Tunable reflectors based on multi-cavity interference
A reflective structure includes an input/output port and an optical splitter coupled to the input/output port. The optical splitter has a first branch and a second branch. The reflective structure also includes a first resonant cavity optically coupled to the first branch of the optical splitter. The first resonant cavity comprises a first set of reflectors and a first waveguide region disposed between the first set of reflectors. The reflective structure further includes a second resonant cavity optically coupled to the second branch of the optical splitter. The second resonant cavity comprises a second set of reflectors and a second waveguide region disposed between the second set of reflectors.
1. A reflective structure comprising:
an input/output port;
an optical splitter coupled to the input/output port, the optical splitter having a first branch and a second branch;
a phase shifter in the first branch of the optical splitter;
a first resonant cavity optically coupled to the first branch of the optical splitter, wherein the first resonant cavity comprises a first set of reflectors and a first waveguide region disposed between the first set of reflectors;
a second resonant cavity optically coupled to the second branch of the optical splitter, wherein the second resonant cavity comprises a second set of reflectors and a second waveguide region disposed between the second set of reflectors; and
a phase control section in the first waveguide region or in the second waveguide region.
2. The reflective structure of claim 1 wherein the phase control element comprises at least one of a heater or a carrier-based element.
3. The reflective structure of claim 1 wherein the optical splitter comprises a directional coupler.
4. The reflective structure of claim 1 wherein the first set of reflectors and the second set of reflectors comprise modulated waveguide structures.
5. The reflective structure of claim 1 wherein a length of the first waveguide region and a length of the second waveguide region are different.
6. The reflective structure of claim 1 wherein the first resonant cavity and the second resonant cavity comprise Fabry-Perot cavities.
7. The reflective structure of claim 1 wherein a reflector, of the first set of reflectors or of the second set of reflectors, is 27 microns long.
8. The reflective structure of claim 1 wherein a reflector, of the first set of reflectors or of the second set of reflectors, has a stop band that extends from ˜1525 nanometers to ˜1575 nanometers.
9. The reflective structure of claim 1 wherein the first branch or the second branch has a bend with a radius of curvature of 7 microns.
10. The reflective structure of claim 1 wherein the first branch or the second branch has a refractive index of 3.48.
11. The reflective structure of claim 1 wherein the first resonant cavity has a waveguide section having a length of 149.3 microns and the second resonant cavity has a waveguide section having a length of 138.1 microns.