear-end support frame and the central drive motor.

[0016] Furthermore, a first annular groove is provided on the front end support frame, and the inner groove surface of the first annular groove is semicircular. The total reflection mirror is arranged in the first annular groove, and a first meshing tooth is provided on the outer circumferential side of the total reflection mirror. The first transmission roller extends into the first annular groove, and a second meshing tooth meshing with the first meshing tooth is provided on the end portion of one side of the first transmission roller close to the front end support frame. The total reflection mirror is rotated in the first annular groove by rotating the first transmission roller, and the total reflection mirror is a convex mirror.

[0017] Furthermore, a second annular groove is provided on the rear end support frame, and the inner groove surface of the second annular groove is semicircular. The output reflector is arranged in the second annular groove, and a third meshing tooth is provided on the outer circumferential side surface of the output reflector. The second transmission roller extends into the second annular groove, and a fourth meshing tooth meshing with the third meshing tooth is provided on the end portion of one side of the second transmission roller close to the rear end support frame. The output reflector rotates in the second annular groove by rotating the second transmission roller, and the output reflector is a plane mirror.

[0018] Furthermore, a gap between the total reflection mirror and the inner groove surface of the first annular groove is 1-3 mm.

[0019] Furthermore, a gap between the output reflector and the inner groove surface of the second annular groove is 3-5 mm.

[0020] Furthermore, the fourth meshing teeth include main meshing teeth and auxiliary meshing teeth, the auxiliary meshing teeth are arranged at intervals among the main meshing teeth, and the arrangement order is that an auxiliary meshing tooth is inserted after every four consecutive main meshing teeth. The tooth height of the auxiliary meshing teeth is higher than the tooth height of the main meshing teeth, and the difference between the two is 3-5mm.

[0021] By adopting the above technical solution, the beneficial effects of the present invention are:

[0022] 1. Compared with the existing laser amplifiers, the technical solution proposed in the present invention better solves the technical problem that the front and rear end glass windows of the existing laser amplifiers undergo local high-temperature denaturation after long-term laser irradiation during use, thereby reducing the service life and decreasing the light transmittance. Specifically, the laser amplifier and the laser oscillator are separately and independently arranged in a functional chamber, and a movable guide rail is arranged on the lower bottom surface of the functional chamber to ensure that the two can move relative to each other, approach each other or move away from each other. The controllable approach or distance between each other is to ensure that the gain of the amplifier lags behind the oscillator for a certain period of time to ensure that the amplified laser beam can maintain the maximum gain effect when passing through. At the same time, the present invention mainly provides an automatic control device to enable the total reflection mirror and the output reflection mirror in the device to move in real time, thereby avoiding the two being locally exposed to laser irradiation for a long time during use and generating local high temperature, thereby affecting the service life of the glass and causing the amplified laser to fail to achieve the expected effect and decrease the transmittance after being output through the output reflection mirror.

[0023] 2. The double-clad optical fiber in the present invention includes a core, an inner cladding, an outer cladding and a protective layer. The inner cladding and the outer cladding have a concentric circular cross-sectional structure. The core has a large refractive index like the core of a single-mode optical fiber, and is used to transmit single-mode signal light. The inner cladding has the same material as the core of an ordinary optical fiber, and its refractive index is between the core and the outer cladding, and is used to transmit multi-mode pump light. The refractive index of the outer cladding is the smallest. The inner cladding and the core form a large core for transmitting pump light, which repeatedly passes through the core in a zigzag manner and is doped and absorbed, so that the proportion of light propagating in the core is increased, thereby increasing the laser amplification efficiency.

[0024] 3. At the same time, the use of double-clad optical fiber in the present invention no longer requires the pump source to be single-mode, and the optical fiber is pumped over the entire length. In particular, when the symmetry of the core and the cladding is slightly damaged, the absorption of the pump light will be greatly increased, so that various shapes of inner cladding can be designed to better match the laser diode as the pump source, so that the multi-mode pump light can be more effectively coupled, and the continuous laser output can be increased to the order of tens of watts or even thousands of watts. Double-clad optical fiber can also be used to make Q-switched lasers to obtain pulse outputs with peak power of thousands of watts, achieving high power and high energy effects.

[0025] 4. The automatic control device in the present invention mainly provides support for the total reflector and the output reflector by setting a front-end support frame and a rear-end support frame, while satisfying that the two can rotate on the front-end support frame and the rear-end support frame respectively, wherein the rotation is mainly achieved by driving the first transmission roller and the second transmission roller through a central drive motor.

[0026] 5. The rotation principle of the total reflection mirror in the present invention is mainly to drive the first transmission roller to rotate through the central driving motor. After the first transmission roller extends into the first annular groove of the front end support frame, it can engage with the total reflection mirror to drive the total reflection mirror to rotate. At the same time, the total reflection mirror adopts a convex mirror, which can gather the laser generated by the laser oscillator and guide it into the double-clad optical fiber for transmission.

[0027] 6. The rotation principle of the output reflector in the present invention is mainly to drive the second transmission roller to rotate through the central driving motor and then drive it to rotate. The principle is the same as that of the total reflector. Because the first transmission roller and the second transmission roller are respectively arranged at the two ends of the central driving motor, the two rotate in opposite directions when driving the total reflector and the output reflector to rotate respectively. The rotation in opposite directions does not affect the laser transmission, but can simplify the output source, that is, only one central driving motor is needed to simultaneously drive the front and rear total reflectors and the output reflector to rotate and displace, ensuring that the laser beam will not act on the same position of the glass lens for a long time, causing local high temperature, and there is no need to make structural improvements to the glass to increase coolant. In other words, there is no need to modify the glass of special material to increase the use cost, and the addition of coolant is also prone to cause the chemical components in the coolant to react chemically with the chemical components in the glass at high temperature due to the high temperature environment, thereby affecting the service life of the glass lens.

[0028] 7. The fourth meshing teeth in the present invention include main meshing teeth and auxiliary meshing teeth. The auxiliary meshing teeth are special teeth, which are higher than the main meshing teeth. When the second transmission roller rotates, the output reflector will shake up and down due to the height difference. At this time, the trajectory of the laser acting on the output reflector is a circular wave shape. This structure mainly assists the rotating output reflector to further extend the laser irradiation trajectory and further reduce the risk of local high temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0030] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0031] Figure 2 It is a schematic diagram of the internal structure of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of the laser amplifier of the present invention;

[0033] Figure 4 Schematic diagram of the internal structure of the double-clad optical fiber in the present invention;

[0034] Figure 5 It is a schematic diagram of the structure of the automatic control device in the laser amplifier of the present invention;

[0035] Figure 6 It is a schematic diagram of the top view of the central driving motor in the automatic control device of the present invention;

[0036] Figure 7It is a schematic diagram of the operation structure of the central drive motor in the automatic control device of the present invention;

[0037] Figure 8 It is a schematic diagram of the fourth meshing tooth structure in the present invention. DETAILED DESCRIPTION

[0038] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0039] See also Figure 1-Figure 8 The present invention provides a multi-pass laser amplifier, comprising a laser amplifier 3 and a laser oscillator 2 that cooperate with each other, wherein the laser amplifier 3 and the laser oscillator 2 are both placed in a functional chamber 1, wherein the functional chamber 1 is a rectangular parallelepiped structure, and a movable guide rail 11 is arranged on the lower bottom surface of the functional chamber 1, wherein the laser amplifier 3 and the laser oscillator 2 are sequentially arranged on the movable guide rail 11, and both of them can move back and forth on the movable guide rail 11 along the length direction of the movable guide rail, and the moving mode is driven by a motor;

[0040] The laser oscillator 2 includes a first receiving plate 12, an optical resonant cavity, a pump source and a gain medium. The optical resonant cavity, the pump source and the gain medium interact with each other and are all arranged on the first receiving plate to form a closed-loop system. When the pump source provides sufficient energy, the atoms or molecules in the gain medium are excited and release photons, which form a resonance effect in the optical resonant cavity and form laser output when a preset threshold is reached. The formation of laser by the interaction of the optical resonant cavity, the pump source and the gain medium is common knowledge in the art. The principle of generating laser by the laser oscillator 2 is not elaborated here, and the laser oscillator 2 also includes all the required components.

[0041] The laser amplifier 3 comprises a second receiving plate 13, a total reflection mirror 5, a double-clad optical fiber 32 and an output reflection mirror 6. The laser amplifier 3 is used to receive the laser light and pump light generated by the laser oscillator 2.

[0042] The laser amplifier 3 further comprises an automatic control device 4 for controlling the total reflection mirror 5 and the output reflection mirror 6. The automatic control device 4 enables the total reflection mirror 5 and the output reflection mirror 6 to move in a rotational manner.

[0043] The double-clad optical fiber 32 comprises a core 323, an inner cladding 321, an outer cladding 322 and a protective layer 324, wherein the transmission paths of the laser light a and the pump light b are as shown in the attached figure. Figure 4The core 323 is a single-mode optical waveguide doped with rare earth elements, the inner cladding 321 is a multi-mode optical waveguide, the lateral size of the inner cladding 321 is larger than the core 323, the refractive index of the inner cladding 321 is smaller than the core 323, the refractive index of the outer cladding 322 is smaller than the inner cladding 321, and the pump light b propagates in the inner cladding 321.

[0044] The automatic control device 4 includes a front-end support frame 31, a rear-end support frame 33, a first transmission roller 41, a second transmission roller 42 and a central drive motor 43. The front-end support frame 31 and the rear-end support frame 33 are respectively arranged at the front, back, left and right ends of the second receiving plate 13. The total reflection mirror 5 is arranged on the front-end support frame 31, and the output reflection mirror 6 is arranged on the rear-end support frame 33. The first transmission roller 41 and the second transmission roller 42 are both meshed and connected with the output end of the central drive motor 43. The first transmission roller 41 connects the front-end support frame 31 and the central drive motor 43, and the second transmission roller 42 connects the rear-end support frame 33 and the central driving motor 43, the front end support frame 31 is provided with a first annular groove 311, the inner groove surface of the first annular groove 311 is semicircular, the total reflection mirror 5 is arranged in the first annular groove 311, the outer circumferential side surface of the total reflection mirror 5 is provided with a first meshing tooth 51, the first transmission roller 41 extends into the first annular groove 311, and the first transmission roller 41 is provided with a second meshing tooth 411 meshing with the first meshing tooth 51 at one end portion of the first transmission roller 41 close to the front end support frame 31, the total reflection mirror 5 is rotated in the first annular groove 311 by the rotation of the first transmission roller 41, and the total reflection mirror 5 is a convex mirror.

[0045] A second annular groove 331 is provided on the rear end support frame 33, and the inner groove surface of the second annular groove 331 is semicircular. The output reflector 6 is arranged in the second annular groove 331, and a third meshing tooth 61 is provided on the outer circumferential side surface of the output reflector 6. The second transmission roller 42 extends into the second annular groove 331, and a fourth meshing tooth 421 meshing with the third meshing tooth 61 is provided on the end portion of one side of the second transmission roller 42 close to the rear end support frame 33. The output reflector 6 rotates in the second annular groove 331 through the rotation of the second transmission roller 42. The output reflector 6 is a plane mirror.

[0046] The gap between the total reflection mirror 5 and the inner groove surface of the first annular groove 311 is 3 mm, and the gap between the output reflection mirror 6 and the inner groove surface of the second annular groove 331 is 5 mm; the fourth meshing teeth 421 include main meshing teeth 4211 and auxiliary meshing teeth 4212, and the auxiliary meshing teeth 4212 are arranged at intervals among the main meshing teeth 4211, and the arrangement order is that an auxiliary meshing tooth 4212 is inserted after every four consecutive main meshing teeth 4211, and the tooth height of the auxiliary meshing tooth 4212 is higher than the tooth height of the main meshing tooth 4211, and the difference between the two is 3 mm.

[0047] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0048] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A multi-pass laser amplifier, comprising a laser amplifier and a laser oscillator that cooperate with each other, characterized in that: The laser amplifier and the laser oscillator are both placed in a functional chamber, the functional chamber is a rectangular parallelepiped structure, a movable guide rail is arranged on the lower bottom surface of the functional chamber, the laser amplifier and the laser oscillator are arranged on the movable guide rail in sequence, and both can move back and forth on the movable guide rail along the length direction of the movable guide rail; The laser oscillator comprises a first receiving plate, an optical resonant cavity, a pump source and a gain medium. The optical resonant cavity, the pump source and the gain medium interact with each other and are all arranged on the first receiving plate to form a closed-loop system. When the pump source provides sufficient energy, atoms or molecules in the gain medium are excited and release photons, which form a resonance effect in the optical resonant cavity and form laser output when a preset threshold is reached. The laser amplifier comprises a second receiving plate, a total reflection mirror, a double-clad optical fiber and an output reflection mirror. The laser amplifier is used to receive the laser light and pump light generated by the laser oscillator. The double-clad optical fiber comprises a core, an inner cladding, an outer cladding and a protective layer. The core is a single-mode optical waveguide doped with rare earth elements, the inner cladding is a multi-mode optical waveguide, the lateral size of the inner cladding is larger than that of the core, the refractive index of the inner cladding is smaller than that of the core, the refractive index of the outer cladding is smaller than that of the inner cladding, and the pump light propagates in the inner cladding; The laser amplifier further comprises an automatic control device for controlling the total reflection mirror and the output reflection mirror, wherein the automatic control device causes the total reflection mirror and the output reflection mirror to move in a rotational manner; The automatic control device includes a front-end support frame, a rear-end support frame, a first transmission roller, a second transmission roller and a central drive motor. The front-end support frame and the rear-end support frame are respectively arranged at the front, back, left and right ends of the second supporting plate. The total reflection mirror is arranged on the front-end support frame, and the output reflection mirror is arranged on the rear-end support frame. The first transmission roller and the second transmission roller are both meshed and connected with the output end of the central drive motor. The first transmission roller connects the front-end support frame and the central drive motor, and the second transmission roller connects the rear-end support frame and the central drive motor.

2. A multi-pass laser amplifier according to claim 1, characterized in that: A first annular groove is provided on the front end support frame, and the inner groove surface of the first annular groove is semicircular. The total reflection mirror is arranged in the first annular groove, and a first meshing tooth is provided on the outer circumferential side surface of the total reflection mirror. The first transmission roller extends into the first annular groove, and a second meshing tooth meshing with the first meshing tooth is provided on the end portion of one side of the first transmission roller close to the front end support frame. The total reflection mirror is rotated in the first annular groove by rotating the first transmission roller, and the total reflection mirror is a convex mirror.

3. A multi-pass laser amplifier according to claim 2, characterized in that: A second annular groove is provided on the rear end support frame, and the inner groove surface of the second annular groove is semicircular. The output reflector is arranged in the second annular groove, and a third meshing tooth is provided on the outer circumferential side surface of the output reflector. The second transmission roller extends into the second annular groove, and a fourth meshing tooth meshing with the third meshing tooth is provided on the end portion of the second transmission roller close to the rear end support frame. The output reflector rotates in the second annular groove by rotating the second transmission roller. The output reflector is a plane mirror.

4. A multi-pass laser amplifier according to claim 3, characterized in that: The gap between the total reflection mirror and the inner groove surface of the first annular groove is 1-3 mm.

5. A multi-pass laser amplifier according to claim 4, characterized in that: The gap between the output reflector and the inner groove surface of the second annular groove is 3-5 mm.

6. A multi-pass laser amplifier according to claim 5, characterized in that: The fourth meshing teeth include main meshing teeth and auxiliary meshing teeth. The auxiliary meshing teeth are arranged at intervals among the main meshing teeth, and the arrangement order is that an auxiliary meshing tooth is inserted after every four consecutive main meshing teeth. The tooth height of the auxiliary meshing teeth is higher than the tooth height of the main meshing teeth, and the difference between the two is 3-5mm.

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