An optical channel add/drop router includes at least one optical waveguide disposed on a substrate, and an optical microcavity resonator. Each waveguide includes a waveguide core, and a multi-layer dielectric stack with alternating high and low refractive index dielectric layers. Light propagates from one of the I/O ports or add/drop port of the waveguide, through one of the waveguide channels. Frequency components of the light that match a resonant mode of the microcavity are coupled into the microcavity, and out of the microcavity onto a different waveguide channel, so that desired channels are added to or dropped from the input signal. Optical power transfer efficiency of over 95% can been achieved at a transfer linewidth of about 1 MHz.