Fiber Coupling Module Based on Double-Junction Laser

Abstract

The present invention relates to the technical field of laser beam combining, and specifically provides an optical fiber coupling module based on a dual-junction laser, which includes at least two dual-junction lasers, at least two fast-axis lenses, at least two slow-axis lenses, at least four reflectors, and a beam combining component. The multiple dual-junction lasers are arranged in a stepped manner, and the fast-axis lenses are set at defocus positions. Due to the existence of defocus amounts, there will be a certain angular offset between two sub-beams. The offset angles of the sub-beams are corrected by two reflectors and are shot parallel to the beam combining component. During the formation and correction of the angular offset, the size in the height direction is effectively compressed, avoiding the problem that the intensity distribution of the combined laser is uneven due to the distance between the two light output ports of the traditional dual-junction laser and there is a serious "gap" problem. On the basis of ensuring miniaturization, the present invention significantly improves the beam quality of the combined laser.

Description

Technical Field

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

[0002] With the development of the semiconductor industry, on the basis of ensuring the output power and beam quality, the semiconductor laser module has been pursuing the goals of miniaturization and light weight. 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 currently.

[0003] The semiconductor laser optical fiber coupling module is widely used in the pumping of optical fiber lasers. In recent years, with the development of optical fiber lasers, higher requirements have also been put forward for the output power, brightness, and beam quality of the semiconductor laser optical fiber coupling module.

[0004] In addition to the conventional single-active-region lasers, there are also double-junction lasers with two active regions and multi-junction lasers with multiple active regions. Among them, the double-junction laser has two emission ends, which can significantly improve the laser output power without increasing the number of lasers. Therefore, an optical fiber coupling module can be designed based on the double-junction laser, collimated by the traditional fast-axis collimation and slow-axis method, and spatially combined in a stepped distribution. Finally, a focusing lens is used to couple the combined laser into the optical fiber. However, the size compression degree of the laser beam obtained by this method in the vertical direction is limited, the combined beam spot size is large, a large-aperture optical fiber is required, and there is a serious stratification phenomenon on the beam spot, that is, there are "gaps" on the beam spot, resulting in poor beam quality after combination and being difficult to meet the application requirements. Summary of the Invention

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

[0006] To achieve the above object, the technical solution of the present invention is realized as follows:

[0007] The present invention provides an optical fiber coupling module based on a double-junction laser, including: at least two double-junction lasers with different heights, the two light output ports of each double-junction laser are arranged along the height direction, and 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 , where 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 an angular offset after passing through the fast-axis lens, and a slow-axis lens is provided in the optical path at the rear end of the fast-axis lens; a first mirror and a second mirror with different heights are provided in the optical path at the rear end of the slow-axis lens, and the two sub-beams are respectively irradiated on the first mirror and the second mirror, and the first mirror and the second mirror shoot the two sub-beams at a parallel angle towards the beam combining component, and the beam combining component is used to couple the sub-beams of all double-junction lasers.

[0008] Preferably, the defocus amount has a value range of micrometers.

[0009] Preferably, the distance between the slow-axis lens and the double-junction laser is equal to the focal length of the slow-axis lens.

[0010] Preferably, the heights of different double-junction lasers are evenly distributed in a stepped manner.

[0011] Preferably, the installation positions of the first mirror and the second mirror have a height difference.

[0012] Preferably, both the first mirror and the second mirror are arranged in front of the imaging points of the two sub-beams, or both are arranged behind the imaging points of the two sub-beams.

[0013] Preferably, either the first mirror or the second mirror is arranged in front of the imaging points of the two sub-beams, and the other is arranged behind the imaging points of the two sub-beams.

[0014] Preferably, the distance between the first mirror and the slow-axis lens is not equal to the distance between the second mirror and the slow-axis lens.

[0015] Preferably, the beam combining component includes: a third mirror, a polarization beam splitter prism, an anti-reflection mirror, a focusing lens and an optical fiber. The third mirror is used to reflect one sub-beam of each double-junction laser towards the polarization beam splitter prism, and the other sub-beam of each double-junction laser directly enters the polarization beam splitter prism. The polarization beam splitter prism performs polarization beam combination on the sub-beams of all double-junction lasers, and the combined light is directed towards the focusing lens and is coupled into the optical fiber after being processed by the focusing lens.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0017] The present invention utilizes the off-axis design of a fast-axis lens to cause the light emitted from a dual-junction laser to form two sub-beams with angular offsets. Then, two reflectors are used for angle correction, and the two sub-beams are parallelly directed towards a beam combining component for polarization beam combination. While increasing the power of the combined laser, the present invention effectively reduces the volume of the fiber coupling module by using a dual-junction laser, and effectively solves the problem of a large "gap" existing in the combined laser of a traditional coupling module. On the basis of ensuring miniaturization, the beam quality of the combined laser is significantly improved, and the distribution uniformity and compression degree of the combined laser in the height direction are increased, reducing the size of the combined laser, enabling the combined laser to be coupled into an optical fiber with a smaller diameter, and improving the brightness of the overall combined laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0019] Figure 1 is a schematic structural diagram of an optical fiber coupling module based on a dual-junction laser according to an embodiment of the present invention;

[0020] Figure 2 is a pattern of the combined beam laser of an optical fiber coupling module based on a dual-junction laser according to an embodiment of the present invention;

[0021] Figure 3 is a schematic structural diagram of a traditional optical fiber coupling module;

[0022] Figure 4 is a pattern of the combined beam laser of a traditional optical fiber coupling module.

[0023] The reference numerals therein include:

[0024] Dual-junction laser 10, fast-axis lens 20, slow-axis lens 30, first reflector 40, second reflector 50, third reflector 60, polarization beam splitter prism 70, anti-reflection mirror 80, fourth reflector 90, focusing lens 100, optical fiber 110. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be 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 present invention and do not constitute a limitation to the present invention. Similar elements in different embodiments are labeled with related similar element numbers. In the following embodiments, many details are described to enable a better understanding of the present invention. 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 elements, materials, and methods. In some cases, some operations related to the present invention are not shown or described in the specification, which is to avoid the core part of the present invention being overwhelmed by excessive description. 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 based on the description in the specification and the general technical knowledge in the field.

[0026] It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other to form various embodiments. At the same time, the steps or actions in the method description can also be adjusted in the order that is obvious to those skilled in the art. Therefore, the various sequences in the specification and drawings are only for clearly describing a certain embodiment and do not mean that they are the necessary sequences, unless it is stated that a certain sequence must be followed.

[0027] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present 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 thus cannot be understood as a limitation to the present invention. In addition, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0028] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" 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 an indirect connection through an intermediate medium, and it can be the communication inside two components. 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 situations.

[0029] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0030] Please refer to Figure 1 , in an embodiment of the present invention, an optical fiber coupling module based on a double-junction laser is provided, which is used for polarization beam combining of multiple double-junction lasers 10. Theoretically, the number of double-junction lasers 10 for beam combining should be at least two. In this embodiment, taking 10 double-junction lasers 10 with a wavelength of 915 nm as an example, the structure of the optical fiber coupling module and the laser beam combining process are described as follows:

[0031] The 10 double-junction lasers 10 are evenly distributed in a stepped manner in space. 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. In the embodiment of the present invention, the height difference is 0.25 mm.

[0032] Each double-junction laser 10 has two light output ports, which are arranged along the height direction, and there is a certain distance between the two light output ports. This is why there are laser "gaps" in the combined laser obtained by the traditional coupling module. Since the double-junction laser 10 has two light output ports, 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 micrometers (μm), and the slow-axis width is 290 μm. 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 output port of the double-junction laser 10 is coated with an antireflection film, and the transmittance can reach more than 99.5%. The output light power of each active region of the double-junction laser 10 is 32.5 watts (W), that is, the output laser power of each light output port is 32.5 W.

[0033] In the embodiment of the present invention, a fast-axis lens 20 and a slow-axis lens 30 are used to perform polarization beam combination on the stepped distributed double-junction laser 10. For each double-junction laser 10, the component design and laser processing on its optical path are the same. Therefore, only the optical path structure and beam processing process of any one double-junction laser 10 are taken as an example for description: On the output optical path of each double-junction laser 10, a fast-axis lens 20 and a slow-axis lens 30 are sequentially arranged. 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 at an out-of-focus position, and the fast-axis lenses 20 of traditional coupling modules are all designed in focus. Specifically, the focal length of the fast-axis lens 20 is 286.1 μm. In order to realize 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, where represents the focal length of the fast-axis lens 20, which is equal to 286.1 μm. is a preset defocus amount, and the defocus amount is a positive number. Usually, the value range of the defocus amount is μm, that is, greater than 0 μm and the maximum can be taken as 100 μm. 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 angular offset, rather than completely collimated parallel beams. Among them, 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.

[0034] The slow-axis lens 30 is arranged on 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 at the focal point. The slow-axis lens 30 is placed at its focal length, and the distance between it and the double-junction laser 10 is 23.5 mm. After the two sub-beams are emitted from the fast-axis lens 20, they are collimated in the slow axis by the slow-axis lens 30 and continue to be transmitted to the positions of the first mirror 40 and the second mirror 50. Among them, the first mirror 40 and the second mirror 50 are arranged near the imaging points of the sub-beams, and the first mirror 40 and the second mirror 50 correspond to the two sub-beams respectively, with different set heights, and generally the height difference between the two should be less than the distance between the two light-emitting ports of the double-junction laser 10. The first mirror 40 is arranged below the central optical axis, and the second mirror 50 is arranged above the central optical axis. In addition, for the convenience of subsequent polarization beam combination, the horizontal positions of the first mirror 40 and the second mirror 50 are also designed differently. The distances between the first mirror 40 and the slow-axis lens 30 on the sub-beam optical paths of each double-junction laser 10 are equal. Similarly, the distances between the second mirror 50 and the slow-axis lens 30 on the sub-beam optical paths of each double-junction laser 10 are also equal. However, for each double-junction laser 10, the distance between the first mirror 40 and the slow-axis lens 30 on its optical path is not equal to the distance between the second mirror 50 and the slow-axis lens 30. One of the sub-beams is directly emitted to the polarization beam splitter prism 70 through the first mirror 40, while the second mirror 50 directly emits the remaining sub-beam to the third mirror 60, and these sub-beams are then emitted to the polarization beam splitter prism 70 through the third mirror 60 for polarization beam combination. The first mirror 40 and the second mirror 50 can correct the deflection angles of the sub-beams and reduce the "gap" of the beams. Therefore, the first mirror 40 and the second mirror 50 on the optical paths of each double-junction laser 10 will divide the emitted light of these 10 double-junction lasers 10 into two sub-beam linear arrays. There is a certain distance between the two sub-beam linear arrays in the horizontal direction. Finally, they are emitted to the polarization beam splitter prism 70 through the third mirror 60 in the beam combination component for polarization beam combination. The polarization beam splitter prism 70 uses the polarization principle of the laser to combine the two sub-beam linear arrays with different polarization states into one linear array. It is a commonly used laser beam combination device. Here, it combines the two sub-beam linear arrays that have completed spatial beam combination through the ladder, that is, it performs beam combination in the horizontal direction. In addition, the beam combination component also includes an anti-reflection mirror 80, a fourth mirror 90, a focusing lens 100, and an optical fiber 110. Among them, the anti-reflection mirror 80 is arranged on the outgoing optical path of the polarization beam splitter prism 70 to prevent the emitted combined laser from returning to the optical path and prevent the laser from damaging the device, and then changes the propagation direction of the combined laser through the fourth mirror 90.The combined laser continues to be transmitted to the focusing lens 100. The focusing lens 100 focuses the combined laser. The focal length of the focusing lens 100 is 19.5 mm. The combined laser is coupled into the optical fiber 110 through the focusing lens 100. In the embodiment of the present invention, the spot pattern of the combined laser is compact, and the size of the spot in the vertical direction is small. Finally, it can be coupled into the optical fiber 110 with NA 0.18 and 200 microns. It can be understood that the optical fiber with NA 0.18 and 200 microns has an optical aperture of 0.18 and a diameter of 200 microns. Please refer to the spot pattern of the combined laser obtained by the optical fiber coupling module proposed in the embodiment of the present invention. Figure 2 , where the abscissa (X coordinate value) of the X-axis in the figure represents the spot coordinate position, reflecting the spot size, and the ordinate (Y coordinate value) represents the incoherent irradiance, indicating the spot intensity. Figure 2 The light intensity uniformity is good, the laser "gap" is not obvious, and the beam height size is small. The combined laser can be coupled into an optical fiber with a smaller diameter, improving the brightness of the overall combined laser and significantly improving the beam quality of the combined laser on the basis of ensuring miniaturization.

[0035] To verify the progressiveness of the present invention, the embodiment of the present invention also gives a control design of a traditional optical fiber coupling module. For details, please refer to Figure 3 , the device selection and the model of the optical device are exactly the same as those of the optical fiber coupling module based on the double-junction laser given in the embodiment of the present invention. The difference is only 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. The light emitted from the double-junction laser 10 forms a collimated parallel beam after being processed by the fast-axis lens 20. And to achieve polarization beam combination, every two double-junction lasers 10 are set at the same height position, and each double-junction laser 10 is only correspondingly provided with a first reflector 40. Finally, the combined laser is coupled into the optical fiber 110 through the third reflector 60, polarization beam splitter prism 70, anti-reflection mirror 80, fourth reflector 90 and focusing lens 100. In this design, the height of the combined laser is not compressed, so the size of the spot in the vertical direction is large. Finally, it needs to be coupled into the optical fiber 110 with NA 0.18 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 is an obvious "gap" in the spot pattern of its combined laser, the light intensity distribution is uneven, and the beam quality of the combined laser is poor.

[0036] In summary, the above description is only the preferred embodiments 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 within the protection scope of this specification.

[0037] The systems, devices, modules or units described in one or more of the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer can 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.

[0038] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, commodity or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the process, method, commodity or device comprising the said element.

[0039] Each embodiment in this specification is described in a progressive manner. The same or similar parts among 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 description of the method embodiment.

[0040] The above describes specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in a different order than in the embodiments and still achieve the desired result. Additionally, the processes depicted in the figures do not necessarily require the particular order or sequential order shown to achieve the desired result. In certain 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 the preset defocus amount, which is a positive number. The value range of micrometers; 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 with 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 the double-junction lasers.

2. 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.

3. 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.

4. 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.

5. The fiber coupling module based on double-junction laser according to claim 4, 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.

6. The fiber coupling module based on double-junction laser according to claim 5, 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.

7. The fiber coupling module based on double-junction laser according to claim 5 or 6, 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.

8. The fiber coupling module based on double-junction laser according to claim 7, 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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