CPC G02B 6/29325 (2013.01) [G02B 6/0083 (2013.01); G02B 6/305 (2013.01)] | 20 Claims |
1. A grating coupler, comprising:
a substrate; and
a plurality of coupling gratings arranged over the substrate along a first direction and having a plurality of lengths, respectively, in the first direction,
wherein each of the plurality of coupling gratings comprises a first portion having a first width in the first direction and a first thickness in a second direction that is perpendicular to the first direction and that is perpendicular to an upper surface of the substrate, a second portion having a second width in the first direction and a second thickness in the second direction, and a third portion having a third width in the first direction and a third thickness in the second direction, the third thickness is greater than the second thickness, and the second thickness is greater than the first thickness, and each of the first widths, the second widths, and the third widths increase in the first direction for each of the plurality of coupling gratings and such that the plurality of lengths, respectively, increase in the first direction.
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