Glass laminate

Abstract

A glass laminate according to the present invention includes a glass substrate that has a refractive index of at least 1.60 and a metasurface layer that is provided on the glass substrate and has a metasurface structure.

Description

glass laminate

[0001] This disclosure relates to glass laminates.

[0002] Planar optical elements with a metasurface structure (hereinafter also referred to as "meta-optical elements") are considered promising as lightweight and thin optical elements. A metasurface structure refers to a surface microstructure that is smaller and more periodic than the wavelength of light targeted by the optical element. As an example of a meta-optical element, a metalens is described in Patent Document 1, for example, which comprises a support substrate and a pattern layer having an array pattern consisting of a plurality of silicon oxide columnar objects or a plurality of holes, in that order, the maximum aspect ratio of the silicon oxide columnar objects or holes in the pattern layer is greater than 6.7, and the pattern layer is made of at least SiO ２ A metalens containing is disclosed.

[0003] International Publication No. 2024 / 014272

[0004] One example of a meta-optical element is a metalens, which is formed on a planar transparent glass substrate in an arbitrary pattern of sub-nano-order three-dimensional structures called metaatoms, which are about 1 / 10th the wavelength of incident light. In a meta-optical element, these metaatoms change the phase and amplitude of light of a specific wavelength, thereby exhibiting functions such as absorption, reflection, and diffraction.

[0005] In recent years, with the miniaturization and weight reduction of devices, optical elements are increasingly required to be small, lightweight, and high-performance. One way to further improve the performance of meta-optical elements is to miniaturize the three-dimensional structure of the meta-atom and increase the aspect ratio. On the other hand, as the three-dimensional structure becomes finer and the aspect ratio increases, the difficulty of processing increases, which can lead to increased costs and decreased yield. Furthermore, from a manufacturing technology standpoint, there are limits to the miniaturization and aspect ratio increase of the three-dimensional structure.

[0006] One embodiment of this disclosure aims to provide a glass laminate that can easily achieve high performance as a meta-optical element.

[0007] This disclosure includes the following embodiments: <1> A glass laminate comprising: a glass substrate having a refractive index of 1.60 or more for light with a wavelength of 587.56 nm at 25°C; and a metasurface layer provided on the glass substrate and having a metasurface structure. <2> The glass laminate according to <1>, wherein the thickness of the glass substrate is 0.1 to 2.0 mm. <3> The glass laminate according to <1> or <2>, wherein the glass substrate contains at least one selected from the group consisting of tellurium oxide, bismuth oxide, titanium dioxide, niobium pentoxide, tantalum pentoxide, barium oxide, zirconium oxide, tungsten trioxide, yttrium oxide, lanthanum oxide, gadolinium oxide, ytterbium oxide, and lutetium oxide. <4> The glass laminate according to <3>, wherein the glass substrate further contains boric acid. <5> The glass laminate according to any one of <1> to <4>, wherein the total amount of alkali metal elements in the glass substrate is 0.5 mol% or less. <6> The glass laminate according to any one of <1> to <5>, wherein the metasurface layer includes at least one selected from the group consisting of silicon, silicon dioxide, gallium, gallium oxide, germanium, germanium oxide, indium, indium oxide, titanium dioxide, sapphire, niobium pentoxide, silicon nitride, and gallium nitride.

[0008] According to one embodiment of this disclosure, a glass laminate is provided that can easily be obtained to have high performance as a meta-optical element.

[0009] This is a schematic cross-sectional view showing an example of a glass laminate according to this embodiment.

[0010] One embodiment of this disclosure is described in detail below. However, this disclosure is not limited to the embodiment described below. In the following disclosure, the components (including elemental steps, etc.) are not essential unless otherwise explicitly stated. The same applies to numerical values ​​and their ranges, and they do not limit this disclosure.

[0011] In this disclosure, the term "process" includes not only processes that are independent of other processes, but also processes that are not clearly distinguishable from other processes, provided that the purpose of the process is achieved. In this disclosure, numerical ranges indicated using "~" include the numbers before and after "~" as the lower and upper limits, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in this disclosure, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples. In this disclosure, the content of each component in a composition means the total content of the multiple substances present in the composition, unless otherwise specified, if there are multiple substances corresponding to each component in the composition. In this disclosure, when multiple elements are listed using "or" or "or," unless otherwise explicitly stated, the selection of a combination of multiple elements is not excluded unless it does not result in a technical inconsistency. Even when an element is expressed in the singular form in this disclosure, unless otherwise explicitly stated, the existence of multiple elements is not excluded unless it does not result in a technical inconsistency. In this disclosure, the various exemplary embodiments described separately may be combined to form new embodiments, provided they do not contradict each other. In this disclosure, the terms “layer” or “film” include cases where, when the region in which the layer or film exists is observed, it is formed not only over the entire region but also over only a portion of the region.

[0012] In this disclosure, the refractive index refers to the refractive index at 587.56 nm. Specifically, the refractive index at 587.56 nm is measured using a precision refractometer in accordance with the V-block method (JIS B 7071-2:2018) under conditions of 25°C. Hereinafter, the refractive index for light with a wavelength of 587.56 nm at 25°C will also be simply referred to as the "refractive index."

[0013] [Glass Laminate] A glass laminate according to one embodiment of the present disclosure comprises a glass substrate having a refractive index of 1.60 or more, and a metasurface layer provided on the glass substrate and having a metasurface structure.

[0014] As mentioned above, further improving the performance of meta-optical elements can be achieved by miniaturizing the three-dimensional structure of the meta-atom and increasing the aspect ratio, but this method is difficult to process and can be technically challenging to manufacture. In contrast, in this embodiment, by using a glass substrate with a refractive index of 1.60 or higher, it is possible to obtain similar performance even with a lower aspect ratio of the three-dimensional structure of the meta-atom. Specifically, for example, in a metalens, light incident from the metasurface layer is focused by the metasurface layer and then transmitted through the glass substrate. In this case, if the refractive index of the glass substrate is high, light incident not only on the center of the lens but also on the outer edge is easily focused efficiently, resulting in higher optical performance such as the aperture ratio (NA), modulation transfer function (MTF), resolution, and field of view (FOV). Therefore, the conditions (aspect ratio, etc.) of the meta-atom required to obtain the desired optical performance are relaxed. As a result, the difficulty of processing is reduced, and it is believed that high performance as a meta-optical element can be easily obtained.

[0015] Figure 1 shows a schematic diagram of an end face of an example of the glass laminate of this embodiment, cut in the thickness direction. The glass laminate 10 shown in Figure 1 comprises a glass substrate 12 having a refractive index of 1.60 or higher, and a metasurface layer 14 provided on the glass substrate 12 and having a metasurface structure. The metasurface layer 14 of the glass laminate 10 shown in Figure 1 has a metasurface structure in which columnar pillars 14A are arranged at equal intervals. The metasurface structure of the glass laminate of this embodiment is not limited to the structure shown in Figure 1, and may be a structure that corresponds to the characteristics required as a meta-optical element. For example, the metasurface structure may be a structure in which pillars 14A are arranged periodically at different intervals, a structure in which columnar holes are arranged periodically in a film, or a structure in which columnar holes are arranged periodically in a film made of a relatively low refractive index material, and a relatively high refractive index material is embedded in the holes. In the glass laminate 10 shown in Figure 1, the metasurface layer 14 is provided in contact with the glass substrate 12. However, the glass laminate of this embodiment is not limited to this, and the metasurface layer 14 may be provided on the glass substrate 12 via other layers. Examples of other layers include a silicon dioxide layer, an etch-stop layer, and a wiring layer.

[0016] <Glass Substrate> (Refractive Index) The glass substrate is not particularly limited as long as it is a plate-shaped glass with a refractive index of 1.60 or higher. The refractive index of the glass substrate is 1.60 or higher, and for example, it is in the range of 1.60 to 2.30. From the viewpoint of easily obtaining high performance as a meta-optical element, the refractive index of the glass substrate is preferably 1.70 or higher, more preferably 1.80 or higher, even more preferably 1.90 or higher, particularly preferably 2.00 or higher, and extremely preferably 2.10 or higher. From the viewpoint of reducing reflectivity at the interface with the meta-surface layer, the refractive index of the glass substrate is preferably 2.25 or lower, and more preferably 2.20 or lower. Means for controlling the refractive index of the glass substrate within the above range include methods such as incorporating a high refractive index component into the glass substrate. Examples of high refractive index components include tellurium oxide (TeO2). ２ ), bismuth oxide (Bi ２ O ３ ), titanium dioxide (TiO２ ), niobium pentoxide (Nb ２ O ５ ), tantalum pentoxide (Ta ２ O ５ ), barium oxide (BaO), zirconium oxide (ZrO ２ ), tungsten trioxide (WO ３ ), yttrium oxide (Y ２ O ３ ), lanthanum oxide (La ２ O ３ ), gadolinium oxide (Gd ２ O ３ ), ytterbium oxide (Yb ２ O ３ ), lutetium oxide (Lu ２ O ３ ), and the like.

[0017] (Light transmittance) The internal transmittance of a glass substrate for light with a wavelength of 532 nm is preferably 80% or more when the thickness is 0.5 mm. From the viewpoint of easily obtaining high performance as a meta-optical element, the above internal transmittance for light with a wavelength of 532 nm is preferably 83% or more, more preferably 85% or more, and still more preferably 90% or more. When the above internal transmittance for light with a wavelength of 532 nm falls within this range, visible light can be appropriately transmitted. In addition, the internal transmittance of a glass substrate for light with a wavelength of 1064 nm is preferably 80% or more when the thickness is 0.5 mm. From the viewpoint of easily obtaining high performance as a meta-optical element, the above internal transmittance for light with a wavelength of 1064 nm is preferably 83% or more, more preferably 85% or more, still more preferably 88% or more, and even more preferably 90% or more. When the above internal transmittance for light with a wavelength of 1064 nm falls within this range, infrared light can be appropriately transmitted.

[0018] In the present disclosure, transmittance is obtained by measuring a spectral transmittance curve using a spectrophotometer or the like. For example, the internal transmittance at a thickness of 0.5 mm can be obtained by correcting a spectral transmittance curve obtained using an ultraviolet-visible spectrophotometer (model UH4150, manufactured by Hitachi High-Technologies Corporation) in consideration of reflection loss at the sample surface and the thickness of the sample.

[0019] (Composition) The glass substrate is composed of TeO as a high refractive index component, from the viewpoint of increasing the refractive index. ２ , Bi ２ O ３ , TiO ２ , Nb ２ O ５ Ta ２ O ５ BaO, ZrO ２ WO ３ , Y ２ O ３ La ２ O ３ , Gd ２ O ３ Yb ２ O ３ , and Lu ２ O ３ It is preferable to include at least one selected from the group consisting of the following: TeO ２ , Bi ２ O ３ , TiO ２ , Nb ２ O ５ Ta ２ O ５ BaO, ZrO ２ WO ３ , Y ２ O ３ La ２ O ３ , Gd ２ O ３ Yb ２ O ３ , and Lu ２ O ３ The total content, based on oxides, can be, for example, 0.0 to 80.0 mol%, and from the viewpoint of increasing the refractive index, 5.0 to 75.0 mol% is preferred, and 8.0 to 70.0 mol% is more preferred. TeO in a glass substrate ２ , Bi ２ O ３ , TiO ２ , Nb ２ O ５ Ta ２ O ５ BaO, ZrO ２ WO ３ , Y ２ O ３, La ２ O ３ , Gd ２ O ３ , Yb ２ O ３ , and Lu ２ O ３ The total content, calculated on an oxide basis, is preferably 10.0 mol% or more, more preferably 15.0 mol% or more, still more preferably 25.0 mol% or more, and particularly preferably 50.0 mol% or more, from the viewpoint of increasing the refractive index.

[0020] From the viewpoint of increasing the refractive index, the glass substrate, among the above high-refractive index components, contains TiO ２ , Nb ２ O ５ , and Ta ２ O ５ It is more preferable that the glass substrate contains at least one selected from the group consisting of, and it is particularly preferable that the glass substrate contains at least one selected from the group consisting of TiO ２ and Nb ２ O ５ In the glass substrate, TiO ２ , Nb ２ O ５ , and Ta ２ O ５ The total content, calculated on an oxide basis, is, for example, 2.0 to 40.0 mol%. In the glass substrate, TiO ２ , Nb ２ O ５ , and Ta ２ O ５ The total content, calculated on an oxide basis, is preferably 4.0 mol% or more, more preferably 10.0 mol% or more, still more preferably 20.0 mol% or more, and particularly preferably 30.0 mol% or more, from the viewpoint of increasing the refractive index. Further, in the glass substrate, TiO ２ , Nb ２ O ５ , and Ta ２ O ５ The total content, calculated on an oxide basis, is preferably 30.0 mol% or less, more preferably 25.0 mol% or less, from the viewpoint of suppressing a decrease in transmittance.

[0021] When the glass substrate contains TiO ２If it contains TiO in the glass substrate, ２ The content can be, for example, 1.0 to 40.0 mol% on an oxide basis. TiO in a glass substrate ２ The content of TiO in the glass substrate is preferably 4.0 mol% or more, more preferably 10.0 mol% or more, even more preferably 20.0 mol% or more, and particularly preferably 30.0 mol% or more, from the viewpoint of increasing the refractive index, based on the oxide. ２ The content of is preferably 30.0 mol% or less, more preferably 25.0 mol% or less, and even more preferably 20.0 mol% or less, based on oxides, from the viewpoint of suppressing a decrease in transmittance. ２ O ５ If it contains Nb in the glass substrate, ２ O ５ The content can be, for example, 2.0 to 40.0 mol% on an oxide basis. Nb in glass substrates ２ O ５ The content of is preferably 4.0 mol% or more, more preferably 10.0 mol% or more, and even more preferably 15.0 mol% or more, based on the oxide, from the viewpoint of increasing the refractive index. ２ O ５ The content of the oxide, from the viewpoint of suppressing a decrease in transmittance, is preferably 30.0 mol% or less, more preferably 25.0 mol% or less, and even more preferably 20.0 mol% or less.

[0022] From the perspective of increasing the refractive index, among the high refractive index components mentioned above, the glass substrate is TeO ２ and Bi ２ O ３ It is also preferable to include at least one selected from the group consisting of the following. ２ and Bi ２ O ３ When containing at least one selected from the group consisting of, TeO in the glass substrate ２ and Bi ２ O ３ The total content, based on oxides, can be, for example, 10.0 to 80.0 mol%. TeO in glass substrates ２ and Bi２ O ３ The total content of TeO in the glass substrate is preferably 20.0 mol% or more, more preferably 30.0 mol% or more, even more preferably 45.0 mol% or more, and particularly preferably 55.0 mol% or more, based on the oxide, from the viewpoint of increasing the refractive index. ２ and Bi ２ O ３ The total content, based on oxides, is preferably 70.0 mol% or less, and more preferably 60.0 mol% or less, from the viewpoint of suppressing a decrease in transmittance.

[0023] The glass substrate is TeO ２ When it contains TeO in the glass substrate, ２ Examples of the content include 5.0 to 40.0 mol% on an oxide basis. TeO in a glass substrate ２ The content of is preferably 10.0 mol% or more, more preferably 15.0 mol% or more, even more preferably 20.0 mol% or more, and particularly preferably 25.0 mol% or more, based on the oxide, from the viewpoint of increasing the refractive index. ２ The content of is preferably 35.0 mol% or less, and more preferably 30.0 mol% or less, on an oxide basis, from the viewpoint of suppressing a decrease in transmittance. ２ O ３ If it contains Bi in the glass substrate ２ O ３ The content can be, for example, 10.0 to 60.0 mol% on an oxide basis. Bi in glass substrates ２ O ３ The content of is preferably 15.0 mol% or more, more preferably 20.0 mol% or more, even more preferably 25.0 mol% or more, and particularly preferably 28.0 mol% or more, based on oxides, from the viewpoint of increasing the refractive index. ２ O ３ The content of the oxide is preferably 50.0 mol% or less, and more preferably 40.0 mol% or less, from the viewpoint of suppressing a decrease in transmittance.

[0024] The glass substrate is made of boric acid (B) from the viewpoint of increasing its mechanical strength. ２ O３ ) may contain. In a glass substrate, B ２ O ３ The content can range from 0.0 to 30.0 mol% based on oxides. ２ O ３ From the viewpoint of suppressing a decrease in refractive index, the content of is preferably 25.0 mol% or less, more preferably 20.0 mol% or less, and even more preferably 16.0 mol% or less. ２ O ３ From the viewpoint of obtaining lightness and mechanical strength, the content of is preferably 3.0 mol% or more, more preferably 5.0 mol% or more, and even more preferably 8.0 mol% or more.

[0025] From the viewpoint of reducing process contamination by alkali metal ions released from the glass substrate, the total amount of alkali metal elements in the glass substrate is preferably 0.5 mol% or less, more preferably 0.1 mol% or less, and even more preferably 0.01 mol% or less. The lower limit of the total amount of alkali metal elements in the glass substrate is not particularly limited and may be 0.0 mol%. The total amount of alkali metal elements in the glass substrate may be 0.0 to 0.5 mol%. In this disclosure, the total amount of alkali metal elements in the glass substrate is calculated by analyzing the content of each alkali metal, such as Na and K, based on the ICP-MS method, and using the sum of the analysis results.

[0026] The glass substrate is made of silicon dioxide (SiO₂) to improve mechanical strength and chemical stability. ２ ) may contain SiO in a glass substrate. ２ The content can be, for example, 5.0 to 60.0 mol% based on the oxide. ２ From the viewpoint of including a large amount of high refractive index components, the content of SiO is preferably 55.0 mol% or less, more preferably 50.0 mol% or less, more preferably 40.0 mol% or less, more preferably 30.0 mol% or less, and even more preferably 15.0 mol% or less. ２ From the viewpoint of improving mechanical strength and chemical stability, the content of is preferably 8.0 mol% or more, more preferably 10.0 mol% or more, and even more preferably 12.0 mol% or more.

[0027] Glass substrates are preferred from the standpoint of manufacturability and chemical durability, and aluminum oxide (Al ２ O ３ ) may contain. In a glass substrate, Al ２ O ３ The content can be, for example, 1.0 to 20.0 mol% based on the oxide. ２ O ３ From the viewpoint of suppressing a decrease in refractive index, the content of Al is preferably 15.0 mol% or less, more preferably 12.0 mol% or less, and even more preferably 10.0 mol% or less. ２ O ３ From the viewpoint of chemical durability, the content of is preferably 2.0 mol% or more, more preferably 4.0 mol% or more, and even more preferably 6.0 mol% or more.

[0028] The glass substrate may contain magnesium oxide (MgO) from the viewpoint of manufacturability and mechanical properties. The MgO content in the glass substrate can be, for example, 1.0 to 25.0 mol% based on oxide content. From the viewpoint of suppressing a decrease in refractive index, the MgO content is preferably 20.0 mol% or less, more preferably 15.0 mol% or less, and even more preferably 10.0 mol% or less. From the viewpoint of mechanical properties, the MgO content is preferably 2.0 mol% or more, more preferably 4.0 mol% or more, and even more preferably 6.0 mol% or more.

[0029] The glass substrate may contain calcium oxide (CaO) from the viewpoint of manufacturability and mechanical properties. The CaO content in the glass substrate can be, for example, 1.0 to 20.0 mol% based on oxide. From the viewpoint of suppressing a decrease in refractive index, the CaO content is preferably 15.0 mol% or less, more preferably 12.0 mol% or less, and even more preferably 10.0 mol% or less. From the viewpoint of mechanical properties, the CaO content is preferably 2.0 mol% or more, more preferably 4.0 mol% or more, and even more preferably 6.0 mol% or more.

[0030] The glass substrate may contain strontium oxide (SrO) from the viewpoint of manufacturability and mechanical properties. The SrO content in the glass substrate can be, for example, 1.0 to 20.0 mol% based on oxide content. From the viewpoint of suppressing a decrease in refractive index, the SrO content is preferably 15.0 mol% or less, more preferably 12.0 mol% or less, and even more preferably 10.0 mol% or less. From the viewpoint of mechanical properties, the SrO content is preferably 2.0 mol% or more, more preferably 4.0 mol% or more, and even more preferably 6.0 mol% or more.

[0031] The glass substrate may contain barium oxide (BaO) from the viewpoint of increasing the refractive index. The BaO content in the glass substrate can be, for example, 1.0 to 20.0 mol% based on the oxide content. From the viewpoint of lightness, the BaO content is preferably 15.0 mol% or less, more preferably 12.0 mol% or less, and even more preferably 10.0 mol% or less. From the viewpoint of suppressing a decrease in refractive index, the BaO content is preferably 2.0 mol% or more, more preferably 4.0 mol% or more, and even more preferably 6.0 mol% or more.

[0032] From the viewpoint of increasing the refractive index, the glass substrate is made of zirconium oxide (ZrO ２ ) may contain ZrO in a glass substrate. ２ The content can be, for example, 1.0 to 15.0 mol% based on the oxide. ２ From the viewpoint of lightness, the content of ZrO is preferably 10.0 mol% or less, more preferably 8.0 mol% or less, and even more preferably 5.0 mol% or less. ２ From the viewpoint of suppressing a decrease in refractive index, the content of is preferably 2.0 mol% or more, more preferably 3.0 mol% or more, and even more preferably 4.0 mol% or more.

[0033] From the viewpoint of increasing the refractive index, the glass substrate is made of yttrium oxide (Y ２ O ３ ) may contain Y in a glass substrate. ２ O ３ The content can be, for example, 1.0 to 15.0 mol% based on oxides. ２ O３ From the viewpoint of lightness, the content is preferably 10.0 mol% or less, more preferably 8.0 mol% or less, and even more preferably 5.0 mol% or less. ２ O ３ From the viewpoint of suppressing a decrease in refractive index, the content of is preferably 2.0 mol% or more, more preferably 3.0 mol% or more, and even more preferably 4.0 mol% or more.

[0034] From the viewpoint of increasing the refractive index, the glass substrate is made of lanthanum oxide (La ２ O ３ ) may contain. In a glass substrate, La ２ O ３ The content can be, for example, 1.0 to 20.0 mol% based on the oxide. ２ O ３ From the viewpoint of lightness, the content is preferably 10.0 mol% or less, more preferably 8.0 mol% or less, and even more preferably 5.0 mol% or less. ２ O ３ From the viewpoint of suppressing a decrease in refractive index, the content of is preferably 2.0 mol% or more, more preferably 3.0 mol% or more, and even more preferably 4.0 mol% or more.

[0035] From the viewpoint of increasing the refractive index, the glass substrate is made of gadolinium oxide (Gd ２ O ３ ) may contain. Gd in a glass substrate ２ O ３ The content can be, for example, 1.0 to 15.0 mol% based on oxides. ２ O ３ From the viewpoint of lightness, the content is preferably 10.0 mol% or less, more preferably 8.0 mol% or less, and even more preferably 5.0 mol% or less. ２ O ３ From the viewpoint of suppressing a decrease in refractive index, the content of is preferably 2.0 mol% or more, more preferably 3.0 mol% or more, and even more preferably 4.0 mol% or more.

[0036] From the viewpoint of increasing the refractive index, the glass substrate is made of lithium oxide (Li ２ O) may be included. Li in a glass substrate ２The O content can be, for example, 1.0 to 20.0 mol% on an oxide basis. ２ From the viewpoint of suppressing a decrease in refractive index, the O content is preferably 18.0 mol% or less, more preferably 15.0 mol% or less, and even more preferably 12.0 mol% or less. ２ From the viewpoint of mechanical properties and light weight, the O content is preferably 2.0 mol% or more, more preferably 5.0 mol% or more, and even more preferably 8.0 mol% or more.

[0037] From the viewpoint of increasing the refractive index, the glass substrate is made of phosphorus oxide (P ２ O ５ ) may contain P ２ O ５ The content can be, for example, 1.0 to 20.0 mol% based on oxides. ２ O ５ From the viewpoint of suppressing a decrease in refractive index, the content of P is preferably 18.0 mol% or less, more preferably 15.0 mol% or less, and even more preferably 12.0 mol% or less. ２ O ５ From the viewpoint of lightness, the content of is preferably 2.0 mol% or more, more preferably 5.0 mol% or more, and even more preferably 8.0 mol% or more.

[0038] The glass substrate may contain zinc oxide (ZnO) from the viewpoint of increasing the refractive index. The ZnO content in the glass substrate can be, for example, 1.0 to 20.0 mol% on an oxide basis. From the viewpoint of suppressing a decrease in refractive index, the ZnO content is preferably 15.0 mol% or less, more preferably 10.0 mol% or less, and even more preferably 8.0 mol% or less. From the viewpoint of mechanical properties, the ZnO content is preferably 2.0 mol% or more, more preferably 3.0 mol% or more, and even more preferably 4.0 mol% or more.

[0039] (Glass substrate A) TiO is the main component of the high refractive index component. ２ A glass substrate A containing TiO is, for example, based on the oxide. ２Examples of glass substrates include those containing 1.0 to 40.0 mol% of TiO. The main component of the high refractive index component refers to the component with the highest content among the high refractive index components. TiO in glass substrate A ２ The content of TiO in the glass substrate A is preferably 5.0 mol% or more, more preferably 10.0 mol% or more, and even more preferably 15.0 mol% or more, from the viewpoint of increasing the refractive index, based on the oxide. ２ The content of the oxide, from the viewpoint of suppressing a decrease in transmittance, is preferably 35.0 mol% or less, more preferably 30.0 mol% or less, and even more preferably 25.0 mol% or less.

[0040] The composition of glass substrate A is SiO2, expressed as a mole percentage based on oxides. ２ : 9.0–15.0 mol%, TiO ２ : 30.0–35.0 mol%, B ２ O ３ : 20.0-25.0 mol%, La ２ O ３ : 18.0 to 23.0 mol% is a possible example. In addition, other compositions of the glass substrate A include SiO, expressed as a mole percentage based on oxide. ２ : 48.0–55.0 mol%, TiO ２ : 1.0 to 10.0 mol%, B ２ O ３ : 1.0-7.0 mol%, Al ２ O ３ : 4.0–14.0 mol%, ZrO ２ : 0.0 to 3.0 mol%, Y ２ O ３ : 2.0 to 8.0 mol% are examples.

[0041] (Glass substrate B) Nb is the main component of the high refractive index component. ２ O ５ The glass substrate B containing Nb is, for example, based on the oxide. ２ O ５ Examples include glass substrates containing 1.0 to 35.0 mol% of Nb in glass substrate B. ２ O ５The content of Nb is preferably 5.0 mol% or more, more preferably 10.0 mol% or more, and even more preferably 15.0 mol% or more, based on the oxide, from the viewpoint of increasing the refractive index. ２ O ５ The content of the oxide, from the viewpoint of suppressing a decrease in transmittance, is preferably 30.0 mol% or less, more preferably 25.0 mol% or less, and even more preferably 20.0 mol% or less.

[0042] The composition of glass substrate B is SiO₂, expressed as a mole percentage based on oxides. ２ : 53.0–59.0 mol%, Nb ２ O ５ : 15.0–20.0 mol%, B ２ O ３ : 0.0 to 5.0 mol%, ZrO ２ Examples include 1.0 to 5.0 mol%.

[0043] (Glass substrate C) Bi is the main component of the high refractive index component. ２ O ３ and TeO ２ As a glass substrate C containing Bi on an oxide basis, for example, ２ O ３ 15.0 to 45.0 mol%, TeO ２ Examples include glass substrates containing 15.0 to 40.0 mol% of Bi in glass substrate C. ２ O ３ The content of is preferably 20.0 mol% or more, more preferably 25.0 mol% or more, and even more preferably 27.5 mol% or more, based on oxides, from the viewpoint of increasing the refractive index. Bi in glass substrate C ２ O ３ The content of TeO in the glass substrate C is preferably 40.0 mol% or less, more preferably 35.0 mol% or less, and even more preferably 32.5 mol% or less, from the viewpoint of suppressing a decrease in transmittance, based on the oxide. ２ The content of TeO in the glass substrate C is preferably 20.0 mol% or more, more preferably 22.5 mol% or more, and even more preferably 25.0 mol% or more, from the viewpoint of increasing the refractive index, based on the oxide. ２The content of the oxide, from the viewpoint of suppressing a decrease in transmittance, is preferably 35.0 mol% or less, more preferably 30.0 mol% or less, and even more preferably 28.5 mol% or less.

[0044] The composition of the glass substrate C is expressed as a mole percentage based on the oxide, Bi ２ O ３ : 27.0–33.0 mol%, TeO ２ : 24.0–30.0 mol%, B ２ O ３ : 18.0–26.0 mol%, Nb ２ O ５ : 4.0 to 11.0 mol% are examples.

[0045] (Thickness) The thickness of the glass substrate is not particularly limited, and examples include 0.1 to 3.0 mm. The thickness of the glass substrate is preferably 3.0 mm or less, more preferably 2.0 mm or less, and even more preferably 1.0 mm or less, considering the viewpoint of repurposing existing semiconductor manufacturing equipment for the manufacture of glass laminates, the efficiency of the backgrinding process, and the need for optical properties as a glass laminate. The thickness of the glass substrate is preferably 0.1 mm or more, preferably 0.3 mm or more, and more preferably 0.5 mm or more, from the viewpoint of easily obtaining high performance as a meta-optical element. If a thinner laminate is desired, a backgrinding process can be introduced in the manufacturing process of the glass laminate. The backgrinding process is a process in which only the glass substrate side of the glass laminate (i.e., the side opposite to the side on which the metasurface layer is formed) is ground and polished to further reduce the thickness of the glass substrate. In this case, the thickness of the glass substrate will be even thinner than 0.5 mm. In this disclosure, the thickness of the glass substrate is measured by an optical interferometry thickness measurement method. Optical interferometry is a method of thickness measurement that uses, for example, Corning-Tropel's optical interferometry thickness measuring device (FlatMaster 200) to measure the phase difference of reflected light from the front and back surfaces.

[0046] (Size) The surface area of ​​the main surface of the glass substrate is not particularly limited and is set according to the purpose. For example, the surface area of ​​the main surface of the glass substrate may be 15 to 300 cm². ２Examples include the following. In this disclosure, the main surface of the glass substrate is the surface of the glass substrate on which the metasurface layer is formed. The area of ​​the main surface of the glass substrate can be measured by image analysis using a transmissive dimensional measuring instrument or the like.

[0047] (Shape) The shape of the main surface of the glass substrate is not particularly limited. From the viewpoint of manufacturing glass laminates with high precision, the shape of the main surface of the glass substrate is preferably circular. The shape of the main surface of the glass substrate may also be elliptical or rectangular. Notches may be present at the edges of the glass substrate to accommodate the process of forming a metasurface layer on the surface of the glass substrate (alignment, stress relief during heat treatment, etc.), and if the main surface of the glass substrate is circular, a part of the outer periphery of the glass substrate may be straight.

[0048] (Density) The density of the glass substrate is not particularly limited, for example, 2.0 to 6.5 g / cm³. ３ One example is the density of the glass substrate, which is set at 6.0 g / cm³ from the viewpoint of reducing the weight of the glass laminate. ３ The following is preferable: 5.6 g / cm³ ３ The following is more preferable: 5.0 g / cm³ ３ The following is even more preferable: 4.6 g / cm³ ３ The following is particularly preferred: 4.0 g / cm³ ３ The following is highly preferable: The density of the glass substrate should be 2.0 g / cm³ from the viewpoint of improving mechanical strength. ３ The above is preferable, specifically 2.2 g / cm³. ３ The above is more preferable, specifically 2.4 g / cm³. ３ The above is even more preferable, 3.0 g / cm³. ３ The above is particularly preferable. The density of the glass substrate is measured in accordance with JIS Z8807 (1976, measurement method by weighing in liquid).

[0049] <Metasurface Layer> (Refractive Index) The refractive index of the metasurface layer can be, for example, 1.45 to 4.50. The refractive index of the metasurface layer may be 2.00 or higher, 2.30 or higher, or 2.50 or higher. The refractive index of the metasurface layer may also be 4.00 or lower, or 3.00 or lower. The refractive index of the metasurface layer can be 1.00 to 3.00 times the refractive index of the glass substrate, and from the viewpoint of suppressing interfacial reflection between the glass substrate and the metasurface layer, 1.00 to 3.00 times is preferred, and 1.00 to 2.00 times is more preferred. The refractive index of the metasurface layer may be higher than the refractive index of the glass substrate.

[0050] The type of material contained in the metasurface layer can be appropriately selected depending on the application of the glass laminate. For example, silicon may be selected for infrared sensing, and titania for visible light lenses. The metasurface layer may contain at least one selected from the group consisting of silicon, metals, and metal oxides, and may also contain at least one selected from the group consisting of silicon, silicon dioxide, gallium, gallium oxide, germanium, germanium oxide, indium, indium oxide, titanium dioxide, sapphire, niobium pentoxide, silicon nitride, and gallium nitride. The metasurface layer may also contain a resin material. Examples of resin materials contained in the metasurface layer include epoxy resins, acrylic resins, silicone resins, and polyimides. Examples of epoxy resins include novolac-based epoxy resins and bisphenol A-based epoxy resins. Examples of acrylic resins include polymethyl methacrylate (PMMA), polyethyl methacrylate (PMA), and polybutyl methacrylate (PBA). Examples of silicone resins include polydimethylsiloxane (PDMS) and polymethylphenylsiloxane (PMPS). Examples of polyimides include aromatic polyimides and thermoplastic polyimides.

[0051] (Thickness) The thickness of the metasurface layer is not particularly limited, for example, it may be 3 μm or less, and from the viewpoint of miniaturizing the glass laminate, it may be 1 μm or less, 850 nm or less, or 750 nm or less. The lower limit of the thickness of the metasurface layer is not particularly limited, and it may be 10 nm or more, 100 nm or more, 250 nm or more, or 500 nm or more. The thickness of the metasurface layer may be, for example, 10 nm to 3 μm. In this disclosure, the thickness of the metasurface layer is measured by a stylus-type surface profile measuring instrument (Dektak). For example, if the metasurface structure has pillars arranged periodically, as in the metasurface layer 14 shown in Figure 1, the thickness of the metasurface layer corresponds to the height of the pillars. Also, for example, if the metasurface structure has columnar holes arranged periodically in the film, the thickness of the metasurface layer corresponds to the thickness of the film at locations other than the holes. The thickness of the metasurface layer can be 0.00001 to 0.01 times the thickness of the glass substrate, and from the viewpoint of processability of the metasurface layer, 0.00001 to 0.005 times is preferred, and 0.0001 to 0.0035 times is more preferred.

[0052] (Metasurface Structure) As stated above, the metasurface structure can be any structure that corresponds to the characteristics required for a meta-optical element. Examples of metasurface structures include a structure in which columnar pillars are periodically arranged (hereinafter also called a "pillar-type structure"), a structure in which columnar holes are periodically arranged in a film (hereinafter also called a "hole-type structure"), and a structure in which columnar holes are periodically arranged in a film and a material with a refractive index relatively higher than that of the film is embedded in the holes. The pillar-type structure is preferred.

[0053] The metasurface structure may be arranged two-dimensionally in the x and y planes. If the metasurface structure is a pillar-type structure, the shape of the pillar may be rotationally symmetric, such as a cylindrical or polygonal prism shape, or an asymmetric nanofin shape. The metasurface structure may consist of cylindrical pillars with diameter φ and height H, arranged periodically at periods U. In the metasurface structure, the diameter φ may have multiple values. In the metasurface structure, the height H may have only one value or multiple values. The diameter φ and period U may be less than or equal to the wavelength of light used. If the metasurface structure is a pillar-type structure, the pillars may be arranged in a grid pattern, for example. The height H of the pillars may be 10 to 1000 nm. The diameter of the pillars may be about 1 / 10 of the wavelength on which they act; for example, when acting in the near-infrared wavelength region, it may be 80 to 1000 nm. The spacing L between adjacent pillars may be 100 to 1000 nm. When the metasurface structure is a pillar-type structure, the aspect ratio (H / φ) of the pillar is a value corresponding to the characteristics required for the meta-optical element, and can be 1 to 15, for example. Even when the metasurface structure is a perforated structure, the depth, diameter, period, spacing, and aspect ratio of the holes can be the same values ​​as those for the pillar height H, diameter φ, period U, spacing L, and aspect ratio in the pillar-type structure, respectively.

[0054] <Manufacturing of Glass Laminates> As a specific example of the manufacturing method of the glass laminates of this disclosure, an example of a manufacturing method for the glass laminate 10 shown in Figure 1 will be described. Examples of a manufacturing method for the glass laminate 10 include a glass substrate preparation step of preparing a glass substrate 12, a film formation step of forming a film on the glass substrate 12, and a metasurface structure formation step of forming a metasurface structure by etching the formed film to form a metasurface layer 14 in which pillars 14A are periodically arranged.

[0055] (Glass Substrate Preparation Process) The glass substrate may be a commercially available one or it may be manufactured. The glass substrate is manufactured, for example, as follows: First, the raw materials are weighed to obtain the desired glass composition and mixed uniformly. The prepared mixture is placed in a platinum crucible, quartz crucible, or alumina crucible and roughly melted. Then, the prepared mixture is placed in a gold crucible, platinum crucible, platinum alloy crucible, reinforced platinum crucible, or iridium crucible and melted at a temperature range of 1200 to 1400°C for 2 to 10 hours. After homogenization by degassing, stirring, etc., and bubble removal, the mixture is cast into a mold and slowly cooled to obtain optical glass. The obtained optical glass is melted and the glass is formed into a plate shape by molding methods such as the float method, fusion method, or roll-out method to obtain a glass substrate. Alternatively, the glass substrate may be manufactured using means such as reheat press molding or precision press molding. Furthermore, the means for manufacturing the glass substrate are not limited to these methods.

[0056] Furthermore, the surface of the glass substrate may be partially or entirely surface-treated. If the glass substrate is surface-treated, impurities contained in the glass substrate (e.g., alkali metal elements) are less likely to leach out during the manufacturing process of the glass laminate, and process contamination due to contamination is less likely to occur. The method of surface treatment is not particularly limited and includes the formation of a protective film (i.e., a protective film to prevent contamination leaching, e.g., a SiO film) and alkali leaching treatment of the outermost layer. In addition, the surface of the glass substrate may be cleaned.

[0057] (Film Formation Process) In the film formation process, for example, a material constituting the metasurface layer (hereinafter also referred to as "metasurface material") is attached to or deposited on a glass substrate. As for the method of attachment or deposition, for example, low-pressure chemical vapor deposition (LPCVD) method (for example, SiH ４Examples of methods include LPCVD (Low-Level Plasma CVD), plasma-enhanced chemical vapor deposition (PECVD), high-density plasma chemical vapor deposition (HDPCCVD), and chemical vapor deposition (CVD). The thickness of the film formed on the glass substrate should be such that the final thickness of the resulting metasurface layer is a desired value; for example, a thickness equivalent to the thickness of the metasurface layer may be used.

[0058] In the film formation process, a film may be obtained by annealing (hereinafter also referred to as the heat treatment process) the metasurface material attached or deposited on the glass substrate. When the metasurface material is annealed, it crystallizes and a film is formed. The attached or deposited metasurface material is annealed at an appropriate temperature for a sufficient time to reduce absorption loss and improve the transmission efficiency of the glass laminate. That is, annealing is not simply performed to crystallize, harden or stabilize the metasurface material, but the annealing process is carried out at an appropriate temperature and for a sufficient amount of time with respect to the specific purpose of reducing the absorption loss of light emission within the target operating bandwidth. In various embodiments, metasurface materials that are not generally considered practical for use at optical frequencies are preferably annealed to reduce absorption loss by as much as 35%. This makes the metasurface material suitable for use at optical frequencies. For example, if the metasurface material is polysilicon, the polysilicon may be annealed at a temperature of 500 to 1100°C for 30 to 90 minutes, depending on the thickness of the polysilicon, the target operating frequency band, and other target properties. For example, the optical properties of a metasurface material are such that the absorption coefficient decreases at shorter wavelengths when exposed to an inert atmosphere gas (e.g., argon, N2). ２ The process may be improved by annealing the metasurface material at a temperature exceeding 1000°C for more than one hour in a suitable environment.

[0059] (Metasurface structure formation process) In the metasurface structure formation process, a metasurface structure is formed by etching the film of the metasurface material obtained in the film formation process. This results in a glass laminate in which a metasurface layer with periodically arranged pillars is provided on a glass substrate. Methods for forming the metasurface structure include photolithography (e.g., deep ultraviolet lithography), electron beam lithography, or nanoimprint lithography.

[0060] Specifically, for example, a resist (e.g., a photoresist) is applied to the annealed metasurface material layer. The resist may be a negative-type photoresist such as Ma-N2403, or a positive-type photoresist in which the masking process and etching process can be reversed or otherwise modified. Next, a photoresist pattern is formed by, for example, electron beam lithography (e-beam lithography: EBL), development, hard baking, etc. of the applied resist. Then, for example, the film of the metasurface material is etched according to the developed photoresist pattern.

[0061] If necessary, residual resist after etching may be removed to expose pillars of the metasurface material extending from the glass substrate. Alternatively, the photoresist mask layer may be removed to expose the partially formed pillars of the metasurface material and the unetched layers of the metasurface material along the substrate. For example, the above-mentioned removal of the resist may involve O ２ Plasma removal, H ２ Plasma removal, application of 1-methyl-2-pyrrolidone, application of dimethyl sulfoxide, combinations thereof, and / or alternative photoresist removal processes may be included. In this manner, the glass laminate of this embodiment is obtained.

[0062] <Applications of Glass Laminates> The glass laminates of this disclosure can be used, for example, as meta-optical elements. Since the glass laminates of this disclosure have a metasurface structure formed on a glass substrate and can control the phase distribution of light to function as lenses, they are preferably used as metalenses among meta-optical elements. In addition to metalenses, other applications of the glass laminates of this disclosure include diffusers, collimator lenses, and light guide plates using metasurfaces.

[0063] The embodiments of this disclosure will be described in detail below with reference to examples, but the embodiments of this disclosure are not limited to these. In the following description, Examples A3 to A5 and B3 to B5 are examples, and Examples A1 to A2 and B1 to B2 are comparative examples.

[0064] [Example A] Numerical analysis based on rigorous coupled-wave analysis (RCWA) was performed using numerical analysis software (MathWorks, Inc., product name: MATLAB®) as the simulation software. Specifically, the pillar height required to make the phase change of the metaatom equal to 2π in a glass laminate in which the metasurface layer described below is formed on the glass substrate described below was determined. The results are shown in Table 1. Note that all of the glass substrates described below have a thickness of 0.5 mm and a main surface area of ​​0.2 mm². ２ The shape of the main surface was set to be circular. The simulation conditions were room temperature: 25°C and light wavelength: 532 nm.

[0065] <Glass Substrate 1> Composition: SiO ２ Refractive index: 1.45 Density: 2.2 g / cm³ ３

[0066] <Glass Substrate 2> Composition: 66SiO ２ -11Al ２ O ３ ―8B ２ O ３ -5MgO-5CaO-5SrO (mol%) Refractive index: 1.50 Density: 2.51 g / cm³ ３ Internal transmittance (532nm): 91% Internal transmittance (1064nm): 92%

[0067] <Glass Substrate 3> Composition: 52SiO ２ -8Al ２ O ３ ―4B ２ O ３ -19MgO-3CaO-4SrO-1ZrO ２ ―5TiO ２ ―4Y ２ O ３ (mol%) Refractive index: 1.62 Density: 2.97 g / cm³ ３ Internal transmittance (532nm): 89% Internal transmittance (1064nm): 89%

[0068] <Glass Substrate 4> Composition: 56SiO ２ -0.5B ２ O ３ -10Li ２ O-7Na ２ O-4.5K ２ O-19Nb ２ O ５ ―3ZrO ２ (mol%) Refractive index: 1.79 Density: 3.32 g / cm³ ３

[0069] <Glass Substrate 5> Composition: 11SiO ２ ―21B ２ O ３ ―7ZrO ２ ―33TiO ２ -3.5Y ２ O ３ ―18La ２ O ３ -3.5Gd ２ O ３ ―3Nb ２ O ５ (mol%) Refractive index: 2.00 Density: 4.94g / cm ３

[0070] <Metasurface Layer> Metasurface structure: Pillar type Pillar shape: Cylindrical Pillar diameter φ: 80 nm to 170 nm Pillar spacing L: 270 nm Pillar aspect ratio: 3 to 9 Metasurface material: TiO ２ Refractive index of the metasurface layer: 2.53; Thickness of the layer: 690 nm to 710 nm

[0071]

[0072] From the above results, it can be seen that in Examples A3 to A5, which use a glass substrate with a refractive index of 1.60 or higher, equivalent performance can be obtained even when the pillar height H is lower compared to Examples A1 to A2.

[0073] [Example B] Using ray tracing design software (Ansys, product name: Zemax Optic Studio) as the simulation software, the aperture ratio (NA), one of the performance characteristics of a metalens, was determined for a glass laminate in which metasurface layers were formed on the glass substrates 1 to 5 described above. The results are shown in Table 2. The simulation conditions were room temperature: 25°C, optical wavelength: 532 nm, and back focus fixed at 1 mm.

[0074] <Glass Laminate> Laminate thickness: 0.5 mm Laminate diameter: 0.5 mm Refractive index of glass substrate: 1.45-2.00

[0075]

[0076] From these results, it was found that in Examples B3 to B5, which use glass substrates with a refractive index of 1.60 or higher, a higher aperture ratio (NA) can be obtained compared to Examples B1 to B2.

[0077] The glass laminates of this disclosure are used in applications such as meta-optical components (e.g., metalenses), thermal control components in metamaterial technology, and electromagnetic wave control components for RIS (Reconfigurable Intelligent Surface), including metasurface technology.

[0078] The disclosure of Japanese Patent Application No. 2025-057001, filed on 28 March 2025, is incorporated herein by reference in its entirety. Furthermore, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated as being incorporated by reference.

[0079] 10 Glass laminate, 12 Glass substrate, 14 Metasurface layer, 14A Pillar

Claims

1. A glass laminate comprising: a glass substrate having a refractive index of 1.60 or more for light with a wavelength of 587.56 nm at 25°C; and a metasurface layer provided on the glass substrate and having a metasurface structure.

2. The glass laminate according to claim 1, wherein the thickness of the glass substrate is 0.1 to 2.0 mm.

3. The glass laminate according to claim 1 or 2, wherein the glass substrate contains at least one selected from the group consisting of tellurium oxide, bismuth oxide, titanium dioxide, niobium pentoxide, tantalum pentoxide, barium oxide, zirconium oxide, tungsten trioxide, yttrium oxide, lanthanum oxide, gadolinium oxide, ytterbium oxide, and lutetium oxide.

4. The glass laminate according to claim 3, wherein the glass substrate further contains boric acid.

5. The glass laminate according to claim 1 or 2, wherein the glass substrate has a total amount of alkali metal elements of 0.5 mol% or less.

6. The glass laminate according to claim 1 or 2, wherein the metasurface layer comprises at least one selected from the group consisting of silicon, silicon dioxide, gallium, gallium oxide, germanium, germanium oxide, indium, indium oxide, titanium dioxide, sapphire, niobium pentoxide, silicon nitride, and gallium nitride.

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