1) Nonlinear “Soliton” Wave Characterization
While linear materials support single-frequency (monochromatic) waves, the fundamental solutions to nonlinear structures are pulses. These solutions, known as solitary waves or “solitons,” propagate without distortion due to frequency dispersion. Our research group has developed a novel technique to analyze and optimize general 1D nonlinear electrical networks. This technique will allow for the design of nonlinear circuits and transmission lines use for frequency-comb generation with applications in radar, material metrology, and mmWave communications.
2) Microwave Photonic Topological Insulators
Discontinuities in microwave structures such as rectangular waveguides, microstrip circuits, and coaxial transmission lines result in undesirable backscattering and reflection. Photonic topological insulators are a class of electromagnetic structures which are often robust to geometrical defects. Our group is investigating analysis techniques for novel photonic topological insulator at microwave frequencies for applications in robust civilian and defense communication systems.
3) Wide-Angle Rectifying Antenna Arrays
In energy-denied environments conventional power generation from solar/wind/hydrological sources is unavailable. Our research group is developing efficient and versatile rectifying antenna (rectenna) modules which can be used to provide emergency power to critical systems. These rectenna modules will allow essential power to be delivered in disaster relief, search-and-rescue, and military scenarios.
4) Subharmonic Radiating Antennas
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 carry out significant frequency translations.
5) Modeling of Discrete Synthetic Motion
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.
6) Active Electromagnetic Surfaces
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.