Our recent research topics

Enhanced electromagnetic fields inside invisible metasurface-bound volumes

Enhanced electromagnetic fields inside invisible metasurface-bound volumes

We study the conditions required for two metasurfaces such that, at the presence of a given incident wave, the fields between them can be tailored while the fields outside remain unchanged. This scenario, which can be considered as an embedded eigenstate, could be useful in applications related to sensing, cloaking, and nonlinear effects.


Time modulated metasurfaces


Time modulated metasurfaces

Capturing, accumulating, and storing energy by lossless loads is the ultimate functionality of efficient batteries. One of the possible ways to obtain such device is to control its’ properties in time. One of our research topics concerns time modulation of properties of electric circuits and metasurfaces. Our study considers accumulation of energy by a time modulated reactance and possible ways to realize it in experiments.


Plane wave to surface wave conversion


Plane wave to surface wave conversion

We propose a technique for converting a homogeneous plane wave into a surface wave with linear power growth using metasurfaces, which outperforms currently available wave couplers. With a dramatic enhancement of conversion efficiency, the proposed metasurface wave couplers will find numerous applications ranging from perfect leaky-wave antennas in the microwaves to ideal photovoltaic cells in the visible.


Wireless power transfer techniques


Wireless power transfer techniques

Wireless power transfer (WPT) technology has been recently proposed for a number of applications including biomedical applications, consumer electronics, transportation and industrial applications. Due to its inherent wireless nature, WPT is an attractive solution for many situations where implementation of physical connectors can be inconvenient, hazardous or impossible. In our research, we are developing new technologies for next generation wireless power transfer. Conventional WPT systems consist of a microwave power generator and a microwave power receiver separated by some distance. In conventional WPT, optimal power transmission condition can only be achieved with energy efficiency less than 50% due to the intrinsic characteristics. We introduce a new paradigm for wireless power delivery based on which the whole system, including transmitter and receiver and the space in between, forms a unified microwave power generator. In our research, the load itself will become a part of generator which creates microwave oscillations directly at the receiver location which eliminates the power-efficiency trade-off limit of the conventional WPT. Our research direction also aims to improve the efficiency and the transferred power to the load, and ensure that the system is robust for a wide range of operating conditions.


See more about our research on the
Department web site.


Decoupling of dipole array in Ultra-High Field MRI using metasurface

Decoupling of dipole array in Ultra-High Field MRI using metasurface

We analytically, numerically and experimentally propose a passive decoupling method for very closely located dipole array, regarding Ultra-High Field Magnetic Resonance Imaging (MRI). The passive scatterer is constituted of metasurface of resonating dipoles or split-loop resonators (SLRs). The use of these metasurfaces not only decouples elements of array, but also does not have negative effect on distributed H^+ field in the phantom.


Software-driven functional metasurfaces (VISORSURF)


Software-driven functional metasurfaces

Adding tunable, sensible, programmable, and (artificially) intelligent abilities to metasurfaces will offer virtually unlimited possibilities in controlling fields of various physical nature using thin intelligent skins. The main objective of our VISORSURF project is the development of a hardware platform, the HyperSurface, whose electromagnetic behavior can be defined programmatically. The key-enablers are the metasurfaces, artificial materials whose electromagnetic properties depend on their internal structure. HyperSurfaces merge metamaterials with a network of miniaturized, custom electronic controllers, the nanonetwork. The nanonetwork receives external programmatic commands and alters the metasurface structure, yielding a desired electromagnetic behavior for the HyperSurface.


Vertical dipoles


Vertical_dipoles

Conventional Huygens' meta-atoms use spectrally overlapped electric and magnetic resonances in order to achieve full control over the transmission phase and full power transmission through metasurfaces. Different bandwidth and mutual coupling of magnetic and electric resonances make this approach rather challenging. One of our research destinations studies achieving of full functionality of Huygens’ meta-atoms using only electric response. The proposed approach can be realized in microwaves as well as in optics and can be used in numerous applications including bending transmitarrays and lenses.


Perfect and tunable absorption in low-quality graphene


Perfect and tunable absorption in low-quality graphene

In almost all of the theoretical literatures, high-quality ( or high carrier mobility) graphene is assumed for improving light-matter interaction in graphene. However, high quality graphene is very difficult to be obtained in experiment since graphene sample will be easily contaminated in transfer or other processes. By placing a complete graphene layer above the metasurface substrates, we demonstrate that full absorption is possible even in very poor quality and unbiased graphene sheet. Meanwhile, we find that the absorption frequency or levels can be modulated in a large scale by tuning the Fermi level of graphene.

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