Compact wavelength-selective switch circuit for integrated optical interconnect

An integrated optical circuit and its transfer function have been derived for on-chip wavelength-selective switching and/or variable power attenuation. The bus waveguide of an all-pass ring resonator has been replaced by a Mach-Zehnder interferometric optical circuit which can be tuned by a couple of phase-shifters. The transfer function of the entire circuit allows a dynamic power throughput from zero-tranmission-state to fully-transparent-state for an induced phase tuning from 0 to π/2. The ring resonator used in the circuit need not be critically coupled.