Optical-coupled resonator structures based on loop-coupled cavities and loop coupling phase

Abstract

A resonator structure includes an input waveguide and an output waveguide. In one embodiment, the resonator structure also includes at least one resonator that couples the input waveguide to the output waveguide and a directional coupler that optically couples the input waveguide to the output waveguide. In another embodiment, the resonator structure includes a plurality of ring resonators that couple the input waveguide to the output waveguide. The plurality of ring resonators include a sequence of ring resonators that form a coupling loop. Each ring resonator in the sequence is coupled to at least two other ring resonators in the sequence and the first ring resonator in the sequence is coupled to the last ring resonator in the sequence so as to form the coupling loop.

1 - 18 . (canceled) 
   
   
       19 . An optical resonator structure, comprising:
 an input waveguide;   an output waveguide;   at least one resonator coupling the input waveguide to the output waveguide; and   a directional coupler optically coupling the input waveguide to the output waveguide.   
   
   
       20 . The structure of  claim 19  further comprising a phase shift in the input waveguide between the directional coupler and the at least one resonator. 
   
   
       21 . The structure of  claim 19  further comprising a phase shift in the output waveguide between the directional coupler and the at least one resonator. 
   
   
       22 . The structure of  claim 19  wherein a length of the input waveguide between the directional coupler and a point at which the at least one resonator couples to the input waveguide is substantially equal to a length of the output waveguide between the directional coupler and a point at which the at least one resonator couples to the output waveguide. 
   
   
       23 . The structure of  claim 19 , wherein a plurality of resonators couple the input waveguide to the output waveguide. 
   
   
       24 . The structure of  claim 23 , wherein the plurality of resonators comprise a sequence of resonators that form a coupling loop, each resonator in the sequence coupled to at least two other resonators in the sequence and a first resonator in the sequence coupled to a last resonator in the sequence so as to form the coupling loop. 
   
   
       25 . The structure of  claim 19 , wherein the optical coupling between the input waveguide and the output waveguide introduced by the directional coupler is substantially broadband over several passband widths. 
   
   
       26 . The structure of  claim 25 , wherein the optical coupling is substantially broadband over at least three passband widths. 
   
   
       27 . The structure of  claim 25 , wherein the optical coupling is substantially broadband over at least ten passband widths. 
   
   
       28 . The structure of  claim 19 , wherein the output waveguide comprises a drop port and the optical resonator structure comprises a spectral response with transmission zeros in the drop port.