Shielding structures between optical waveguides
Methods and structures for shielding optical waveguides are provided. A method includes forming a first optical waveguide core and forming a second optical waveguide core adjacent to the first optical waveguide core. The method also includes forming an insulator layer over the first optical waveguide core and the second optical waveguide core. The method further includes forming a shielding structure in the insulator layer between the first optical waveguide core and the second optical waveguide core.
1. An optical waveguide device, comprising:
a first optical waveguide core on an insulator layer;
a second optical waveguide core adjacent to the first optical waveguide core;
an upper insulator layer over the first optical waveguide core and the second optical waveguide core and directly contacting opposing sides of the first optical waveguide core and the second optical waveguide core; and
a shielding structure in the upper insulator layer with a portion of the upper insulator layer between the opposing sides of the first optical waveguide core and sidewalls of the shielding structure and between the opposing sides of the second optical waveguide core and the sidewalls of the shielding structure,
wherein the shielding structure comprises a reflective material in a trench in the upper insulator layer.
2. The device of claim 1 , wherein the reflective material is a metal comprising one of tungsten (W), Aluminum (Al) or Copper (Cu).
3. The device of claim 1 , wherein the reflective material is a highly reflective material.
4. The device of claim 3 , wherein the first optical waveguide core and the second optical waveguide core comprise silicon.
5. The device of claim 4 , wherein the highly reflective material is a material having an optical reflectivity of at least 50% at a wavelength of light propagated in the first optical waveguide core and in the second optical waveguide core.
6. The device of claim 1 , wherein the shielding structure extends into the insulator layer lower than bottom surfaces of the first optical waveguide core and the second optical waveguide core.
7. The device of claim 1 , wherein the shielding structure is confined to locations corresponding to bends in the first optical waveguide core and the second optical waveguide core to permit the first optical waveguide core and the second optical waveguide core to have a pitch finer than a minimum pitch present without the shielding structure.
8. The device of claim 7 , wherein the highly reflective material is a material having an optical reflectivity of at least 50% at a wavelength of light propagated in the first optical waveguide core and in the second optical waveguide core, and the highly reflective material extends below bottom surfaces of the first optical waveguide core and the second optical waveguide core to improve immunity to crosstalk between the first optical waveguide core and the second optical waveguide core.
9. An optical waveguide device, comprising:
a first optical waveguide core on an insulator layer;
a second optical waveguide core adjacent to the first optical waveguide core;
an upper insulator layer directly on a top surface of the first optical waveguide core and the second optical waveguide core;
a shielding structure in the upper insulator layer between the first optical waveguide core and the second optical waveguide core; and
a cladding layer directly contacting the first optical waveguide core and the second optical waveguide core and underneath the upper insulator layer,
wherein the shielding structure comprises a highly reflective material which directly covers select portions of the cladding layer over the first optical waveguide core and the second optical waveguide core and adjacent to the first optical waveguide core and the second optical waveguide core.
10. The device of claim 9 , wherein the upper insulator layer is on and over the cladding layer.
11. The device of claim 9 , wherein the first optical waveguide core and the second optical waveguide core are composed of silicon.
12. The device of claim 9 , wherein the cladding layer comprises nitride.
13. The device of claim 9 , wherein the upper insulator layer comprises oxide.
14. The device of claim 9 , wherein the highly reflective material is in a trench in the upper insulator layer.
15. The device of claim 9 , wherein the shielding structure extends into the insulator layer lower than bottom surfaces of the first optical waveguide core and the second optical waveguide core.
16. The device of claim 9 , wherein the upper insulator layer is directly on a top surface of the cladding layer over the first optical waveguide core and the second optical waveguide core.
17. The device of claim 16 , wherein the highly reflective material is a material having an optical reflectivity of at least 50% at a wavelength of light propagated in the first optical waveguide core and in the second optical waveguide core, and the highly reflective material extends between the first optical waveguide core and the second optical waveguide core to improve immunity to crosstalk between the first optical waveguide core and the second optical waveguide core.
18. The device of claim 17 , wherein the highly reflective material and the upper insulator layer both directly contact the cladding layer.
19. An optical waveguide device, comprising:
a substrate;
an insulator layer on the substrate;
a plurality of waveguide cores directly on the insulator layer;
an upper insulator layer directly on at least one waveguide core of the plurality of waveguide cores and on the insulator layer; and
a shielding layer directly on waveguide cores of the plurality of waveguide cores which are not covered by the upper insulator layer and covering an entire top surface of the plurality of waveguide cores which are not covered by the upper insulator layer.
20. The device of claim 19 , wherein the upper insulator layer extends between the plurality of waveguide cores and the shielding structure layer.