Optical element

Abstract

According to the present disclosure, light input from the lateral direction can be output in the vertical direction (for example, upward) with high efficiency, and / or light input from the vertical direction (for example, from above) can be output in the lateral direction with high efficiency. An optical element (10) according to the present disclosure is provided with a grating structure (101) having a first surface (10a) and a second surface (10b) which face each other. The grating structure (101) is provided with a plurality of grooves (101a) arranged side by side on the first surface (10a). A plurality of through holes (TH) are provided side by side along the extension direction of the groove (101a), the plurality of through holes (TH) penetrating an inter-groove portion (101c) which is a part between adjacent grooves (101a) and a portion on the second surface (10b) side of the inter-groove portion (101c), and / or a portion on the second surface (10b) side of the groove (101a) adjacent to the inter-groove portion (101c).

Description

Optical element

[0001] The technology disclosed herein (hereinafter also referred to as "this technology") relates to optical elements.

[0002] Conventionally, optical elements having a grating are known (for example, Patent Documents 1 to 3).

[0003] For example, Patent Document 1 discloses a grating coupler having a structure in which a high refractive index layer positioned on the upper side of the grating gradually decreases along the direction of light propagation.

[0004] For example, Patent Document 2 discloses an integrated photonic coupler in which an additional grating is provided above the grating.

[0005] For example, Patent Document 3 discloses a grating coupler in which a two-layer cladding structure is provided on the upper side of the grating.

[0006] Japanese Patent Publication No. 2018-45071, Japanese Patent Publication No. 2015-121787, International Publication No. 2016 / 170859

[0007] However, in conventional optical elements (for example, Patent Documents 1 to 3), there was room for improvement in terms of efficiently outputting light input from the side in the vertical direction (for example, upwards), and / or efficiently outputting light input from the vertical direction (for example, upwards) in the sideways direction.

[0008] Therefore, it is desirable to provide an optical element that can output light input from the side in a vertical direction (for example, upward) with high efficiency, and / or output light input from the vertical direction (for example, upward) in a horizontal direction with high efficiency.

[0009] An optical element according to one embodiment of the present disclosure comprises a grating structure having opposing first and second surfaces, wherein the grating structure has a plurality of grooves arranged side by side on the first surface, and a plurality of through holes arranged side by side along the extending direction of the grooves, penetrating the intergroove portions which are the portions between adjacent grooves, the portions on the second surface side of the intergroove portions, and / or the portions on the second surface side of grooves adjacent to the intergroove portions.

[0010] Figure 1 is a perspective view of an optical element according to Example 1 of one embodiment of this technology. Figure 2 is a plan view of an optical element according to Example 1 of one embodiment of this technology. Figure 3 is a partial cross-sectional view (part 1) of an optical element according to Example 1 of one embodiment of this technology. Figure 4 is a partial cross-sectional view (part 2) of an optical element according to Example 1 of one embodiment of this technology. Figure 5 is a graph showing the relationship between the wavelength of light input to an optical element according to Example 1 of one embodiment of this technology and the power ratio of the optical element. Figure 6 is a plan view of an optical element according to Example 2 of one embodiment of this technology. Figure 7 is a plan view of an optical element according to Example 3 of one embodiment of this technology. Figure 8 is a plan view of an optical element according to Example 4 of one embodiment of this technology. Figure 9 is a plan view of an optical element according to Example 5 of one embodiment of this technology. Figure 10 is a plan view of an optical element according to Example 6 of one embodiment of this technology. Figure 11 is a plan view of an optical element according to Example 7 of one embodiment of this technology. Figure 12 is a plan view of an optical element according to Example 8 of one embodiment of this technology. Figure 13 is a plan view of an optical element according to Example 9 of one embodiment of this technology. Figure 14A is a schematic diagram showing the plan view of the grating structure of an optical element according to Example 10 of one embodiment of this technology. Figure 14B is a schematic diagram showing the plan view of the grating structure of an optical element according to Example 11 of one embodiment of this technology. Figure 14C is a schematic diagram showing the plan view of the grating structure of an optical element according to Example 12 of one embodiment of this technology. Figure 15A is a schematic diagram showing the plan view of the connection portion and waveguide of an optical element according to Example 13 of one embodiment of this technology. Figure 15B is a schematic diagram showing the plan view of the connection portion and waveguide of an optical element according to Example 14 of one embodiment of this technology. Figure 15C is a schematic diagram showing the plan view of the connection portion and waveguide of an optical element according to Example 15 of one embodiment of this technology. Figure 16A is a longitudinal cross-sectional view of a waveguide connected via a connection portion to the grating structure of an optical element according to Example 16 of one embodiment of this technology. Figure 16B is a plan view of a waveguide connected via a connector to the grating structure of an optical element according to Embodiment 16 of one embodiment of this technology. Figure 17A is a cross-sectional view of a waveguide connected via a connector to the grating structure of an optical element according to Embodiment 17 of one embodiment of this technology.Figure 17B is a plan view of a waveguide connected via a connector to the grating structure of an optical element according to Example 17 of one embodiment of this technology. Figure 18A is a cross-sectional view of a waveguide connected via a connector to the grating structure of an optical element according to Example 18 of one embodiment of this technology. Figure 18B is a plan view of a waveguide connected via a connector to the grating structure of an optical element according to Example 18 of one embodiment of this technology. Figure 19A is a cross-sectional view of a waveguide connected via a connector to the grating structure of an optical element according to Example 19 of one embodiment of this technology. Figure 19B is a plan view of a waveguide connected via a connector to the grating structure of an optical element according to Example 19 of one embodiment of this technology. Figure 20A is a diagram showing the plan view shape of a through-hole in an optical element according to Example 20 of one embodiment of this technology. Figure 20B is a diagram showing the plan view shape of a through-hole in an optical element according to Example 21 of one embodiment of this technology. Figure 21A shows the plan view shape of the through-hole of an optical element according to Example 22 of one embodiment of this technology. Figure 21B shows the plan view shape of the through-hole of an optical element according to Example 23 of one embodiment of this technology. Figure 22A shows the pitch change of the through-hole of an optical element according to Example 24 of one embodiment of this technology. Figure 22B shows the pitch change of the groove of an optical element according to Example 25 of one embodiment of this technology. Figure 23A shows the pitch change of the through-hole of an optical element according to Example 26 of one embodiment of this technology. Figure 23B shows the pitch change of the groove of an optical element according to Example 27 of one embodiment of this technology. Figure 24A shows the pitch change of the through-hole of an optical element according to Example 28 of one embodiment of this technology. Figure 24B shows the pitch change of the groove of an optical element according to Example 29 of one embodiment of this technology. Figure 25A shows the change in the size of the through-hole of an optical element according to Example 30 of one embodiment of this technology. Figure 25B shows the change in the width of the groove of an optical element according to Example 31 of one embodiment of this technology. Figure 26A shows the change in the width direction of the groove in the through hole of an optical element according to Embodiment 32 of one embodiment of this technology. Figure 26B shows the change in the width direction of the groove in the through hole of an optical element according to Embodiment 33 of one embodiment of this technology.Figure 27 is a partial cross-sectional view of an optical element according to Example 34 of one embodiment of the present technology. Figure 28 is a partial cross-sectional view of an optical element according to Example 35 of one embodiment of the present technology. Figure 29 is a partial cross-sectional view of an optical element according to Example 36 of one embodiment of the present technology. Figure 30 is a partial cross-sectional view of an optical element according to Example 37 of one embodiment of the present technology. Figure 31 is a partial cross-sectional view of an optical element according to Example 38 of one embodiment of the present technology. Figure 32 is a schematic diagram showing an optical transmitting device equipped with an optical element according to Example 1 of one embodiment of the present technology as at least part of a transmitting antenna. Figure 33 is a schematic diagram showing an optical receiving device equipped with an optical element according to Example 1 of one embodiment of the present technology as at least part of a receiving antenna. Figure 34 is a schematic diagram showing an optical communication device equipped with an optical element according to Example 1 of one embodiment of the present technology as at least part of a coupler. Figure 35A is a partial cross-sectional view (part 1) of an optical element according to Modification 1 of Example 1 of one embodiment of the present technology. Figure 35B is a partial cross-sectional view (part 2) of an optical element according to Modification 1 of Example 1 of the present technology. Figure 36 is a plan view of an optical element relating to Modification 2 of Example 1 of one embodiment of this technology. Figure 37 is a plan view of an optical element relating to Modification 3 of Example 1 of one embodiment of this technology. Figure 38 is a plan view of an optical element relating to Modification 4 of Example 1 of one embodiment of this technology. Figure 39 is a plan view of an optical element relating to Modification 5 of Example 1 of one embodiment of this technology. Figure 40 is a plan view of an optical element relating to Modification 6 of Example 1 of one embodiment of this technology. Figure 41 is a plan view of an optical element relating to Modification 7 of Example 1 of one embodiment of this technology. Figure 42 is a plan view of an optical element relating to Modification 8 of Example 1 of one embodiment of this technology. Figure 43 is a plan view of an optical element relating to Modification 9 of Example 1 of one embodiment of this technology. Figure 44 is a plan view of an optical element relating to Modification 10 of Example 1 of one embodiment of this technology. Figure 45 is a plan view of an optical element relating to Modification 11 of Example 1 of one embodiment of this technology. Figure 46A is a partial cross-sectional view of an optical element relating to Modification 12 of Example 1 of one embodiment of this technology. Figure 46B is a partial cross-sectional view of an optical element according to a modified example 13 of one embodiment of the present technology. Figure 47 is a partial cross-sectional view of an optical element according to a modified example 14 of one embodiment of the present technology.Figure 48 is a perspective view of a comparative example grating structure. Figure 49 is a diagram showing a modified example of the through-holes in the grating structure. Figure 50 is a partial cross-sectional view of an optical element according to modified example 15 of one embodiment of the present technology. Figure 51 is a partial cross-sectional view of an optical element according to modified example 16 of one embodiment of the present technology. Figure 52 is a partial cross-sectional view of an optical element according to modified example 17 of one embodiment of the present technology. Figure 53 is a partial cross-sectional view showing an overview of the manufacturing method 1 of an optical element according to modified example 15 of one embodiment of the present technology. Figure 54 is a partial cross-sectional view showing an overview of the manufacturing method 2 of an optical element according to modified example 15 of one embodiment of the present technology. Figure 55 is a partial cross-sectional view showing an overview of the manufacturing method 3 of an optical element according to modified example 15 of one embodiment of the present technology. Figure 56 is a partial cross-sectional view showing an overview of the manufacturing method 4 of an optical element according to modified example 15 of one embodiment of the present technology.

[0011] Preferred embodiments of the present technology will be described in detail below with reference to the attached drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant explanations will be omitted. The embodiments described below represent typical embodiments of the present technology, and this will not be interpreted as narrowing the scope of the present technology. Even if the optical element relating to the present technology is described in this specification as having multiple effects, the optical element relating to the present technology only needs to have at least one effect. The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0012] The explanation will proceed in the following order: 0. Introduction 1. Optical element according to Example 1 of one embodiment of this technology 2. Optical element according to Example 2 of one embodiment of this technology 3. Optical element according to Example 3 of one embodiment of this technology 4. Optical element according to Example 4 of one embodiment of this technology 5. Optical element according to Example 5 of one embodiment of this technology 6. Optical element according to Example 6 of one embodiment of this technology 7. Optical element according to Example 7 of one embodiment of this technology 8. Optical element according to Example 8 of one embodiment of this technology 9. Optical element according to Example 9 of one embodiment of this technology 10. Optical element according to Example 10 of one embodiment of this technology 11. Optical element according to Example 11 of one embodiment of this technology 12. Optical element according to Example 12 of one embodiment of this technology 13. Optical element according to Example 13 of one embodiment of this technology 14. Optical element according to Example 14 of one embodiment of this technology 15. Optical element according to Example 15 of one embodiment of this technology 16. Optical element according to Example 16 of one embodiment of this technology 17. 18. Optical element according to Example 17 of one embodiment of this technology 19. Optical element according to Example 19 of one embodiment of this technology 20. Optical element according to Example 20 of one embodiment of this technology 21. Optical element according to Example 21 of one embodiment of this technology 22. Optical element according to Example 22 of one embodiment of this technology 23. Optical element according to Example 23 of one embodiment of this technology 24. Optical element according to Example 24 of one embodiment of this technology 25. Optical element according to Example 25 of one embodiment of this technology 26. Optical element according to Example 26 of one embodiment of this technology 27. Optical element according to Example 27 of one embodiment of this technology 28. Optical element according to Example 28 of one embodiment of this technology 29. Optical element according to Example 29 of one embodiment of this technology 30. Optical element according to Example 30 of one embodiment of this technology 31. Optical element according to Example 31 of one embodiment of this technology 32. Optical element according to Example 32 of one embodiment of this technology 33. Optical element according to Example 33 of one embodiment of this technology 34. Optical element according to Example 34 of one embodiment of this technology 35. Optical element according to Example 35 of one embodiment of this technology 36. Optical element according to Example 36 of one embodiment of this technology37. Optical element according to Example 37 of one embodiment of the present technology 38. Optical element according to Example 38 of one embodiment of the present technology 39. Optical transmitting device equipped with an optical element according to Example 1 of one embodiment of the present technology 40. Optical receiving device equipped with an optical element according to Example 1 of one embodiment of the present technology 41. Optical communication device equipped with an optical element according to Example 1 of one embodiment of the present technology 42. Modifications of the present technology 43. Other embodiments

[0013] <0. Introduction> Conventionally, optical circuits formed by silicon photonics, for example, are known to have optical elements with a grating structure in optical input / output interfaces, optical antennas, etc. It is important for improving the efficiency and stability of the optical circuit that these optical elements have characteristics such as high upward emissivity and / or high downward incidence, and / or low back reflectivity. Conventional optical elements have apodized structures or subwavelength structures to obtain the above characteristics, but the minimum structure of the grating becomes very small, making manufacturing extremely difficult.

[0014] Specifically, the inability to obtain the above characteristics has led to limitations in measurement distance, instability of the laser light source, increased power consumption, and limitations in communication distance in devices such as LiDAR (Light Detection and Ranging) and optical communication equipment.

[0015] Therefore, after diligent study, the inventors devised a novel technique of forming through holes in a grating structure having multiple grooves, and succeeded in giving the grating structure the characteristics of having high upward emissivity and / or high downward incidence, and / or low back reflectivity.

[0016] The inventors then developed an optical element related to this technology, which embodies this new technology.

[0017] Hereinafter, an optical element according to one embodiment of this technology will be described in detail with reference to several examples. In this specification, the term "identical" includes not only completely identical elements but also substantially identical elements (even if there are slight differences in effectiveness).

[0018] <1. Optical element according to Example 1 of one embodiment of this technology>

[0019] The optical element 10 according to Example 1 of one embodiment of this technology will be described below. Figure 1 is a perspective view of the optical element 10 according to Example 1 of one embodiment of this technology. Figure 2 is a plan view of the optical element 10 according to Example 1 of one embodiment of this technology. Figure 3 is a partial cross-sectional view (part 1) of the optical element 10 according to Example 1 of one embodiment of this technology. Figure 4 is a partial cross-sectional view (part 2) of the optical element 10 according to Example 1 of one embodiment of this technology. Figure 3 is a cross-sectional view taken along line 3-3 of Figure 2. Figure 4 is a cross-sectional view taken along line 4-4 of Figure 2.

[0020] The optical element 10 is provided, for example, in an optical integrated circuit (hereinafter also simply referred to as an "optical integrated circuit") formed using silicon photonics. Silicon photonics is a high-density optical device integration platform technology based on silicon electronic device manufacturing technology, which enables the formation of ultra-small, low-environmental-impact, and low-cost optical integrated circuits, and also offers excellent reliability and integration with electronic circuits.

[0021] Specifically, the optical element 10 can be mounted on an optical integrated circuit that constitutes an FMCW (Frequency Modulated Continuous Wave) LiDAR (Light Detection and Ranging), for example, and can function as at least part of a transmitting / receiving optical antenna. The FMCW LiDAR can be mounted on mobile devices such as automobiles, airplanes (including drones), ships, and robots.

[0022] Furthermore, the optical element 10 can be incorporated into, for example, an optical integrated circuit that constitutes Wavelength Division Multiplexing (WDM), and can function as at least part of an interface (e.g., a coupler) for optical input and / or output. Wavelength Division Multiplexing can be used, for example, in optical transceiver modules for communication within or between data centers.

[0023] Furthermore, the optical element 10 can be mounted as an antenna or incorporated as a coupler in an optical integrated circuit for various sensing applications (e.g., biosensing, gyro sensors, optical microphones, ion traps, etc.).

[0024] (Configuration of the optical element) As an example, the optical element 10 is an optical element having opposing first surfaces 10a (e.g., top surface) and second surfaces 10b (bottom surface), as shown in Figures 1 to 4, and includes a grating structure 101 on the first surface 10a (e.g., top surface) in which a plurality (e.g., five) grooves 101a (dark gray portion in Figure 2, and the same in other plan views) are arranged side by side. Here, the grating structure 101 such that the first surface 10a (e.g., top surface) constitutes a part of the first surface 10a of the optical element 10, and the second surface 10b (e.g., bottom surface) of the grating structure 101, which is opposite to the first surface 10a, constitutes a part of the second surface 10b of the optical element 10.

[0025] As an example, the optical element 10 is a generally plate-shaped optical element that includes a grating structure 101 and a connecting portion 102 and waveguide 103, which will be described later. Here, the optical element 10 is made of a single material. Examples of materials for the optical element 10 include semiconductors such as Si and Ge, SiN, and SiO ２ Examples of dielectrics include the following. In other words, the optical element 10 does not require any special materials.

[0026] For example, multiple grooves 101a are arranged periodically. Here, multiple grooves 101a are arranged in the in-plane direction at a constant pitch (period, distance between centers). Multiple grooves 101a function as a diffraction grating. For example, multiple grooves 101a have the same width and depth. However, at least two of the multiple grooves 101a may differ in at least one of their width and depth.

[0027] For example, the grating structure 101 is approximately arc-shaped in plan view, and the multiple grooves 101a are approximately arc-shaped and concentric in plan view. That is, in plan view, the width of the grating structure 101 gradually narrows from one side (outer circumference) to the other side (inner circumference) in the radial direction, which is the direction in which the multiple grooves 101a are aligned.

[0028] The optical element 10 further includes, for example, a connecting portion 102 that connects the grating structure 101 and the waveguide 103. For example, the waveguide 103 extends along the direction in which the grating structure 101 and the connecting portion 102 are aligned. For example, the connecting portion 102 is provided between the inner circumference end 101e (the inner circumference end) of the grating structure 101 and the waveguide 103. In this case, the width of the connecting portion 102 gradually narrows from the grating structure 101 side to the waveguide 103 side in a plan view. For example, the connecting portion 102 is roughly fan-shaped in a plan view, and the width of the end on the waveguide 103 side is the same as the width of the waveguide 103.

[0029] As an example, the grating structure 101 and the connecting portion 102, that is, the portion of the optical element 10 excluding the waveguide 103, have a roughly sector-shaped external form in plan view. More specifically, the connecting portion 102, which is roughly sector-shaped in plan view, is provided on the inner circumference side of the grating structure 101, which is arc-shaped in plan view, concentrically and at the same central angle so as to correspond to the grating structure 101 (so that the inner circumference end 101e of the grating structure 101 and the outer circumference end of the connecting portion 102 coincide). Here, the central angle of the sector is acute, but it may also be a right angle or an obtuse angle.

[0030] The connection section 102 constitutes a slab waveguide that confines light in the vertical direction (up and down direction) while propagating it horizontally. The slab waveguide as the connection section 102 is realized by the refractive index difference between a flat plate-shaped core, which is in the high refractive index region, and the air, which is in the low refractive index region above and below the core.

[0031] As an example, the optical element 10 includes the waveguide 103 as a component. The waveguide 103 is, for example, a channel waveguide (e.g., a linear waveguide) that propagates light while confining it in the longitudinal and transverse directions. Here, the channel waveguide as waveguide 103 is realized by the refractive index difference between a linear core, which is a high refractive index region, and air, which is a low refractive index region above, below, left, and right of the core. One end of the waveguide 103 (the end opposite to the connection part 102 side) can be optically coupled to an optical integrated circuit.

[0032] Since the optical element 20 has a fan shape in which the grating structure 101 and the connecting portion 102 as a whole narrow as they approach the waveguide 103, the change in the effective refractive index of light propagating continuously through the grating structure 101, the connecting portion 102 and the waveguide 103 can be minimized (apodizing effect), thereby improving the propagation efficiency of the light (reducing losses).

[0033] Preferably, the grating structure 101 has multiple through holes TH arranged in a row along the extending direction of the groove 101a, penetrating the inter-groove portion 101c (light gray portion in Figure 2), which is the portion between adjacent grooves 101a, the portion 101d on the second surface 10b side (for example, the lower surface side, hereinafter the same) of the inter-groove portion 101c, and / or the portion 101b on the second surface 10b side of the groove 101a adjacent to the inter-groove portion 101c.

[0034] Here, multiple through holes TH are provided in a row along the extending direction of the groove 101a (for example, the direction in which the arc extends), penetrating the inter-groove portion 101c, which is the portion between adjacent grooves 101a in each pair, the portion 101d on the second surface 10b side of the inter-groove portion 101c, and the portion 101b on the second surface 10b side of the groove 101a adjacent to the above-mentioned side (outer circumference side) of the inter-groove portion 101c.

[0035] Furthermore, as an example, multiple through holes TH are provided in a row along the extending direction of the groove 101a, penetrating the portion of the innermost groove 101a on the second surface 10b side and the inner circumferential end 101e of the grating structure 101.

[0036] Multiple through-holes TH aligned along the extending direction of each groove 101a constitute a composite diffraction grating together with the groove 101a. Here, the plan view shape of each through-hole TH is square. Here, the size (area) of each through-hole TH is the same, but at least two of the through-holes TH may be of different sizes. Here, the ratio of the region of the through-hole TH that penetrates the portion 101b on the second surface 10b side of the groove 101a to the region that penetrates the inter-groove portion 101c and the portion 101d on the second surface 10b side of the inter-groove portion 101c is the same, but may be different.

[0037] As an example, the outer peripheral portion of the outermost groove 101a of the grating structure 101 and the portion of this portion on the second surface 10b side constitute the outer peripheral end 101f of the grating structure 101.

[0038] As an example, the plurality of through-holes TH are arranged periodically. As an example, the plurality of through-holes TH are arranged at a constant pitch (period, center-to-center distance). As an example, the plurality of through-holes TH have the same shape and size. Note that at least two of the plurality of through-holes TH may differ in at least one of shape and size.

[0039] The grating structure 101 configured as described above can have a minimum dimension in the structure of, for example, 100 nm or more, and can be easily formed by processing a base material (e.g., a substrate) by dry etching, for example.

[0040] Here, as shown in FIG. 3, the through-hole TH having a vertically symmetric refractive index distribution (symmetric with respect to the intermediate position in the direction perpendicular to the plane), the groove 101a having a vertically asymmetric refractive index distribution (asymmetric with respect to the intermediate position in the direction perpendicular to the plane), and the portion 101b of the groove 101a on the second surface 10b side form an optical interference region OIA that causes light to interfere. That is, the grating structure 101 includes a plurality of optical interference regions OIA each having a first in-plane region whose refractive index distribution is symmetric (vertically symmetric) with respect to the intermediate position in the direction perpendicular to the plane, and a second in-plane region adjacent to the first in-plane region in the in-plane direction whose refractive index distribution is asymmetric (vertically asymmetric) with respect to the intermediate position in the direction perpendicular to the plane. In this case, it is preferable that the plurality of optical interference regions OIA are two-dimensionally arranged in the in-plane direction. It is more preferable that the plurality of optical interference regions OIA are arranged along substantially concentric arcs in a plan view. It is more preferable that the outer shape of the grating structure 101 and the connecting portion 102 as a whole in a plan view is substantially sector-shaped.

[0041] In the optical interference region OIA, light incident from the lateral direction can be caused to interfere, making it possible to increase the upward emissivity and reduce the back reflectance (the reflectance in the direction opposite to the incident direction). Further, in the optical interference region OIA, light incident from the longitudinal direction (e.g., upward direction) can be caused to interfere, making it possible to increase the lateral incident rate and reduce the back reflectance (the reflectance in the direction opposite to the incident direction). Supplementally, in the optical interference region OIA, the upward emissivity can be improved by controlling the phases of light emitted upward and downward. More specifically, in the optical interference region OIA, the phases of light emitted upward and downward from a first in-plane region having a vertically symmetric refractive index distribution are in phase, while the phases of light emitted upward and downward from a second in-plane region having a vertically asymmetric refractive index distribution are shifted by π (become opposite in phase). By combining these regions, light interferes destructively downward and interferes constructively upward, resulting in increased upward emissivity.

[0042] That is, the grating structure 101 can output light input from the lateral direction (the connecting portion 102 side) to the longitudinal direction (e.g., upward direction) with high efficiency, and / or can input light incident from the longitudinal direction (e.g., upward direction) to the lateral direction (the connecting portion 102 side) with high efficiency.

[0043] In the grating structure 101, the light input / output efficiency between the longitudinal direction and the lateral direction can be adjusted by, for example, the number, length, width, depth, and pitch of the grooves 101a, as well as the position, size, shape, number, and pitch of the through holes TH.

[0044] (Operation of the optical element) In the optical element 10, for example, light (optical signal) input from one end of the waveguide 103 and passing through the waveguide 103 is input from the other end of the waveguide 103 to the connection part 102 (slab waveguide) with little change in effective refractive index. The light input to the connection part 102 propagates within the connection part 102 (slab waveguide) while spreading radially in the lateral direction with very little change in effective refractive index, and is input to the grating structure 101. The light input to the grating structure 101 propagates within the grating structure 101 while spreading laterally, interferes and reinforces in each optical interference region OIA, is diffracted by the grooves 101a and through holes TH corresponding to the optical interference region OIA, and is output to the first surface 10a side (for example, the upper side) of the grating structure 101 with high upward emissivity and low back reflectivity (reflectivity toward the connection part 102 side).

[0045] In the optical element 10, for example, light input (incident) from the first surface 10a side (e.g., the upper side) of the grating structure 101 interferes constructively in each optical interference region OIA, is diffracted by the grooves 101a and through holes TH corresponding to the optical interference regions OIA, and is incident on the connection section 102 (slab waveguide) with a high incidence rate and low back reflectance (reflectance to the upper side). The light input to the connection section 102 propagates within the connection section 102 while narrowing laterally with a very small change in effective refractive index, enters the waveguide 103 with a small change in effective refractive index, and is output to one end of the waveguide 103 via the waveguide 103.

[0046] Figure 5 is a graph showing the relationship between the wavelength of light input to an optical element 10 according to Embodiment 1 of one embodiment of this technology and the power ratio of the optical element 10. As shown in Figure 5, the optical element 10 can achieve a high upward emissivity of 80% or more and a low backward reflectivity of about 1% when the wavelength of light input from one end of the waveguide 103 is, for example, in the wavelength range of 1450 nm to 1550 nm, and can also achieve a radiation angle of about 8 degrees that is close to vertical. Similarly, when light is incident from above the grating structure 101, a high lateral incidence rate and low backward reflectivity can be obtained, and a near-vertical incidence angle can also be obtained.

[0047] A brief explanation of a method for manufacturing the optical element 10 is provided. The overall process involves forming multiple optical elements 10 as a single unit on a substrate (e.g., a Si substrate, a SiN substrate, etc.) using photolithography and dry etching, and then separating them into individual pieces by dicing (e.g., stealth dicing) to obtain multiple optical elements 10.

[0048] First, scribe lines are formed on the substrate along the outline of each optical element 10. Next, multiple grooves 101a of each optical element 10 are formed on the substrate by photolithography and dry etching. Then, multiple through holes TH of each optical element 10 are formed on the substrate by photolithography and dry etching. Finally, the optical elements are diced along the scribe lines to form individual pieces.

[0049] (Effects of the optical element) The optical element 10 described above comprises a grating structure 101 having opposing first surfaces 10a and second surfaces 10b. The grating structure 101 has a plurality of grooves 101a arranged side by side on the first surface 10a, and a plurality of through holes TH are arranged side by side along the extending direction of the grooves 101a, penetrating the inter-groove portions 101c which are the parts between adjacent grooves 101a, the portion 101d on the second surface 10b side of the inter-groove portions 101c, and / or the portion 101b on the second surface 10b side of the groove 101a adjacent to the inter-groove portions 101c.

[0050] In the optical element 10, an optical interference region OIA is formed by a through hole TH whose refractive index distribution is vertically symmetrical, and a groove 101a whose refractive index distribution is vertically asymmetrical, and the portion 101b of the groove 101a on the second surface 10b side, thereby causing light to interfere.

[0051] As a result, the optical element 10 can efficiently output light input from the side in the vertical direction (for example, upwards), and / or output light input from the vertical direction (for example, upwards) in the side direction with high efficiency.

[0052] Furthermore, in the optical element 10, since the groove 101a and the through hole TH are combined in the grating structure 101, the change in the effective refractive index in the vertical direction relative to the change in the effective refractive index in the lateral direction can be mitigated, and the constraints on the minimum processing dimensions are relaxed. On the other hand, in the comparative example grating structure having a through groove, as shown in Figure 48, for example, the change in the effective refractive index in the yz cross-section relative to the change in the effective refractive index in the x direction becomes abrupt, so the constraints on the minimum processing dimensions become stricter.

[0053] Multiple grooves 101a are arranged periodically, and multiple through holes TH are also arranged periodically. As a result, multiple optical interference regions OIA are arranged periodically along the extension direction of each of the periodically arranged grooves 101a, so that the upward emissivity and / or downward incidence can be increased substantially uniformly within the plane of the grating structure 101, and the backward reflectivity can be decreased substantially uniformly within the plane of the grating structure 101.

[0054] The through-hole TH penetrates the groove 101c, the portion 101d on the second surface 10b side of the groove 101c, and the portion 101b on the second surface 10b side of the groove 101a adjacent to the groove 101c. As a result, the optical interference region OIA spans the groove 101a and the groove 101c, which improves the upward emissivity and / or downward incidence and reduces the back reflectance, thereby substantially improving the upward emissivity and / or downward incidence. If the optical interference region OIA does not span the groove 101a and the groove 101c, the upward emissivity and / or downward incidence may be somewhat lower, and the back reflectance may be somewhat higher. This is thought to be because the constructive and destructive interference of light in the optical interference region OIA described above cannot be effectively produced.

[0055] In a plan view, the grating structure 101 gradually narrows in width from one side (outer circumference) to the other side (inner circumference) in the direction in which the multiple grooves 101a are aligned. This allows the optical element 10, which propagates light between one end of the waveguide 103 with a small cross-sectional area and the outer circumference 101f of the grating structure 101, to gradually change the effective refractive index of light propagating laterally (in-plane direction) within the grating structure 101, thereby suppressing back reflection returning to the waveguide 103.

[0056] The grating structure 101 is approximately arc-shaped in plan view, and the multiple grooves 101a are approximately concentric arcs in plan view. This makes it possible to more gradually change the effective refractive index of light propagating laterally (in-plane direction) within the grating structure 101 in the optical element 10 which propagates light laterally between one end of the waveguide 103 with a small cross-sectional area and the outer peripheral end 101f of the grating structure 101, thereby suppressing back reflection returning to the waveguide 103.

[0057] The optical element 10 further includes a connecting portion 102 that connects the other end (inner circumference side) of the grating structure 101 to the waveguide 103, and the width of the connecting portion 102 gradually narrows from the grating structure 101 side to the waveguide 103 side in a plan view. As a result, in an optical element 10 that propagates light laterally between one end of the waveguide 103, which has a small cross-sectional area, and the outer circumference end 101f of the grating structure 101, the change in the effective refractive index of the light propagating laterally (in-plane direction) through the connecting portion 102 can be made more gradual, and consequently, back reflection returning to the waveguide 103 can be suppressed.

[0058] The grating structure 101 and the connecting portion 102 have a roughly fan-shaped overall shape when viewed from above. This makes it possible to reduce the footprint of the optical element 10, which propagates light laterally between one end of the waveguide 103 with a small cross-sectional area and the outer peripheral end 101f of the grating structure 101, and to make the change in the effective refractive index of the light propagating laterally through the grating structure 101 and the connecting portion 102 as gradual as possible.

[0059] The optical element 10 further includes a waveguide 103. This facilitates optical coupling between the optical element 10 and the optical integrated circuit.

[0060] <2. Optical element according to Example 2 of one embodiment of this technology>

[0061] The optical element 20 according to Example 2 of one embodiment of this technology will be described below. Figure 6 is a plan view of the optical element 20 according to Example 2 of one embodiment of this technology.

[0062] As shown in Figure 6, the optical element 20 has the same configuration as the optical element 10 according to Embodiment 1, except that it does not have a waveguide 103.

[0063] Although the optical connectivity between the connection portion 102 and the waveguide on the optical integrated circuit side is inferior, the optical element 20 allows for a simplified configuration while achieving generally the same function and effect as the optical element 10 in Example 1.

[0064] <3. Optical element according to Example 3 of one embodiment of this technology>

[0065] The optical element 30 according to Example 3 of one embodiment of this technology will be described below. Figure 7 is a plan view of the optical element 30 according to Example 3 of one embodiment of this technology.

[0066] As shown in Figure 7, the optical element 30 has the same configuration as the optical element 10 according to Embodiment 1, except that it does not have a waveguide 103 and the planar shape of the connection portion 102 is different.

[0067] In the optical element 30, the planar shape of the connection portion 102 (slab waveguide) is roughly a sector shape with the roughly triangular inner side removed. The optical element 30 is used, for example, as a light-gathering optical element.

[0068] The optical element 20 allows for simplification and miniaturization (reduced footprint) of its configuration while achieving generally the same functions and effects as the optical element 10 in Example 1.

[0069] <4. Optical element according to Example 4 of one embodiment of this technology>

[0070] The optical element 40 according to Embodiment 4 of one embodiment of this technology will be described below. Figure 8 is a plan view of the optical element 30 according to Embodiment 4 of one embodiment of this technology.

[0071] As shown in Figure 8, the optical element 40 has the same configuration as the optical element 10 according to Embodiment 1, except that the plan view of the grating structure 101 (which in this case has four grooves 101a) is rectangular, and the plan view of the connecting portion 102 (slab waveguide) is stepped tapered (multi-stage tapered).

[0072] With the optical element 20, although the change in effective refractive index at the boundary between the grating structure 101 and the connection portion 102 is somewhat large and the optical loss is somewhat large, the same operation and effect as the optical element 10 according to Example 1 can be obtained.

[0073] <5. Optical element according to Example 5 of one embodiment of this technology>

[0074] The optical element 50 according to Example 5 of one embodiment of this technology will be described below. Figure 9 is a plan view of the optical element 50 according to Example 5 of one embodiment of this technology.

[0075] As shown in Figure 9, the optical element 50 has the same configuration as the optical element 40 according to Embodiment 4, except that it does not have a waveguide 103.

[0076] Although the optical connectivity between the connection portion 102 and the optical integrated circuit is inferior to that of the optical element 50, the configuration is simplified while obtaining generally the same functions and effects as the optical element 40 in Example 4.

[0077] <6. Optical element according to Example 6 of one embodiment of this technology>

[0078] The optical element 60 according to Example 6 of one embodiment of this technology will be described below. Figure 10 is a plan view of the optical element 60 according to Example 6 of one embodiment of this technology.

[0079] As shown in Figure 10, the optical element 60 has the same configuration as the optical element 40 according to Embodiment 4, except that it does not have a waveguide 103 and a connecting portion 102.

[0080] The optical element 60 has a rectangular shape when viewed from a plan (more specifically, the rectangular shape of the grating structure 101 when viewed from a plan). The optical element 60 is used, for example, as a light-gathering optical element.

[0081] With the optical element 60, while simplifying the configuration and miniaturizing (reducing the footprint), the same functions and effects as the optical element 40 in Example 4 can be obtained.

[0082] <7. Optical element according to Example 7 of one embodiment of this technology>

[0083] The optical element 70 according to Example 7 of one embodiment of this technology will be described below. Figure 11 is a plan view of the optical element 70 according to Example 7 of one embodiment of this technology.

[0084] As shown in Figure 11, the optical element 70 has a configuration that is generally the same as the optical element 10 according to Embodiment 1, except that the outer shape in plan view of the portion that combines the grating structure 101 (which has four grooves 101a in this case) and the connecting portion 102, i.e., the portion excluding the waveguide 103, is approximately triangular (for example, approximately isosceles triangle).

[0085] The optical element 70 has a roughly triangular shape (for example, a roughly isosceles triangle) in plan view, excluding the waveguide 103.

[0086] In the optical element 70, the plan view of the grating structure 101 is substantially arc-shaped, and the plan view of the connecting portion 102 (slab waveguide) is substantially fan-shaped, with the inner circumferential end 101e of the grating structure 101 and the outer circumferential end of the connecting portion 102 coinciding. In other words, in the optical element 70, the grating structure 101 and the connecting portion 102 as a whole are substantially fan-shaped.

[0087] In the optical element 70, the multiple grooves 101a are concentric arcs in a plan view. Here, each groove 101a is composed of multiple (for example, three) straight grooves (straight grooves) connected to form a roughly arc shape. The number of these straight grooves can be changed as appropriate.

[0088] With the optical element 70, the same functions and effects as those of the optical element 10 in Example 1 can be obtained.

[0089] <8. Optical element according to Example 8 of one embodiment of the present technology>

[0090] The optical element 80 according to Example 8 of one embodiment of this technology will be described below. Figure 12 is a plan view of the optical element 80 according to Example 8 of one embodiment of this technology.

[0091] As shown in Figure 12, the optical element 80 has the same configuration as the optical element 70 according to Embodiment 7, except that it does not have a waveguide 103.

[0092] Although the optical connectivity between the connection portion 102 and the optical integrated circuit is inferior to that of the optical element 80, the configuration is simplified while obtaining generally the same functions and effects as the optical element 70 in Example 7.

[0093] <9. Optical element according to Example 9 of one embodiment of this technology>

[0094] The optical element 90 according to Example 9 of one embodiment of this technology will be described below. Figure 13 is a plan view of the optical element 90 according to Example 9 of one embodiment of this technology.

[0095] As shown in Figure 13, the optical element 90 has the same configuration as the optical element 70 according to Embodiment 7, except that it does not have a waveguide 103 and the planar shape of the connection portion 102 is different.

[0096] In the optical element 90, the plan view shape of the connection portion 102 (slab waveguide) is roughly a sector shape with the roughly triangular inner side removed. The optical element 30 is used, for example, as a light-gathering optical element.

[0097] The optical element 20 achieves a simplified and miniaturized structure (reduced footprint) while providing generally the same functions and effects as the optical element 10 in Example 1. It has the same configuration as the optical element 70 in Example 7, except that it does not have a waveguide 103 and a connecting portion 102.

[0098] The optical element 90 is used, for example, as a light-gathering optical element.

[0099] With the optical element 90, while simplifying the configuration and miniaturizing (reducing the footprint), the same functions and effects as the optical element 70 in Example 7 can be obtained.

[0100] Incidentally, in the optical elements 10, 20, 30, 70, 80, and 90 of Examples 1 to 3 and 7 to 9, the plan view shape of the grating structure 101 is approximately arc-shaped, but in the optical elements of Examples 10 to 12 below, the plan view shape of the grating structure 101 is expressed by a polynomial, and for example, optimization calculations for beam shape control can be introduced.

[0101] <10. Optical element according to Example 10 of one embodiment of the present technology>

[0102] Figure 14A is a schematic diagram showing the plan view outline of the grating structure 101 of an optical element according to Example 10 of one embodiment of the present technology.

[0103] The optical element according to Example 10 has the same configuration as any of the optical elements 10, 20, 30, 70, 80, and 90 according to Examples 1 to 3 and 7 to 9, except that the plan view shape of the grating structure 101 is at least a part of an ellipse (for example, a semi-ellipse).

[0104] The optical element according to Example 10 provides effects that are generally similar to those of any of the optical elements 10, 20, 30, 70, 80, and 90 according to Examples 1 to 3 and 7 to 9.

[0105] <11. Optical element according to Example 11 of one embodiment of the present technology> Figure 14B is a schematic diagram showing the plan view of the grating structure 101 of the optical element according to Example 11 of one embodiment of the present technology.

[0106] The optical element according to Example 11 has the same configuration as any of the optical elements 10, 20, 30, 70, 80, and 90 according to Examples 1 to 3 and 7 to 9, except that the planar shape of the grating structure 101 is represented by an exponential function, as shown in Figure 14B.

[0107] The optical element according to Example 11 provides effects that are generally similar to those of any of the optical elements 10, 20, 30, 70, 80, and 90 according to Examples 1 to 3 and 7 to 9.

[0108] <12. Optical element according to Example 12 of one embodiment of the present technology> Figure 14C is a schematic diagram showing the plan view of the grating structure 101 of the optical element according to Example 12 of one embodiment of the present technology.

[0109] The optical element according to Example 12 has the same configuration as any of the optical elements 10, 20, 30, 70, 80, and 90 according to Examples 1 to 3 and 7 to 9, except that the plan view shape of the grating structure 101 is a stepped tapered shape (multi-stepped tapered shape), as shown in Figure 14C. Here, the number of steps in the stepped tapered shape is one, but there may be multiple steps.

[0110] The optical element according to Example 12 provides the same effects as any of the optical elements 10, 20, 30, 70, 80, and 90 according to Examples 1 to 3 and 7 to 9.

[0111] Incidentally, the optical elements 10, 20, 30, 70, 80, and 90 in Examples 1 to 3 and 7 to 9 have a roughly fan-shaped plan view of the connection portion 102, but the optical elements in Examples 13 to 15 below have a plan view of the connection portion 102 that can be expressed by a polynomial, which allows for the introduction of calculations such as reflection reduction, loss reduction, and beam shape optimization.

[0112] <13. Optical element according to Example 13 of one embodiment of the present technology>

[0113] Figure 15A is a schematic diagram showing the plan view outline of the optical element connection portion 102 and waveguide 103 according to Embodiment 13 of one embodiment of the present technology.

[0114] The optical element according to Example 13 has the same configuration as any of the optical elements 10, 20, 30, 70, 80, and 90 according to Examples 1 to 3 and 7 to 9, except that the plan view shape of the connecting portion 102 is at least a part of an ellipse (for example, a semi-ellipse).

[0115] The optical element according to Example 13 provides effects that are generally similar to those of any of the optical elements 10, 20, 30, 70, 80, and 90 according to Examples 1 to 3 and 7 to 9.

[0116] <14. Optical element according to Example 14 of one embodiment of the present technology> Figure 15B is a schematic diagram showing the plan view outline of the connection portion 102 and waveguide 103 of the optical element according to Example 14 of one embodiment of the present technology.

[0117] The optical element according to Example 14 has the same configuration as any of the optical elements 10, 20, 30, 70, 80, and 90 according to Examples 1 to 3 and 7 to 9, except that the planar shape of the connection portion 102 is represented by an exponential function, as shown in Figure 15B.

[0118] The optical element according to Example 14 provides effects that are generally similar to those of any of the optical elements 10, 20, 30, 70, 80, and 90 according to Examples 1 to 3 and 7 to 9.

[0119] <15. Optical element according to Example 15 of one embodiment of the present technology> Figure 15C is a schematic diagram showing the plan view outline of the connection portion 102 and waveguide 103 of the optical element according to Example 15 of one embodiment of the present technology.

[0120] The optical element according to Example 15 has the same configuration as any of the optical elements 10, 20, 30, 70, 80, and 90 according to Examples 1 to 3 and 7 to 9, except that the plan view shape of the connection portion 102 is a stepped tapered shape (multi-stepped tapered shape), as shown in Figure 15C. Here, the number of steps in the stepped tapered shape is one, but there may be multiple steps.

[0121] The optical element according to Example 15 provides effects that are generally similar to those of any of the optical elements 10, 20, 30, 70, 80, and 90 according to Examples 1 to 3 and 7 to 9.

[0122] The following examples 16 to 19 show specific examples of the waveguide 103.

[0123] <16. Optical element according to Example 16 of one embodiment of the present technology> Figures 16A and 16B are a cross-sectional view and a plan perspective view, respectively, of a waveguide 103 connected via a connection portion to the grating structure of an optical element according to Example 16 of one embodiment of the present technology.

[0124] In Example 16, as shown in Figures 16A and 16B, the waveguide 103 is a rectangular waveguide, which is a type of channel waveguide. The rectangular waveguide 103 consists of a core 103a which is an elongated high refractive index medium (e.g., Si, SiN, etc.) with a rectangular cross-section, and a low refractive index region (e.g., SiO2) surrounding the core 103a. ２ The waveguide has a cladding 103b, which is made of air. The cladding 103b is not essential, and the area around the core 103a may be air. This rectangular waveguide is basically suitable for the propagation of single-mode light, but from the viewpoint of loss, it may also be used to propagate multi-mode light.

[0125] <17. Optical element according to Example 17 of one embodiment of the present technology> Figures 17A and 17B are a cross-sectional view and a plan perspective view, respectively, of a waveguide 103 connected via a connection portion to the grating structure of an optical element according to Example 17 of one embodiment of the present technology.

[0126] In Example 17, as shown in Figures 17A and 17B, the waveguide 103 is a rib-type waveguide. The rib-type waveguide 103 consists of a core 103a which is an elongated high refractive index medium with a substantially T-shaped cross-section, and a low refractive index region (for example, SiO₂) surrounding the core 103a. ２ It has a cladding 103b, which is a rib waveguide. The cladding 103b is not essential, and the area around the core 103a may be air. This rib waveguide is highly compatible with, for example, a phase shifter that controls the phase of light connected to an antenna.

[0127] <18. Optical element according to embodiment 18 of one embodiment of the present technology> Figures 18A and 18B are a cross-sectional view and a plan perspective view, respectively, of a waveguide 103 connected via a connection portion to the grating structure of an optical element according to embodiment 18 of one embodiment of the present technology.

[0128] In Example 18, as shown in Figures 18A and 18B, the waveguide 103 is a slot waveguide. The slot waveguide 103 has a structure that enables high-density, high-intensity optical confinement, in which the optical field is localized in a nano-order low refractive index region 103c2 (slot) sandwiched between two high refractive index media 103c1, and is expected to have applications in various sensing applications (e.g., biosensing applications).

[0129] <19. Optical element according to Example 19 of one embodiment of the present technology> Figures 19A and 19B are a cross-sectional view and a plan perspective view, respectively, of a waveguide 103 connected via a connection portion to the grating structure of an optical element according to Example 19 of one embodiment of the present technology.

[0130] In Example 19, as shown in Figures 19A and 19B, the waveguide 103 is a photonic crystal waveguide. A photonic crystal waveguide is an optical waveguide in which a localized linear defect is introduced within the two-dimensional photonic bandgap of a photonic crystal having a two-dimensional periodic refractive index distribution (e.g., a two-dimensional vacancy arrangement), and is an optical waveguide that propagates light along the linear defect.

[0131] The photonic crystal waveguide, as waveguide 103, has a structure in which a photonic crystal slab 103d into which linear defects 103d1 are introduced is sandwiched between cladding 103b. Light is controlled in the in-plane direction by a two-dimensional photonic bandgap and in the perpendicular direction by total internal reflection confinement due to a large refractive index difference between the slab and cladding.

[0132] In addition to the waveguides shown in Examples 16 to 19 above, the waveguide 103 may also be a dielectric optical waveguide, a plasmonic waveguide (negative dielectric optical waveguide), an embedded waveguide, a strip-loaded waveguide, a ridge waveguide, a diffusion waveguide, or the like.

[0133] Incidentally, the plan view shape of the through-hole TH is not limited to a square; for example, it can be the shape shown in the following embodiments 20 to 23. The optical element according to this technology exhibits a wavelength dependence of emissivity that varies depending on the plan view shape of the through-hole TH. The shape of the through-hole TH may be controlled to match the required wavelength band.

[0134] <20. Optical element according to Example 20 of one embodiment of the present technology> Figure 20A is a diagram showing the plan view shape of the through hole TH of the optical element according to Example 20 of one embodiment of the present technology.

[0135] As shown in Figure 20A, the optical element according to Example 20 has a rectangular (rectangular) shape in plan view of the through hole TH.

[0136] <21. Optical element according to Example 21 of one embodiment of the present technology> Figure 20B is a diagram showing the plan view shape of the through hole TH of the optical element according to Example 21 of one embodiment of the present technology. In the optical element according to Example 21, as shown in Figure 20B, the plan view shape of the through hole TH is triangular (for example, an isosceles triangle).

[0137] <22. Optical element according to Example 22 of one embodiment of the present technology> Figure 21A is a diagram showing the plan view shape of the through hole TH of the optical element according to Example 22 of one embodiment of the present technology. In the optical element according to Example 22, as shown in Figure 21A, the plan view shape of the through hole TH is circular.

[0138] <23. Optical element according to Example 23 of one embodiment of the present technology> Figure 21B is a diagram showing the plan view shape of the through hole TH of the optical element according to Example 23 of one embodiment of the present technology. In the optical element according to Example 23, as shown in Figure 21B, the plan view shape of the through hole TH is elliptical.

[0139] By the way, in each of the above embodiments, the pitch, spacing and size of the through holes TH, the position in the groove width direction, and the pitch, spacing and width of the grooves 101a are constant. However, as an example, as shown in embodiments 24 to 33 below, it is also possible to modulate the pitch of the through holes TH or grooves 101a, modulate the size or spacing of the through holes TH while keeping the pitch of the through holes TH constant, or modulate the width or spacing of the grooves 101a while keeping the pitch of the grooves 101a constant, in order to obtain an apodizing effect, for example.

[0140] <24. Optical element according to Example 24 of one embodiment of the present technology> Figure 22A is a diagram showing the pitch change of the through-hole TH of the optical element according to Example 24 of one embodiment of the present technology. For convenience, only the through-hole TH is shown in Figure 22A.

[0141] In the optical element according to Example 24, as shown in Figure 22A, the center position of some of the through holes TH is shifted from the position where the pitch is equal (dashed line), and the pitch (period) of the through holes TH is changing.

[0142] <25. Optical element according to Example 25 of one embodiment of the present technology> Figure 22B is a diagram showing the pitch change of the groove 101a of the optical element according to Example 25 of one embodiment of the present technology. For convenience, only the groove 101a and the intergroove portion 101c are shown in Figure 22B.

[0143] In the optical element according to Example 25, as shown in Figure 22B, the center position of some of the grooves 101a is shifted from the position where the pitch is equal (dashed line), and the pitch of the grooves 101a is changed.

[0144] <26. Optical element according to Example 26 of one embodiment of the present technology> Figure 23A is a diagram showing the pitch change of the through-hole TH of the optical element according to Example 26 of one embodiment of the present technology. For convenience, only the through-hole TH is shown in Figure 23A.

[0145] In the optical element according to Example 26, as shown in Figure 23A, the spacing between the through-holes TH is constant, and the size (area) of the through-holes TH changes linearly, and the pitch of the through-holes TH changes.

[0146] <27. Optical element according to Example 27 of one embodiment of the present technology> Figure 23B is a diagram showing the pitch change of the groove 101a of the optical element according to Example 27 of one embodiment of the present technology. For convenience, only the groove 101a and the intergroove portion 101c are shown in Figure 23B.

[0147] In the optical element according to Example 27, as shown in Figure 23B, the spacing between the grooves 101a is constant, the width of the grooves 101a changes linearly, and the pitch of the grooves 101a changes.

[0148] <28. Optical element according to Example 28 of one embodiment of the present technology> Figure 24A is a diagram showing the pitch change of the through-hole TH of the optical element according to Example 28 of one embodiment of the present technology. For convenience, only the through-hole TH is shown in Figure 24A.

[0149] In the optical element according to Example 28, as shown in Figure 24A, the spacing between the through-holes TH is constant, and the size (area) of the through-holes TH changes exponentially, resulting in a change in the pitch of the through-holes TH.

[0150] <29. Optical element according to Example 29 of one embodiment of the present technology> Figure 24B is a diagram showing the pitch change of the groove 101a of the optical element according to Example 29 of one embodiment of the present technology. For convenience, only the groove 101a and the intergroove portion 101c are shown in Figure 24B.

[0151] In the optical element according to Example 29, as shown in Figure 24B, the spacing between the grooves 101a is constant, and the width of the grooves 101a changes exponentially, resulting in a change in the pitch of the grooves 101a.

[0152] <30. Optical element according to Example 30 of one embodiment of the present technology> Figure 25A is a diagram showing the change in the size of the through-hole TH of the optical element according to Example 30 of one embodiment of the present technology. For convenience, only the through-hole TH is shown in Figure 25A.

[0153] In the optical element according to Example 30, as shown in Figure 25A, the spacing between the through-holes TH is constant, and large through-holes TH and small through-holes are arranged alternately; that is, the size of the through-holes TH changes while the pitch of the through-holes TH remains constant. Alternatively, the spacing between the through-holes TH may be alternated while keeping the size of the through-holes TH constant, thereby changing the spacing between the through-holes TH while keeping the pitch of the through-holes TH constant.

[0154] <31. Optical element according to embodiment 31 of one embodiment of the present technology> Figure 25B is a diagram showing the change in the width of the groove 101a of the optical element according to embodiment 31 of one embodiment of the present technology. For convenience, only the groove 101a and the inter-groove portion 101c are shown in Figure 25B.

[0155] In the optical element according to Example 31, as shown in Figure 25B, the spacing between the grooves 101a is the same, and wide grooves 101a and narrow grooves 101a are arranged alternately, that is, the width of the grooves 101a changes while the pitch of the grooves 101a remains constant. Alternatively, the spacing between the grooves 101a may be changed while keeping the width of the grooves 101a constant, by alternating between wide and narrow grooves 101a.

[0156] <32. Optical element according to embodiment 32 of one embodiment of the present technology> Figure 26A is a diagram showing the change in the length in the width direction (groove width direction) of the groove 101a of the through hole TH of the optical element according to embodiment 32 of one embodiment of the present technology.

[0157] As shown in Figure 26A, the optical element according to Embodiment 32 includes at least two through-holes TH in which the ratio of the region THa that penetrates the inter-groove portion 101c and the portion 101d on the second surface 10b side of the inter-groove portion 101c to the region THb that penetrates the portion 101b on the second surface 10b side of the groove 101a adjacent to the inter-groove portion 101c is different from that of the other two through-holes TH.

[0158] More specifically, in the optical element according to Example 32, a group of through-holes THG, each containing at least two (for example, two) through-holes TH with different ratios of region THa to region THb, is arranged periodically (for example, at a constant pitch) along the extending direction of the groove 101a. Here, in each through-hole TH, region THa is larger than region THb, but region THb may be larger than region T1.

[0159] In other words, in the optical element according to Example 34, through holes TH with a long length in the groove width direction and through holes TH with a short length in the groove width direction are arranged alternately at a constant pitch.

[0160] <33. Optical element according to embodiment 33 of one embodiment of the present technology> Figure 26B is a diagram showing the change in the length in the width direction (groove width direction) of the groove 101a of the through hole TH of the optical element according to embodiment 33 of one embodiment of the present technology.

[0161] As shown in Figure 26B, the optical element according to Embodiment 33 includes at least two through-holes TH in which the ratio of the region THa that penetrates the inter-groove portion 101c and the portion 101d on the second surface 10b side of the inter-groove portion 101c to the region THb that penetrates the portion 101b on the second surface 10b side of the groove 101a adjacent to the inter-groove portion 101c is different from that of the other two through-holes TH.

[0162] More specifically, in the optical element according to Example 33, a group of through-holes THG, each containing at least two (e.g., three) through-holes TH with different ratios of region THa to region THb, is arranged periodically (e.g., at a constant pitch) along the extending direction of the groove 101a. Here, in each through-hole TH, region THa is larger than region THb, but region THb may be larger than region T1.

[0163] The above examples 24 to 33 can be combined as appropriate.

[0164] <34. Optical element according to embodiment 34 of one embodiment of the present technology> Figure 27 is a partial cross-sectional view of an optical element according to embodiment 34 of one embodiment of the present technology.

[0165] As shown in Figure 27, the optical element according to Example 34 includes a slab containing a grating structure 101 and a connecting portion 102, each made of Si, which is a high refractive index material, and a low refractive index material SiO2 provided around the slab. ２ It comprises a clad 201 made of the same material.

[0166] The thickness of the slab is, for example, about 150 to 3000 nm. The depth of the groove 101a is, for example, about 1 / 3 to 2 / 3 of the thickness of the slab.

[0167] <35. Optical element according to embodiment 35 of one embodiment of the present technology> Figure 28 is a partial cross-sectional view of an optical element according to embodiment 35 of one embodiment of the present technology.

[0168] As shown in Figure 28, the optical element according to Example 35 includes a slab containing a grating structure 101 and a connecting portion 102, each made of SiN, which is a high refractive index material, and a low refractive index material SiO2 provided around the slab. ２ It comprises a clad 201 made of the same material.

[0169] The thickness of the slab is, for example, about 150 to 3000 nm. The depth of the groove 101a is preferably, for example, 1 / 10 to 9 / 10 of the slab thickness, more preferably 1 / 5 to 4 / 5, more preferably 3 / 10 to 7 / 10, more preferably 1 / 3 to 3 / 5, and more preferably 1 / 3 to 2 / 3.

[0170] In the above embodiments, an optical interference region (OIA) is formed by a through hole TH with a vertically symmetric refractive index distribution and a groove 101a and a portion 101b of the groove 101a on the second surface 10b side, where the refractive index distribution is vertically asymmetric. However, as shown in the following embodiments 36 to 38, additional components can be added to form the optical interference region (OIA) in order to mitigate the change in effective refractive index and improve the upward emissivity and / or downward incidence rate. For example, it is preferable that the component makes the vertical asymmetry of the refractive index distribution of the groove 101a and the portion 101b of the groove 101a on the second surface 10b side more pronounced.

[0171] <36. Optical element according to Example 36 of one embodiment of the present technology> Figure 29 is a partial cross-sectional view of an optical element according to Example 36 of one embodiment of the present technology.

[0172] In the optical element according to Example 36, as shown in Figure 29, the groove 101a or the intergrooved portion 101c has a stepped portion S. That is, the groove 101a has a stepped structure with a stepped portion S, or the intergrooved portion 101c has a stepped structure with a stepped portion S. The groove 101a having a stepped structure and the portion 101b of the groove 101a on the second surface 10b side and the intergrooved portion 101c adjacent to the groove 101a form an optical interference region OIA, or the groove 101a and the portion 101b of the groove 101a on the second surface 10b side and the intergrooved portion 101c adjacent to the groove 101a having a stepped structure form an optical interference region OIA. Here, a cladding 201 (low refractive index layer) is provided around the slab (high refractive index layer) including the grating structure 101 and the connecting portion 102.

[0173] <37. Optical element according to Example 37 of one embodiment of the present technology> Figure 30 is a partial cross-sectional view of an optical element according to Example 37 of one embodiment of the present technology.

[0174] The optical element according to Embodiment 37 further comprises a grating portion 301 provided on the first surface 10a side (e.g., upper side) of the grating structure 101. The grating portion 301 has a plurality of through holes 301a arranged in the direction of alignment of the plurality of grooves 101a. The refractive index (material refractive index) of the material of the grating portion 301 (e.g., Si) is higher than the refractive index (material refractive index) of the material of the grating structure 101 (e.g., SiN). The grooves 101a, the portion 101b on the second surface 10b side of the grooves 101a, the inter-groove portion 101c adjacent to the grooves 101a, and the grating portion 301 form an optical interference region (OIA). The inter-through hole portion 301b of the grating portion 301, which is the portion between adjacent through holes 301a, is positioned corresponding to the grooves 101a. Here, a slab (high refractive index layer) including the grating structure 101 and the connecting portion 102, and a cladding 201 (low refractive index layer) are provided around the grating portion 301.

[0175] <38. Optical element according to embodiment 38 of one embodiment of the present technology> Figure 31 is a partial cross-sectional view of an optical element according to embodiment 38 of one embodiment of the present technology.

[0176] The optical element according to Example 38 further comprises a multilayer film 401 provided on the first surface 10a side (e.g., upper side) of the grating structure 101. The multilayer film 401 is made up of multiple layers with different refractive indices (e.g., multiple semiconductor layers or multiple dielectric layers) stacked periodically. That is, the multilayer film 401 is a semiconductor multilayer reflector or a dielectric multilayer reflector. The groove 101a, the portion 101b on the second surface 10b side of the groove 101a, the intergroove portion 101c adjacent to the groove 101a, and the multilayer film 401 form an optical interference region (OIA). Here, a slab (high refractive index layer) including the grating structure 101 and the connecting portion 102, and a cladding 201 (low refractive index layer) are provided around the multilayer film 401.

[0177] <39. Optical transmitting device equipped with an optical element according to Embodiment 1 of one embodiment of the present technology> Figure 32 is a schematic diagram showing an optical transmitting device 1 equipped with an optical element 10 according to Embodiment 1 of one embodiment of the present technology as at least part of a transmitting antenna.

[0178] As an example, the optical transmitting device 1 (optical circuit device) includes, as shown in Figure 32, an optical integrated circuit 1000, an optical element 10 mounted on the optical integrated circuit 1000 which constitutes part of the transmitting optical antenna, and a lens 2000 which constitutes the other part of the optical antenna and is positioned on the optical path of the optical transmission signal TW radiated from the optical element 10. Note that the lens 2000 is not essential.

[0179] The optical integrated circuit 1000 is, for example, a PIC (Photon Integrated Circuit) and has an element portion that is optically coupled to the optical element 10.

[0180] Examples of the element components include optical transceivers, LiDAR, free-space optical communication, Doppler vibrometers, OCT (Optical Coherence Tomography), fiber sensors, fiber probers, and optical gyroscopes.

[0181] According to the optical transmission device 1, the optical signal generated by the optical integrated circuit 1000 can be converted into an optical transmission signal TW with high efficiency by the optical element 10 and transmitted.

[0182] In the optical transmitting device 1, an optical element according to another embodiment may be used instead of the optical element 10 according to Embodiment 1.

[0183] <40. Receiving device equipped with an optical element according to Embodiment 1 of one embodiment of the present technology> Figure 33 is a schematic diagram showing an optical receiving device 2 equipped with an optical element 10 according to Embodiment 1 of one embodiment of the present technology as at least part of a receiving antenna.

[0184] As an example, the optical receiving device 2 (optical circuit device) includes an optical integrated circuit 1000, an optical element 10 mounted on the optical integrated circuit 1000 which constitutes part of a receiving optical antenna, and a lens 2000 positioned on the optical path of the optical receiving signal RW incident on the optical element 10. Note that the lens 2000 is not essential.

[0185] The optical integrated circuit 1000 is, for example, a PIC (Photon Integrated Circuit) and has an element portion that is optically coupled to the optical element 10.

[0186] Examples of the element components include optical transceivers, LiDAR, free-space optical communication, Doppler vibrometers, OCT (Optical Coherence Tomography), fiber sensors, fiber probers, and optical gyroscopes.

[0187] According to the optical receiving device 2, the optical receiving signal RW can be received by the optical element 10, converted into an optical signal with high efficiency, and output to the optical integrated circuit 1000.

[0188] In the optical receiving device 2, an optical element according to another embodiment may be used instead of the optical element 10 according to Embodiment 1.

[0189] Furthermore, it is also possible to configure an optical transceiver by mounting the optical element 10 on the optical integrated circuit 1000 as at least part of the optical antenna for transmitting and receiving.

[0190] <41. Optical communication device equipped with an optical element according to Example 1 of one embodiment of the present technology> Figure 34 is a schematic diagram showing an optical communication device 3 equipped with an optical element 10 according to Example 1 of one embodiment of the present technology as at least part of a coupler.

[0191] The optical communication device 3 (optical circuit device) includes, as an example, an optical integrated circuit 1000 and an optical element 10 that constitutes at least a part of a coupler that optically connects the optical integrated circuit 1000 and an optical fiber 3000.

[0192] The optical integrated circuit 1000 is, for example, a PIC (Photon Integrated Circuit) and has an element portion that is optically coupled to the optical element 10.

[0193] Examples of the element components include optical transceivers, LiDAR, free-space optical communication, Doppler vibrometers, OCT (Optical Coherence Tomography), fiber sensors, fiber probers, and optical gyroscopes.

[0194] The optical communication device 3 can transmit and receive optical signals with high efficiency and speed between it and other optical communication devices optically coupled via the optical fiber 3000.

[0195] Furthermore, it is also possible to configure a transmitting and receiving device by mounting the optical element 10 on the optical integrated circuit 1000 as at least part of the optical antenna for transmitting and receiving.

[0196] <42. Modifications of this technology> This technology can be modified as appropriate, not limited to the examples described above.

[0197] For example, in each of the above embodiments, each through-hole TH penetrates both the groove portion 101c and the portion of the groove portion 101c on the second surface 10b side (the former), and the portion of the groove 101a adjacent to the groove portion 101c on the second surface 10b side (the latter). However, it is not limited to this, and it is sufficient for each through-hole TH to penetrate at least one of the former and the latter.

[0198] (Modification 1 of Example 1) Specifically, for example, as shown in Figure 35A (cross-sectional view corresponding to Figure 3) and Figure 35B (cross-sectional view corresponding to Figure 4), the positional relationship between the groove 101a and the through hole TH may be reversed compared to the optical element 10 of Example 1.

[0199] (Modification 2 of Example 1) For example, as shown in Figure 36 (plan view corresponding to Figure 2), the optical element 110 according to Modification 2 of Example 1 may have only a through hole TH1 that penetrates only the portion 101b on the second surface 10b side of the groove 101a.

[0200] (Modification 3 of Example 1) For example, as shown in Figure 37 (plan view corresponding to Figure 2), the optical element 120 according to Modification 3 of Example 1 may have only a through hole TH2 that penetrates only the groove portion 101c and the portion 101d on the second surface 10b side of the groove portion 101c.

[0201] (Modification 4 of Example 1) For example, as shown in Figure 38 (plan view corresponding to Figure 2), an optical element 130 according to Modification 4 of Example 1 may be provided, in which a plurality of through holes TH are provided along the extending direction of a part of the groove 101a, and a plurality of through holes TH1 are provided along the extending direction of the other part of the groove 101a that penetrate only the portion 101b on the second surface 10b side of the groove 101a.

[0202] (Modification 5 of Example 1) For example, as shown in Figure 39 (plan view corresponding to Figure 2), an optical element 140 according to Modification 5 of Example 1 may be provided, in which a plurality of through holes TH are provided along the extending direction of a part of the groove 101a, and a plurality of through holes TH2 are provided along the extending direction of the other part of the groove 101a, penetrating only the inter-groove portion 101c adjacent to the groove 101a and the portion 101d on the second surface 10b side of the inter-groove portion 101c.

[0203] (Modification 6 of Example 1) For example, as shown in Figure 40 (plan view corresponding to Figure 2), an optical element 150 according to Modification 6 of Example 1 may be provided, with through holes TH and through holes TH1 that penetrate only the portion 101b of the groove 101a on the second surface 10b side, along the extending direction of each groove 101a.

[0204] (Modification 7 of Example 1) For example, as shown in Figure 41 (plan view corresponding to Figure 2), an optical element 160 according to Modification 7 of Example 1 may be provided, through holes TH and through holes TH2 that penetrate only the through holes TH and the inter-groove portion 101c adjacent to the groove 101a and the portion 101d on the second surface 10b side of the inter-groove portion 101c, along the extending direction of each groove 101a.

[0205] (Modification 8 of Example 1) For example, as shown in Figure 42 (plan view corresponding to Figure 2), the optical element 170 according to Modification 8 of Example 1 may have a group of grooves including a plurality of grooves 101a through which the through hole TH penetrates the portion on the second surface 10b side, sandwiched between grooves 101a1 through which the through hole does not penetrate the portion on the second surface 10b side.

[0206] (Modification 9 of Example 1) For example, as shown in Figure 43 (plan view corresponding to Figure 2), the optical element 180 according to Modification 9 of Example 1 may have alternating grooves 101a through which the through-hole TH passes and grooves 101a1 through which the through-hole does not pass.

[0207] (Modification 10 of Example 1) For example, as shown in Figure 44 (plan view corresponding to Figure 2), the optical element 190 according to Modification 10 of Example 1 may have a group of grooves 101a through which the through holes TH pass, sandwiched between a group of through holes TH3 provided along the inner circumferential end 101e of the grating structure 101 and a group of through holes TH4 provided along the outer circumferential end 101f of the grating structure 101.

[0208] (Modification 11 of Example 1) For example, as shown in Figure 45 (plan view corresponding to Figure 2), the optical element 200 according to Modification 11 of Example 1 may be provided with a through hole TH and a through hole TH' that penetrates only the groove portion 101c and the portion 101d of the groove portion 101c on the second surface 10b side.

[0209] (Modification 12 of Example 1) For example, as shown in Figure 46A (a cross-sectional view corresponding to Figure 3), an optical element according to modification 12 of Example 1 may be formed without through holes, with a groove HG provided and a groove portion 101c having a vertically symmetric refractive index distribution, and an adjacent groove 101a having a vertically asymmetric refractive index distribution and a portion 101b of the groove 101a on the second surface 10b side, forming an optical interference region OIA.

[0210] (Modification 13 of Example 1) For example, as shown in Figure 46B (a cross-sectional view corresponding to Figure 3), an optical element according to modification 13 of Example 1 may be formed without through holes, with a groove HG provided and a groove portion 101c having a vertically symmetric refractive index distribution, and a groove 101a adjacent to the groove portion 101c having a vertically asymmetric refractive index distribution, and a portion 101b of the groove 101a on the second surface 10b side, which together form an optical interference region OIA. As an example, the optical element according to modification 13 of Example 1 is constructed by bonding together two substrates of the same material.

[0211] (Modification 14 of Example 1) For example, as shown in Figure 47 (cross-sectional view corresponding to Figure 3), an optical element according to Modification 14 of Example 1 may be provided in the groove 101a, wherein the refractive index of a different refractive index material 101g (e.g., semiconductor, dielectric, etc.) is different from that of the portion 101b on the second surface 10b side of the groove 101a, and the through hole TH, the portion 101b on the second surface 10b side of the groove 101a, and the different refractive index material 101g may form an optical interference region OIA.

[0212] (Modification 15 of Example 1) Figure 50 is a partial cross-sectional view (corresponding to Figure 3) of an optical element according to modification 15 of Example 1 of one embodiment of the present technology.

[0213] For example, the optical element may have a structure in which a grating structure 101 is formed on top of the BOX layer 501, as shown in the modified example 15 of Embodiment 1 in Figure 50. The material of the BOX layer 501 is SiO ２ It is also possible that the material of the grating structure 101 is Si. The optical element according to the modified example 15 of Example 1 may be manufactured by processing an SOI (Silicone on Insulator) substrate as described later in the manufacturing method (Figures 53 to 56). In the grating structure 101, there are no steps or recessed parts in the side walls of the grooves 101a and the inter-groove portions 101c that form the through holes TH, and the side walls may be substantially vertical. This prevents increased light scattering in the side wall portions and suppresses the loss of light propagation.

[0214] (Modification 16 of Example 1) Figure 51 is a partial cross-sectional view (corresponding to Figure 3) of an optical element according to modification 16 of Example 1 of one embodiment of the present technology.

[0215] For example, as in the optical element according to Modification 16 of Embodiment 1 shown in Figure 51, a grating structure 101 is formed on the BOX layer 501, and the entire structure is made of SiOx or SiO ２ The structure may be covered with a flat film made of the same material. The material of the flat film covering the entire structure shall have a refractive index higher than that of the BOX layer 501. If the refractive index of the flat film is Nb and the refractive index of the BOX layer 501 is Na, then the material shall satisfy Nb > Na. In addition, a stepped groove-down through hole THc may be formed at the bottom of the through hole TH (directly below the groove 101a).

[0216] The optical element according to Modification 16 of Example 1 may be manufactured by processing an SOI substrate, similar to the optical element according to Modification 15. At the bottom of the through-hole TH, the groove-down through-hole THc may be formed to a depth of, for example, 20 nm or less than the surrounding depth of the groove-down through-hole THc. As a method for forming the flat film after forming the grating structure 101, for example, HDP (High Density Plasma), ALD (Atomic Layer Deposition), or TEOS (Tetraethyl Orthosilicate) may be used.

[0217] According to the optical element of Modification 16 of Example 1, a groove-down through-hole THc is formed in a stepped manner at the bottom of the through-hole TH, and the difference in refractive index between the BOX layer 501 and the flat film at the bottom of the through-hole TH increases the radioactivity. As the area directly below the groove 101a becomes deeper, a diffraction grating-like step is created, and the incident light is diffracted toward the direction with the higher refractive index (upwards).

[0218] (Modification 17 of Example 1) Figure 52 is a partial cross-sectional view (corresponding to Figure 3) of an optical element according to modification 17 of Example 1 of one embodiment of the present technology.

[0219] The optical element according to Modification 17 of Example 1 differs from the optical element according to Modification 16 in that the angle of the side wall forming the through hole TH is different. For example, as shown in Figure 52, in the cross-section, the angle of the side wall of the groove 101a portion (the side wall of the portion forming the groove-under through hole THc) is the groove-under through hole angle θ2, the angle of the side wall of the inter-groove portion 101c portion is the inter-groove portion angle θ3, and the angle of the side wall of the portion opposite the side wall of the groove 101a portion is the through hole angle θ1. In this case, for example, the groove-under through hole angle θ2 and the inter-groove portion angle θ3 may be approximately 0° with respect to the vertical direction, and the side wall of the groove 101a portion and the side wall of the inter-groove portion 101c portion may be approximately vertical. Alternatively, the through hole angle θ1 may be greater than 0° with respect to the vertical direction, and the side wall of the portion opposite the side wall of the groove 101a portion may be inclined (tapered).

[0220] In the optical element according to modification 17 of Example 1, the shape of the opposing side wall portions forming the through-hole TH becomes asymmetrical, and the radiation increases. In the example of Figure 52, upward radiation increases in the tapered portion. If the tapered shape is at the opposite angle to that of the example of Figure 52, downward radiation increases. When processing Si to form the through-hole TH and the grooved through-hole THc, the processing time differs between the through-hole TH and the grooved through-hole THc. The side wall of the grooved through-hole THc becomes vertical as the volume of the Si-based deposit increases.

[0221] (Method for manufacturing an optical element 1) Figure 53 is a partial cross-sectional view (corresponding to Figure 50) showing an overview of the method for manufacturing an optical element 1 according to a modified example 15 of one embodiment of the present technology.

[0222] First, a groove pattern is formed on the Si portion above the BOX layer 501 in the SOI substrate, which will serve as the basis for the groove 101a (Figure 53(A)). The groove width is formed to, for example, 150 nm to 200 nm, and the depth to, for example, 50 nm to 100 nm. The angle of the groove is, for example, approximately vertical.

[0223] Next, before forming the through-holes TH, a buffer film is placed in the groove to flatten the surface, and then the through-holes TH are formed so as to span the area with the underlying groove (Figure 53 (B)). The through-holes TH are formed, for example, with a short diameter of 140 nm to 200 nm and a long diameter of 340 nm to 400 nm. The processing process is carried out under optimal conditions for both the buffer layer and the Si. At that time, conditions are selected so that each film is not etched on the sides in order to create a fine pattern. In addition, the conditions for etching the Si are determined by the underlying SiO ２ The most selective conditions are selected. Note that in the case of the configuration of Modification 16 of Example 1 (Figure 51), the depth of the through-hole THc below the groove should be within 20 nm. Also, in the case of the configuration of Modification 17 of Example 1 (Figure 52), the through-hole angle θ1 may be approximately 2° with respect to the vertical direction.

[0224] Next, at the same time as the formation of the waveguide 103, the contours of the connection portion 102 and the grating structure 101 are formed (Figure 53(C)). Subsequently, in the case of the configuration of the modified example 16 (Figure 51), the entire structure is made of SiOx or SiO２ covering with a flat film to achieve planarization.

[0225] (Second Manufacturing Method of Optical Element) FIG. 54 is a partial cross-sectional view (a cross-sectional view corresponding to FIG. 50) illustrating an outline of the second manufacturing method of an optical element according to Modification 15 of Example 1 of an embodiment of the present technology.

[0226] The second manufacturing method is a method in which a through hole TH is formed earlier compared to the first manufacturing method. First, a pattern of the through hole TH is formed on a silicon portion above a BOX layer 501 in an SOI substrate ((A) of FIG. 54).

[0227] Next, a pattern of a groove 101a is formed ((B) of FIG. 54).

[0228] Next, outlines of a connection portion 102 and a grating structure 101 are formed at the same timing as forming a waveguide 103 ((C) of FIG. 54).

[0229] Other features may be substantially the same as those of the first manufacturing method.

[0230] (Third Manufacturing Method of Optical Element) FIG. 55 is a partial cross-sectional view (a cross-sectional view corresponding to FIG. 50) illustrating an outline of the third manufacturing method of an optical element according to Modification 15 of Example 1 of an embodiment of the present technology.

[0231] The third manufacturing method is a method in which the through hole TH, the connection portion 102 and the outlines of the grating structure 101 are formed simultaneously compared to the first manufacturing method. First, a groove pattern serving as a base of the groove 101a is formed on a silicon portion above the BOX layer 501 in the SOI substrate ((A) of FIG. 55).

[0232] Next, the through hole TH, the connection portion 102 and the outlines of the grating structure 101 are formed simultaneously ((B) of FIG. 55).

[0233] Other features may be substantially the same as those of the first manufacturing method.

[0234] (Fourth Manufacturing Method of Optical Element) FIG. 56 is a partial cross-sectional view (a cross-sectional view corresponding to FIG. 50) illustrating an outline of the fourth manufacturing method of an optical element according to Modification 15 of Example 1 of an embodiment of the present technology.

[0235] Manufacturing method 4 is a method in which the through hole TH, the connecting portion 102, and the outline of the grating structure 101 are formed simultaneously before the formation of the groove 101a, compared to manufacturing method 1. First, the through hole TH, the connecting portion 102, and the outline of the grating structure 101 are formed in the Si portion on the BOX layer 501 of the SOI substrate (Figure 55(A)).

[0236] Next, the groove pattern 101a is formed (Figure 55(B)).

[0237] Other aspects may be substantially the same as in manufacturing method 1.

[0238] (Other variations) For example, as shown in Figure 49, the side surface of the through hole TH may be inclined in a cross-sectional view with respect to the direction perpendicular to the surface of the grating structure 101 (the vertical direction in Figure 49).

[0239] For example, at least one of a groove, a through hole, and a through groove may be provided between the grating structure 101 and the connection portion 102 (slab waveguide), or in the connection portion 102.

[0240] For example, the optical element may have a reflection suppression structure in front of or behind (e.g., above) the grating structure 101, which includes at least one of a waveguide, a groove, a through hole, and a through groove.

[0241] For example, the planar shape of the groove 101a may be V-shaped, W-shaped, zigzag, or the like.

[0242] For example, the grating structure 101 may be composed of multiple layers.

[0243] Furthermore, some of the configurations of the above embodiments and modified examples may be combined within a range that does not contradict each other.

[0244] <43. Other Embodiments> The technology described herein is not limited to the above-described embodiment and can be implemented in various modified forms.

[0245] For example, this technology can also take the following configuration. With this configuration, it is possible to provide an optical element that can output light input from the side in the vertical direction (e.g., upward) with high efficiency, and / or output light input from the vertical direction (e.g., upward) in the side direction with high efficiency.

[0246] (1) An optical element comprising a grating structure having opposing first and second surfaces, wherein the grating structure has a plurality of grooves arranged side by side on the first surface, and a plurality of through holes are arranged side by side along the direction of extension of the grooves, penetrating the intergroove portions which are the portions between adjacent grooves, the portions of the intergroove portions on the second surface side, and / or the portions of the grooves adjacent to the intergroove portions on the second surface side. (2) The optical element according to (1) above, wherein the through holes penetrate the intergroove portions, the portions of the intergroove portions on the second surface side, and the portions of the grooves adjacent to the intergroove portions on the second surface side. (3) The optical element according to (1) or (2) above, wherein the grating structure, in plan view, gradually narrows in width from one side to the other in the direction in which the plurality of grooves are arranged. (4) The optical element according to (3) above, wherein the grating structure has a substantially arc shape in plan view, and the plurality of grooves are concentric substantially arc shapes in plan view. (5) The optical element according to (3) or (4) above, further comprising a connecting portion for connecting the other end of the grating structure to a waveguide, wherein the width of the connecting portion gradually narrows from the grating structure side to the waveguide side in a plan view. (6) The optical element according to any one of (3) to (5) above, further comprising a connecting portion for connecting the other end of the grating structure to a waveguide, wherein the grating structure and the connecting portion have an overall substantially fan-shaped external form in a plan view. (7) The optical element according to (6) above, further comprising the waveguide. (8) The optical element according to any one of (1) to (7) above, wherein the plan view shape of the through hole is one of polygonal, circular, or elliptical. (9) The optical element according to (2) above, wherein the plurality of through holes include at least two through holes in which the ratio of the region penetrating the inter-groove portion and the second-surface portion of the inter-groove portion is different from the ratio of the region penetrating the second-surface portion of the groove adjacent to the inter-groove portion. (10) The optical element according to (9) above, wherein the group of through holes including the at least two through holes is arranged periodically along the extending direction of the groove. (11) The optical element according to any one of (1) to (10) above, wherein the plurality of grooves are arranged periodically.(12) An optical element according to any one of (1) to (11) above, wherein the plurality of through holes are arranged periodically. (13) An optical element according to any one of (1) to (12) above, wherein the pitch of the plurality of through holes is varied. (14) An optical element according to any one of (1) to (13) above, wherein the pitch of the plurality of grooves is varied. (15) An optical element according to any one of (1) to (14) above, wherein the grating structure is made of Si or a dielectric. (16) An optical element according to any one of (1) to (15) above, wherein the groove or the intergroove portion has a stepped portion. (17) An optical element according to any one of (1) to (16) above, further comprising a grating portion provided on the first surface side of the grating structure, wherein the average refractive index of the grating portion is higher than the average refractive index of the grating structure. (18) The optical element according to any one of (1) to (17) above, further comprising a multilayer film provided on the first surface side of the grating structure, wherein the multilayer film comprises a plurality of layers having different refractive indices stacked periodically. (19) The optical element according to any one of (1) to (18) above, which constitutes at least a part of a transmitting and / or receiving optical antenna mounted on an optical integrated circuit. (20) The optical element according to any one of (1) to (19) above, which constitutes at least a part of a coupler that optically couples an optical integrated circuit and an optical fiber. (21) The optical element comprising a grating structure that includes a plurality of optical interference regions, each having a first in-plane region whose refractive index distribution is symmetric with respect to an intermediate position in the direction perpendicular to the plane, and a second in-plane region adjacent to the first in-plane region in the in-plane direction, wherein the refractive index distribution is asymmetric with respect to the intermediate position. (22) The optical element according to (21) above, wherein the plurality of optical interference regions are arranged two-dimensionally in the in-plane direction. (23) The optical element according to (21) or (22) above, wherein the grating structure has a substantially arc shape in plan view, and the plurality of optical interference regions are arranged along a substantially arc that is concentric in plan view.(24) The optical element according to any one of (21) to (23) above, further comprising a connecting portion for connecting the inner circumferential end of the grating structure to a waveguide, wherein the grating structure and the connecting portion have an overall substantially fan-shaped external form when viewed from a plan view. (25) An optical circuit device comprising the optical element according to any one of (1) to (24) above.

[0247] This application claims priority based on Japanese Patent Application No. 2025-41290, filed with the Japan Patent Office on 14 March 2025, and all contents of that application are incorporated herein by reference.

[0248] Those skilled in the art will understand that various modifications, combinations, subcombinations, and changes can be conceived depending on design requirements and other factors, and that these fall within the scope of the attached claims and their equivalents.

Claims

1. An optical element comprising a grating structure having opposing first and second surfaces, wherein the grating structure has a plurality of grooves arranged side by side on the first surface, and a plurality of through holes arranged side by side along the extending direction of the grooves, penetrating the inter-groove portions which are the portions between adjacent grooves, the portions of the inter-groove portions on the second surface side, and / or the portions of the grooves adjacent to the inter-groove portions on the second surface side.

2. The optical element according to claim 1, wherein the through hole penetrates the inter-groove portion, the portion of the inter-groove portion on the second surface side, and the portion of the groove adjacent to the inter-groove portion on the second surface side.

3. The optical element according to claim 1, wherein the grating structure, in a plan view, gradually narrows in width from one side to the other in the direction in which the plurality of grooves are aligned.

4. The optical element according to claim 3, wherein the grating structure has a substantially arc shape in plan view, and the plurality of grooves are concentric and substantially arc-shaped in plan view.

5. The optical element according to claim 3, further comprising a connecting portion for connecting the other end of the grating structure to a waveguide, wherein the width of the connecting portion gradually narrows from the grating structure side to the waveguide side in a plan view.

6. The optical element according to claim 3, further comprising a connecting portion for connecting the other end of the grating structure to a waveguide, wherein the grating structure and the connecting portion have a substantially fan-shaped overall shape when viewed from a plan view.

7. The optical element according to claim 6, further comprising the waveguide.

8. The optical element according to claim 1, wherein the plan view shape of the through hole is one of a polygon, a circle, or an ellipse.

9. The optical element according to claim 2, wherein the plurality of through holes include at least two through holes in which the ratio of the region penetrating the inter-groove portion and the second-face side portion of the inter-groove portion is different from the ratio of the region penetrating the second-face side portion of the groove adjacent to the inter-groove portion.

10. The optical element according to claim 9, wherein the group of through holes, including at least two through holes, is periodically arranged along the direction of extension of the groove.

11. The optical element according to claim 1, wherein the plurality of grooves are arranged periodically.

12. The optical element according to claim 1, wherein the plurality of through holes are arranged periodically.

13. The optical element according to claim 1, wherein the pitch of the multiple through holes is varied.

14. The optical element according to claim 1, wherein the pitch of the plurality of grooves is varied.

15. The optical element according to claim 1, wherein the grating structure is made of Si or a dielectric material.

16. The optical element according to claim 1, wherein the groove or the space between the grooves has a stepped portion.

17. The optical element according to claim 1, further comprising a grating portion provided on the first surface side of the grating structure, wherein the refractive index of the material of the grating portion is higher than the refractive index of the material of the grating structure.

18. The optical element according to claim 1, further comprising a multilayer film provided on the first surface side of the grating structure, wherein the multilayer film is periodically stacked with a plurality of layers having different refractive indices.

19. An optical element according to claim 1, comprising at least a portion of a transmitting and / or receiving optical antenna mounted on an optical integrated circuit.

20. The optical element according to claim 1, which constitutes at least a part of a coupler that optically connects an optical integrated circuit and an optical fiber.

21. An optical element comprising a grating structure that includes a plurality of optical interference regions, each having a first in-plane region in which the refractive index distribution is symmetric with respect to an intermediate position perpendicular to the plane, and a second in-plane region adjacent to the first in-plane region in the in-plane direction, wherein the refractive index distribution is asymmetric with respect to the intermediate position.

22. The optical element according to claim 21, wherein the plurality of optical interference regions are arranged two-dimensionally in the in-plane direction.

23. The optical element according to claim 22, wherein the grating structure has a substantially arc shape in plan view, and the plurality of optical interference regions are arranged along a substantially arc that is concentric in plan view.

24. The optical element according to claim 23, further comprising a connecting portion for connecting the inner circumferential end of the grating structure to a waveguide, wherein the grating structure and the connecting portion have a substantially fan-shaped overall external shape when viewed from a plan view.

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