Optical fiber coupling module based on double-junction laser

Abstract

The invention relates to the technical field of laser beam combination, in particular to an optical fiber coupling module based on double-junction lasers, which comprises at least two double-junction lasers, at least two fast-axis lenses, at least two slow-axis lenses, at least four reflectors and a beam combining assembly, and is characterized in that the multiple double-junction lasers are arranged in a step shape, the fast-axis lenses are arranged at out-of-focus positions, and the slow-axis lenses are arranged at out-of-focus positions; due to the existence of the defocusing amount, a certain angle deviation exists between the two sub-light beams, the deviation angle of the sub-light beams is corrected through the two reflectors, the sub-light beams are emitted to the beam combining assembly in parallel, the size in the height direction is effectively compressed in the angle deviation forming and correcting process, and the size of the sub-light beams is reduced. The problems of non-uniform light intensity distribution of the combined laser and serious gaps caused by the distance between two light outlets of a traditional double-junction laser are solved, and the beam quality of the combined laser is remarkably improved on the basis of ensuring miniaturization.

Description

Technical Field

[0001] The invention belongs to the technical field of laser beam combining, and in particular relates to an optical fiber coupling module based on a double-junction laser. Background Art

[0002] With the development of the semiconductor industry, semiconductor laser modules have been pursuing the goal of miniaturization and lightweight on the basis of ensuring output power and beam quality. How to further improve the output power and beam quality of the pump source on the basis of miniaturization is a technical problem that needs to be solved at present.

[0003] Semiconductor laser fiber coupling modules are widely used in the pumping of fiber lasers. In recent years, with the development of fiber lasers, higher requirements have been placed on the output power, brightness and beam quality of semiconductor laser fiber coupling modules.

[0004] In addition to conventional lasers with a single active region, there are also double-junction lasers with two active regions and multi-junction lasers with multiple active regions. Among them, the double-junction laser contains two emitting ends, which can significantly increase the laser output power without increasing the number of lasers. Therefore, a fiber coupling module can be designed based on the double-junction laser, and collimation is performed through the traditional fast-axis collimation and slow-axis method, and spatial beam combining is achieved in a step-by-step distribution. Finally, a focusing mirror is used to couple the combined laser into the optical fiber. However, the laser beam obtained in this way has a limited degree of size compression in the vertical direction, and the combined beam spot size will be large, requiring a large-diameter optical fiber, and the spot will have serious stratification, that is, there is a "gap" on the spot, resulting in poor beam quality after combining, which is difficult to meet application requirements. Summary of the invention

[0005] In view of this, the invention aims to provide a fiber coupling module based on a double-junction laser, which significantly improves the beam quality of the output beam while ensuring miniaturization, and effectively solves the problems of beam "gaps", poor beam uniformity, and reduced combined light quality in traditional laser coupling.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows: The present invention provides a fiber coupling module based on a double-junction laser, comprising: at least two double-junction lasers of different heights, two light outlets of each double-junction laser arranged along the height direction, a fast axis lens is provided on the optical path of each double-junction laser, and the distance between the fast axis lens and the double-junction laser is equal to ,in, represents the focal length of the fast axis lens, is a preset defocus amount, which is a positive number; the output light of the double-junction laser forms two sub-beams with angle offset after passing through the fast-axis lens, and a slow-axis lens is provided in the rear-end optical path of the fast-axis lens; the rear-end optical path of the slow-axis lens is provided with a first reflector and a second reflector of different heights, and the two sub-beams are irradiated on the first reflector and the second reflector respectively, and the first reflector and the second reflector direct the two sub-beams to the beam combining component at parallel angles, and the beam combining component is used to couple the sub-beams of all the double-junction lasers.

[0007] Preferably, the defocus amount The value range of Micrometer.

[0008] Preferably, the distance between the slow axis lens and the double junction laser is equal to the focal length of the slow axis lens.

[0009] Preferably, the heights of different double-junction lasers are evenly distributed in a stepped manner.

[0010] Preferably, there is a height difference between the arrangement positions of the first reflector and the second reflector.

[0011] Preferably, the first reflector and the second reflector are both arranged at the front end of the imaging points of the two sub-beams, or are both arranged at the rear end of the imaging points of the two sub-beams.

[0012] Preferably, any one of the first reflector and the second reflector is arranged at the front end of the imaging point of the two sub-beams, and the other is arranged at the rear end of the imaging point of the two sub-beams.

[0013] Preferably, the distance between the first reflecting mirror and the slow-axis lens is not equal to the distance between the second reflecting mirror and the slow-axis lens.

[0014] Preferably, the beam combining component includes: a third reflector, a polarization beam splitter prism, an anti-reflection mirror, a focusing mirror and an optical fiber. The third reflector is used to reflect one sub-beam of each double-junction laser toward the polarization beam splitter prism, and the other sub-beam of each double-junction laser is directly emitted into the polarization beam splitter prism. The polarization beam splitter prism polarizes and combines the sub-beams of all the double-junction lasers. The combined light is emitted toward the focusing mirror and coupled into the optical fiber after being processed by the focusing mirror.

[0015] Compared with the prior art, the invention can achieve the following beneficial effects: The present invention utilizes the out-of-focus design of the fast axis lens to form the output light of the double-junction laser into two sub-beams with angle offset, and then uses two reflectors to correct the angle. The two sub-beams are directed to the beam combining component in parallel to perform polarization beam combining. The present invention effectively reduces the volume of the fiber coupling module while increasing the power of the beam combining laser through the double-junction laser, and effectively solves the problem of a large "gap" in the beam combining laser existing in the traditional coupling module. The beam quality of the beam combining laser is significantly improved while ensuring miniaturization, and the distribution uniformity and compression degree of the beam combining laser are improved in the height direction, reducing the size of the beam combining laser, so that the beam combining laser can be coupled into an optical fiber with a smaller diameter, thereby improving the brightness of the overall beam combining laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 is a schematic structural diagram of a fiber coupling module based on a double-junction laser according to an embodiment of the present invention; Figure 2 is a pattern of a combined beam laser of a fiber coupling module based on a double-junction laser provided in accordance with an embodiment of the present invention; Figure 3 It is a schematic diagram of the structure of a traditional fiber coupling module; Figure 4 This is a diagram of the combined beam laser of a traditional fiber-coupled module.

[0017] Reference numerals include: Double-junction laser 10 , fast-axis lens 20 , slow-axis lens 30 , first reflecting mirror 40 , second reflecting mirror 50 , third reflecting mirror 60 , polarization beam splitting prism 70 , anti-reflection mirror 80 , fourth reflecting mirror 90 , focusing mirror 100 , and optical fiber 110 . DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the invention clearer, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the invention and do not constitute a limitation to the invention. Similar components in different embodiments use associated similar component numbers. In the following embodiments, many detailed descriptions are to enable the invention to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other components, materials, and methods. In some cases, some operations related to the invention are not shown or described in the specification, in order to avoid the core part of the invention being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0019] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to form various implementation methods. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a necessary sequence, unless otherwise specified that a certain sequence must be followed.

[0020] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0021] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" 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 or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0022] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0023] See also Figure 1 In one embodiment of the present invention, a fiber coupling module based on a double-junction laser is provided, which is used to polarization-combine multiple double-junction lasers 10. Theoretically, the number of double-junction lasers 10 used for combining should be at least two. In this embodiment, taking 10 double-junction lasers 10 with a wavelength of 915nm as an example, the structure of the fiber coupling module and the laser combining process are described as follows: The 10 double-junction lasers 10 are evenly distributed in space in a stepped manner, and each double-junction laser 10 is at a step height, that is, the light output heights of different double-junction lasers 10 are different, and the height difference between adjacent double-junction lasers 10 is constant, and in the embodiment of the present invention, the height difference is 0.25 mm.

[0024] Each double-junction laser 10 has two light outlets, which are arranged in the height direction and there is a certain distance between the two light outlets. This is why the combined laser beam obtained by the traditional coupling module has a laser "gap". Since the double-junction laser 10 has two light outlets, the slow axis width of the output light of the double-junction laser 10 is usually much larger than the fast axis width. In the embodiment of the present invention, the fast axis width of the double-junction laser 10 is 2.2 microns (μm), and the slow axis width is 290μm. The fast axis divergence angle of the double-junction laser 10 is 52°, and the slow axis divergence angle is 10°. The front cavity surface of the light outlet of the double-junction laser 10 is coated with an anti-reflection film, and the transmittance can reach more than 99.5%. The output light power of each active area of ​​the double-junction laser 10 is 32.5 watts (W), that is, the output laser power of each light outlet is 32.5W.

[0025] In the embodiment of the present invention, a fast axis lens 20 and a slow axis lens 30 are used to polarize-combine the stepped-distributed double-junction laser 10. For each double-junction laser 10, the design of the components in the optical path and the laser processing are the same, so only the optical path structure and the beam processing process of any double-junction laser 10 are used as an example for description: a fast axis lens 20 and a slow axis lens 30 are provided in sequence in the optical path of the outgoing light of each double-junction laser 10. The function of the fast axis lens 20 is to collimate the fast axis beam of the double-junction laser 10 to reduce its divergence angle; the function of the slow axis lens 30 is to collimate the slow axis beam of the double-junction laser 10 to reduce its divergence angle. Among them, the fast axis lens 20 is set in an out-of-focus position, and the fast axis lens 20 of the conventional coupling module adopts an in-focus design. Specifically, the focal length of the fast axis lens 20 is 286.1μm. In order to achieve the size compression of the combined laser in the height direction and eliminate the laser "gap", in the embodiment of the present invention, the fast axis lens 20 is set at a distance of from the double-junction laser 10. The location of represents the focal length of the fast axis lens 20, which is equal to 286.1 μm. The defocus value is a positive number. The value range of Micrometer, that is, greater than 0μm, and the maximum can be 100μm. This design can adjust the focusing characteristics of the output light of the double-junction laser 10, so that the overall output light emitted from the two light outlets of the double-junction laser 10, after being processed by the fast axis lens 20, forms two sub-beams with a certain angle offset, rather than a completely collimated parallel beam, wherein the sub-beam with a relatively lower optical axis position will be offset upward by a certain angle; the sub-beam with a relatively higher optical axis position will be offset downward by a certain angle.

[0026] The slow axis lens 30 is arranged in the rear optical path of the fast axis lens 20, and the focal length of the slow axis lens 30 is 23.5 mm. The slow axis lens 30 is designed to be in focus, and the slow axis lens 30 is placed at its focal length, and the distance between the slow axis lens 30 and the double junction laser 10 is 23.5 mm. After the two sub-beams are emitted by the fast axis lens 20, they are slow-axis collimated by the slow axis lens 30, and continue to be transmitted to the positions of the first reflector 40 and the second reflector 50, wherein the first reflector 40 and the second reflector 50 are arranged near the imaging point of the sub-beams, and the first reflector 40 and the second reflector 50 correspond to the two sub-beams respectively, and the heights are different, and usually the height difference between the two should be less than the distance between the two light outlets of the double junction laser 10. The first reflector 40 is arranged below the central optical axis, and the second reflector 50 is arranged above the central optical axis. In addition, in order to facilitate the subsequent polarization beam combining, the horizontal positions of the first reflector 40 and the second reflector 50 are also designed differently. The distance between the first reflector 40 and the slow axis lens 30 on the optical path of the sub-beam of each double-junction laser 10 is equal. Similarly, the distance between the second reflector 50 and the slow axis lens 30 on the optical path of the sub-beam of each double-junction laser 10 is also equal. However, for each double-junction laser 10, the distance between the first reflector 40 and the slow axis lens 30 on its optical path is not equal to the distance between the second reflector 50 and the slow axis lens 30. The first reflector 40 is used to directly direct one of the sub-beams to the polarization beam splitter prism 70, while the second reflector 50 is used to directly direct the remaining sub-beam to the third reflector 60. The sub-beams are then directed to the polarization beam splitter prism 70 for polarization beam combining through the third reflector 60. The first reflector 40 and the second reflector 50 can correct the offset angle of the sub-beams and reduce the "gap" of the beams. Therefore, the first reflector 40 and the second reflector 50 on the optical path of each double-junction laser 10 will divide the output light of the 10 double-junction lasers 10 into two sub-beam linear arrays, and the two sub-beam linear arrays are at a certain distance in the horizontal direction. Finally, they are directed to the polarization beam splitter prism 70 through the third reflector 60 in the beam combining component for polarization beam combining. The polarization beam splitter prism 70 combines two sub-beam linear arrays with different polarization states into one linear array by using the polarization principle of the laser. It is a commonly used laser beam combining device. Here, the two sub-beam linear arrays that complete the spatial beam combining through the ladder are combined into one beam, that is, the beam combining is performed in the horizontal direction. In addition, the beam combining component also includes an anti-reflection mirror 80, a fourth reflector 90, a focusing mirror 100 and an optical fiber 110, wherein the anti-reflection mirror 80 is arranged on the output optical path of the polarization beam splitter prism 70 to prevent the output combined laser from returning to the optical path, to prevent the laser from damaging the device, and then change the propagation direction of the combined laser through the fourth reflector 90.The combined laser beam is further transmitted to the focusing mirror 100, which focuses the combined laser beam. The focal length of the focusing mirror 100 is 19.5 mm. The combined laser beam is coupled into the optical fiber 110 through the focusing mirror 100. In the embodiment of the present invention, the spot shape of the combined laser beam is compact, and the vertical size of the spot is small, and it can be finally coupled into the NA0.18, 200 micron optical fiber 110. It can be understood that the NA0.18, 200 micron optical fiber has an optical aperture of 0.18 and a diameter of 200 microns. Please refer to the spot pattern of the combined laser beam obtained by the optical fiber coupling module proposed in the embodiment of the present invention. Figure 2 In the figure, the X-axis horizontal coordinate (X coordinate value) represents the coordinate position of the light spot, reflecting the size of the light spot, and the vertical coordinate (Y coordinate value) represents the incoherent irradiance, indicating the intensity of the light spot. Figure 2 The light intensity uniformity is good, the laser "gap" is not obvious, and the beam height is small, which allows the combined laser to be coupled into a smaller diameter optical fiber, thereby increasing the overall brightness of the combined laser and significantly improving the beam quality of the combined laser while ensuring miniaturization.

[0027] In order to verify the advancement of the present invention, the present invention also provides a comparative design of a traditional optical fiber coupling module. Figure 3 The selection of devices and the model of optical devices are exactly the same as those of the fiber coupling module based on double-junction laser given in the embodiment of the present invention, except that the fast axis lens 20 is set at the focal length f Position, that is, the distance between the double-junction laser 10 and the fast-axis lens 20 is 286.1 μm, and the output light of the double-junction laser 10 is processed by the fast-axis lens 20 to form a parallel light beam after fast-axis collimation. In addition, in order to achieve polarization beam combining, every two double-junction lasers 10 are set at the same height position, and each double-junction laser 10 is only corresponding to a first reflector 40. Finally, the combined laser is coupled into the optical fiber 110 through the third reflector 60, the polarization beam splitter prism 70, the anti-reflection mirror 80, the fourth reflector 90 and the focusing mirror 100. In this design, the height of the combined laser is not compressed, so the vertical size of the spot is relatively large, and finally it needs to be coupled into the optical fiber 110 with NA0.18 and 350 microns. Compared with the optical fiber coupling module of the embodiment of the present invention, the diameter of the optical fiber 110 required by the traditional optical fiber coupling module is larger, and please refer to Figure 4 , there are obvious "gaps" in the spot pattern of the combined laser, the light intensity distribution is uneven, and the beam quality of the combined laser is poor.

[0028] In short, the above description is only a preferred embodiment of this specification and is not intended to limit the protection scope of this specification. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this specification shall be included in the protection scope of this specification.

[0029] The systems, devices, modules or units described in one or more of the above embodiments may be implemented by a computer chip or entity, or by a product having a certain function. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0030] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0031] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0032] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A fiber coupling module based on a double-junction laser, characterized in that: include: At least two double-junction lasers with different heights, the two light outlets of each double-junction laser are arranged along the height direction, a fast axis lens is provided on the optical path of each double-junction laser, and the distance between the fast axis lens and the double-junction laser is equal to ,in, represents the focal length of the fast axis lens, is a preset defocus amount, which is a positive number; the output light of the double-junction laser forms two sub-beams with angle offset after passing through the fast-axis lens, and a slow-axis lens is provided in the rear-end optical path of the fast-axis lens; the rear-end optical path of the slow-axis lens is provided with a first reflector and a second reflector of different heights, and the two sub-beams are respectively irradiated on the first reflector and the second reflector, and the first reflector and the second reflector direct the two sub-beams to a beam combining component at parallel angles, and the beam combining component is used to couple the sub-beams of all double-junction lasers.

2. The fiber coupling module based on double-junction laser according to claim 1, characterized in that: Defocus The value range of Micrometer.

3. The fiber coupling module based on double-junction laser according to claim 1, characterized in that: The distance between the slow axis lens and the double junction laser is equal to the focal length of the slow axis lens.

4. The fiber coupling module based on double-junction laser according to claim 1, characterized in that: The heights of the different double-junction lasers are evenly distributed in a stepped manner.

5. The fiber coupling module based on double-junction laser according to claim 1, characterized in that: The first reflector and the second reflector are disposed at positions with a height difference.

6. The fiber coupling module based on double-junction laser according to claim 5, characterized in that: The first reflector and the second reflector are both arranged at the front end of the imaging points of the two sub-beams, or are both arranged at the rear end of the imaging points of the two sub-beams.

7. The fiber coupling module based on double-junction laser according to claim 6, characterized in that: Any one of the first reflector and the second reflector is arranged at the front end of the imaging point of the two sub-beams, and the other one is arranged at the rear end of the imaging point of the two sub-beams.

8. The optical fiber coupling module based on double-junction laser according to claim 6 or 7, characterized in that: The distance between the first reflecting mirror and the slow-axis lens is not equal to the distance between the second reflecting mirror and the slow-axis lens.

9. The fiber coupling module based on double-junction laser according to claim 8, characterized in that: The beam combining component includes: a third reflector, a polarization beam splitter prism, an anti-reflection mirror, a focusing mirror and an optical fiber. The third reflector is used to reflect one sub-beam of each double-junction laser toward the polarization beam splitter prism, and the other sub-beam of each double-junction laser is directly emitted into the polarization beam splitter prism. The polarization beam splitter prism performs polarization beam combining on all the sub-beams of the double-junction lasers, and the combined light is emitted toward the focusing mirror, and is coupled into the optical fiber after being processed by the focusing mirror.

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