| (19) |  |
| (11) | EP 4 235 277 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
| (88) | Date of publication A3: | | 06.09.2023 Bulletin 2023/36 |
| (43) | Date of publication A2: | | 30.08.2023 Bulletin 2023/35 |
| (22) | Date of filing: 22.05.2018 |
| | (51) | International Patent Classification (IPC): |
| (52) | Cooperative Patent Classification (CPC): | | G02F 1/035 |
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| (84) | Designated Contracting States: | | AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
| (62) | Application number of the earlier application in accordance with Art. 76 EPC: | | 18920077.7 / 3798718 |
| (71) | Applicant: NGK Insulators, Ltd. | | Nagoya-shi, Aichi 467-8530 (JP) |
| | (72) | Inventors: | | - TAI, Tomoyoshi
Nagoya-shi, 467-8530 (JP) - KONDO, Jungo
Nagoya-shi, 467-8530 (JP)
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| (74) | Representative: Müller-Boré & Partner
Patentanwälte PartG mbB | | Friedenheimer Brücke 21
80639 München
80639 München (DE) |
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| | |
| (54) | COMPOSITE SUBSTRATE FOR ELECTRO-OPTICAL ELEMENT AND METHOD FOR MANUFACTURING SAME |
(57) A composite substrate for an electro-optic element is disclosed. The composite substrate includes: an electro-optic crystal substrate having an electro-optic effect; a support substrate bonded to the electro-optic crystal substrate at least via an amorphous layer; and a low-refractive-index layer located between the electro-optic crystal substrate and the amorphous layer and having a lower refractive index than the electro-optical crystal substrate. The amorphous layer is constituted of one or more elements that constitute a layer or a substrate contacting the amorphous layer from one side and one or more elements that constitute a layer or a substrate contacting the amorphous layer from another side and has a thickness of 0.1 nanometer or more and 100 nanometers or less.