Gigahertz optical tuning of an on-chip radio frequency photonic delay line

Rapid and continuous tunability of time delay is a crucial functionality for radio frequency (RF) photonic signal processing systems. Recent developments in photonic integration have enabled realizations of integrated microwave photonic (MWP) delay lines based on optical resonant devices such as ring resonators, typically tuned by slow thermo-optic effect. Here, we introduce an optical tuning approach to controlling and switching RF time delay from integrated optical ring resonators with a fast tuning speed. We demonstrate seamless tuning between pulse delay and advancement, as well as gigahertz switch capability without modifying the properties of resonators. This scheme opens the possibility for wideband advanced time-delay manipulation of RF signals for phase-arrayed antennas and radar applications in a general and compatible approach.