CPC G02B 6/29325 (2013.01) [G02B 6/0083 (2013.01)] | 20 Claims |
1. An apparatus for optical coupling, comprising:
a substrate; and
a grating coupler disposed on the substrate and comprising a plurality of coupling gratings arranged along a first direction, wherein effective refractive indices of the plurality of coupling gratings gradually decrease along the first direction,
wherein each of the plurality of coupling gratings comprises a first portion, a second portion and a third portion arranged along the first direction, a thickness of the second portion is larger than a thickness of the first portion, a thickness of the third portion is larger than the thickness of the second portion, and in any two adjacent coupling gratings in the first direction, the third portion of one coupling grating is directly connected to the first portion of the other coupling grating, and
wherein the thickness of the third portion is larger than or equal to 200 nm and less than or equal to 500 nm,
wherein the thickness of the first portion is larger than 0 nm and less than or equal to 210 nm,
wherein the thickness of the second portion is larger than or equal to 70 nm and less than or equal to 270 nm.
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