Abstract
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.
Highlights
Microwave photonic (MWP) delay lines are key components in signal filtering, signal synchronization, and radar target simulators in advanced defense and radio frequency (RF) communication systems [1,2,3,4]
We note that the symmetry of the phase responses originates from the dispersive response imparted by optical resonances, and the phase amplification is transparent to the chirp of modulated RF signals as the relative phase offset of two sidebands is fixed
The scheme we proposed shows a distinct advantage over other works based on electric switches [25], micro-electro-mechanical system (MEMS) devices [26], laser frequency tuning [27], thermal tuning [28], and spatial light modulators (SLMs) [29], with a much faster speed by 4–5 orders of magnitude
Summary
Microwave photonic (MWP) delay lines are key components in signal filtering, signal synchronization, and radar target simulators in advanced defense and radio frequency (RF) communication systems [1,2,3,4]. To avoid suffering from large footprints, MWP delay lines are preferably implemented in compact photonic devices based on optical resonances where the dispersive properties determine the signal group delay responses [6,7,8]—for instance, fiber Bragg gratings (FBGs) [9] and stimulated Brillouin scattering (SBS) [10] in fiber. These schemes require long-length waveguides and high pump power. The results presented in this work imply the feasibility of wideband operation and compatibility with existing schemes based on dispersive photonic devices
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