Waveguide structure and method for forming the same
An optical attenuating structure is provided. The optical attenuating structure includes a substrate, a waveguide, doping regions, an optical attenuating member, and a dielectric layer. The waveguide is extended over the substrate. The doping regions are disposed over the substrate, and include a first doping region, a second doping region opposite to the first doping region and separated from the first doping region by the waveguide, a first electrode extended over the substrate and in the first doping region, and a second electrode extended over the substrate and in the second doping region. The first optical attenuating member is coupled with the waveguide and disposed between the waveguide and the first electrode. The dielectric layer is disposed over the substrate and covers the waveguide, the doping regions and the first optical attenuating member.
1 . An optical attenuating structure, comprising:
a first protrusion and a second protrusion of a substrate, wherein the first protrusion and the second protrusion extend along a first direction; and
a third protrusion of the substrate, disposed between the first protrusion and the second protrusion and contacted with the first protrusion,
wherein the third protrusion includes a first portion and a second portion coupled to the first portion, a first distance between the first portion and the second protrusion along a second direction orthogonal to the first direction is substantially greater than a second distance between the second portion and the second protrusion along the second direction, and a first height of the first portion along a third direction orthogonal to the first direction and the second direction is substantially less than a second height of the second portion along the third direction.
2 . The optical attenuating structure of claim 1 , wherein a height of the first protrusion is substantially greater than the first height and the second height respectively.
3 . The optical attenuating structure of claim 2 , wherein the first height is about ⅓ of the height of the first protrusion.
4 . The optical attenuating structure of claim 2 , wherein the second height is about ⅔ of the height of the first protrusion.
5 . The optical attenuating structure of claim 1 , wherein a height of the second protrusion is substantially greater than the first height and the second height respectively.
6 . The optical attenuating structure of claim 1 , wherein a height of the first protrusion is substantially the same as a height of the second protrusion.
7 . The optical attenuating structure of claim 1 , wherein a width of the third protrusion is 1/20 to 1/200 of a distance between the second protrusion and the first protrusion.
8 . An optical attenuating structure, comprising:
a first protrusion of a substrate extending along a first direction, wherein the first protrusion includes a first portion and a second portion coupled with the first portion; and
a second protrusion of the substrate, disposed opposite to the first protrusion and extending along the first direction,
wherein a first distance between the first portion and the second protrusion along a second direction orthogonal to the first direction is substantially greater than a second distance between the second portion and the second protrusion along the second direction, and a first height of the first portion along a third direction orthogonal to the first direction and the second direction is substantially less than a second height of the second portion along the third direction.
9 . The optical attenuating structure of claim 8 , wherein a length of the first portion along the first direction is substantially greater than a length of the second portion along the first direction.
10 . The optical attenuation structure of claim 8 , wherein a width of the first portion along the second direction is substantially less than a width of the second portion along the second direction.
11 . The optical attenuation structure of claim 8 , wherein the first protrusion is coupled to an electrode extending along the first direction.
12 . The optical attenuation structure of claim 11 , wherein the electrode is in parallel to the second protrusion.
13 . The optical attenuation structure of claim 8 , wherein the second protrusion is a waveguide.
14 . An optical attenuating structure, comprising:
a first protrusion and a second protrusion of a substrate, wherein the first protrusion and the second protrusion extend along a first direction; and
a third protrusion of the substrate, disposed between the first protrusion and the second protrusion, contacted with the first protrusion and extending along the first direction,
wherein the third protrusion includes a first portion and a second portion coupled to the first portion and disposed between the first protrusion and the first portion, a first distance between the first portion and the second protrusion along a second direction orthogonal to the first direction is substantially less than a second distance between the second portion and the second protrusion along the second direction, and a first height of the first portion along a third direction orthogonal to the first direction and the second direction is substantially less than a second height of the second portion along the third direction.
15 . The optical attenuation structure of claim 14 , wherein a height of the first protrusion is substantially equal to a height of the second protrusion along the third direction.
16 . The optical attenuation structure of claim 15 , wherein the first height is substantially less than the height of the second protrusion.
17 . The optical attenuation structure of claim 15 , wherein the second height is substantially less than the height of the second protrusion along the third direction.
18 . The optical attenuation structure of claim 14 , wherein the third protrusion is coupled to an electrode extending along the first direction.
19 . The optical attenuation structure of claim 18 , wherein a distance between the electrode and the second protrusion is consistent along the first direction.
20 . The optical attenuation structure of claim 18 , wherein a sidewall of the electrode facing to the second protrusion is partially exposed through the third protrusion.