A variable optical buffer queue, particularly useful either as an input or an output queue in an optical packet router in a wavelength-division multiplexing (WDM) communication network. An input queue includes plural separately controllable optical delay units disposed on wavelength channels between a demultiplexer and tunable wavelength converters controlling switching through a wavelength router. An output queue includes for each output port of a wavelength router plural separately controllable optical delay units tuned to different wavelengths. The delay units may induce selective amounts of delay and may be implemented as a series of controlled microresonators coupled to waveguide. Such a structure is usable as a controllably accessible optical memory.