A composite optical waveguide is constructed using an array of waveguide cores, in which one core is tapered to a larger dimension, so that all the cores are used as a composite input port, and the one larger core is used as an output port. In addition, transverse couplers can be fabricated in a similar fashion. The waveguide cores are preferably made of SiN. In some cases, a layer of SiN which is provided as an etch stop is used as at least one of the waveguide cores. The waveguide cores can be spaced away from a semiconductor layer so as to minimize loses.
1. A composite waveguide, comprising:
a first group of waveguide cores on a substrate, said first group of waveguide cores having an optical propagation direction, each of said first group of waveguide cores having at a respective first end thereof a first cross section defined by two dimensions measured along orthogonal coordinates and having at a respective second end thereof a second cross section defined by two dimensions measured along orthogonal coordinates;
said first group of waveguide cores having an input port comprising at least one of:
said respective first ends together comprising said optical input port for directed illumination, and
a segment of one or more of said first group of waveguide cores comprising said optical input port for evanescent waves; and
said first group of waveguide cores having an output port comprising at least one of:
said respective second ends comprising said output port for directed illumination; and
a segment of one or more of said first group of waveguide cores comprising said optical output port for evanescent waves.
2. The composite waveguide of claim 1 , wherein said substrate is a semiconductor chip.
3. The composite waveguide of claim 1 , wherein one or more of said first group of waveguide cores has a different second cross section than the second cross section of each of the remaining ones of said first group of waveguide cores.
4. The composite waveguide of claim 1 , configured to operate bidirectionally.
5. The composite waveguide of claim 1 , wherein at least one of said first end and said second end is configured as a coupler selected from the group of couplers consisting of a butt coupler, a taper coupler and an evanescent coupler.
6. The composite waveguide of claim 1 , wherein all of said first group of waveguide cores having substantially equal first cross sections.
7. The composite waveguide of claim 1 , wherein at least two of said first group of waveguide cores have unequal first cross sections.
8. The composite waveguide of claim 1 , wherein said first group of waveguide cores disposed in an array are disposed in a one-dimensional array.
9. The composite waveguide of claim 1 , wherein said first group of waveguide cores disposed in an array are disposed in a two-dimensional array.
10. The composite waveguide of claim 1 , wherein said first group of waveguide cores comprise a material selected from the group of materials consisting of crystalline silicon, poly-silicon, amorphous silicon, silicon nitride, silicon oxynitride, silicon dioxide, doped silicon dioxide and a polymer.
11. The composite waveguide of claim 10 , wherein said first cross section defined by two dimensions measured along orthogonal coordinates has a first dimension and a second dimension each no larger than 1 micron.
12. The composite waveguide of claim 1 , wherein said respective first end of each of said first group of waveguide cores is located at a facet.
13. The composite waveguide of claim 12 , wherein said facet is a facet selected from the group of facets consisting of etched facets, polished facets, sawed facets, angled facets and curved facets.
14. The composite waveguide of claim 1 , wherein said respective first end of each of said first group of waveguide cores is located within 50 microns of a facet.
15. The composite waveguide of claim 1 , further comprising:
a second group of waveguide cores having a second optical propagation direction, said second group of waveguide cores disposed on said substrate, said second group of waveguide cores displaced from said first group of waveguide cores in a direction transverse to said optical propagation direction of said first group of waveguide cores, said second group of waveguide cores in optical communication with said first group of waveguide cores;
each of said second group of waveguide cores having at a respective first end thereof a first cross section defined by two dimensions measured along orthogonal coordinates and at a respective second end thereof a second cross section defined by two dimensions measured along orthogonal coordinates;
said second group of waveguide cores having an input port comprising at least one of:
said respective first ends together comprising said optical input port for directed illumination, and
a segment of one or more of said second group of waveguide cores comprising said optical input port for evanescent waves; and
said second group of waveguide cores having an output port comprising at least one of:
said respective second ends comprising said output port for directed illumination, and
a segment of one or more of said second group of waveguide cores comprising said optical output port for evanescent waves.
16. The composite waveguide of claim 15 , wherein one or more of said second group of waveguide cores has a different second cross section than the second cross section of each of the remaining ones of said second group of waveguide cores.
17. The composite waveguide of claim 15 , configured to operate bidirectionally.
18. The composite waveguide of claim 15 , wherein at least one of said first end and said second end is configured as a coupler selected from the group of couplers consisting of a butt coupler, a taper coupler and an evanescent coupler.
19. The composite waveguide of claim 15 , wherein said second group of waveguide cores is configured to provide an optical signal at a location displaced in said transverse direction from said optical input port of said first group of waveguide cores.
20. The composite waveguide of claim 15 , wherein said second group of waveguide cores comprise a material selected from the group of materials consisting of crystalline silicon, poly-silicon, amorphous silicon, silicon nitride, silicon oxynitride, silicon dioxide, doped silicon dioxide and a polymer.
21. The composite waveguide of claim 20 , wherein said first cross section defined by two dimensions measured along orthogonal coordinates has a first dimension and a second dimension each no larger than 1 micron.
22. The composite waveguide of claim 15 , wherein said respective first end of each of said second group of waveguide cores is located at a facet.
23. The composite waveguide of claim 22 , wherein said facet is a facet selected from the group of facets consisting of etched facets, polished facets, sawed facets, angled facets and curved facets.
24. The composite waveguide of claim 15 , wherein said respective first end of each of said second group of waveguide cores is located within 50 microns of a facet.
25. The composite waveguide of claim 15 , wherein said second optical propagation direction is parallel to said optical propagation direction of said first group of waveguide cores.
26. A composite waveguide having a first group of waveguide cores on a substrate, said first group of waveguide cores having an optical propagation direction, each of said first group of waveguide cores having at a respective first end thereof a first cross section defined by two dimensions measured along orthogonal coordinates and having at a respective second end thereof a second cross section defined by two dimensions measured along orthogonal coordinates;
wherein the improvement comprises:
said first group of waveguide cores having an input port comprising at least one of:
said respective first ends together comprising said optical input port for directed illumination, and
a segment of one or more of said first group of waveguide cores comprising said optical input port for evanescent waves; and
said first group of waveguide cores having an output port comprising at least one of:
said respective second ends comprising said output port for directed illumination; and
a segment of one or more of said first group of waveguide cores comprising said optical output port for evanescent waves.