Glass component and method for manufacturing glass component

Abstract

To provide a glass component that can change the mode field diameter of light propagating through an optical waveguide and reduce optical loss.SOLUTION: A glass component comprises an optical waveguide. The optical waveguide is provided inside a glass substrate and has a first end and a second end on the opposite side of the first end. The optical waveguide includes a plurality of reformed areas arranged side by side in a direction intersecting an optical waveguide direction, and an aggregate of the plurality of reformed areas forms the optical waveguide. The optical waveguide includes the plurality of reformed areas to have a refractive index higher than the refractive index of an area around the optical waveguide. The center-to-center interval of the plurality of reformed areas at the first end is larger than the center-to-center interval of the plurality of reformed areas at the second end. The average refractive index of the optical waveguide at the first end is smaller than the average refractive index of the optical waveguide at the second end. The mode field diameter of the optical waveguide in the arrangement direction of the plurality of reformed areas at the first end is larger than the mode field diameter of the optical waveguide in the arrangement direction of the plurality of reformed areas at the second end.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to glass components and methods for making glass components. [Background technology]

[0002] Patent Document 1 discloses a technique for forming an optical waveguide by irradiating a glass plate with a laser beam having a pulse width on the order of femtoseconds. Patent Document 1 also discloses that the region in which the refractive index increases can be expanded by irradiating the glass plate with multiple rows of laser beams. Non-Patent Document 1 discloses providing a low refractive index portion called a "tapered structure" on the side of the optical waveguide in order to change the refractive index difference of the optical waveguide formed using a laser beam having a pulse width on the order of femtoseconds. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2020 / 0109084 [Non-patent literature]

[0004] [Non-Patent Document 1] Zhengming Liu et al., "Fabrication of an OpticalWaveguide-Mode-Field Compressor in Glass Using a Femtosecond Laser" Materials,Volume 11, No.1926, 2018 Summary of the Invention [Problem to be solved by the invention]

[0005] It is sometimes necessary to mutually couple two optical waveguides with different widths. For example, with the recent advances in optical circuit technology (silicon photonics), there is a demand for coupling an optical fiber to an optical waveguide on a silicon substrate. Since the mode field diameter of light propagating through an optical waveguide on a silicon substrate is different from that of light propagating through an optical fiber, it is desirable to change the mode field diameter of the propagating light in order to efficiently couple them.

[0006] In this regard, a technique for forming an optical waveguide by irradiating a glass substrate with a laser beam having a pulse width on the order of femtoseconds is known. For example, using the technique described in Non-Patent Document 1, the mode field diameter of propagating light can be changed by changing the refractive index difference of the optical waveguide in the optical waveguiding direction. However, the technique described in Non-Patent Document 1 has the problem that the loss of propagating light increases in the region where the electric field of the propagating light overlaps with the tapered structure. It is presumed that the tapered structure is formed by destroying the glass structure with a high-intensity laser beam. Therefore, when the propagating light comes into contact with the tapered structure, scattering occurs there, leading to optical loss.

[0007] An object of the present disclosure is to provide a glass component and a method for manufacturing the glass component that can change the mode field diameter of light propagating through an optical waveguide and reduce optical loss. [Means for solving the problem]

[0008] A glass component according to an embodiment of the present disclosure includes an optical waveguide therein, the optical waveguide having a first end and a second end opposite the first end. The optical waveguide includes a plurality of modified regions aligned in a direction intersecting the optical waveguiding direction, and the aggregate of the plurality of modified regions forms the optical waveguide. Due to the presence of the plurality of modified regions, the optical waveguide has a refractive index higher than that of the region surrounding the optical waveguide. The center-to-center spacing of the plurality of modified regions at the first end is greater than the center-to-center spacing of the plurality of modified regions at the second end. The average refractive index of the optical waveguide at the first end is smaller than that of the optical waveguide at the second end. The mode field diameter of the optical waveguide at the first end in the direction of alignment of the plurality of modified regions is greater than the mode field diameter of the optical waveguide at the second end in the direction of alignment of the plurality of modified regions. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a glass component and a method for manufacturing a glass component that can change the mode field diameter of light propagating through an optical waveguide and reduce optical loss. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a top view showing a glass component according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a front view showing an end face of the glass component 1. As shown in FIG. [Figure 3] FIG. 3 is a rear view showing an end face of the glass member 1. As shown in FIG. [Figure 4] FIG. 4 is a diagram showing a process for forming a plurality of modified regions. [Figure 5] FIG. 5 is a graph showing the relationship between the refractive index difference (%) between an actually fabricated optical waveguide and its surroundings and the center-to-center spacing of modified regions (scan pitch, μm). [Figure 6] FIG. 6 is a micrograph showing a plurality of modified regions that were actually fabricated and etched with hydrofluoric acid. [Figure 7] FIG. 7 is a side view showing a glass component according to a modified example of the above embodiment. [Figure 8]FIG. 8 is a front view showing an end face of the glass component. [Figure 9] FIG. 9 is a rear view showing the end face of the glass component. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Description of the embodiments of the present disclosure] First, the details of the embodiments of the present disclosure will be listed and described. [1] A glass component according to one embodiment of the present disclosure includes a glass substrate and an optical waveguide provided inside the glass substrate, the optical waveguide having a first end and a second end opposite the first end. The optical waveguide includes a plurality of modified regions aligned in a direction intersecting the optical waveguiding direction, and the aggregate of the plurality of modified regions forms the optical waveguide. Due to the inclusion of the plurality of modified regions, the optical waveguide has a refractive index higher than that of the region surrounding the optical waveguide. The center-to-center spacing of the plurality of modified regions at the first end is greater than the center-to-center spacing of the plurality of modified regions at the second end. The average refractive index of the optical waveguide at the first end is smaller than the average refractive index of the optical waveguide at the second end. The mode field diameter of the optical waveguide at the first end in the direction of alignment of the plurality of modified regions is greater than the mode field diameter of the optical waveguide at the second end in the direction of alignment of the plurality of modified regions.

[0012] In this glass component, the center-to-center spacing of the multiple modified regions at the first end is greater than the center-to-center spacing of the multiple modified regions at the second end. As the center-to-center spacing of the multiple modified regions increases, the width of the optical waveguide increases, while the density of the modified regions decreases, resulting in a lower average refractive index. Furthermore, as the center-to-center spacing of the multiple modified regions decreases, the width of the optical waveguide decreases, while the density of the modified regions increases, resulting in a higher average refractive index. Therefore, with this glass component, the mode field diameter of guided light at the first end can be made larger than the mode field diameter of guided light at the second end. Furthermore, this glass component does not require scattering elements present around the optical waveguide, such as the tapered structure disclosed in Non-Patent Document 1. Therefore, with this glass component, the mode field diameter of light propagating through the optical waveguide can be changed and optical loss can be reduced.

[0013] [2] In the glass component of [1] above, the modified regions may be arranged one-dimensionally in a cross section perpendicular to the optical waveguide direction at the first end, and the modified regions may be arranged two-dimensionally in a cross section perpendicular to the optical waveguide direction at the second end. In this case, the degree of freedom in the cross-sectional shape of the optical waveguide can be increased.

[0014] [3] In the glass component of [1] above, the modified regions may be arranged one-dimensionally in a cross section perpendicular to the optical waveguide direction at the second end, and the modified regions may be arranged two-dimensionally in a cross section perpendicular to the optical waveguide direction at the first end. In this case, the degree of freedom in the cross-sectional shape of the optical waveguide can be increased.

[0015] [4] In the glass components [1] to [3] above, the ratio (P1 / P2) of the center-to-center spacing P1 of the plurality of modified regions at the first end to the center-to-center spacing P2 of the plurality of modified regions at the second end may be 1.0 or more and 4.0 or less. The glass component [1] above allows for the center-to-center spacing to vary within this range, for example.

[0016] [5] A method for manufacturing a glass component according to an embodiment of the present disclosure is a method for manufacturing a glass component including an optical waveguide therein, the optical waveguide having a first end and a second end opposite the first end, and includes a step of forming, within a glass substrate, a plurality of modified regions aligned in a direction intersecting the optical waveguiding direction of the optical waveguide. A collection of the plurality of modified regions forms the optical waveguide. In the forming step, the plurality of modified regions are formed by repeating a step of focusing a laser beam having a pulse width on the order of femtoseconds at a focal point within the glass substrate while moving the focal point in the optical waveguiding direction, while shifting the focal point position, multiple times. In the forming step, the center-to-center spacing of the plurality of modified regions at the first end is set larger than the center-to-center spacing of the plurality of modified regions at the second end. This manufacturing method, like the glass component described in [1] above, can change the mode field diameter of light propagating through the optical waveguide and reduce optical loss.

[0017] [Details of the embodiments of the present disclosure] Specific examples of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. In the following description, the same elements in the description of the drawings will be given the same reference numerals, and duplicate explanations will be omitted.

[0018] [First embodiment] Fig. 1 is a top view showing a glass component 1 according to a first embodiment of the present disclosure. Fig. 2 is a front view showing an end face 22 of the glass component 1. Fig. 3 is a rear view showing an end face 23 of the glass component 1. An XYZ Cartesian coordinate system is shown in these figures for ease of understanding.

[0019] The glass component 1 includes a glass substrate 20 and an optical waveguide 10. The glass substrate 20 is, for example, plate-shaped or rectangular parallelepiped-shaped and has a top surface 21, end surfaces 22, and end surfaces 23. The top surface 21, end surfaces 22, and end surfaces 23 are, for example, flat surfaces. The top surface 21 has a planar shape, for example, a rectangle. The end surfaces 22 and 23 are aligned in a direction along the long side of the top surface 21 (X direction) and are oriented opposite to each other. The end surfaces 22 and 23 may be parallel to each other or may be inclined relative to each other. The end surfaces 22 and 23 may be perpendicular to the top surface 21 or may be inclined relative to the top surface 21. The material of the glass substrate 20 is, for example, quartz glass, alkali-free glass (e.g., EAGLE XG (registered trademark)), or borosilicate glass (e.g., BOROFLOAT (registered trademark)).

[0020] The optical waveguide 10 is a core formed inside the glass substrate 20 (i.e., inside the glass component 1). The optical waveguide 10 extends in a direction (X direction) along the long side of the top surface 21 and propagates light in that direction. The optical waveguide 10 has a first end 11 and a second end 12 opposite the first end 11. The first end 11 is included in an end surface 22 of the glass substrate 20. The second end 12 is included in an end surface 23 of the glass substrate 20. That is, the optical waveguide 10 reaches both the end surface 22 and the end surface 23. The optical waveguide 10 may guide light from the first end 11 to the second end 12, or may guide light from the second end 12 to the first end 11. Although one optical waveguide 10 is shown in the figure, the glass component 1 may include multiple optical waveguides 10. However, the present invention is not limited to this example, and the optical waveguide 10 does not necessarily have to reach at least one of the end faces 22 and 23 .

[0021] The optical waveguide 10 includes multiple modified regions 13. While six modified regions 13 are shown in the figure, the number of modified regions 13 is not limited to this. Each of the multiple modified regions 13 is a refractive index change region having a refractive index higher than that of the surrounding glass substrate 20. Each of the multiple modified regions 13 is a laser-processed region formed by focusing and scanning a laser beam having an extremely short time width, for example, on the order of femtoseconds, inside the glass substrate 20 to modify the glass through multiphoton absorption. When modified regions are formed by such a method, the cross-sectional shape of the modified region tends to extend elongatedly in the direction of incidence of the laser beam. In this embodiment, since the laser beam is incident from the top surface 21 as described below, the cross-sectional shape of each modified region 13 extends elongatedly in the normal direction (Z direction) of the top surface 21. Note that although the cross-sectional shape of each modified region 13 is depicted as a rectangle in the figure, it may also be an oval or ellipse. Furthermore, since the multiple modified regions 13 have approximately the same length in the Z direction, an optical waveguide 10 with a rectangular cross section is formed. The width of each modified region 13 in the Y direction is, for example, 0.1 μm or more and 1.0 μm or less. The width of each modified region 13 in the Z direction is, for example, 1.0 μm or more and 10.0 μm or less.

[0022] The multiple modified regions 13 are aligned in a direction intersecting the optical waveguide direction. The figure illustrates an example in which the multiple modified regions 13 are aligned in a row in the Y direction along the upper surface 21, but the multiple modified regions 13 may also be arranged two-dimensionally in a plane perpendicular to the optical waveguide direction (X direction). The optical waveguide 10 is formed by an aggregate of multiple modified regions 13. In other words, a bundle of multiple modified regions 13 forms one optical waveguide 10. By including multiple modified regions 13, the optical waveguide 10 has a refractive index higher than the refractive index of the region (cladding) surrounding the optical waveguide 10.

[0023] The multiple modified regions 13 are arranged at equal intervals in a cross section at any position in the optical waveguide direction. 2 and 3, the center-to-center spacing P1 of the multiple modified regions 13 at the first end 11 is larger than the center-to-center spacing P2 of the multiple modified regions 13 at the second end 12. Therefore, the center-to-center spacing of the multiple modified regions 13 gradually decreases from the first end 11 toward the second end 12. However, the multiple modified regions 13 extend parallel to each other at and near the first end 11 and at and near the second end 12.

[0024] In one example, the ratio (P1 / P2) of the center-to-center distance P1 at the first end 11 to the center-to-center distance P2 at the second end 12 is equal to or greater than 1.0 and equal to or less than 4.0.

[0025] Due to the change in the center-to-center spacing, the density of the multiple modified regions 13 at the first end 11 is lower than the density of the multiple modified regions 13 at the second end 12. As a result, the average refractive index of the optical waveguide 10 at the first end 11 is lower than the average refractive index of the optical waveguide 10 at the second end 12. Therefore, the mode field diameter of the optical waveguide 10 in the arrangement direction (Y direction) of the multiple modified regions 13 at the first end 11 is larger than the mode field diameter of the optical waveguide 10 in the arrangement direction (Y direction) of the multiple modified regions 13 at the second end 12. The mode field diameter of the optical waveguide 10 in the Y direction is, for example, 7 μm or more and 10 μm or less at a wavelength of 1310 nm. The ratio (D1 / D2) of the mode field diameter D1 at the first end 11 to the mode field diameter D2 at the second end 12 is, for example, 1.0 or more and 4.0 or less at a wavelength of 1310 nm. The mode field diameter can be measured by, for example, a far-field distribution sweep method.

[0026] A method for manufacturing the glass component 1 described above will now be described. This manufacturing method includes the steps of preparing a glass substrate 20 and forming multiple modified regions 13 inside the glass substrate 20. FIG. 4 illustrates the step of forming multiple modified regions 13. In this step, a laser beam 32 having a pulse width on the order of femtoseconds is incident on the glass substrate 20 from the upper surface 21 and focused at a focusing point 24 inside the glass substrate 20. The wavelength of the laser beam 32 is, for example, 500 nm to 550 nm, or 750 nm to 850 nm, or 1000 nm to 1100 nm. The pulse width of the laser beam 32 is, for example, 50 fs to 500 fs. The pulse interval of the laser beam 32 is, for example, 0.1 ns to 100 ns. The average power of the laser beam 32 is, for example, 10 mW to 500 mW. Then, while focusing the laser beam 32, the focal point 24 is moved (scanned) along the optical waveguide direction (X direction). The dashed line 33 in the figure represents the trajectory of the laser beam 32 on the upper surface 21. If the modified region 13 to be formed is curved, the trajectory of the focal point 24 is curved accordingly. This process is repeated the same number of times as the number of modified regions 13 while shifting the position of the focal point 24 in the Y direction. The amount of shift in the Y direction is referred to as the scan pitch. This results in the formation of multiple modified regions 13 within the glass substrate 20. In this process, as shown in FIGS. 2 and 3, the center-to-center spacing P1 of the multiple modified regions 13 at the first end 11 is set larger than the center-to-center spacing P2 of the multiple modified regions 13 at the second end 12.

[0027] The effects achieved by the glass component 1 and manufacturing method thereof according to the present embodiment described above will now be described. In the glass component 1 according to the present embodiment, the center-to-center spacing P1 of the multiple modified regions 13 at the first end 11 is greater than the center-to-center spacing P2 of the multiple modified regions 13 at the second end 12. As the center-to-center spacing of the multiple modified regions 13 increases, the width of the optical waveguide 10 increases, but the density of the modified regions 13 decreases, resulting in a lower average refractive index. Furthermore, as the center-to-center spacing of the multiple modified regions 13 decreases, the width of the optical waveguide 10 decreases, but the density of the modified regions 13 increases, resulting in a higher average refractive index. Figure 5 is a graph showing the relationship between the refractive index difference (%) between an actually fabricated optical waveguide 10 and its surroundings and the center-to-center spacing (scan pitch, μm) of the modified regions 13. Referring to Figure 5, it can be seen that the refractive index difference increases as the center-to-center spacing of the modified regions 13 decreases. The refractive index difference is measured using, for example, a quantitative phase microscope. The refractive index difference Δn is defined as Δn=(n1−n0) / n0, where n1 is the refractive index of the optical waveguide 10 and n0 is the refractive index of the glass substrate 20.

[0028] Therefore, according to the glass component 1 and its manufacturing method of this embodiment, the mode field diameter of guided light at the first end 11 can be made larger than the mode field diameter of guided light at the second end 12. Furthermore, this glass component 1 does not require scattering elements present around the optical waveguide 10, such as the tapered structure disclosed in Non-Patent Document 1. Therefore, according to this glass component 1, it is possible to change the mode field diameter of light propagating through the optical waveguide 10 and reduce optical loss.

[0029] The glass component 1 of this embodiment is used, for example, when converting the mode field diameter. For example, the first end 11 is coupled to a single-mode optical fiber, and the second end 12 is coupled to an optical waveguide in a silicon photonics chip. In general, the mode field diameter of a single-mode optical fiber is larger than the mode field diameter of the optical waveguide in the silicon photonics chip. Furthermore, the refractive index difference of the core of the single-mode optical fiber is smaller than the refractive index difference of the optical waveguide in the silicon photonics chip. The glass component 1 of this embodiment can effectively convert the mode field diameter and refractive index difference between the single-mode optical fiber and the silicon photonics chip, thereby reducing optical loss.

[0030] As in the present embodiment, the ratio (P1 / P2) of the center-to-center spacing P1 of the multiple modified regions 13 at the first end 11 to the center-to-center spacing P2 of the multiple modified regions 13 at the second end 12 may be 1.0 or more and 4.0 or less. With the glass component 1 of the present embodiment, for example, the center-to-center spacing can be changed within this range.

[0031] The modified regions 13 are selectively etched relative to the surrounding regions using an etchant such as hydrofluoric acid. FIG. 6 is a micrograph showing the modified regions 13 that have actually been fabricated and etched with hydrofluoric acid. This photograph shows the voids 41 formed by etching. The voids 41 are formed by etching each of the modified regions 13. In this way, it is easy to confirm the center-to-center spacing and number of the modified regions 13 after forming them.

[0032] [Variations] Fig. 7 is a side view showing a glass component 2 according to a modified example of the above embodiment. Fig. 8 is a front view showing an end face 22 of the glass component 2. Fig. 9 is a rear view showing an end face 23 of the glass component 2. An XYZ Cartesian coordinate system is shown in these figures for ease of understanding.

[0033] The glass component 2 of this modification includes an optical waveguide 14 instead of the optical waveguide 10 of the above embodiment. The optical waveguide 14 is formed inside the glass substrate 20 (i.e., inside the glass component 2). The optical waveguide 14 extends in a direction (X direction) along the long side of the top surface 21 and propagates light in that direction. The optical waveguide 14 has a first end 15 and a second end 16 opposite to the first end 15. The first end 15 is included in an end surface 22 of the glass substrate 20. The second end 16 is included in an end surface 23 of the glass substrate 20. In other words, the optical waveguide 14 reaches both the end surface 22 and the end surface 23. The optical waveguide 14 may guide light from the first end 15 to the second end 16, or may guide light from the second end 16 to the first end 15. Although one optical waveguide 14 is shown in the figure, the glass component 2 may include multiple optical waveguides 14. Alternatively, the glass component 2 may include the optical waveguide 10 of the above embodiment in addition to the optical waveguide 14. This is not limited to this modified example, and the optical waveguide 14 may not reach at least one of the end faces 22 and 23.

[0034] The optical waveguide 14 includes a plurality of modified regions 17 and a plurality of modified regions 18. Although three modified regions 17 and 18 are shown in the figure, the number of modified regions 17 and 18 is not limited to this. Furthermore, the number of modified regions 17 may be the same as or different from the number of modified regions 18. Each of the modified regions 17 and 18 is formed by the same method as the modified region 13 in the above embodiment. The cross-sectional shape of each of the modified regions 17 and 18 may be the same as the cross-sectional shape of the modified region 13 in the above embodiment.

[0035] The modified regions, including the modified regions 17 and 18, are aligned in a direction intersecting the optical waveguide direction. In this modification, in a cross section perpendicular to the optical waveguide direction at the second end 16, the modified regions, including the modified regions 17 and 18, are aligned one-dimensionally. Furthermore, in a cross section perpendicular to the optical waveguide direction at the first end 15, the modified regions, including the modified regions 17 and 18, are aligned two-dimensionally. Specifically, at the second end 16, the modified regions 17 and 18 are aligned alternately in a row along the Y direction. Furthermore, at the first end 15, the modified regions 17 are aligned in a row along the Y direction, and the modified regions 18 are aligned in a row along the Y direction. Furthermore, at the first end 15, a group of the modified regions 17 and a group of the modified regions 18 are aligned in the Z direction. Therefore, when viewed along the Y direction, the central axes of the modified regions 17 and the modified regions 18 are inclined with respect to the X direction (see FIG. 7). When viewed along the Y direction, the central axis of the modified region 17 or the central axis of the modified region 18 may be parallel to the X direction. Furthermore, in a cross section perpendicular to the optical waveguide direction of the first end 15, multiple modified regions including the modified regions 17 and 18 may be arranged one-dimensionally, and in a cross section perpendicular to the optical waveguide direction of the second end 16, multiple modified regions including the modified regions 17 and 18 may be arranged two-dimensionally.

[0036] The optical waveguide 14 is formed by an aggregate of multiple modified regions, including the modified regions 17 and 18. That is, a bundle of multiple modified regions forms one optical waveguide 14. By including multiple modified regions, the optical waveguide 14 has a refractive index higher than that of the region surrounding the optical waveguide 14.

[0037] 8 and 9 , the center-to-center spacing P3 between the multiple modified regions 17 and the center-to-center spacing P4 between the multiple modified regions 18 at the first end 15 are larger than the center-to-center spacing P5 between the modified regions 17 and the modified regions 18 at the second end 16. Due to this change in center spacing, the density of the multiple modified regions at the first end 15 is smaller than the density of the multiple modified regions at the second end 16. As a result, the average refractive index of the optical waveguide 14 at the first end 15 is smaller than the average refractive index of the optical waveguide 14 at the second end 16. Therefore, the mode field diameter of the optical waveguide 14 at the first end 15 is larger than the mode field diameter of the optical waveguide 14 at the second end 16.

[0038] As in this modification, multiple modified regions may be arranged one-dimensionally in a cross section perpendicular to the optical waveguide direction at the second end 16, and multiple modified regions may be arranged two-dimensionally in a cross section perpendicular to the optical waveguide direction at the first end 15. Alternatively, multiple modified regions may be arranged one-dimensionally in a cross section perpendicular to the optical waveguide direction at the first end 15, and multiple modified regions may be arranged two-dimensionally in a cross section perpendicular to the optical waveguide direction at the second end 16. In these cases, the degree of freedom in the cross-sectional shape of the optical waveguide 14 can be increased. [Explanation of symbols]

[0039] 1,2...Glass parts 10,14...Optical waveguide 11,15…1st end 12,16…2nd end 13, 17, 18...Modified area 20...Glass substrate 21…Top surface 22,23...end face 24...Convergence point 32...Laser beam 33...dashed line 41...Void P1,P2,P3,P4,P5…center distance

Claims

1. A glass substrate; an optical waveguide provided within the glass substrate, the optical waveguide having a first end and a second end opposite the first end; the optical waveguide includes a plurality of modified regions aligned in a direction intersecting a light guiding direction, and an aggregate of the plurality of modified regions forms the optical waveguide; the optical waveguide includes the plurality of modified regions, and thereby has a refractive index higher than a refractive index of a region surrounding the optical waveguide; a center-to-center spacing of the modified regions at the first end is greater than a center-to-center spacing of the modified regions at the second end; an average refractive index of the optical waveguide at the first end is smaller than an average refractive index of the optical waveguide at the second end; A glass component, wherein the mode field diameter of the optical waveguide at the first end in the direction of arrangement of the multiple modified regions is larger than the mode field diameter of the optical waveguide at the second end in the direction of arrangement of the multiple modified regions.

2. the modified regions are arranged one-dimensionally in a cross section perpendicular to the optical waveguide direction of the first end, 2. The glass part according to claim 1, wherein the plurality of modified regions are arranged two-dimensionally in a cross section of the second end perpendicular to the optical waveguide direction.

3. the modified regions are arranged one-dimensionally in a cross section perpendicular to the optical waveguide direction of the second end, The glass part according to claim 1 , wherein the plurality of modified regions are arranged two-dimensionally in a cross section of the first end perpendicular to the optical waveguide direction.

4. 4. The glass part according to claim 1, wherein a ratio (P1 / P2) of a center-to-center spacing P1 of the plurality of modified regions at the first end to a center-to-center spacing P2 of the plurality of modified regions at the second end is 1.0 or greater and 4.0 or less.

5. A method of manufacturing a glass component having an optical waveguide therein, the optical waveguide having a first end and a second end opposite to the first end, the method comprising: forming a plurality of modified regions arranged in a direction intersecting the optical waveguiding direction of the optical waveguide within a glass substrate; an assembly of the plurality of modified regions forms the optical waveguide; In the forming step, a step of focusing a laser beam having a pulse width on the order of femtoseconds at a focusing point inside the glass substrate while moving the focusing point in the optical waveguide direction is repeated multiple times while shifting the position of the focusing point, thereby forming the multiple modified regions; In the forming step, the center-to-center spacing of the plurality of modified regions at the first end is made larger than the center-to-center spacing of the plurality of modified regions at the second end.

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