Lens, optical component, and method for manufacturing optical component

Abstract

To provide a compact lens which can be easily attached to an optical component and can reduce reflectance, and to provide the optical component and a method for manufacturing the optical component.SOLUTION: A lens according to an embodiment includes a first surface that is a flat surface perpendicular to a first axis extending along a first direction and on which light is incident, and a second surface that is a curved surface and from which the light incident on the first surface is emitted. The second surface has a plurality of protrusions formed in a stripe shape extending along a second direction intersecting the first direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to lenses, optical components, and methods for manufacturing optical components. [Background technology]

[0002] Patent Document 1 describes an optical element equipped with an anti-reflection coating. The anti-reflection coating reduces the reflectance of the optical element for perpendicularly incident light and obliquely incident light. The anti-reflection coating includes a plurality of convex structures formed on at least one light-transmitting surface included in an optical waveguide. The maximum diameter of each convex structure and the space formed between two adjacent convex structures are smaller than the minimum wavelength of any of the visible light. Each convex structure included in the anti-reflection coating has a nano-moth-eye structure that tapers from the bottom to the top. The multiple convex structures are formed by curing using ultraviolet irradiation or heating.

[0003] Patent Document 2 describes an anti-reflective coating. The anti-reflective coating has a support substrate and a moth-eye pattern made of a photoresist material, the dimensions of which increase toward the support substrate. The cross-sectional shape of the moth-eye pattern is a triangle, a trapezoid, or a half ellipse. In a moth-eye pattern, the refractive index is low at the top and high at the bottom. Tapered patterns can be formed by using a resist material with high absorption or a resist material with low dissolution contrast.

[0004] Patent Document 3 describes a glass lens. The glass lens has a moth-eye structure formed on its surface facing the object side by processing an anti-reflection film into a moth-eye structure. The moth-eye structure is composed of an arrangement of multiple pillars formed from the film material of the anti-reflection film. The multiple pillars have a roughly conical shape with rounded apexes, and are arranged across the entire surface of the lens so that the overall shape resembles a moth-eye shape.

[0005] Patent Document 4 describes a light-emitting device including a light-emitting section, a drive circuit, a power supply circuit, and a light-emitting optical system. The light-emitting section is provided inside an LD (Laser Diode) chip. The LD chip includes a substrate, a laminated film, a plurality of light-emitting elements, a plurality of anode electrodes, and a plurality of cathode electrodes. A plurality of lenses are formed on the rear surface of the substrate. The light-emitting device includes a moth-eye structure on the surface of each lens. The moth-eye structure has convex and concave portions, which are randomly formed on the surface of the lens. The moth-eye structure is formed by treating the surface of the lens with a mixed solution containing hydrogen peroxide and ozone.

[0006] Patent Document 5 describes a method for manufacturing an article with a moth-eye pattern. In this manufacturing method, an article including a curved surface in a region where a moth-eye pattern is to be formed is prepared, and an inverted mold on which a moth-eye pattern is formed is also prepared. A film-forming material is applied between the article and the moth-eye pattern on the inverted mold, and then the article is pressed against the inverted mold to form a moth-eye pattern on the article. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 2022-530453 [Patent Document 2] Japanese Patent Application Publication No. 2019-113838 [Patent Document 3] Japanese Patent Application Publication No. 2019-60956 [Patent Document 4] Patent Publication No. 2021-136321 [Patent Document 5] Japanese Patent Application Publication No. 2019-15826 Summary of the Invention [Problem to be solved by the invention]

[0008] However, there are cases where optical components such as optical fibers and lenses attached to optical components are required to be miniaturized. There is a need to attach miniaturized lenses to optical components. Furthermore, there is a need to reduce reflection in miniaturized lenses.

[0009] The present disclosure aims to provide a small lens, an optical component, and a method for manufacturing an optical component that can be easily attached to an optical component and can reduce reflectance. [Means for solving the problem]

[0010] The lens according to the present disclosure includes a first surface, which is a flat surface perpendicular to a first axis extending along a first direction and on which light is incident, and a curved second surface, which emits the light incident on the first surface. The second surface has a plurality of protrusions formed in a stripe pattern extending along a second direction intersecting the first direction. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a small lens that can be easily attached to an optical component and that can reduce reflectance. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view showing an optical component according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing a lens according to the embodiment. [Figure 3] FIG. 3 is a diagram showing a convex portion of the lens according to the embodiment. [Figure 4] FIG. 4 is a diagram showing the formation of a lens by irradiation with laser light from a 3D printer. [Figure 5] FIG. 5 is a perspective view showing an optical component according to a first modified example. [Figure 6] FIG. 6 is a perspective view showing an optical component according to a second modified example. [Figure 7]FIG. 7 is a perspective view showing an optical component according to a third modified example. [Figure 8] FIG. 8 is a cross-sectional perspective view showing a lens according to a fourth modified example. [Figure 9] FIG. 9 is a graph showing an example of the relationship between the spread angle of light, the reflectance, and the light intensity in the case where there are convex portions and in the case where there are no convex portions. [Figure 10] FIG. 10 is a graph showing an example of the relationship between the width and height of the convex portion and the light reflectance. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Description of the embodiments of the present disclosure] First, the contents of the embodiments of the present disclosure will be listed and explained. (1) A lens according to one embodiment includes a first surface, which is a flat surface perpendicular to a first axis extending along a first direction and on which light is incident, and a curved second surface, which emits the light incident on the first surface. The second surface has a plurality of protrusions formed in a stripe pattern extending along a second direction intersecting the first direction.

[0014] This lens has a first surface that is a plane perpendicular to a first axis extending along a first direction. Because the first surface is a plane perpendicular to the first axis, the first surface onto which light is incident can be easily fixed to an optical component, allowing a miniaturized lens to be easily attached to the optical component. A plurality of convex portions are formed in a stripe pattern on the curved second surface, and each of the convex portions extends in a second direction intersecting the first direction. Each of the convex portions formed in a stripe pattern extends in the same direction, and this direction is also referred to as the stripe direction in this application. In other words, the second direction is an example of the stripe direction. By forming a plurality of convex portions extending in the second direction intersecting the first direction in a stripe pattern on the second surface, the reflectance of light at the second surface can be reduced. Therefore, the reflectance can be reduced.

[0015] (2) In (1) above, the cross-sectional shape of the lens perpendicular to the first direction may be a circle, and the diameter of the circle may be 10 μm or more and 100 μm or less. In this case, the lens can be made smaller. Furthermore, the miniaturized lens can be attached to an optical component, and the optical component to which the lens is attached can be made smaller.

[0016] (3) In (1) or (2) above, the light may be polarized, and the second direction may coincide with the polarization direction in which the electric field of the light oscillates. When the electric field of the light oscillates in only one direction, that direction is called the polarization direction. Light in this state is called polarized light. In this way, the light may be polarized, and the convex portions may extend along the polarization direction. For example, the stripe direction may be the same as the polarization direction. In this case, the multiple convex portions formed on the second surface can reduce the reflectance of light on the second surface compared to when the second direction is different from the polarization direction of the light.

[0017] (4) In any of (1) to (3) above, the lens may have an optical axis extending in a direction connecting the center of the first surface and the center of the second surface. The second surface may have a first portion where a divergence angle of light incident on the first surface along the optical axis is equal to or smaller than the Brewster angle and where multiple convex portions are formed, and a second portion where a divergence angle of light incident on the first surface along the optical axis is greater than the Brewster angle and where multiple convex portions are not formed. If convex portions are formed in the second portion of the second surface where a divergence angle of light incident on the first surface is greater than the Brewster angle when the divergence angle of light incident on the first surface is greater than the Brewster angle, the reflectance of light in the second portion may be increased. In contrast, as described above, if no convex portions are formed in the second portion, the reflectance of light in the second portion can be reduced. Therefore, the reflectance of light can be further reduced.

[0018] (5) In any of the above (1) to (4), the reflectance of light on the second surface may be 0.1% or less, which can further reduce the reflectance of light on the second surface.

[0019] (6) An optical component according to the present disclosure is an optical component including the lens described above and an optical component optically coupled to the lens. The lens is fixed to an end face of the optical component where light enters or exits the optical component. For example, when light enters or exits an end face of an optical waveguide provided in the optical component, the lens is fixed to match the position of the end face. Because this optical component includes the lens described above, it achieves the same effects as those described above.

[0020] (7) A method for manufacturing an optical component according to the present disclosure is a method for manufacturing an optical component including the lens described above and an optical component optically coupled to the lens. The manufacturing method includes a step of forming a lens using a 3D printer that irradiates an end face of the optical component with laser light. The step of forming the lens includes a step of moving the laser light along a second direction. In the step of forming the lens, the laser light is irradiated onto an uncured material applied to the end face of the optical component. In the step of forming the lens, the laser light is moved in a direction that matches the direction in which the convex portion extends. This method for manufacturing an optical component forms the lens described above, thereby achieving the same effect as the lens described above. Furthermore, a small lens can be easily formed on the end face of the optical component using a 3D printer. The laser light moves along the second direction when forming the lens. Therefore, a small lens with low reflectance can be easily formed on the end face of the optical component.

[0021] [Details of the embodiments of the present disclosure] Specific examples of lenses, optical components, and methods for manufacturing optical components according to embodiments of the present disclosure will be described below with reference to the drawings. The present disclosure is not limited to the examples below, but is defined by the claims, and is intended to include all modifications within the scope equivalent to the claims. In the description of the drawings, identical or corresponding elements are given the same reference numerals, and redundant description will be omitted as appropriate. For ease of understanding, some parts of the drawings may be simplified or exaggerated, and dimensional proportions and the like are not limited to those shown in the drawings.

[0022] FIG. 1 is a perspective view showing an optical component 1 according to an embodiment. As shown in FIG. 1, the optical component 1 includes a lens 10 to which light is incident and an optical fiber 2 optically coupled to the lens 10. For example, light emitted from the optical fiber 2 is incident on the lens 10. The optical fiber 2 is an example of an optical component. The optical component 1 includes, for example, an optical fiber array 3. The optical fiber array 3 includes, for example, at least one optical fiber 2 and a V-groove substrate 4 having at least one V-groove 4b formed therein, into which the optical fiber 2 is inserted. For example, one optical fiber 2 is fixed in one V-groove 4b. For example, the optical fiber array 3 may further include a holding substrate (not shown), which may hold the optical fiber 2 in the V-groove 4b. In the optical component 1, the optical fiber 2 and the V-groove 4b extend along a first direction D1. The optical component 1 includes a plurality of optical fibers 2, and the V-groove substrate 4 includes a plurality of V-grooves 4b. The plurality of optical fibers 2 and the plurality of V-grooves 4b are aligned along a second direction D2 intersecting the first direction D1. For example, one of the plurality of optical fibers 2 is fixed in one of the plurality of V-grooves 4b. A holding substrate may hold the plurality of optical fibers 2 in the plurality of V-grooves 4b.

[0023] For example, the optical component 1 has a plurality of lenses 10, and the plurality of lenses 10 are lined up along the second direction D2. The plurality of lenses 10 may be arranged in an array. For example, the plurality of lenses 10 may be arranged at regular intervals along the second direction D2. The optical fiber 2 extends along the first direction D1 and has an end face 2b at one end in the first direction D1 to which the lens 10 is fixed. The lens 10 is optically coupled to the core of the optical fiber 2. For example, the lens 10 is fixed to the end face 2b of the optical fiber 2, where the light L enters and exits the optical fiber 2. For example, the lens 10 is fixed to the end face 2b in alignment with the position of the core of the optical fiber 2.

[0024] The end face 2b extends along the second direction D2 and the third direction D3 at one end of the optical fiber 2 in the first direction D1. The end face 2b may be planar extending along the second direction D2 and the third direction D3. The end face 2b has, for example, a circular outer shape. The third direction D3 is a direction intersecting (for example, perpendicular to) both the first direction D1 and the second direction D2. Hereinafter, the direction in which the bottom of the V-groove 4b is located as viewed from the optical fiber 2 placed in the V-groove 4b may be referred to as "down," "lower side," or "downward," and the direction in which the optical fiber 2 is located as viewed from the bottom of the V-groove 4b may be referred to as "upper side," "upward," or "upward." However, these directions are used for convenience of explanation and do not limit the arrangement position or direction of an object.

[0025] Next, the lens 10 will be described in detail. FIG. 2 is a perspective view showing the lens 10. As shown in FIGS. 1 and 2, the lens 10 emits light L. The refractive index of the lens 10 is, for example, 1.4 or more and 1.6 or less. For example, the lens 10 is produced by curing uncured raw material with laser light using a 3D printer. However, the method for producing the lens 10 is not particularly limited and may be a method other than a 3D printer. The lens 10 is made of resin. For example, the lens 10 contains an acrylic resin. The material of the lens 10 may also be glass or silicon.

[0026] The lens 10 has a first surface 11, a second surface 12 facing away from the first surface 11, and a third surface 13 connecting the first surface 11 and the second surface 12. The lens 10 is, for example, columnar. As an example, the lens 10 is cylindrical. The lens 10 is, for example, a small lens small enough to be attached to the end surface 2b of the optical fiber 2. When the first surface 11 is circular, the diameter of the first surface 11 is smaller than the diameter of the end surface 2b. When the lens 10 is cylindrical, the diameter of the lens 10 is equal to the diameter of the first surface 11, which corresponds to the bottom surface of the cylinder. For example, the diameter of the lens 10 is 10 μm or more and 100 μm or less. In the following description, the direction in which light L is emitted may be referred to as the Y direction, the upward direction as the Z direction, and the direction perpendicular to both the Y and Z directions as the X direction. In this case, the Y direction in which light L is emitted may also be referred to as the optical axis direction.

[0027] The first surface 11 is a surface onto which light L is incident from outside the lens 10. For example, the first surface 11 is an incident surface onto which the light L is incident. For example, the light L propagating through the optical fiber 2 is incident on the first surface 11 via the end surface 2b. The first surface 11 is a plane perpendicular to a first axis extending along the Y direction. That is, the first surface 11 is flat (a flat surface). The Y direction is an example of the first direction D1. The first surface 11 extends, for example, along the Z direction and the X direction. The first surface 11 is a surface that can be fixed to the end surface 2b of the optical fiber 2. The first surface 11 is, for example, circular and has a center O1. The third surface 13 extends from the first surface 11 in the Y direction. The third surface 13 extends, for example, along a circumferential direction that is a direction along a ring centered on the first axis. For example, in the lens 10, the third surface 13 has a circular shape in a cross section perpendicular to the first direction D1 or in a cross section parallel to the first surface 11.

[0028] The second surface 12 is, for example, an exit surface from which light L exits. The second surface 12 is curved. The second surface 12 is, for example, aspherical. The second surface 12 has a center O2 when viewed along the Y direction (i.e., in a plan view of the second surface 12). For example, the second surface 12 protrudes in the Y direction. In this case, the lens 10 is a convex lens. For example, the distance between the center of the second surface 12 and the first surface 11 is greater than the length of the third surface 13 in the Y direction. For example, the lens 10 may be a condensing lens that condenses light L incident on the first surface 11 before emitting it from the second surface 12. Alternatively, the lens 10 may be a collimating lens that converts light L incident on the first surface 11 into parallel light before emitting it from the second surface 12. However, the lens 10 may also be a concave lens, in which case the second surface 12 is recessed in the direction opposite to the Y direction. In this case, the distance between the center of the second surface 12 and the first surface 11 is shorter than the length of the third surface 13 in the Y direction. For example, a lens 10 configured as a concave lens emits light L as diffused light. The lens 10 has an optical axis extending along a straight line connecting the center O1 of the first surface 11 and the center O2 of the second surface 12. The direction in which the optical axis extends is also referred to as the optical axis direction. The first direction D1 may be the same as the optical axis direction. When light L enters the first surface 11 along the optical axis, it is emitted from the second surface 12 along the optical axis. In this case, the light L has the same optical axis as the optical axis of the lens 10. Note that, for example, if the second surface 12 is spherical, the center O2 may be the center of curvature. The second surface 12 has multiple convex portions 12c each extending in a direction intersecting the first direction D1.

[0029] For example, each of the multiple convex portions 12c extends along the Z direction in a plan view of the second surface 12. Each of the multiple convex portions 12c is aligned along the X direction in a plan view of the second surface 12. A gap 12b is provided between two adjacent convex portions 12c. That is, each of the multiple convex portions 12c is separated by a corresponding one of the multiple gaps 12b. In this manner, the multiple convex portions 12c are arranged in a striped pattern. The multiple convex portions 12c formed in a striped pattern on the second surface 12 of the lens 10 form, for example, a metamaterial structure in which the refractive index of light passing through the lens 10 gradually changes along the Y direction. The multiple convex portions 12c forming the metamaterial structure are a reflection reduction structure that reduces reflection of light L passing through the lens 10. The reflectance of the lens 10 (second surface 12) is, for example, 0.1% or less.

[0030] FIG. 3 is an enlarged view of the multiple protrusions 12c as viewed along the Z direction. As shown in FIGS. 2 and 3, the protrusions 12c are, for example, rectangular when viewed along the Z direction. However, the shape of the protrusions 12c as viewed along the Z direction may be rectangular with rounded outer corners or, for example, semi-elliptical, and is not limited to a shape with angular corners. For example, the second surface 12 is curved to protrude in the Y direction. The second surface 12 has a gap 12b formed between two protrusions 12c aligned along the curved surface in the X direction. The gap 12b is also referred to as a recess. Each of the multiple protrusions 12c is separated from the other by a gap 12b. The second surface 12 has multiple protrusions 12c, and the protrusions 12c and the gaps 12b are alternately arranged in this order on the second surface 12 in the X direction. The shape of the bottom of the void 12b when viewed along the Z direction may be rounded, for example, similar to the shape of the outer corner of the protrusion 12c when viewed along the Z direction. In this case, for example, the protrusion 12c may have a rounded convex shape on the second surface 12, and the void 12b may have a rounded concave shape on the second surface 12. On the surface of the second surface 12, the multiple protrusions 12c and the multiple voids 12b form periodic unevenness along the X direction.

[0031] For example, the height H of the protrusion 12c (depth of the void 12b) is 200 nm or more and 500 nm or less. The height H of the protrusion 12c refers to the length of the protrusion 12c from the bottom of the void 12b in a direction perpendicular to the bottom of the void 12b. The protrusion 12c is provided on the second surface 12, and if the outer corners of the protrusion 12c are rounded, the height H of the protrusion 12c may be the distance from the second surface 12 to the portion of the protrusion 12c that protrudes most from the second surface 12 (for example, the apex). The width W of the protrusion 12c is, for example, 200 nm or more and 600 nm or less. The width W of the protrusion 12c refers to the length of the protrusion 12c in a direction parallel to the direction in which the bottom of the void 12b extends when viewed along the Z direction. The width W of each protrusion 12c can be measured as the distance between two voids 12b sandwiching one protrusion 12c. For example, if the bottoms of the voids 12b are rounded, the distance between the voids 12b may be measured at half the height H of the protrusions 12c. The multiple protrusions 12c are arranged at equal intervals on the second surface 12 along the X direction. In this case, the period T of the multiple protrusions 12c is, for example, 400 nm or more and 1000 nm or less. The period T of the multiple protrusions 12c refers to the distance from the center of one protrusion 12c in a direction parallel to the extension direction of the bottom surfaces of the voids 12b when viewed along the Z direction to the center of the adjacent protrusion 12c in that direction. The period T is equal to the sum of the width W of the protrusions 12c and the width of the voids 12b.

[0032] Next, an example of a method for manufacturing an optical component according to this embodiment will be described. An example of a method for manufacturing an optical component 1 including a lens 10 and an optical fiber 2, which is an optical component, will be described below. As an example, an optical fiber array 3 is fabricated by preparing a V-groove substrate 4 having a V-groove 4b formed therein and placing optical fibers 2 in the V-groove 4b. Then, a lens 10 is formed on the end face 2b of the optical fiber 2. In the optical fiber array 3, a plurality of optical fibers 2 are placed at regular intervals in the direction in which the plurality of optical fibers 2 are arranged.

[0033] As described above, for example, the lens 10 is formed on the end face 2b by a 3D printer. As schematically shown in FIG. 4, the 3D printer forms the lens 10 on the end face 2b by, for example, moving the laser beam A using a condenser lens R to continuously form a cured region B of the raw material (e.g., resin) of the lens 10 on the end face 2b in three dimensions. The raw material of the lens 10 is applied to the end face 2b in an uncured state. When the uncured raw material is heated and cured by irradiation with the laser beam A, the lens 10 is fixed on the end face 2b by the curing. The cured region B has an elliptical shape with a major axis extending along the Z1 direction. The Z1 direction is the traveling direction of the laser beam A and is the optical axis direction of the condenser lens R. The width (length of the minor axis) of the cured region B is, for example, 400 nm, and the length (length of the major axis) of the cured region B is 1200 nm. The hardened region B intersects with the Z1 direction and has a minor axis in at least one of the X1 direction and the Y1 direction which intersect with each other.

[0034] As described above, a lens 10 is formed on the end surface 2b by moving the laser beam A on the end surface 2b using a 3D printer to continuously form hardened regions B in three dimensions (a process of forming a lens using a 3D printer). In forming the lens 10, the projections 12c on the second surface 12 are formed by moving the irradiated laser beam A. At this time, the 3D printer moves the laser beam A in a direction that coincides with the direction in which stripes formed by the multiple projections 12c extend (stripe direction). For example, the 3D printer irradiates the laser beam A toward the second surface 12 along the Z1 direction. By moving the laser beam A in either the X1 direction or the Y1 direction to continuously form hardened regions B in the stripe direction, the width W of the projections 12c can be reduced according to the length (width) of the hardened regions B in the minor axis direction. When the uncured raw material of lens 10 is cured by irradiation with laser light A to form multiple convex portions 12c on second surface 12, voids 12b are formed by forming one convex portion 12c adjacent to another convex portion 12c at a distance. In this way, second surface 12, on which convex portions 12c and voids 12b are formed in an alternating striped pattern, is formed by the 3D printer, and then lens 10 is completed, completing the series of steps in the method for manufacturing optical component 1.

[0035] Next, the effects obtained from the lens 10, optical component 1, and manufacturing method of the optical component according to this embodiment will be described. In the lens 10, optical component 1, and manufacturing method of the optical component according to this embodiment, the lens 10 has a first surface 11 that is a plane perpendicular to a first axis extending along a first direction D1. Because the first surface 11 is a plane perpendicular to the first axis, the first surface 11 can be easily fixed to the end surface 2b of the optical fiber 2, making it possible to easily attach a miniaturized lens 10 to the optical fiber 2. For example, if the end surface 2b is flat, the first surface 11 can be easily attached by making the first surface 11 a plane facing the flat end surface 2b. The first axis may be the optical axis of the lens 10. Note that if the end surface 2b has irregularities, the first surface 11 may be provided with irregularities that match the irregularities so that the end surface 2b and the first surface 11 are in close contact with each other. The curved second surface 12 has a plurality of protrusions 12c formed thereon, each of which extends in a striped pattern in a direction intersecting the optical axis. A metamaterial structure is formed by forming a plurality of protrusions 12c extending in a direction intersecting the optical axis in a striped pattern on the second surface 12, each spaced apart by gaps 12b, and this reduces the reflectance of light L on the second surface 12. Therefore, the reflectance can be reduced.

[0036] As mentioned above, the diameter of lens 10 may be 10 μm or more and 100 μm or less. In this case, lens 10 can be made smaller. Because the diameter of first surface 11 of lens 10 is smaller than the diameter of end face 2b of optical fiber 2, lens 10 can be easily attached to optical fiber 2. Furthermore, the optical component 1 in which lens 10 is attached to optical fiber 2 can be made smaller. As mentioned above, the reflectance of light L at second surface 12 may be 0.1% or less. In this case, the reflectance of light L at second surface 12 can be further reduced.

[0037] The method for manufacturing an optical component according to this embodiment makes it possible to easily form the lens 10 on the end face 2b of the optical fiber 2 using a 3D printer. When forming the lens 10, the laser light A irradiated onto the second surface 12 is moved in a direction (e.g., the Z direction) that coincides with the direction in which the convex portions 12c extend in a stripe shape. Therefore, a small lens 10 with low reflectance can be easily formed on the end face 2b of the optical fiber 2.

[0038] Next, lenses, optical components, and methods for manufacturing optical components according to modified examples will be described. Some of the lenses, optical components, and methods for manufacturing optical components according to each modified example described below are the same as the lens 10, optical component 1, and methods for manufacturing optical components according to the above-described embodiment. Therefore, in the following description, descriptions that overlap with the methods for manufacturing lens 10, optical component 1, and optical components described above will be omitted as appropriate.

[0039] FIG. 5 is a perspective view showing an optical component 1A according to a first modification. As shown in FIG. 5, the optical component 1A includes a lens 10 and an optical semiconductor element 2A optically coupled to the lens 10. The optical semiconductor element 2A is an example of an optical component. The optical semiconductor element 2A includes, for example, a laser diode (LD). The optical semiconductor element 2A may include at least one of an optical modulator and a semiconductor optical amplifier. The optical semiconductor element 2A includes, for example, a compound semiconductor such as indium phosphide (InP). The optical semiconductor element 2A is capable of emitting an optical signal and has an end face 2d that intersects with a substrate surface 2c of the optical semiconductor element 2A. A lens 10 is formed on the end face 2d. For example, a first surface 11 of the lens 10 is in contact with the end face 2d. For example, the light L is polarized light, and the stripes of the multiple convex portions 12c extend along the polarization direction of the light L. The light L is polarized light in which the electric field oscillates in only one direction, and the direction in which the electric field oscillates is called the polarization direction. "Vertical" in Fig. 5 shows an example in which the polarization direction is the Z direction, and "horizontal" in Fig. 5 shows an example in which the polarization direction is the X direction. In "vertical" in Fig. 5, the stripe direction of the multiple protrusions 12c is along the Z axis, and in "horizontal" in Fig. 5, the stripe direction of the multiple protrusions 12c is along the X axis.

[0040] A method for manufacturing the optical component 1A will now be described. The method for manufacturing the optical component 1A when the polarization direction of the light L is the Z direction is the same as the method for manufacturing the optical component 1 described above. When the polarization direction of the light L is the X direction, the optical semiconductor element 2A is erected so that the substrate surface 2c extends along the X direction and the Z direction (step of erecting the optical component). With the optical semiconductor element 2A erected in this manner, uncured raw material (e.g., resin) of the lens 10 is applied to the end face 2d, and a 3D printer irradiates the raw material on the end face 2d with laser light A (step of irradiating laser light). At this time, the laser light A is irradiated along the Z direction.

[0041] Then, by irradiating end face 2d with laser light A, hardened region B is continuously formed in three dimensions from the unhardened raw material, thereby forming lens 10 on end face 2d (a process of forming a lens using a 3D printer). At this time, second surface 12 having convex portions 12c parallel to substrate surface 2c is formed by irradiating end face 2d with laser light A. After multiple convex portions 12c having a stripe direction parallel to substrate surface 2c are formed on second surface 12, the formation of lens 10 on optical semiconductor element 2A is completed. Then, optical semiconductor element 2A is tilted so that substrate surface 2c faces the Z direction, just as it did before the process of erecting the optical component, and the series of processes in the method of manufacturing optical component 1A is completed.

[0042] As described above, in the optical component 1A, a plurality of convex portions 12c are formed in a stripe pattern on the curved second surface 12, and each of the plurality of convex portions 12c extends in a direction intersecting the first axis. Therefore, in the optical component 1A, similar to the optical component 1 described above, a metamaterial structure is formed by the plurality of convex portions 12c extending in a direction intersecting the first axis being formed in a stripe pattern on the second surface 12, and the reflectance of light L at the second surface 12 can be reduced. Furthermore, the light L is polarized light, and the stripes formed by the plurality of convex portions 12c extend along the polarization direction. Therefore, the plurality of convex portions 12c formed in a stripe pattern on the second surface 12 can reduce the reflectance of light L at the second surface 12.

[0043] FIG. 6 is a perspective view showing an optical component 1B according to a second modification. As shown in FIG. 6, the optical component 1B includes a lens 10 and a silicon photonics device 2B optically coupled to the lens 10. The silicon photonics device 2B is an example of an optical component. The silicon photonics device 2B has an optical waveguide 2f formed on its upper surface, extending in both the X and Y directions. The silicon photonics device 2B has an end face 2h that intersects with the upper surface and to which the lens 10 is fixed. The end face 2h extends in both the X and Z directions. The lens 10 fixed to the end face 2h is optically coupled to the optical waveguide 2f. For example, the lens 10 is fixed to the end face 2h so that the position of the optical waveguide 2f on the end face 2h coincides with the center O1 of the first surface 11 of the lens 10. The manufacturing method of the optical component 1B is the same as the manufacturing method of the optical component 1A described above.

[0044] FIG. 7 is a perspective view showing an optical component 1C according to a third modification. The optical component 1C includes a lens 10 and a polarization-maintaining fiber 2C. The polarization-maintaining fiber 2C is an example of an optical component. The polarization-maintaining fiber 2C has an end face 2j to which the lens 10 is fixed and a pair of stress-applying portions 2k exposed at the end face 2j. The end face 2j, for example, emits light propagating through the polarization-maintaining fiber 2C along the Y direction. The shape of the stress-applying portions 2k exposed at the end face 2j is, for example, circular, but is not particularly limited. The axis along the arrangement direction of the pair of stress-applying portions 2k is the slow axis ZS, and the axis perpendicular to the slow axis ZS is the fast axis ZF. For example, the slow axis ZS extends along the Z direction, and the fast axis ZF extends along the X direction. The lens 10 fixed to the end face 2j is optically coupled to the core of the polarization-maintaining fiber 2C. For example, lens 10 is fixed to end face 2j so that the position of the core on end face 2j coincides with center O1 of first surface 11 of lens 10. The method for manufacturing optical component 1C is the same as the method for manufacturing optical component 1A described above.

[0045] FIG. 8 is a cross-sectional perspective view showing a lens 10A according to a fourth modification. As shown in FIG. 8, the lens 10A has a first surface 11 and a second surface 12A that is curved and extends convexly from the first surface 11 in the Y direction. The lens 10A does not have the third surface 13 of the lens 10 described above. The second surface 12A is formed and connected to the first surface 11. The surface of the lens 10A is composed of the first surface 11 and the second surface 12A. The curvature of the second surface 12A is greater than the curvature of the second surface 12 of the lens 10. For example, the second surface 12A is aspherical. However, the shape of the second surface 12A is closer to a sphere than the shape of the second surface 12. The second surface 12A may also be spherical. The first surface 11 has a center O1. For example, if the first surface 11 is circular, the center O1 is the center point of the circle. The second surface 12A has a center O2. For example, when second surface 12A is circular when viewed along the Y direction, center O2 is the center point of the circle. Lens 10A has an optical axis OA that is a straight line passing through centers O1 and O2.

[0046] The second surface 12A has a first portion 12p where protrusions 12c are formed in a stripe pattern, and a second portion 12q where no protrusions 12c are formed. The first portion 12p is a region of the second surface 12A where the spread angle θ of light L, which is incident on the first surface 11 along the optical axis OA and spreads inside the lens 10A, is equal to or smaller than the Brewster's angle. The second portion 12q is a region of the second surface 12A where the spread angle θ of light L, which is incident on the first surface 11 along the optical axis OA and spreads inside the lens 10A, is greater than the Brewster's angle.

[0047] FIG. 9 is a graph showing the relationship between the product (n×sinθ) of the divergence angle θ and the refractive index n and the reflectance at second surface 12A for the case where protrusions 12c formed in a stripe pattern are provided (with protrusions) and the case where protrusions 12c are not provided (without protrusions), and also the relationship between n×sinθ and the light intensity of light emitted from lens 10A. The reflectance represents the ratio of the light intensity of light reflected by second surface 12A to the light intensity of light incident on first surface 11 within lens 10A. In FIG. 9, the value of n is 1.53. As shown in FIGS. 8 and 9, when n×sinθ is 1.0 or less (e.g., θ is 40° or less), the reflectance at second surface 12A can be reduced more when protrusions 12c formed in a stripe pattern are provided than when protrusions 12c are not provided.

[0048] However, when n × sin θ exceeds 1.0, the reflectance at second surface 12A can be reduced more effectively when no convex portions 12c are provided than when striped convex portions 12c are provided. Therefore, in lens 10A, the reflectance of light L at second surface 12A can be further reduced by not providing convex portions 12c in second portion 12q of second surface 12A, where divergence angle θ is greater than the Brewster angle.

[0049] As described above, in lens 10A, second surface 12A has first portion 12p, in which convex portions 12c are formed in a stripe pattern, and in which the spread angle θ of light L incident on first surface 11 along optical axis OA when light L spreads inside lens 10A is equal to or smaller than the Brewster angle, and second portion 12q, in which the spread angle θ of light L when light L incident on first surface 11 along optical axis OA when light L spreads inside lens 10A is greater than the Brewster angle and in which convex portions 12c are not formed. When convex portions 12c are formed in a stripe pattern in second portion 12q of second surface 12A, the spread angle θ of light L when light L incident on first surface 11 when light L spreads inside lens 10A is greater than the Brewster angle, the reflectance of light L at second portion 12q may be increased. In contrast, as described above, when convex portions 12c are not formed in second portion 12q, the reflectance of light L at second portion 12q can be reduced. Therefore, the reflectance of the light L can be further reduced.

[0050] Next, examples of lenses according to the present disclosure will be described. Note that the present disclosure is not limited to the following examples. In the examples, an analysis was performed to verify the width W, height H, and period T of the convex portions 12c of a lens 10 having the convex portions 12c shown in FIG. 3. Note that the distance between two adjacent convex portions 12c (the width of the gap 12b) is the period T minus the width W. In the examples, the reflectance of the second surface 12 was analyzed when light L having a peak wavelength λ of 1550 nm was incident on the first surface 11 of the lens 10 from the core of the optical fiber 2. The refractive index of the core of the optical fiber 2 was set to 1.44, and the refractive index n of the lens 10 was set to 1.53.

[0051] As a result of the above analysis, when the period T is λ / n or more, for example, when the period T is 1000 nm or more, loss due to diffraction occurs. On the other hand, it was found that when the period T is λ / n or less (1000 nm or less), light loss due to diffraction at the second surface 12 can be reduced. Figure 10 is a graph showing the reflectance of the second surface 12 according to the width W and height H when the period T is 800 nm. In the graph of Figure 10, the darker the color, the lower the reflectance, and the lighter the color, the higher the reflectance.

[0052] As shown in FIG. 10, the reflectance at second surface 12 can be further reduced when width W is 300 nm or more and 700 nm or less and height H is 250 nm or more and 450 nm or less. As an example, the reflectance at second surface 12 can be further reduced when period T is approximately 800 nm, width W is approximately 470 nm, and height H is approximately 360 nm. Furthermore, it has been found that the reflectance at second surface 12 can be further reduced when height H is λ / 6 or more and λ / 3. Even when the peak wavelength λ is other than 1550 nm, the reflectance at second surface 12 can be reduced in the same manner as in the case of the peak wavelength λ being 1550 nm by appropriately setting the period T, width W, and height H of the stripe shape according to the peak wavelength λ of light transmitted through lens 10 and the refractive index n of lens 10.

[0053] The above describes embodiments, various modifications, and examples of the lenses, optical components, and manufacturing methods for optical components according to the present disclosure. However, the lenses, optical components, and manufacturing methods for optical components according to the present disclosure are not limited to the above-described embodiments, modifications, or examples, and may be further modified within the scope of the gist described in the claims. In other words, the configuration, shape, size, material, number, and arrangement of each part of the lenses and optical components according to the present disclosure, as well as the content and order of the steps in the manufacturing method for optical components, can be modified as appropriate within the scope of the above-described gist. [Explanation of symbols]

[0054] 1, 1A, 1B, 1C...Optical components 2...Optical fiber (optical component) 2A...Optical semiconductor elements (optical components) 2b...end face 2B...Silicon photonics element (optical component) 2c...Board surface 2C...Polarization-maintaining fiber (optical component) 2d...end face 2f...Optical waveguide 2h,2j…end face 2k...Stress applying section 3...Optical fiber array 4...V-groove substrate 4b…V groove 10,10A...lens 11...Side 1 12,12A…Second side 12b...Void 12c...Convex part 12p…first part 12q…Second part 13...Third side A...Laser light B…Curing area L…Light O1, O2…center OA…Optical axis R...Condenser lens ZS...Slow axis ZF...fast shaft

Claims

1. a first surface that is a plane perpendicular to a first axis extending along a first direction and on which light is incident; a second surface that is curved and that emits the light that has entered the first surface; Equipped with the second surface has a plurality of protrusions formed in a stripe shape extending along a second direction intersecting the first direction; lens.

2. a cross-sectional shape of the lens perpendicular to the first direction is a circle, The diameter of the circle is 10 μm or more and 100 μm or less. The lens of claim 1 .

3. the light is polarized; The second direction coincides with the polarization direction in which the electric field of the light oscillates. The lens according to claim 1 or claim 2.

4. the lens has an optical axis extending in a direction connecting the center of the first surface and the center of the second surface, The second surface is a first portion in which a spread angle of the light incident on the first surface along the optical axis and spreads inside the lens is equal to or smaller than the Brewster angle, and in which a plurality of the convex portions are formed; a second portion in which a spread angle of the light incident on the first surface along the optical axis when the light spreads inside the lens is larger than the Brewster angle, and in which the plurality of convex portions are not formed, The lens according to claim 1 or claim 2.

5. the reflectance of the light on the second surface is 0.1% or less; The lens according to claim 1 or claim 2.

6. The lens according to claim 1 or 2; an optical component optically coupled to the lens; An optical component comprising: The lens is fixed to an end surface of the optical component through which light enters and exits the optical component. Optical components.

7. The lens according to claim 1 or 2; an optical component optically coupled to the lens; A method for manufacturing an optical component comprising: forming the lens by a 3D printer that irradiates a laser beam onto an end surface of the optical component; the step of forming the lens includes the step of moving the laser beam along the second direction. Manufacturing method for optical components.

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