Reflective-Type Microring Resonator for On-Chip Reconfigurable Microwave Photonic Systems

Microring resonator (MRR) is regarded as one of the most widely-used building blocks in photonic integration, which is employed to implement optical filtering, routing, sensing, true time delay, signal processing, logic operations and so on. However, a single MRR intrinsically produces Lorentzian or Lorentzian-derivative shape responses with very sharp peaks, which is incapable of handling wideband signals for microwave photonic systems. In this paper, we introduce a reflective-type MRR with a reflector connected to the drop port of an add-drop MRR. Thanks to the reflector, reconfigurable intensity and group delay responses can be achieved by setting the coupling coefficients of the MRR, leading to the implementation of flat-top filtering, wideband optical true time delay, XNOR/XOR optical logic operation and electro-optic modulation. Both theoretical analysis and experimental demonstration are carried out. This new MRR structure may enable a new, compact and low-cost design strategy for the integrated reconfigurable or programmable microwave photonic systems.