Fast axis collimation lens for semiconductor laser and forming method, optical transmission system

Abstract

A fast axis collimation lens for a semiconductor laser, a forming method and an optical emission system, the fast axis collimation lens comprising: a base having a first surface; a first fast axis collimation section on the first surface, the first fast axis collimation section having a different refractive index from the base; the first fast axis collimation section being adapted to transmit a light beam generated by the semiconductor laser and compress a divergence angle of the light beam in a first direction. The present application can select appropriate materials for the first fast axis collimation section and the base according to specific optical path design, effectively improve the flexibility of the arrangement, break through the limitation of the fast axis collimation lens on the optical path design, and be conducive to reducing the assembly difficulty and improving the collimation effect.

Description

Technical Field

[0001] This invention relates to the field of lidar, and in particular to a fast-axis collimating lens for semiconductor lasers, a method for forming such a lens, and a light emission system. Background Technology

[0002] LiDAR is a commonly used ranging sensor with advantages such as long detection range, high resolution, and low susceptibility to environmental interference. It is widely used in fields such as intelligent robots, drones, and autonomous driving. The working principle of LiDAR is to use the time it takes for light to travel round-trip between the radar and the target to obtain the target's distance information.

[0003] In lidar, semiconductor lasers are typically used as the light source. However, some types of semiconductor lasers produce beams with a non-circular cross-sectional shape perpendicular to the laser propagation direction. For example... Figure 1 As shown, the divergence angle of the laser beam formed by the emitting region 11 of the edge-emitting laser (EEL) 10 is different in the direction parallel to the length of the emitting region and in the direction parallel to the width of the emitting region. Specifically, the divergence angle of the formed laser beam in the direction parallel to the width of the emitting region (approximately 25° to 35°) is much larger than the divergence angle in the direction parallel to the length of the emitting region (approximately 8° to 10°). Therefore, the laser spot 12 formed in the plane perpendicular to the laser propagation direction is an ellipse with its major axis y parallel to the width of the emitting region and its minor axis x parallel to the length of the emitting region. The direction parallel to the width of the emitting region is usually referred to as the fast axis direction of the semiconductor laser, that is, the direction of the major axis y of the spot 12 is the fast axis direction.

[0004] In lasers of this type, which are typically edge-emitting lasers, the divergence angle in the fast axis direction is relatively large. Therefore, a fast-axis collimating lens is needed for collimation to reduce the divergence angle in the fast axis direction.

[0005] However, existing fast-axis collimating lenses are generally integral structures made of the same material, such as D-type microlenses and cylindrical optical fibers. The size of conventional lenses varies depending on the requirements, with diameters typically ranging from 10mm to 50mm; while the height and width of fast-axis collimating lenses are generally less than 0.5mm, hence they are also called microlenses.

[0006] When the fast-axis collimating lens is made of only one material, its refractive index is fixed. Therefore, when the fast-axis collimating lens is applied to lidar, in order to ensure the collimation effect, the fast-axis collimating lens has great limitations on the optical path design, which can easily lead to problems such as increased assembly difficulty and poor collimation effect.

[0007] Furthermore, D-type microlenses are generally aspherical plano-convex lenses, typically small in size. The difficulty in fabricating these lenses lies in how to manufacture a small aspherical plano-convex structure while maintaining processing accuracy and reducing costs. Optical fibers, used as collimating lenses, employ cylindrical fibers for fast-axis collimation, offering simple and low-cost fabrication, but with poorer collimation performance. In addition, existing lens fabrication methods include grinding and polishing, molding, and photolithography. Grinding and polishing are traditional mechanical processing methods with low production efficiency, high costs, and difficulty in mass production; molding uses materials with low glass transition temperature (T0). g The glass is placed in a mold, heated, and then pressed into shape. However, the precision is not high enough, and the size of the lens after processing is not small enough. Photolithography uses ultraviolet light to etch the photoresist and transfer the feature pattern to the mask layer. The process is more complex and has high environmental requirements. Summary of the Invention

[0008] The problem solved by this invention is to provide a fast-axis collimating lens for semiconductor lasers, a method for forming such a lens, and a light emission system, which effectively improves the flexibility of setup and thus reduces assembly difficulty and improves collimation effect.

[0009] To address the above problems, the present invention provides a fast-axis collimating lens for semiconductor lasers, comprising:

[0010] The base has a first surface; a first fast-axis collimator located on the first surface, the refractive index of the first fast-axis collimator being different from that of the base; the first fast-axis collimator is adapted to transmit a beam generated by the semiconductor laser and compress the divergence angle of the beam in a first direction.

[0011] Optionally, the surface of the first fast axis collimation part that is opposite to the first surface is a convex surface.

[0012] Optionally, the base also has a second surface disposed opposite to the first surface, and the fast-axis collimating lens further includes: a second fast-axis collimating part, which is located on the second surface, and the refractive index of the second fast-axis collimating part is different from the refractive index of the base.

[0013] Optionally, the surface of the second fast axis collimator facing away from the base is a convex surface or a concave surface.

[0014] Optionally, the surface of the second fast axis collimator facing away from the base is a convex surface, and the radius of curvature of the convex surface of the second fast axis collimator is greater than the radius of curvature of the convex surface of the first fast axis collimator.

[0015] Optionally, the surface of the second fast-axis collimating portion facing away from the base is concave, and the refractive index of the second fast-axis collimating portion is greater than the refractive index of the first fast-axis collimating portion.

[0016] Optionally, the first fast-axis collimation section includes: multiple collimation layers, which form a stacked structure, and adjacent collimation layers have different refractive indices.

[0017] Optionally, the first fast axis collimation section includes a negative collimation layer and a positive collimation layer sequentially located on the first surface, wherein the surface of the negative collimation layer facing the positive collimation layer is concave, and the surface of the positive collimation layer facing the negative collimation layer and the surface away from the negative collimation layer are both convex.

[0018] Optionally, the refractive index of the negative collimation layer is greater than that of the positive collimation layer.

[0019] Optionally, the base is a layered structure; the base includes a support layer and at least one optical functional layer.

[0020] Optionally, the optical functional layer includes at least one of a pitch adjustment layer, an aperture layer, and a filter layer; wherein the aperture layer includes an ink layer and a light-transmitting hole penetrating the ink layer; and the refractive index of the pitch adjustment layer is greater than 1.7 or less than 1.5.

[0021] Optionally, there may be multiple first fast axis collimating portions, and all of the multiple first fast axis collimating portions may be located on the first surface.

[0022] Optionally, a plurality of the first fast axis collimating portions are arranged along a first direction, and the first fast axis collimating portions extend along a second direction, the second direction being perpendicular to the first direction.

[0023] Optionally, the dimension of the first fast axis collimation portion along the second direction is larger than the dimension along the first direction.

[0024] Optionally, a plurality of the first fast axis collimating portions are arranged in an array with the first direction as the column direction and the second direction as the row direction, the second direction being perpendicular to the first direction; along the second direction, there is a gap between adjacent first fast axis collimating portions.

[0025] This invention provides an optical emitting system for lidar, comprising:

[0026] Semiconductor laser; fast-axis collimating lens, wherein the fast-axis collimating lens is the fast-axis collimating lens of the present invention.

[0027] Optionally, the distance between the semiconductor laser and the fast-axis collimating lens is related to the refractive index of the first fast-axis collimating portion and the base.

[0028] Optionally, a plurality of first fast-axis collimating portions are arranged along a first direction, and the first fast-axis collimating portions extend along a second direction, the second direction being perpendicular to the first direction; a plurality of semiconductor lasers are arranged with the first direction as the column direction and the second direction as the row direction; each first fast-axis collimating portion corresponds to a row of semiconductor lasers.

[0029] Optionally, a plurality of the first fast-axis collimating portions are arranged in an array with the first direction as the column direction and the second direction as the row direction, the second direction being perpendicular to the first direction; a plurality of the semiconductor lasers are arranged with the first direction as the column direction and the second direction as the row direction; the first fast-axis collimating portions and the semiconductor lasers correspond one-to-one.

[0030] This invention provides a method for forming a fast-axis collimating lens for a semiconductor laser, comprising:

[0031] A base is provided, the base having a first surface; an imprinting step is performed to form a first fast axis collimation portion at least on the first surface of the base; the imprinting step includes: forming an imprinting material layer on the surface of the base; and imprinting the imprinting material layer using a master plate.

[0032] Optionally, the process may also include performing the imprinting step multiple times, wherein the refractive index of the imprinted material is different in each imprinting step.

[0033] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0034] In the technical solution of the present invention, the refractive index of the first fast-axis collimating part is different from that of the base. Therefore, the appropriate materials of the first fast-axis collimating part and the base can be selected according to the specific optical path design, which can effectively improve the flexibility of the setup, break through the limitation of the fast-axis collimating lens on the optical path design, and thus help reduce the assembly difficulty and improve the collimation effect.

[0035] In an optional embodiment of the present invention, the fast-axis collimating lens further includes a second fast-axis collimating section, wherein the first collimating section and the second collimating section cooperate to achieve collimation. Collimation is achieved by using two fast-axis collimating sections located on two surfaces of the base, which further improves the collimation effect.

[0036] In an optional embodiment of the present invention, the surface of the first fast-axis collimating part not located on the first surface is convex, and the surface of the second fast-axis collimating part facing away from the base is also convex. This configuration can effectively correct the aberrations of the fast-axis collimating lens. Furthermore, since the surface of the second fast-axis collimating part facing away from the base is convex, and the radius of curvature of the convex surface of the second fast-axis collimating part is greater than that of the convex surface of the first fast-axis collimating part, it can further reduce aberrations and improve the collimation effect.

[0037] In an optional embodiment of the present invention, the surface of the first fast-axis collimating part facing away from the base is convex, and the surface of the second fast-axis collimating part facing away from the base is concave. This arrangement can, on the one hand, reduce the distance between the fast-axis collimating lens and the semiconductor laser to improve the collimation effect, and can even allow the collimating lens to be directly placed on the substrate of the semiconductor laser; on the other hand, the combination of concave and convex lenses can achieve mutual compensation to eliminate dispersion.

[0038] In an optional embodiment of the present invention, the first fast-axis collimation section can be a stacked structure, including: multiple collimation layers, wherein the refractive indices of the materials of adjacent collimation layers are not equal, thereby further improving the design freedom and achieving the purpose of balancing aberration correction and improving collimation effect; moreover, the multiple collimation layers may include: a negative collimation layer and a positive collimation layer arranged sequentially along the optical path, thereby forming a combination of concave and convex lenses to mutually compensate for chromatic aberration.

[0039] In an optional embodiment of the present invention, the base is a stacked structure; the base includes a support layer and at least one optical functional layer, the optical functional layer including at least one of a pitch adjustment layer, an aperture layer, and a filter layer; wherein, the aperture layer includes an ink layer and a light-transmitting hole penetrating the ink layer along the optical path; the refractive index of the pitch adjustment layer is greater than 1.7 or less than 1.5; through the stacked arrangement of the base, the optical function of the fast-axis collimating lens can be effectively expanded. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the light-emitting region of a semiconductor laser and the light spot it produces;

[0041] Figure 2 This is a three-dimensional structural schematic diagram of the first embodiment of the fast-axis collimating lens for semiconductor lasers according to the present invention;

[0042] Figure 3 yes Figure 2 A schematic cross-sectional view of the fast-axis collimating lens embodiment shown along line A1-A2;

[0043] Figure 4 yes Figure 2 The diagram shows the optical path structure of a fast-axis collimating lens embodiment applied to a lidar system.

[0044] Figure 5 This is a schematic diagram of the structure of the second embodiment of the fast-axis collimating lens for semiconductor lasers according to the present invention;

[0045] Figure 6 yes Figure 5 The diagram shows the optical path structure of a fast-axis collimating lens embodiment applied to a semiconductor laser.

[0046] Figure 7 This is a schematic diagram of the structure of the third embodiment of the fast-axis collimating lens for semiconductor lasers according to the present invention;

[0047] Figure 8 yes Figure 7 The diagram shows the optical path structure of a fast-axis collimating lens embodiment applied to a semiconductor laser.

[0048] Figure 9 This is a schematic diagram of the fourth embodiment of the fast-axis collimating lens for semiconductor lasers according to the present invention;

[0049] Figure 10 This is a schematic diagram of the fifth embodiment of the fast-axis collimating lens for semiconductor lasers according to the present invention;

[0050] Figure 11 This is a schematic diagram of the sixth embodiment of the fast-axis collimating lens for semiconductor lasers according to the present invention;

[0051] Figure 12 This is a schematic diagram of the structure of the seventh embodiment of the fast-axis collimating lens for semiconductor lasers according to the present invention;

[0052] Figure 13 This is a three-dimensional structural schematic diagram of the eighth embodiment of the fast-axis collimating lens for semiconductor lasers according to the present invention;

[0053] Figure 14 yes Figure 13 A schematic cross-sectional view of the fast-axis collimating lens embodiment shown along line B1-B2;

[0054] Figure 15 This is a three-dimensional structural schematic diagram of the ninth embodiment of the fast-axis collimating lens for semiconductor lasers according to the present invention;

[0055] Figure 16 yes Figure 15 The diagram shows a top view of the fast-axis collimating lens embodiment along direction C;

[0056] Figure 17 This is a schematic diagram of the structure of each step in an embodiment of the method for forming a fast-axis collimating lens for a semiconductor laser according to the present invention;

[0057] Figure 18 This is a schematic diagram of the structure of each step in another embodiment of the method for forming a fast-axis collimating lens for a semiconductor laser according to the present invention. Detailed Implementation

[0058] As can be seen from the background art, the fast-axis collimating lens of the semiconductor laser in the prior art has the problem of poor collimation effect.

[0059] To address the aforementioned technical problem, the present invention provides a fast-axis collimating lens for a semiconductor laser, comprising: a base having a first surface facing away from the semiconductor laser; a first fast-axis collimating portion located on the first surface, the refractive index of the first fast-axis collimating portion being different from the refractive index of the base; the first fast-axis collimating portion being adapted to transmit a light beam generated by the semiconductor laser and compress the divergence angle of the light beam in a first direction.

[0060] The technical solution of this invention allows for the selection of appropriate materials for the first fast-axis collimating part and the base according to the specific optical path design, which can effectively improve the flexibility of the setup, overcome the limitations of the fast-axis collimating lens on the optical path design, and thus help reduce the assembly difficulty and improve the collimation effect.

[0061] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0062] refer to Figure 2 and Figure 3 A schematic diagram of the structure of a first embodiment of the fast-axis collimating lens for a semiconductor laser of the present invention is shown, wherein... Figure 2 This is a three-dimensional structural schematic diagram of an embodiment of the fast-axis collimating lens. Figure 3 yes Figure 2 The cross-sectional structure of the fast-axis collimating lens embodiment shown is along line A1-A2.

[0063] The fast-axis collimating lens includes: a base 110 having a first surface 111 facing away from the semiconductor laser; a first fast-axis collimating portion 120 located on the first surface 111, the refractive index of the first fast-axis collimating portion 120 being different from the refractive index of the base 110; the first fast-axis collimating portion 120 being adapted to transmit the light beam generated by the semiconductor laser and compress the divergence angle of the light beam in a first direction Y.

[0064] Reference Figure 4 The diagram illustrates the optical path structure of the fast-axis collimating lens embodiment applied to a lidar system. The base 110 has a first surface 111 and a second surface (not shown) arranged opposite to each other. The light beam propagates along the direction from the second surface to the first surface 111; that is, the light beam enters the base 110 from the second surface and exits the base 110 from the first surface 111. Therefore, the first surface 111 faces away from the semiconductor laser.

[0065] like Figure 2As shown, the fast-axis collimating lens is an elongated strip extending along the second direction, meaning that the dimension of the fast-axis collimating lens along the second direction is larger than its dimension along the first direction. Specifically, in a plane parallel to the first surface 111, the cross-section of the fast-axis collimating lens is a rectangle extending along the second direction X, wherein the second direction X is perpendicular to the first direction Y.

[0066] The base 110 serves to provide a process operation platform and provides support within the fast-axis collimating lens. In some embodiments of the present invention, the base 110 can be made of transparent materials such as glass or plexiglass. Specifically, in some embodiments, the thickness of the base 110 is in the range of 0.1 mm to 1 mm.

[0067] The first fast-axis collimating portion 120 is used to compress the divergence angle of the light beam in the first direction Y. The refractive index of the material of the first fast-axis collimating portion 120 is not equal to the refractive index of the material of the base portion 110. In some embodiments of the present invention, the material of the first fast-axis collimating portion 120 is an imprinting adhesive, such as a UV-curable adhesive or a thermosetting adhesive.

[0068] As mentioned earlier, some types of semiconductor lasers, such as edge-emitting lasers, produce beams with a cross-sectional shape that is not circular perpendicular to the laser propagation direction, resulting in a fast axis direction and a slow axis direction. The fast axis collimating lens is used to compress the divergence angle of the beam formed by the semiconductor laser in the fast axis direction; therefore, the first direction Y is parallel to the fast axis direction of the semiconductor laser.

[0069] Therefore, the fast-axis collimating lens is configured as a stacked structure including a fast-axis collimating part and a base, which effectively improves the flexibility of the configuration. While overcoming the limitations of optical path design and reducing the difficulty of assembly, it can also obtain better beam shaping effect, thereby achieving the purpose of improving the performance of lidar.

[0070] In some embodiments of the present invention, the fast-axis collimating lens is suitable for edge-emitting semiconductor lasers (such as...). Figure 1 As shown, the edge-emitting semiconductor laser can be used as a lidar light source to generate laser light for detection.

[0071] like Figure 4As shown, the fast-axis collimating lens 200 is fixed to the drive circuit board 130 by means of adhesive or other methods. The semiconductor laser 140 and the fast-axis collimating lens 200 are arranged sequentially along the optical path, and the semiconductor laser 140 is located at the focal plane of the first fast-axis collimating section 120, that is, the distance between the semiconductor laser 140 and the first fast-axis collimating section 120 is equal to the focal length f of the first fast-axis collimating section 120. Since the fast-axis collimating lens 200 has a stacked structure, the position of the focal plane will change with the change of the refractive index of each layer of material in the stacked structure. Therefore, a suitable material can be selected according to the distance requirement between the semiconductor laser 140 and the fast-axis collimating lens 200 in the optical path so that the focal length of the fast-axis collimating lens 200 meets the requirements.

[0072] Specifically, the semiconductor laser 140 is located on the side of the base 110 away from the first fast-axis collimator 120, that is, the base 110 is located between the semiconductor laser 140 and the first fast-axis collimator 120. The light beam generated by the semiconductor laser 140 is transmitted sequentially through the base 110 and the first fast-axis collimator 120.

[0073] Therefore, in some embodiments of the present invention, the surface of the first fast-axis collimating portion 120 opposite to the first surface 111 is a convex surface to compress the divergence angle of the light beam in the first direction Y. Specifically, the surface of the first fast-axis collimating portion 120 opposite to the first surface 111 is a cylindrical surface. In some embodiments of the present invention, the radius of curvature of the convex surface of the first fast-axis collimating portion 120 opposite to the first surface 111 is in the range of 0.1 mm to 0.5 mm. In other embodiments of the present invention, the convex surface of the first fast-axis collimating portion opposite to the first surface may also be an aspherical surface.

[0074] It should be noted that, in order to achieve beam shaping and compress the fast-axis divergence angle of the beam generated by the semiconductor laser using the fast-axis collimating lens, the first direction Y is parallel to the fast-axis direction of the semiconductor laser. Therefore, the second direction X extending from the fast-axis collimating lens is parallel to the slow-axis direction of the semiconductor laser.

[0075] Unlike the plano-convex structure of the first embodiment, in other embodiments of the present invention, the fast-axis collimating lens may also be a biconvex structure to obtain a better collimation effect.

[0076] like Figure 5 and Figure 6As shown, in some embodiments, the base 210 of the fast-axis collimating lens has a first fast-axis collimating portion 220 on a first surface 211; the base 210 also has a second surface 212 disposed opposite to the first surface 211, and the fast-axis collimating lens further includes a second fast-axis collimating portion 230, which is located on the second surface 212, and the refractive index of the second fast-axis collimating portion 230 is different from the refractive index of the base 210.

[0077] It should be noted that, Figure 5 Is with Figure 3 The corresponding cross-sectional structural diagram; Figure 6 Is with Figure 4 A schematic diagram of the corresponding optical path structure.

[0078] The second fast-axis collimating part 230 cooperates with the first fast-axis collimating part 220 to achieve beam collimation. Since any optical lens has various aberrations such as spherical aberration, coma, and chromatic aberration, collimation is achieved by using the two fast-axis collimating parts 220 and 230 on the two surfaces of the base, which can correct aberrations to a certain extent, thereby improving the collimation effect.

[0079] Furthermore, compared to a planar-convex structure, the thickness of each fast-axis collimating portion in a biconvex structure can be smaller. Specifically, under the premise of comparable collimation effect, the thickness of at least one of the first fast-axis collimating portion 220 and the second fast-axis collimating portion 230 is in the range of 0.02 mm to 0.1 mm. The radius of curvature of at least one of the surfaces of the first fast-axis collimating portion 220 and the second fast-axis collimating portion 230 facing away from the base 210 is in the range of 0.1 mm to 0.3 mm.

[0080] It should also be noted that the first surface 211 and the second surface 212 are arranged opposite to each other, with the first surface 211 facing away from the semiconductor laser 240, and therefore the second surface 212 facing the semiconductor laser 240. Thus, the second fast-axis collimating portion 230, the base portion 210, and the first fast-axis collimating portion 220 are arranged sequentially along the optical path. Compared to the first fast-axis collimating portion 220, the second fast-axis collimating portion 230 is closer to the semiconductor laser 240, meaning the light beam enters the fast-axis collimating lens from the second fast-axis collimating portion 230.

[0081] like Figure 5 and Figure 6As shown, in some embodiments of the present invention, the surface of the second fast-axis collimating portion 230 facing away from the base 210 is a convex surface. The radius of curvature R1 of the convex surface of the second fast-axis collimating portion 230 into which the light beam is incident is greater than the radius of curvature R2 of the convex surface of the first fast-axis collimating portion 220, thereby further improving the effect of aberration correction. Specifically, in some embodiments, the radius of curvature R1 of the convex surface of the second fast-axis collimating portion 230 is in the range of 0.2 mm to 0.3 mm; the radius of curvature R2 of the convex surface of the first fast-axis collimating portion 220 is in the range of 0.1 mm to 0.2 mm.

[0082] In other embodiments, the fast-axis collimating lens may also have a concave-convex structure, meaning the fast-axis collimating lens as a whole is meniscus. Specifically, refer to... Figure 7 The surface of the second fast axis collimating portion 330 facing away from the base 310 is concave, and the refractive index of the second fast axis collimating portion 330 is greater than the refractive index of the first fast axis collimating portion 320.

[0083] A fast-axis collimating lens with a concave-convex structure is equivalent to a combination of a negative lens and a positive lens. Under the premise of constant focal length, the distance between the concave surface and the focal plane is smaller, thereby reducing the distance between the fast-axis collimating lens and the semiconductor laser. It is even possible to directly integrate the fast-axis collimating lens and the semiconductor laser on the same substrate. Moreover, the smaller the distance between the concave surface and the focal plane, the less the beam divergence, and the corresponding collimation effect can be further improved.

[0084] On the other hand, the combination of meniscus-shaped positive and negative lenses, and the fact that the refractive index of the second fast axis collimating portion 330 is greater than that of the first fast axis collimating portion 320, can mutually compensate for chromatic aberration and reduce chromatic aberration.

[0085] Specifically, the first fast axis collimating part 320 is convex, and the material of the first fast axis collimating part 320 has a low refractive index and a large Abbe number; the second fast axis collimating part 330 is concave, and the material of the second fast axis collimating part 330 has a relatively high refractive index and a small Abbe number.

[0086] In some embodiments of the present invention, the surface of the first fast-axis collimating portion 320 facing away from the base 310 is convex. The thickness of the first fast-axis collimating portion 320 is in the range of 0.02 mm to 0.1 mm. The radius of curvature of the convex surface is in the range of 0.1 mm to 1 mm. The material of the first fast-axis collimating portion 320 can be a UV-curable imprinting adhesive. The refractive index of the material of the first fast-axis collimating portion 320 is in the range of 1.5 to 1.55.

[0087] The material of the first fast axis collimation section 320 has an Abbe number greater than 50.

[0088] In some embodiments of the present invention, the surface of the second fast-axis collimating portion 330 facing away from the base 310 is concave. The thickness of the second fast-axis collimating portion 330 is in the range of 0.02 mm to 0.1 mm. The radius of curvature of the concave surface is in the range of 0.1 mm to 1 mm. The material of the second fast-axis collimating portion 330 can be a UV-curable imprinting adhesive. The refractive index of the material of the first fast-axis collimating portion 320 is in the range of 1.55 to 1.6.

[0089] The Abbe number of the material of the first fast axis collimation section 320 is less than 50.

[0090] In some embodiments of the present invention, the material of the base 310 may be glass, and the thickness of the base 310 is in the range of 0.1 mm to 0.3 mm.

[0091] It should be noted that in some other embodiments of the present invention, at least one of the base, the first fast axis collimation portion, and the second fast axis collimation portion can be a stacked structure.

[0092] refer to Figure 9 This diagram illustrates a cross-sectional view of another embodiment of the fast-axis collimating lens for a semiconductor laser according to the present invention. Figure 9 Is with Figure 3 The corresponding cross-sectional structural diagram.

[0093] In some embodiments of the present invention, the base 410 is a layered structure. For example... Figure 9 As shown, the base includes a support layer 411 and at least one optical functional layer. Specifically, the base 410 includes a support layer 411 and three optical functional layers.

[0094] It should be noted that the thickness of the at least one optical functional layer can be the same or different. In some embodiments of the present invention, a suitable thickness can be selected based on the function and effect of the fast-axis collimating lens.

[0095] In some embodiments of the present invention, the optical functional layer includes at least one of a pitch adjustment layer 414, an aperture layer 413, and a filter layer 412.

[0096] The adjusting layer 414 is suitable for controlling the distance between the fast-axis collimating lens and the semiconductor laser. In some embodiments of the present invention, the refractive index of the adjusting layer 414 is greater than 1.7 or less than 1.5. Specifically, if the distance between the fast-axis collimating lens and the semiconductor laser is too small, the fast-axis collimating lens may come into contact with the active region of the semiconductor laser, easily damaging the semiconductor laser; if the distance between the fast-axis collimating lens and the semiconductor laser is too large, the fast-axis collimating lens is difficult to integrate directly onto the substrate of the semiconductor laser, easily causing low integration density. Therefore, the refractive index of the adjusting layer 414 is greater than 1.7 to reduce the distance between the fast-axis collimating lens and the semiconductor laser; the refractive index of the adjusting layer 414 is less than 1.5 to increase the distance between the fast-axis collimating lens and the semiconductor laser.

[0097] The aperture layer 413 is used to block stray light and limit the divergence angle of the incident light. In some embodiments of the present invention, the aperture layer 413 includes an ink layer (not shown in the figure) and a light-transmitting hole penetrating the ink layer (not shown in the figure). Specifically, an ink layer can be imprinted on one side of the support layer 411, and a light-transmitting hole penetrating the thickness can be formed in the ink layer to form the aperture layer 413. To ensure the blocking and limiting effect, the thickness of the aperture layer 413 is in the range of 0.1 mm to 0.3 mm, that is, the thickness of the ink layer is in the range of 0.1 mm to 0.3 mm.

[0098] The filter layer 412 is used to allow light within a specific wavelength range to pass through while filtering out light of other wavelengths, thereby giving the fast-axis collimating lens filtering characteristics and suppressing wavelength shift caused by temperature drift in the semiconductor laser. Specifically, the filter layer 412 is made of a filter material.

[0099] It should be noted that, as Figure 9 As shown, the adjustment layer 414 is located on the surface of the support layer 411 facing the first fast axis collimation portion 420; the filter layer 412 and the aperture layer 413 are sequentially located on the surface of the support layer 411 facing away from the first fast axis collimation portion 420. However, this arrangement is only an example; the at least one optical functional layer can be disposed on the surface of the support layer 411, and the present invention does not limit the specific position of the at least one optical functional layer.

[0100] It should also be noted that the support layer 411 can also be a stacked structure. Specifically, the first fast-axis collimating part and different optical functional layers can be respectively disposed on different support layers, and then the surfaces of the different support layers without optical functional layers can be glued together to form a stacked support layer structure, thereby obtaining the fast-axis collimating lens. For example, a filter layer can be disposed on one surface of one support layer; the first fast-axis collimating part can be disposed on one surface of another support layer; and a fast-axis collimating lens with filter characteristics can be obtained by gluing the two support layers together.

[0101] In other embodiments of the present invention, the first fast-axis collimation portion may also be a stacked structure, that is, the first fast-axis collimation portion includes: a plurality of collimation layers, the plurality of collimation layers forming a stacked structure, the refractive indices of adjacent collimation layers being different, i.e., the first fast-axis collimation portion may be multi-layered, for example, two layers (e.g., ...). Figure 10 (as shown) or 3 layers (such as) Figure 11 (as shown), to achieve the effect of multiple lenses.

[0102] All optical lenses exhibit various aberrations such as spherical aberration, coma, and chromatic aberration; the first fast axis collimating section of a stacked structure is equivalent to multiple lenses. Compared to a single lens, multiple lenses can correct aberrations to a certain extent, thereby improving the collimation effect.

[0103] In some embodiments of the present invention, the refractive index of any of the collimating layers is in the range of 1.5 to 1.6; the thickness of any of the collimating layers is in the range of 0.02 mm to 0.05 mm; and the radius of curvature of the surface of any of the collimating layers is in the range of 0.1 mm to 0.3 mm.

[0104] Specifically, such as Figure 10 As shown, the first fast-axis collimation portion 520 includes a first collimation layer 521 and a second collimation layer 522 sequentially stacked on the first surface 511 of the base 510; as Figure 11 As shown, the first fast axis collimation portion 620 includes a first collimation layer 621, a second collimation layer 622 and a third collimation layer 623 sequentially stacked on the first surface 611 of the base portion 610.

[0105] It should be noted that, in some embodiments of the present invention, the first fast-axis collimating portion of the stacked structure can also be equivalent to a concave-convex lens group. For example... Figure 12 As shown, the first fast axis collimation section 720 includes a negative collimation layer 721 and a positive collimation layer 722 sequentially located on the first surface 711. The surface of the negative collimation layer 721 facing the positive collimation layer 722 is concave, and the surface of the positive collimation layer 722 facing the negative collimation layer 721 and the surface away from the negative collimation layer 721 are both convex.

[0106] In some embodiments of the present invention, the refractive index of the negative collimation layer 721 is greater than that of the positive collimation layer 722 to reduce chromatic aberration. Specifically, the material of the positive collimation layer 722 has a smaller refractive index, ranging from 1.5 to 1.55; the material of the negative collimation layer 721 has a larger refractive index, ranging from 1.55 to 1.6, thus compensating for each other to reduce chromatic aberration.

[0107] It should be noted that in the foregoing embodiments, in the fast-axis collimating lens, only one first fast-axis collimating portion is provided on the first surface of the base. However, this is only an example; in other embodiments of the present invention, multiple first fast-axis collimating portions may also be provided on the first surface of the base.

[0108] refer to Figure 13 and Figure 14 This diagram illustrates a structural schematic of yet another embodiment of the fast-axis collimating lens of the present invention for a semiconductor laser. Figure 13 This is a three-dimensional structural schematic diagram of the embodiment of the fast-axis collimating lens; Figure 14 yes Figure 13 The cross-sectional structure of the fast-axis collimating lens embodiment shown is a schematic diagram along line B1-B2.

[0109] In the fast-axis collimating lens, there are multiple first fast-axis collimating portions 820, and all of the multiple first fast-axis collimating portions 820 are located on the first surface 811 of the base 810. For example... Figure 13 and Figure 14 As shown, a plurality of first fast axis collimation portions 820 are arranged along a first direction Y, and the first fast axis collimation portions 820 extend along a second direction X, the second direction X being perpendicular to the first direction Y.

[0110] Specifically, multiple first fast-axis collimating portions 820 are closely arranged, meaning adjacent first fast-axis collimating portions 820 are in contact with each other. In other embodiments of the present invention, the first fast-axis collimating portions are spaced apart, meaning there is a gap between adjacent first fast-axis collimating portions, and the size of the gap between adjacent first fast-axis collimating portions is related to the spacing between adjacent semiconductor lasers in the laser array. In some embodiments, the gap between adjacent first fast-axis collimating portions is in the range of 1 mm to 10 mm.

[0111] The fast-axis collimating lens is suitable for simultaneously compressing the divergence angle of beams generated by multiple semiconductor lasers. Specifically, the multiple semiconductor lasers are arranged in an array to form a laser array, wherein the laser array has a row direction parallel to the slow axis and a column direction parallel to the fast axis. The fast-axis collimating lens is positioned in a first direction Y parallel to the column direction of the laser array to compress the divergence angle of the semiconductor lasers in the fast axis direction.

[0112] In other embodiments of the present invention, such as Figure 15 and Figure 16 As shown, where Figure 16 yes Figure 15 A view along direction C. Multiple first fast axis collimators 920 are arranged in an array with the first direction Y as the column direction and the second direction X as the row direction, the second direction X being perpendicular to the first direction Y. Along the second direction X, adjacent first fast axis collimators 920 are spaced apart to avoid interference.

[0113] It should be noted that the dimensions of the multiple first fast axis collimating portions 920 arranged in an array along the second direction X are larger than the dimensions along the first direction Y, so as to achieve the function of compressing the divergence angle in the first direction.

[0114] It should also be noted that when multiple first fast axis collimating parts are provided on the first surface of the base, the bases below different first fast axis collimating parts are connected and form an integral structure, that is, multiple first fast axis collimating parts are provided on the same base.

[0115] The present invention also provides an optical emission system for lidar.

[0116] refer to Figure 4 The diagram shows a schematic representation of an embodiment of the optical emission system for lidar according to the present invention.

[0117] The optical emission system includes: a semiconductor laser 140; and a fast-axis collimating lens 200.

[0118] In some embodiments of the present invention, the cross-sectional shape of the beam formed by the semiconductor laser 140 perpendicular to the laser propagation direction is not circular, thus there are fast axis direction and slow axis direction. The fast axis collimating lens 200 is used to compress the divergence angle of the beam formed by the semiconductor laser in the fast axis direction; therefore, the first direction Y is parallel to the fast axis direction of the semiconductor laser 140.

[0119] It should be noted that the distance d between the semiconductor laser 140 and the fast-axis collimating lens 200 is related to the refractive indices of the first fast-axis collimating portion 120 and the base 110. The semiconductor laser 140 is disposed at the focal plane of the first fast-axis collimating portion 120, that is, the distance between the semiconductor laser 140 and the first fast-axis collimating portion 120 is equal to the focal length f of the first fast-axis collimating portion 120. Since the refractive indices of the first fast-axis collimating portion and the base are related to the focal length f of the fast-axis collimating lens 200, the distance d between the semiconductor laser 140 and the fast-axis collimating lens 200 is related to the refractive indices of the first fast-axis collimating portion 120 and the base 110. That is, the distance d between the semiconductor laser 140 and the fast-axis collimating lens 200 is set according to the refractive indices of the first fast-axis collimating portion 120 and the base 110.

[0120] The optical emission system serves as the light source for the lidar. The fast-axis collimating lens, by compressing the fast-axis divergence angle, brings the divergence angle of the beam close to that of the slow-axis, thus shaping the beam to obtain a circular cross-section. Specifically, in the plane perpendicular to the laser transmission direction, the emitted beam spot is circular, making the beam shape approximate the shape of the lens aperture in the optical path. This fully utilizes the emission aperture, avoids aperture waste, improves output power, and extends the measurement distance. Furthermore, the full utilization of the optical aperture results in a larger spot area for the same output power, effectively reducing the energy density within the beam cross-section and improving lidar safety. In addition, in lidar, the product of the spot width and the divergence angle is constant. When the fast-axis collimating lens compresses the fast-axis divergence angle to obtain a circular cross-section beam, the divergence angle is smaller and the spot width is larger in the direction parallel to the fast axis, resulting in a greater distance between adjacent beams. Therefore, the spots of adjacent channels are less likely to overlap, thus improving lidar resolution.

[0121] like Figure 13 and Figure 14 As shown, in some embodiments of the present invention, a plurality of first fast axis collimating portions 820 are arranged along a first direction Y, and the first fast axis collimating portions 820 extend along a second direction X, the second direction X being perpendicular to the first direction Y; a plurality of semiconductor lasers 840 are arranged with the first direction Y as the column direction and the second direction X as the row direction; each first fast axis collimating portion 820 corresponds to a row of semiconductor lasers 840 (i.e., a plurality of semiconductor lasers arranged along the row direction).

[0122] like Figure 15 and Figure 16In other embodiments of the present invention, a plurality of first fast axis collimating portions 920 are arranged in an array with the first direction Y as the column direction and the second direction X as the row direction, the second direction X being perpendicular to the first direction Y; a plurality of semiconductor lasers (not shown in the figure) are arranged with the first direction Y as the column direction and the second direction X as the row direction; the first fast axis collimating portions 920 and the semiconductor lasers correspond one-to-one.

[0123] In addition, the present invention also provides a method for forming a fast-axis collimating lens for a semiconductor laser.

[0124] The forming method includes: providing a base having a first surface; performing an imprinting step to form a first fast axis collimation portion at least on the first surface of the base; the imprinting step includes: forming an imprinting material layer on the surface of the base; and imprinting the imprinting material layer using a master plate.

[0125] A base is provided, the base having a first surface. Specifically, the base is a cut substrate, so the step of providing the base includes providing a substrate having a first surface. In some embodiments of the present invention, the substrate is a glass substrate. The thickness of the substrate is in the range of 0.1 mm to 1 mm.

[0126] Reference Figure 17 The specific process of the imprinting step is shown.

[0127] The imprinting step includes:

[0128] Step S121A: Prepare master template 1500. Master template 1500 is a master template with nanometer-level precision. One surface of master template 1500 has a feature shape corresponding to the first fast axis collimation portion. In some embodiments of the present invention, the feature shape within the surface of master template 1500 is an aspherical or spherical depression. The radius of curvature of the depression is generally in the range of 0.1 mm to 0.5 mm.

[0129] Step S121 involves forming an imprinting material layer 1101 on the surface of the substrate. Specifically, step S121 includes forming an imprinting material layer 1201 on the first surface of the substrate 1101. In some embodiments of the present invention, the imprinting material layer 1201 is an imprinting adhesive. The thickness of the imprinting adhesive is in the range of 0.2 mm to 0.5 mm. In some embodiments of the present invention, the imprinting adhesive can be a UV-curable adhesive or a thermosetting adhesive. The refractive index of the imprinting adhesive is comparable to that of the substrate, and the refractive index of the imprinting adhesive is in the range of 1.4 to 1.9.

[0130] Step S122: Imprinting the imprinting material layer 1201 using the master plate 1500. Pressure is applied to the master plate 1500, thereby transferring the feature shape within one surface of the master plate 1500 to the imprinting material layer to form the first fast axis collimation portion 1202.

[0131] Step S123: Curing and demolding. The curing process is performed according to the type of the imprinting adhesive: when the imprinting material layer 1201 is a UV-curable adhesive, it is cured by UV irradiation; when the imprinting material layer 1201 is a thermosetting adhesive, it is cured by heating. After curing, the master mold 1500 is removed to obtain a substrate with a plurality of first fast-axis collimation portions on the first surface.

[0132] Step S124: Cut the substrate to obtain the fast-axis collimating lens. Specifically, the substrate 1101 is cut with a blade or laser to separate the base 1102 below the different first fast-axis collimating portions 1202, thereby obtaining a single fast-axis collimating lens. The base 1102 of each fast-axis collimating lens is made of glass, and the first fast-axis collimating portion 1202 is made of imprinting adhesive.

[0133] It should be noted that, in other embodiments of the present invention, the forming method further includes: performing the imprinting step multiple times, wherein the refractive index of the imprinted material formed in each imprinting step is different. Multiple imprinting steps are performed to form multiple collimating layers, thereby giving the first fast-axis collimating portion a stacked structure to achieve the effect of multiple lenses (e.g., ...). Figure 10 and Figure 11 (As shown).

[0134] It should also be noted that in some embodiments of the present invention, the base has a second surface opposite to the first surface, and an imprinting step is performed to form a first fast-axis alignment portion located on the first surface of the base and a second fast-axis alignment portion located on the second surface of the base. Specifically, during the imprinting step, while the first fast-axis alignment portion is formed on the first surface of the base, the second fast-axis alignment portion is formed on the second surface of the base. That is, as shown in the figure... Figure 18 As shown, the imprinting material layers on two opposite surfaces of the substrate 2101 are simultaneously imprinted by the first master plate 2501 and the second master plate 2502 to form a first fast axis collimation portion 2202 on one surface of the substrate 2101 and a second fast axis collimation portion 2201 on the other surface of the substrate 2101.

[0135] In summary, in the technical solution of the present invention, the refractive index of the first fast-axis collimating part is different from that of the base. Therefore, the appropriate materials for the first fast-axis collimating part and the base can be selected according to the specific optical path design, thereby effectively improving the flexibility of the setup, breaking through the limitations of the fast-axis collimating lens on the optical path design, and thus helping to reduce the assembly difficulty and improve the collimation effect.

[0136] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A fast-axis collimating lens for semiconductor lasers, characterized in that, The semiconductor laser and the fast-axis collimating lens are used in the optical emission system of a lidar, wherein the fast-axis collimating lens comprises: Base, the base having a first surface; A first fast-axis collimating portion is located on the first surface. The refractive index of the first fast-axis collimating portion is different from that of the base. The first fast-axis collimating portion extends along a second direction. The dimension of the first fast-axis collimating portion along the second direction is larger than the dimension along the first direction. The surface of the first fast-axis collimating portion facing away from the base is a cylindrical surface. The second direction is perpendicular to the first direction. The first fast-axis collimation section is adapted to transmit the beam generated by the semiconductor laser and compress the divergence angle of the beam in a first direction, which is adapted to be parallel to the fast-axis direction of the semiconductor laser.

2. The fast-axis collimating lens as described in claim 1, characterized in that, The surface of the first fast axis collimation part that is opposite to the first surface is a convex surface.

3. The fast-axis collimating lens as described in claim 2, characterized in that, The base also has a second surface disposed opposite to the first surface, and the fast-axis collimating lens further includes: a second fast-axis collimating part, which is located on the second surface, and the refractive index of the second fast-axis collimating part is different from the refractive index of the base.

4. The fast-axis collimating lens as described in claim 3, characterized in that, The surface of the second fast axis collimating part facing away from the base is either convex or concave.

5. The fast-axis collimating lens as described in claim 4, characterized in that, The surface of the second fast axis collimating part facing away from the base is a convex surface, and the radius of curvature of the convex surface of the second fast axis collimating part is greater than the radius of curvature of the convex surface of the first fast axis collimating part.

6. The fast-axis collimating lens as described in claim 4, characterized in that, The surface of the second fast axis collimator facing away from the base is concave, and the refractive index of the second fast axis collimator is greater than that of the first fast axis collimator.

7. The fast-axis collimating lens as described in claim 1, characterized in that, The first fast-axis collimation section includes multiple collimation layers, which form a stacked structure, and adjacent collimation layers have different refractive indices.

8. The fast-axis collimating lens as described in claim 7, characterized in that, The first fast axis collimation section includes a negative collimation layer and a positive collimation layer located sequentially on the first surface. The surface of the negative collimation layer facing the positive collimation layer is concave, and the surface of the positive collimation layer facing the negative collimation layer and the surface away from the negative collimation layer are both convex.

9. The fast-axis collimating lens as described in claim 8, characterized in that, The refractive index of the negative collimator is greater than that of the positive collimator.

10. The fast-axis collimating lens as described in claim 1, characterized in that, The base has a layered structure; the base includes a support layer and at least one optical functional layer.

11. The fast-axis collimating lens as described in claim 10, characterized in that, The optical functional layer includes at least one of the following: a distance adjustment layer, an aperture layer, and a filter layer; The aperture layer includes an ink layer and a light-transmitting hole penetrating the ink layer; the refractive index of the adjustment layer is greater than 1.7 or less than 1.

5.

12. The fast-axis collimating lens as described in claim 1, characterized in that, There are multiple first fast axis collimation sections, and all of the multiple first fast axis collimation sections are located on the first surface.

13. The fast-axis collimating lens as described in claim 12, characterized in that, Multiple first fast axis collimation sections are arranged along a first direction.

14. The fast-axis collimating lens as described in claim 12, characterized in that, Multiple first fast axis collimation sections are arranged in an array with the first direction as the column direction and the second direction as the row direction, and the second direction is perpendicular to the first direction; Along the second direction, there is a gap between adjacent first fast axis collimation portions.

15. A light emitting system for lidar, characterized in that, include: Semiconductor lasers; A fast-axis collimating lens, wherein the fast-axis collimating lens is any one of claims 1 to 14.

16. The optical emitting system as described in claim 15, characterized in that, The distance between the semiconductor laser and the fast-axis collimating lens is related to the refractive index of the first fast-axis collimating portion and the base.

17. The optical emitting system as claimed in claim 15, characterized in that, A plurality of first fast axis collimating portions are arranged along a first direction, and the first fast axis collimating portions extend along a second direction, the second direction being perpendicular to the first direction; The plurality of said semiconductor lasers are arranged with the first direction as the column direction and the second direction as the row direction; Each of the first fast-axis collimation sections corresponds to a row of semiconductor lasers.

18. The optical emitting system as described in claim 15, characterized in that, Multiple first fast axis collimation sections are arranged in an array with the first direction as the column direction and the second direction as the row direction, and the second direction is perpendicular to the first direction; The plurality of said semiconductor lasers are arranged with the first direction as the column direction and the second direction as the row direction; The first fast-axis collimation section corresponds one-to-one with the semiconductor laser.

19. A method for forming a fast-axis collimating lens for a semiconductor laser as described in any one of claims 1 to 14, characterized in that, A base is provided, the base having a first surface; An imprinting step is performed to form the first fast axis collimation portion at least on the first surface of the base; The imprinting step includes: An embossing material layer is formed on the surface of the base; The embossing material layer is embossed using a master plate.

20. The forming method as described in claim 19, characterized in that, Also includes: The imprinting process is performed multiple times, and the refractive index of the imprinted material is different in each imprinting step.

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