Progress in Silicon Microresonator-Based Passive Devices: Optical Delay Lines, Switch Matrix, and Linear-Absorption-Induced Thermo-Optical Dispersion

This invited paper reviews our recent progress in silicon microresonator-based passive devices for potential on-chip optical interconnect applications. Specifically, we report our proposals and initial demonstrations of (i) many-element cascaded microdisk resonators as optical delay lines, and (ii) cascaded microring switch matrix. We also report our study on surface-state absorption-induced thermo-optical dispersion in silicon microresonators. Due to the spatial overlap between the cavity whispering-gallery mode field and the cavity sidewalls and surfaces, we find that the surface-state absorption of cavity optical power in the range of milliwatt is sufficient to cause an undesirable resonance wavelength red-shift in the order of 0.1 nm.