CPC G02B 6/124 (2013.01) [G02B 2006/12107 (2013.01)] | 20 Claims |
1. A semiconductor structure, comprising:
a substrate;
a grating coupler structure over the substrate; and
a multi-layers film structure over the grating coupler structure, comprising:
a first layer comprising a first refractive index;
a second layer over the first layer and comprising a second refractive index; and
a third layer over the second layer and comprising a third refractive index; and
wherein the second refractive index is greater than the first refractive index and is greater than the third refractive index of the third layer, and
wherein a thickness of each layer of the multi-layers film structure is within a range from λ/4 to λ/2, λ is a wavelength of light.
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