Double-end-face LD pumping crystal rod amplification module

Abstract

The invention belongs to the technical field of laser amplification, and relates to a double-end-face LD pumping crystal rod amplification module which comprises a light beam polarizing and light splitting part and a light beam amplification part which are sequentially arranged in the light path direction. The light beam polarizing and splitting part comprises a seed source laser, a 1 / 4 wave plate, an optical isolator, a second PBS (Phosphate Buffer Solution) prism, a first 45-degree reflecting mirror and a first shaping lens which are sequentially arranged along the light path direction; the light beam amplification part comprises a second 45-degree reflecting mirror, a laser crystal, a third 45-degree reflecting mirror, a second shaping lens and a total reflection mirror which are sequentially arranged along the light path direction; a first LD pumping module, a second LD pumping module, a first collimating focus lens group and a second collimating focus lens group are symmetrically distributed on the two sides of the end face of the laser crystal. The double-end-face LD pumping crystal rod amplification module can meet the requirements of high light beam quality and high laser power at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of laser amplification, and in particular relates to a double-end-face LD pumped crystal rod amplification module. Background Art

[0002] Laser amplifier module refers to a device that uses stimulated radiation of light to amplify the energy (power) of light. By using laser amplifier module, 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.). It is often used in high-power laser systems in major technologies such as controlled nuclear fusion, nuclear explosion simulation, and ultra-long laser ranging. The laser amplifier module requires that the working material has a sufficient number of inverted particles to ensure that the gain obtained when the optical pulse signal passes through the laser amplifier module is greater than the various losses inside the medium. When the seed light enters the laser amplifier module, the active medium therein should be stimulated to be in the state of maximum particle number inversion, that is, a resonant transition is generated and amplified.

[0003] LD (semiconductor laser) pumped laser is a laser developed on the basis of traditional lamp pumped laser. Compared with traditional lamp pumped laser, its optical mode is better and its structure is more compact, and it has the tendency to replace traditional lamp pumped laser. However, LD pumped laser is still used as a common laser in the industrial field. As the existing laser amplification module cannot meet the requirements of high beam quality and high laser power at the same time, LD pumped laser has not been deeply applied to the field of high-end laser processing technology.

[0004] Therefore, it is urgent to propose a double-end LD pumped crystal rod amplifier module to solve the technical problem that the existing laser amplifier modules cannot meet the requirements of high beam quality and high laser power at the same time. Summary of the invention

[0005] Aiming at the technical problem that the laser amplification module in the prior art cannot meet the requirements of high beam quality and high laser power at the same time, the present invention proposes a double-end LD pumped crystal rod amplification module to solve at least one of the above technical problems.

[0006] In a preferred embodiment of the present invention, a double-end LD pumped crystal rod amplifier module is provided, wherein the double-end LD pumped crystal rod amplifier module comprises a beam polarization splitting part and a beam amplification part sequentially arranged along the optical path direction; The beam polarization and splitting part comprises a seed source laser, a quarter wave plate, an optical isolator, a second PBS beam splitter prism, a first 45° reflector, and a first shaping lens which are sequentially arranged along the optical path direction; The beam amplification part includes a second 45° reflector, a laser crystal, a third 45° reflector, a second shaping lens, and a total reflector, which are sequentially arranged along the optical path direction; wherein, The optical isolator includes a first PBS beam splitter prism, a Faraday rotator, and a 1 / 2 wave plate; A first LD pump module, a second LD pump module, a first collimating and focusing lens group, and a second collimating and focusing lens group are symmetrically distributed on both sides of the laser crystal end face.

[0007] Preferably, the first plastic lens and the second plastic lens are selected from any one of a plano-convex spherical lens, a bi-convex spherical lens, a plano-convex aspheric lens, a bi-convex aspheric lens, a plano-concave spherical lens, a bi-concave spherical lens, a plano-concave aspheric lens, and a bi-concave aspheric lens, and the focal length of the first plastic lens and the second plastic lens is between 50-300 mm.

[0008] Preferably, the first LD pump module and the second LD pump module are both fiber coupling modules.

[0009] Preferably, the first LD pump module and the second LD pump module are cooled by water.

[0010] Preferably, the output powers of the first LD pump module and the second LD pump module are consistent.

[0011] Preferably, the first collimating and focusing lens group and the second collimating and focusing lens group are both composed of a plurality of lenses, the lenses are collimating and focusing lenses, and the beam expansion factor of the collimating and focusing lenses is between 2.5X and 8X.

[0012] Preferably, the laser crystal is selected from Nd:YVO 4 Crystal, Nd:YAG crystal, Nd:GaYVO 4 Any of the crystals.

[0013] Compared with the prior art, the present invention can bring at least one of the following beneficial effects: A double-end LD pumped crystal rod amplifier module of the present application is configured with a first shaping lens and a second shaping lens so that the incident spot of the seed light on the end face of the laser crystal is optimally matched with the spot diameter of the LD pump module after collimation and focusing, and the spot diameter of the LD pump module is optimally matched with the end face diameter of the laser crystal. The LD pump module injects energy to excite the doped particles in the laser crystal to the upper energy level, and the incident light (seed light shaping to match the spot diameter) causes the largest proportion of upper energy level examples to spontaneously transition and radiate, and the seed light obtains the maximum energy gain, thereby obtaining a laser beam with good beam quality and high power. The present application adopts the design of double-end LD pumped crystal rod amplification, which can obtain a laser output with a peak power of tens of megawatts, and the dual-pass amplification structure designed using the principle of secondary spherical aberration compensation can well control the beam quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The preferred implementation scheme will be described below in a clear and understandable manner with reference to the accompanying drawings to further illustrate the above-mentioned characteristics, technical features, advantages and their implementation methods.

[0015] Figure 1 It is a schematic structural diagram of a double-end LD pumped crystal rod amplifier module according to a specific embodiment of the present invention; Figure 2 It is a schematic structural diagram of a collimating and focusing lens assembly according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0016] Various aspects of the present invention are described in further detail below.

[0017] Unless otherwise defined or indicated, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein can be applied to the method of the present invention.

[0018] Unless otherwise clearly specified and limited, the "or" mentioned in the present invention includes the relationship of "and". The "and" is equivalent to the Boolean logic operator "AND", the "or" is equivalent to the Boolean logic operator "OR", and "AND" is a subset of "OR".

[0019] It is to be understood that although the terms "first", "second", etc. may be used herein to describe different elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Therefore, the first element may be referred to as the second element without departing from the teachings of the present invention.

[0020] In the present invention, the terms "consisting mainly of" and "consisting of" are included in the terms "containing", "including" or "comprising".

[0021] Unless otherwise clearly specified and limited, the terms "connected", "connected" and "connection" in the present invention should be understood in a broad sense, for example, it can be a fixed connection, or it can be connected through an intermediary medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0022] For example, if an element (or component) is referred to as being on, coupled to, or connected to another element, the element may be directly formed on, coupled to, or connected to the other element, or there may be one or more intervening elements between them. In contrast, if the expressions "directly on," "directly coupled to," and "directly connected to" are used herein, then no intervening elements are indicated. Other words used to describe the relationship between elements should be similarly interpreted, such as "between" and "directly between," "attached" and "directly attached," "adjacent" and "directly adjacent," etc.

[0023] It should also be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the drawings. The words "inner" and "outer" used refer to directions toward or away from the geometric center of a particular component, respectively. It can be understood that these terms are used here to describe the relationship of one element, layer or region relative to another element, layer or region as shown in the drawings. In addition to the orientations described in the drawings, these terms should also include other orientations of the device.

[0024] Other aspects of the present invention will be apparent to those skilled in the art in view of the disclosure herein.

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0026] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show the components related to the present application and are not drawn according to the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in actual implementation may be changed arbitrarily, and the component layout may also be more complicated. For example, the thickness of the components in the drawings may be exaggerated for the sake of clarity.

[0027] See attached Figure 1-2 In a preferred embodiment of the present invention, a double-end LD pumped crystal rod amplifier module is provided, wherein the double-end LD pumped crystal rod amplifier module comprises a beam polarization splitting part and a beam amplification part sequentially arranged along the optical path direction; The beam polarization and splitting part includes a seed source laser, a quarter wave plate 1, an optical isolator, a second PBS beam splitter prism 5, a first 45° reflector 6, and a first shaping lens 7 which are sequentially arranged along the optical path direction; The beam amplification part includes a second 45° reflector 8, a laser crystal 9, a third 45° reflector 10, a second shaping lens 11, and a total reflector 12 which are sequentially arranged along the optical path direction; wherein, The optical isolator comprises a first PBS beam splitter prism 2, a Faraday rotator 3, and a 1 / 2 wave plate 4; A first LD pump module 15 , a second LD pump module 13 , a first collimating and focusing lens group 16 , and a second collimating and focusing lens group 14 are symmetrically distributed on both sides of the end surface of the laser crystal 9 .

[0028] It should be noted that the double-end LD pumped crystal rod amplifier module can obtain better beam quality compared to the side pumping amplification method. The first LD pump module 15, the second LD pump module 13, the first collimating and focusing lens group 16, and the second collimating and focusing lens group 14 that constitute the amplification energy injection part are symmetrically distributed on both sides of the end face of the laser crystal 9.

[0029] It should be noted that the 1 / 4 wave plate 1 of the beam polarization and splitting part converts the incident circularly polarized seed light into linearly polarized polarized light. The direction of polarized light can be adjusted by rotating the 1 / 4 wave plate 1, and the power of the seed laser passing through the PBS beam splitter prism is further determined. Only parallel polarized light can pass through the PBS beam splitter prism. In addition, the first PBS beam splitter prism 2, the Faraday rotator 3, and the 1 / 2 wave plate 4 form a Faraday isolator, which is used to prevent the parallel polarized light in the amplified laser from returning to the seed cavity and causing damage to the seed light. The incident horizontally polarized seed light is rotated 45° clockwise in the Faraday rotator 3, and then the 1 / 2 wave plate 4 rotates the 45° clockwise seed light 45° counterclockwise to become horizontal linear polarized light again, passes through the second PBS beam splitter prism 5, and the first 45° reflector 6 turns the light path of the seed light into the beam amplification part. When the returned amplified laser passes through the horizontal polarized light of the second PBS beam splitter prism 5, it passes through the 1 / 2 wave plate 4 again and is rotated 45° counterclockwise, and then passes through the Faraday rotator 3 and is rotated 45° counterclockwise to become vertically polarized light, which is reflected by the first PBS beam splitter prism 2 and outputs the amplified laser.

[0030] It should be noted that the amplification part is provided with a second 45° reflector 8, a laser crystal 9, a third 45° reflector 10, a second shaping lens 11, and a total reflector 12 along the optical path direction; the first LD pump module 15, the second LD pump module 13, the first collimating and focusing lens group 16, and the second collimating and focusing lens group 14 are symmetrically distributed on both sides of the end face of the laser crystal 9. The first LD pump module 15 and the second LD pump module 13 provide amplification pumping, and the amplified pump laser passes through the collimating and focusing lens group, and the focal position and Rayleigh length are obtained by measurement. The starting point of the Rayleigh length is made to coincide with the end face of the laser crystal by adjusting the front and rear positions of the collimating and focusing lens group to obtain the best amplification energy injection.

[0031] As a preferred embodiment, the first shaping lens 7 and the second shaping lens 11 are selected from any one of a plano-convex spherical lens, a bi-convex spherical lens, a plano-convex aspheric lens, a bi-convex aspheric lens, a plano-concave spherical lens, a bi-concave spherical lens, a plano-concave aspheric lens, and a bi-concave aspheric lens, and the focal length of the first shaping lens and the second shaping lens is between 50-300 mm.

[0032] It should be noted that, through the arrangement and optical design of the first shaping lens 7, the second shaping lens 11, the first collimating and focusing lens group 16, and the second collimating and focusing lens group 14, the best seed light spot and the amplified pump light spot obtained on the end face of the laser crystal 9 are matched, ensuring that the beam quality remains at a good level under the condition that the laser power is significantly improved after passing through the amplifying module, and the seed light is circularly polarized light, and after passing through the amplifying module, a vertically linearly polarized amplified laser is obtained.

[0033] It should be noted that the first shaping lens 7 and the second shaping lens 11 shape the seed light into a spot size that matches the spot of the amplifier-stage pump light, so that the best extraction efficiency can be obtained, thereby obtaining the best power.

[0034] As a preferred embodiment, the first LD pump module 15 and the second LD pump module 13 are both fiber coupling modules.

[0035] As a preferred embodiment, the first collimating and focusing lens group 16 and the second collimating and focusing lens group 14 are both composed of a plurality of lenses, wherein the lenses are collimating and focusing lenses, and the beam expansion factor of the collimating and focusing lenses is between 2.5X and 8X.

[0036] It should be noted that the first LD pump module 15 and the second LD pump module 13 are both fiber coupling modules with consistent fiber diameters; the first collimating and focusing lens group 16 and the second collimating and focusing lens group 14 use a 4X collimating and focusing lens group provided by Nanjing Optical Technology Co., Ltd., and they are precisely calibrated so that the spot sizes at the focal points of the two collimating and focusing lens groups are consistent and the working focal lengths are consistent.

[0037] As a preferred embodiment, the first LD pump module 15 and the second LD pump module 13 are cooled by water.

[0038] As a preferred embodiment, the output powers of the first LD pump module 15 and the second LD pump module 13 are consistent.

[0039] As a preferred embodiment, the laser crystal 9 is selected from Nd:YVO 4 Crystal, Nd:YAG crystal, Nd:GaYVO 4 Any of the crystals.

[0040] Based on this application, it should be understood by those skilled in the art that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0041] It should be noted that the above embodiments can be freely combined as needed. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention.

[0042] All documents mentioned in the present invention are cited as references in this application, just as each document is cited as reference separately. In addition, it should be understood that after reading the above content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A double-end LD pumped crystal rod amplifier module, characterized in that: The double-end LD pumped crystal rod amplification module comprises a beam polarization splitting part and a beam amplification part which are sequentially arranged along the optical path direction; The beam polarization and splitting part comprises a seed source laser, a quarter wave plate, an optical isolator, a second PBS beam splitter prism, a first 45° reflector, and a first shaping lens which are sequentially arranged along the optical path direction; The beam amplification part includes a second 45° reflector, a laser crystal, a third 45° reflector, a second shaping lens, and a total reflector, which are sequentially arranged along the optical path direction; wherein, The optical isolator includes a first PBS beam splitter prism, a Faraday rotator, and a 1 / 2 wave plate; A first LD pump module, a second LD pump module, a first collimating and focusing lens group, and a second collimating and focusing lens group are symmetrically distributed on both sides of the laser crystal end face.

2. A double-end LD pumped crystal rod amplifier module according to claim 1, characterized in that: The first shaping lens and the second shaping lens are selected from any one of a plano-convex spherical lens, a bi-convex spherical lens, a plano-convex aspheric lens, a bi-convex aspheric lens, a plano-concave spherical lens, a bi-concave spherical lens, a plano-concave aspheric lens, and a bi-concave aspheric lens, and the focal length of the first shaping lens and the second shaping lens is between 50-300 mm.

3. A double-end LD pumped crystal rod amplifier module according to claim 1, characterized in that: The first LD pump module and the second LD pump module are both fiber coupling modules.

4. A double-end LD pumped crystal rod amplifier module according to claim 3, characterized in that: The first LD pump module and the second LD pump module are cooled by water.

5. A double-end LD pumped crystal rod amplifier module according to claim 4, characterized in that: The output powers of the first LD pump module and the second LD pump module are consistent.

6. A double-end LD pumped crystal rod amplifier module according to claim 5, characterized in that: The first collimating and focusing lens group and the second collimating and focusing lens group are both composed of a plurality of lenses, wherein the lenses are collimating and focusing lenses, and the beam expansion multiple of the collimating and focusing lenses is between 2.5X and 8X.

7. A double-end LD pumped crystal rod amplifier module according to claim 6, characterized in that: The laser crystal is selected from any one of Nd:YVO4 crystal, Nd:YAG crystal and Nd:GaYVO4 crystal.

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