Research
Highlights:

Proper design of space-time modulated structures can lead to unique electromagnetic behaviors. In this research project, staggered time-modulation is applied to a loaded monopole antenna to simultaneously perform radiation and subharmonic frequency conversion. This allows for low-cost low-frequency oscillators to carryout significant frequency translations.

Traveling-wave modulation of electromagnetic structures can be leveraged to remove some of the fundamental constraints applied to linear, time-invariant systems. This “synthetic motion” removes constraints including energy conservation and time-reversal symmetry. Further, spatial discretization introduces photonic bandgaps which can be leveraged for additional functionality like frequency-filtering and group-delay engineering. In this research project, efficient numerical and semi-analytical techniques are developed for designing and optimizing discretized media under synthetic motion. The procedure is used to design parametric amplifiers, one-way mirrors, and frequency-converters.

In an age where form factor dominates design, multifunctional devices which can be applied to conformal geometries and readily reconfigured in space and time are highly desirable. This research direction is focused on the theoretical and experimental development of metasurfaces which can be designed in real-time to perform polarization conversion, frequency translation, beam-shaping, amplification, and retro-reflection. The developments produced by this research effort have resulted in dramatic reductions in the computational cost of simulating and designing space-time modulated metasurfaces.