Low-Loss Microdisk-Based Delay Lines for Narrowband Optical Filters

Over-coupled microdisk resonators with high intrinsic quality factors are proposed as compact and low-insertion-loss delay lines for narrowband optical filters. Design challenges including dealing with the multimode nature of the microdisk resonator and achieving a strong coupling to the selected mode are addressed. Employing the microdisk-based delay line, we demonstrate a compact first-order tunable narrowband filter in a silicon-on-insulator platform, whose 3-dB bandwidth can be tuned from 0.47 to 4 GHz within an area of 0.05 mm2.