Apodized SCISSORs for filtering and switching

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This paper presents 1550-nm simulation results on the waveguided silicon-on-insulator four-port optical filtering and switching devices known as "SCISSOR" (an in-line array of microring resonators wherein each ring is coupled to two bus waveguides). We optimized the array number, the ring-bus coupling and the inter-ring spacing in order to obtain "rectangular" filter-passband shapes that have not heretofore been reported in the resonant-optics literature. We were able to engineer a box-like bandpass whose wavelength width could be anywhere from 5 to 50 % of the free spectral range (FSR). We then performed ring-bus apodization of the array that increased side-lobe suppression on the main filter band and widened the band. By reducing the FSR to 2.51 nm with increased ring diameter, we also showed that complete, high-extinction 2 x 2 optical switching is attained when the effective index of each ring in the group is changed by 2 x 10(-3), giving 1.02-nm shift of the 0.77-nm passband. Tunable filtering, sensing, reconfigurable add/drop and wavelength-division demultiplexing is offered in addition to switching.