Optical waveguide components and methods for manufacturing optical waveguide components
The optical waveguide component addresses shape distortion issues by surrounding the high refractive index region with low refractive index regions, ensuring efficient light transmission through precise laser processing.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-09-11
- Publication Date
- 2026-03-24
AI Technical Summary
Existing optical waveguide components face issues with the distortion of the high refractive index region, leading to suboptimal light transmission due to deviations from the desired Gaussian shape.
The optical waveguide component includes a base material with a modified portion comprising a high refractive index region surrounded by low refractive index regions on all four sides, formed through laser processing, maintaining the desired shape and improving refractive index uniformity.
This configuration maintains the desired shape of the high refractive index region, reducing light leakage and enhancing light transmission efficiency.
Smart Images
Figure 2026052448000001_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to an optical waveguide component and a method for manufacturing an optical waveguide component.
Background Art
[0002] Optical waveguide components having a modified portion inside a base material portion are known (Non-Patent Document 1 and Patent Document 2). The modified portion extends in a first direction inside the base material portion and has a refractive index different from that of the base material portion. The modified portion includes a high refractive index region having a refractive index higher than that of the base material portion.
Prior Art Documents
Non-Patent Documents
[0003]
Non-Patent Document 1
Non-Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0004] In Non-Patent Documents 1 and 2, a low refractive index region having a refractive index lower than that of the substrate is arranged near the high refractive index region mentioned above. This improves the refractive index of the high refractive index region. This high refractive index region corresponds to an optical waveguide. However, in this case, the shape of the high refractive index region may become distorted. If the high refractive index region deviates from its Gaussian shape, the desired light transmission may not be achieved.
[0005] This disclosure aims to provide an optical waveguide component that maintains a desired shape in the high refractive index region described above, and a method for manufacturing an optical waveguide component. [Means for solving the problem]
[0006] An optical waveguide component according to the embodiment of this disclosure comprises a base portion and a modified portion. The modified portion extends in a first direction within the base portion and has a refractive index different from that of the base portion. The modified portion includes a high refractive index region and a low refractive index region. The high refractive index region has a refractive index higher than that of the base portion. The low refractive index region has a refractive index lower than that of the base portion. The low refractive index region is arranged on all four sides of the high refractive index region in a cross-section intersecting the first direction. [Effects of the Invention]
[0007] According to this disclosure, it is possible to provide an optical waveguide component that maintains a desired shape in the high refractive index region, and a method for manufacturing an optical waveguide component. [Brief explanation of the drawing]
[0008] [Figure 1] Figure 1 is a schematic perspective view showing the optical waveguide components in an embodiment. [Figure 2] Figure 2 is a cross-sectional view of an optical waveguide component showing an example of the shape of the modified section. [Figure 3] Figure 3 shows the refractive index profile of the modified section. [Figure 4] Figure 4 is a magnified view of the modified area. [Figure 5] Figure 5 shows the profile of the beam guided in the optical waveguide component. [Modes for carrying out the invention]
[0009] [Description of Embodiments in this Disclosure] First, the contents of each embodiment of this disclosure will be listed and described individually.
[0010] (1) An optical waveguide component according to the embodiment of the present disclosure comprises a base material and a modified portion. The modified portion extends in a first direction within the base material and has a refractive index different from that of the base material. The modified portion includes a high refractive index region and a low refractive index region. The high refractive index region has a refractive index higher than that of the base material. The low refractive index region has a refractive index lower than that of the base material. The low refractive index region is arranged on all four sides of the high refractive index region in a cross section intersecting the first direction.
[0011] In this optical waveguide component, low refractive index regions are arranged on all four sides of the high refractive index region within a cross-section intersecting the first direction. In this case, the low refractive index regions improve the refractive index of the high refractive index region, and the high refractive index region is formed into a desired shape.
[0012] (2) In the optical waveguide component described in (1) above, the high refractive index region may have a pair of ends. The base material may include a first end face, a second end face, a first main surface, and a second main surface. The first end face may have the first end of the pair of ends exposed. The second end face may have the second end of the pair exposed and be located on the opposite side of the first end face in the first direction. The first main surface may connect the first end face and the second end face. The second main surface may connect the first end face and the second end face and be located on the opposite side of the first main surface in the second direction intersecting the first direction. The low refractive index region may include a first low refractive index region and a second low refractive index region that are separated from each other in the first direction and a third direction intersecting the second direction. The high refractive index region may be located between the first low refractive index region and the second low refractive index region. A part of the base material may be located between the first low refractive index region and the high refractive index region. In this case, leakage of light propagating in the high refractive index region into the first low refractive index region is reduced.
[0013] (3) In the optical waveguide component described in (2) above, the shortest distance between the high refractive index region and the first low refractive index region may be greater than half the width of the first low refractive index region in the third direction. In this case, leakage of light propagating in the high refractive index region into the first low refractive index region is further reduced.
[0014] (4) In the optical waveguide component described in (2) above, the shortest distance between the high refractive index region and the first low refractive index region may be less than twice the width of the first low refractive index region in the second direction. In this case, leakage of light propagating in the high refractive index region into the first low refractive index region is further reduced.
[0015] (5) In any one of the optical waveguide components described in (2) to (4) above, the width of the first low refractive index region may be longer than the width of the high refractive index region in the second direction. In this case, leakage of light propagating in the high refractive index region into the first low refractive index region is further reduced.
[0016] (6) In the method for manufacturing an optical waveguide according to an embodiment of the present disclosure, the base material portion has a first end face, a second end face, a first main face, and a second main face. The second end face is located on the opposite side of the first end face in the first direction. The second main face connects the first end face and the second end face and is located on the opposite side of the first main face in a second direction intersecting the first direction. With respect to the base material portion, a laser is scanned from the first main face side in the first direction, and a modified portion that extends in the first direction inside the base material portion and has a refractive index different from that of the base material portion is formed. The modified portion includes a high refractive index region having a refractive index higher than that of the base material portion and a low refractive index region having a refractive index lower than that of the base material portion. In the formation of the modified portion, the low refractive index region is formed on four sides of the high refractive index region in a cross section intersecting the first direction. Thereby, the refractive index of the high refractive index region is improved by the low refractive index region, and the desired shape of the high refractive index region is maintained.
[0017] [Details of Embodiments of the Present Disclosure]
[0018] Specific examples of embodiments of the present disclosure will be described below with reference to the drawings. The present invention is not limited to these examples, and is shown by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. In the description of the drawings, the same reference numerals are given to the same elements, and duplicate descriptions are omitted.
[0019] FIG. 1 is a perspective view schematically showing an optical waveguide component according to an embodiment. In these figures, an XYZ orthogonal coordinate system is shown for easy understanding.
[0020] The optical waveguide component 1 guides light in a desired direction. The optical waveguide component 1 is used, for example, to convert a mode field diameter. With the optical waveguide component 1, the conversion of the mode field diameter and the refractive index difference between an optical fiber connected to the optical waveguide component 1 and a silicon photonics chip is preferably performed, and the optical loss is reduced. The optical waveguide component 1 guides, for example, light from an optical fiber to an optical waveguide of a silicon photonics chip. The optical waveguide component 1 includes a base material portion 11 and a modified portion 12.
[0021] The base material part 11 has a surface S1 on which the modification part 12 is exposed. As shown in FIG. 1, the surface S1 includes a pair of main surfaces 11a, 11b, a pair of end surfaces 11c, 11d, and a pair of side surfaces 11e, 11f. The pair of main surfaces 11a, 11b, the pair of end surfaces 11c, 11d, and the pair of side surfaces 11e, 11f are, for example, flat surfaces and are rectangular. The base material part 11 is, for example, substantially rectangular parallelepiped-shaped. The base material part 11 is plate-shaped, and the Z-axis direction corresponds to the thickness direction. The base material part 11 is, for example, made of glass. The material of the base material part 11 is, for example, quartz glass, non-alkali glass, or borosilicate glass.
[0022] The pair of main surfaces 11a, 11b are along the X-axis direction and the Z-axis direction and face each other in the Y-axis direction. One of the pair of main surfaces 11a, 11b is located on the opposite side of the other in the Y-axis direction. The pair of main surfaces 11a, 11b are arranged in the Y-axis direction and may be parallel to each other or inclined to each other. The main surface 11a connects the side surfaces 11e and 11f. The main surface 11b connects the side surfaces 11e and 11f and is located on the opposite side of the main surface 11a in the Y-axis direction.
[0023] The pair of end surfaces 11c, 11d are along the X-axis direction and the Y-axis direction and face each other in the Z-axis direction. One of the pair of end surfaces 11c, 11d is located on the opposite side of the other in the Z-axis direction. The pair of end surfaces 11c, 11d are arranged in the Z-axis direction and may be parallel to each other or inclined to each other. The end surface 11c connects the main surfaces 11a and 11b. The end surface 11d connects the main surfaces 11a and 11b and is located on the opposite side of the end surface 11c in the Z-axis direction.
[0024] The pair of sides 11e and 11f are aligned along the Y-axis and Z-axis and face each other in the X-axis direction. One of the pair of sides 11e and 11f is located on the opposite side of the other in the X-axis direction. The pair of sides 11e and 11f are aligned along the X-axis direction and may be parallel to each other or inclined to each other. Side 11e connects end face 11c and end face 11d. Side 11f connects end face 11c and end face 11d and is located on the opposite side of end face 11c in the Z-axis direction.
[0025] The modified portion 12 extends in the Z-axis direction within the base material portion 11 and has a refractive index different from that of the base material portion 11. As shown in Figure 2, the modified portion 12 includes a high refractive index region 20 and a low refractive index region 30.
[0026] The high refractive index region 20 has a refractive index higher than that of the substrate portion 11. As shown in Figure 2, the high refractive index region 20 includes high refractive index regions 21, 22, 23, and 24. The high refractive index region 21 is a core formed inside the substrate portion 11. The high refractive index region 21 corresponds to an optical waveguide through which light propagates.
[0027] The high refractive index region 21 extends in the Y-axis direction and propagates light in that direction. The high refractive index region 21 has a pair of ends 21a and 21b. The pair of ends 21a and 21b include a first end 21a and a second end 21b opposite to the first end 21a. The first end 21a is exposed to the end face 11c of the base material portion 11. The second end 21b is exposed to the end face 11d of the base material portion 11. For example, the first end 21a is coupled to the optical fiber 2, and the second end 21b is coupled to the optical waveguide of a silicon photonics chip. The high refractive index region 21 may guide light from the first end 21a to the second end 21b, or from the second end 21b to the first end 21a.
[0028] The high refractive index regions 22, 23, and 24 are located along the low refractive index region 30. Each of the high refractive index regions 22, 23, and 24 is located closer to the main surface 11b than the low refractive index region 30 in the Z-axis direction.
[0029] The low refractive index region 30 has a refractive index lower than that of the substrate portion 11. The low refractive index region 30 is located on all four sides of the high refractive index region 20 within the cross section 11g intersecting the Z-axis direction. As shown in Figure 3, the high refractive index region 20 is surrounded by the low refractive index regions 31a, 31b, 31c, and 31d. The low refractive index region 30 includes the low refractive index regions 31a, 31b, 31c, and 31d.
[0030] Low refractive index region 31a and low refractive index region 31b are aligned in the Y-axis direction. Low refractive index region 31a and low refractive index region 31b are separated from each other in the Y-axis direction. Low refractive index region 31a is located closer to the main surface 11b than low refractive index region 31b. For example, high refractive index region 21 is located between low refractive index region 31a and low refractive index region 31b. High refractive index region 23 is located closer to the main surface 11b than low refractive index region 31a. In the Y-axis direction, low refractive index region 31a, low refractive index region 31b, high refractive index region 21, and high refractive index region 23 are arranged to overlap each other. In the Y-axis direction, from the side closest to the main surface 11b, they are arranged in the order of high refractive index region 23, low refractive index region 31a, high refractive index region 21, and low refractive index region 31b.
[0031] The high refractive index region 22 is located closer to the main surface 11b than the low refractive index region 31c. In the Y-axis direction, the low refractive index region 31c and the high refractive index region 22 are arranged to overlap each other. In the Y-axis direction, they are arranged in the order of high refractive index region 22, followed by low refractive index region 31c, from the side closest to the main surface 11b.
[0032] The high refractive index region 24 is located closer to the main surface 11b than the low refractive index region 31d. In the Y-axis direction, the low refractive index region 31d and the high refractive index region 24 are arranged to overlap each other. In the Y-axis direction, the high refractive index region 22 and the low refractive index region 31c are arranged in that order from the side closer to the main surface 11b.
[0033] Low refractive index region 31c and low refractive index region 31d are aligned in the X-axis direction. Low refractive index region 31c and low refractive index region 31d are separated from each other in the X-axis direction. Low refractive index region 31d is located closer to side surface 11f than low refractive index region 31c. For example, high refractive index region 21 is located between low refractive index region 31c and low refractive index region 31d. In the X-axis direction, low refractive index region 31c, low refractive index region 31d, and high refractive index region 21 are arranged to overlap each other. In the X-axis direction, they are arranged in the order of low refractive index region 31c, high refractive index region 21, and low refractive index region 31d, starting from the side closest to side surface 11e.
[0034] The low refractive index region 31c and the high refractive index region 21 are separated from each other in the X-axis direction. A portion of the base material 11 is positioned between the low refractive index region 31c and the high refractive index region 21. The low refractive index region 31d and the high refractive index region 21 are separated from each other in the X-axis direction. A portion of the base material 11 is positioned between the low refractive index region 31d and the high refractive index region 21.
[0035] Figure 4 is a partially enlarged view of the modified portion 12 at the end face 11c. As shown in Figure 4, in the Y-axis direction, the width L2 of the low refractive index regions 31c and 31d is longer than the width L1 of the high refractive index region 21. The shortest distance L4 between the high refractive index region 21 and the low refractive index region 31c is less than twice the width L2 of the low refractive index region 31c in the Y-axis direction. The shortest distance L4 between the high refractive index region 21 and the low refractive index region 31c is greater than half the width L3 of the low refractive index region 31c in the X-axis direction.
[0036] The widths L1, L2, L3, and the shortest distance L4 are determined based on the coordinates of the edges that indicate the contours of the low refractive index regions 31c, 31d and the high refractive index region 21. The coordinates are those observed in a measuring microscope. The measuring microscope is, for example, an STM7. For example, the edges of the high refractive index region 21 are detected using the edge detection function of the measuring microscope at a magnification that allows both the low refractive index region 31c, 31d and the high refractive index region to be simultaneously visible in the measuring microscope. The edges of the low refractive index regions 31c, 31d are detected, for example, by sweeping in the X-axis direction from the detection of the edges of the high refractive index region 21 and using the edge detection function of the measuring microscope. For example, the shortest distance L4 between the high refractive index region 21 and the low refractive index region 31c is the absolute value of the difference between the X-coordinate of the edge in the high refractive index region 21 and the X-coordinate of the edge in the low refractive index region 31c. The X-coordinate is a coordinate on the X-axis.
[0037] In the configuration shown in Figure 2, the low refractive index region 31a and the high refractive index region 21 are separated from each other in the Y-axis direction. For example, a part of the base material 11 is located between the low refractive index region 31a and the high refractive index region 21. The low refractive index region 31b and the high refractive index region 21 are separated from each other in the Y-axis direction. A part of the base material 11 is located between the low refractive index region 31b and the high refractive index region 21.
[0038] The modified portion 12 is formed by scanning a laser beam LS in the Z-axis direction from the outside of the main surface 11a with respect to the substrate portion 11. For example, the modified portion 12 is a laser-processed region formed when a laser beam LS having an extremely short time width, such as on the order of femtoseconds, is focused and scanned inside the substrate portion 11, and the glass is modified by multiphoton absorption.
[0039] For example, in the formation of the modified portion 12, scanning the laser beam LS in the Z-axis direction forms low refractive index regions 30 on all sides of the high refractive index region 21 within the cross-section 11g. Scanning the laser beam LS in the Z-axis direction forms low refractive index region 31a, high refractive index region 21, and low refractive index region 31b. Furthermore, scanning the laser beam LS in the Z-axis direction forms low refractive index regions 31c and 31d. For example, scanning the laser beam LS in the Z-axis direction forms high refractive index region 23 together with low refractive index region 31a, high refractive index region 21 together with low refractive index region 31b, high refractive index region 22 together with low refractive index region 31c, and high refractive index region 24 together with low refractive index region 31d.
[0040] For example, scanning the laser beam LS in the Z-axis direction forms a high refractive index region 23 and a low refractive index region 31a, and after the high refractive index region 23 and the low refractive index region 31a are formed, scanning the laser beam LS in the Z-axis direction forms a high refractive index region 21 and a low refractive index region 31b. As a modification of this embodiment, scanning the laser beam LS in the Z-axis direction forms a high refractive index region 21 and a low refractive index region 31b, and after the high refractive index region 21 and the low refractive index region 31b are formed, scanning the laser beam LS in the Z-axis direction may form a low refractive index region 31a.
[0041] By scanning the laser beam LS, the high refractive index region 20 is formed on the side closer to the main surface 11a than the low refractive index region 31a, and at a position that overlaps with the low refractive index region 31a when viewed along the Y-axis. By scanning the laser beam LS, the low refractive index region 31b is formed on the side closer to the main surface 11a than the high refractive index region 21, and at a position that overlaps with the low refractive index region 31a when viewed along the Y-axis. By scanning the laser beam LS, the low refractive index regions 31c and 31d are formed to overlap with the high refractive index region 21 when viewed along the X-axis, and at positions that sandwich the high refractive index region 21 when viewed along the X-axis.
[0042] Referring to Figure 5, the effect of the optical waveguide component 1 will be explained. In this optical waveguide component 1, low refractive index regions 30 are arranged on all four sides of the high refractive index region 21 within the cross-section 11g. In this case, the low refractive index regions 30 improve the refractive index of the high refractive index region 21, and the high refractive index region 21 is formed into the desired shape. Figure 5 shows the profile of the beam LB guided in the optical waveguide component 1. The MFD is shown. In Figure 5, the beam profile is imaged using the NFP (Near Field Pattern) method. The radius w0 is calculated by Gaussian fitting the distribution projected onto the x and y axes, and twice this value of w0 becomes the MFD for each axis. The MFD in the x-axis direction is r1, and the MFD in the y-axis direction is r2. r1 and r2 are approximately equal, and the MFD is formed to be almost a perfect circle.
[0043] In the optical waveguide component 1, the high refractive index region 21 has a pair of ends 21a and 21b. The base material portion 11 includes an end face 11c, an end face 11d, a main surface 11a, and a main surface 11b. The end face 11c exposes one of the pair of ends 21a and 21b. The end face 11d exposes the other of the pair of ends 21a and 21b and is located on the opposite side of the end face 11c in the Z-axis direction. The main surface 11a connects the side surface 11e and the side surface 11f. The main surface 11b connects the side surface 11e and the side surface 11f and is located on the opposite side of the main surface 11a in the Y-axis direction. The low refractive index region 30 includes low refractive index regions 31c and 31d, which are separated from each other in the X-axis direction. The high refractive index region 21 is located between the low refractive index region 31c and the low refractive index region 31d. A portion of the substrate 11 may be positioned between the low refractive index region 31c and the high refractive index region 21. In this case, leakage of light propagating through the high refractive index region 21 into the low refractive index region 31c is reduced.
[0044] In optical waveguide component 1, the shortest distance L4 between the high refractive index region 21 and the low refractive index region 31c is greater than half the width L3 of the low refractive index region 31c in the X-axis direction. In this case, leakage of light propagating through the high refractive index region 21 into the low refractive index region 31c is further reduced.
[0045] In the optical waveguide component 1, the shortest distance L4 between the high refractive index region 21 and the low refractive index region 31c is less than twice the width L2 of the low refractive index region 31c in the Y-axis direction. In this case, leakage of light propagating through the high refractive index region 21 into the low refractive index region 31c is further reduced.
[0046] In the optical waveguide component 1, the width L2 of the low refractive index region 31c may be longer than the width L1 of the high refractive index region 21 in the Y-axis direction. In this case, leakage of light propagating in the high refractive index region 21 into the low refractive index region 31c is further reduced.
[0047] Although embodiments of this disclosure have been described in detail above, the present invention is not limited to the above embodiments and can be applied to various embodiments.
[0048] For example, in this embodiment, the low refractive index region 30 is divided into multiple low refractive index regions 31a, 31b, 31c, and 31d, which are arranged apart from each other. However, the multiple low refractive index regions 31a, 31b, 31c, and 31d may be partially in contact with each other. [Explanation of Symbols]
[0049] 1… Optical waveguide components 2… Fiber optic 11...Base material part 11a, 11b...main surface 11c,11d...end face 11e,11f…side 11g...Cross section 12…Modification section 20, 21, 22, 23, 24… High refractive index region 21a, 21b...ends 30, 31a, 31b, 31c, 31d… Low refractive index region L1, L2, L3... width L4...shortest distance LB... Beam LS... Laser beam S1…Surface
Claims
1. Base material part, The material comprises a modified portion that extends in a first direction within the base material and has a refractive index different from that of the base material, The modified portion includes a high refractive index region having a refractive index higher than that of the substrate portion and a low refractive index region having a refractive index lower than that of the substrate portion. The low refractive index region is an optical waveguide component located on all four sides of the high refractive index region within a cross-section intersecting the first direction.
2. The high refractive index region has a pair of ends, The base material portion includes a first end surface on which the first end of the pair of ends is exposed, a second end surface on which the second end of the pair of ends is exposed and located on the opposite side of the first end surface in the first direction, a first main surface connecting the first end surface and the second end surface, and a second main surface connecting the first end surface and the second end surface and located on the opposite side of the first main surface in a second direction intersecting the first direction. The low refractive index region includes a first low refractive index region and a second low refractive index region that are separated from each other in a third direction that intersects the first direction and the second direction. The high refractive index region is located between the first low refractive index region and the second low refractive index region. The optical waveguide component according to claim 1, wherein a portion of the base material is arranged between the first low refractive index region and the high refractive index region.
3. The optical waveguide component according to claim 2, wherein the shortest distance between the high refractive index region and the first low refractive index region is greater than half the width of the first low refractive index region in the third direction.
4. The optical waveguide component according to claim 2, wherein the shortest distance between the high refractive index region and the first low refractive index region is less than twice the width of the first low refractive index region in the second direction.
5. The optical waveguide component according to any one of claims 2 to 4, wherein in the second direction, the width of the first low refractive index region is longer than the width of the high refractive index region.
6. The present invention relates to a substrate having a first end face, a second end face located opposite to the first end face in a first direction, a first main surface connecting the first end face and the second end face, and a second main surface connecting the first end face and the second end face and located opposite to the first main surface in a second direction intersecting the first direction, and involves scanning a laser from the first main surface side in the first direction to form a modified portion extending in the first direction within the substrate and having a refractive index different from that of the substrate. The modified portion includes a high refractive index region having a refractive index higher than that of the substrate portion and a low refractive index region having a refractive index lower than that of the substrate portion. A method for manufacturing an optical waveguide component, wherein, in the formation of the modified portion, the low refractive index region is formed on all four sides of the high refractive index region within a cross-section intersecting the first direction.