US Patent 7831119 Tunable optical group delay based on microresonator structures

This invention provides a tunable delay of an optical signal having multiple frequency components. The delay comprises at least a first and a second integrated resonators coupled sequentially to a waveguide; the resonators have angular resonant frequencies ω1=ω0−Δω and ω2=ω0+Δω respectively, ω0 is a median frequency of an input optical signal and Δω is a tunable deviation from the median frequency. The device is providing a nearly equal true time delay to all frequency components in the output signal.