University of Michigan

Universal Display Corporation

Ohio State Innovation Foundation

Anthony Grbic

Stephen R Forrest

Xin Xu

Sanjay Krishna

Luis Fernando Gomez

Theodore J Ronningen

Christopher Ball

Roberto D Merlin

Luis Hernandez-Garcia

Steve Young

Gurkan Gok

Alireza Kazemi

Eric Michielssen

Faris Alsolamy

Cody Scarborough

Brian Raeker

Carl Pfeiffer

Mohammadamin Ranjbaraskari

Seyedmohammadreza Faghih Imani

Qingyuan Shu

Traveling-wave modulation is a form of space-time modulation which has been shown to enable unique electromagnetic phenomena such as non-reciprocity, beam-steering, frequency conversion, and amplification. The capability to accurately simulate spatially-discrete traveling-wave modulated structures is critical to design. However, simulating these structures is challenging due to the complex space-time dependence of the constituent unit cells. Thus, an interpath relation is derived for spatially-discrete traveling-wave modulated structures. The interpath relation reveals that the field within a single time-modulated unit cell (rather than an entire spatial period) is sufficient to determine the field solution throughout space. It is shown that the interpath relation can be incorporated into existing periodic method of moments solvers simply by modifying the source basis functions. As a result, the computational domain is reduced from an entire spatial period to a single time-modulated unit cell, dramatically reducing the number of unknowns.

Efficient computation of spatially-discrete traveling-wave modulated structures

Electromagnetic fields within a waveguide can be expressed in terms of the complex amplitudes of the electromagnetic modes it supports. The electromagnetic fields can be shaped by controlling the complex amplitudes of modes. Here, mode-converting metasurfaces are designed to transform a set of incident modes on one side to a different set of desired modes on the opposite side of the metasurface. A mode-converting metasurface comprises multiple inhomogeneous (spatially-varying) reactive electric sheets that are separated by dielectric spacers. The reactance profile of each electric sheet to perform the needed mode conversion is found through optimization. The optimization routine takes advantage of a multimodal solver that uses two main concepts: modal network theory and a discrete Fourier transform algorithm. With modal network theory, the modes can be translated between the electric sheets using matrix multiplication. Additionally, modal network theory accounts for the multiple reflections between the reactive electric sheets, as well as coupling between the sheets.

Metasurface-based converters for controlling guided modes and antenna apertures

An apparatus for light detection includes a light, or photon, detector assembly and a dielectric resonator layer coupled to the detector assembly. The dielectric resonator layer is configured to receive transmission of incident light that is directed into the detector assembly by the dielectric resonator layer. The dielectric resonator layer resonates with a range of wavelengths of the incident light.

Photonic detector coupled with a dielectric resonator antenna

A compound metaoptic is presented. The compound metaoptic is comprised of at least two phase-discontinuous metasurfaces, which can convert an incident light beam to an aperture field with a desired magnitude, phase, and polarization profile. Each of the constitutive metasurfaces is designed to exhibit specific refractive properties, which vary along the metasurface. Furthermore, due to its transmission-based operation, the metaoptic can operate without lenses and be low profile: potentially having a thickness on the order of a few wavelengths or less. A systematic design procedure is also presented, which allows conversion between arbitrary complex-valued field distributions without reflection, absorption or active components. Such compound metaoptics may find applications where a specific complex field distribution is desired, including displaying holographic images and augmented or virtual reality systems.

Compound metaoptics for amplitude and phase control of wavefronts

A near-field plate is a non-periodically patterned surface that can overcome the diffraction limit and confine electromagnetic fields to subwavelength dimensions. By controlling the interference of the electromagnetic fields radiated by the near-field plate with that of a source, the near-field plate can form a subwavelength near-field pattern in a forward direction, while suppressing fields in other directions, such as those reflected. The resulting unidirectional near-field plate may find utility in many applications such as high resolution imaging and probing, high density data storage, biomedical targeting devices, and wireless power transfer.

Unidirectional near-field focusing using near-field plates

Wireless power transfer using multiple near-field plates

An improved apparatus is provided for transcranial magnetic stimulation in a brain of a subject. The apparatus is comprised of: a plurality of coils electrically connected in series to each other; and a single source of current electrically coupled to one of the plurality of coils. Each coil may include one or more windings of similar dimensions although the size of the windings varies between coils. Each of the coils is further dimensioned to stimulate brain tissue at a given distance while minimizing volume of the brain tissue excited by the magnetic field. During operation, the current source injects time varying current into the coils to create a magnetic field which in turn induces electric fields and eddy-currents inside the brain tissue of the subject.

Multi-coil transcranial magnetic stimulation

Disclosed herein is a method of fabricating an antenna in which a flexible stamp is formed from a first wafer, the first wafer transferring a pattern to the flexible stamp, in which an antenna substrate is shaped into a three-dimensional contour with a second mold, in which the flexible stamp is positioned in the second mold to deform the flexible stamp into the three-dimensional contour, and in which a metallic layer on the flexible stamp is cold welded to create a set of antenna traces on the antenna substrate in accordance with the pattern. The antenna traces may then be electroplated.

Antenna fabrication with three-dimensional contoured substrates

Tensor transmission-line metamaterial unit cells are formed that allow the creation of any number of optic/electromagnetic devices. A desired electromagnetic distribution of the device is determined, from which effective material parameters capable of creating that desired distribution are obtained, for example, through a transformation optics/electromagnetics process. These effective material parameters are then linked to lumped or distributed circuit networks that achieve the desired distribution.

Tensor transmission-line metamaterials

Planar sub-wavelength structures provide superlensing, i.e., electromagnetic focusing beyond the diffraction limit. The planar structures use diffraction to force the input field to converge to a spot on the focal plane. The sub-wavelength patterned structures manipulate the output wave in such a manner as to form a sub-wavelength focus in the near field. In some examples, the sub-wavelength structures may be linear grating-like structures that can focus electromagnetic radiation to lines of arbitrarily small sub-wavelength dimension, or two dimensional grating-like structures and Bessel (azimuthally symmetric) structures that can focus to spots of arbitrarily small sub-wavelength dimensions. The particular pattern for the sub-wavelength structures may be derived from the desired focus. Some examples describe sub-wavelength structures that have been implemented to focus microwave radiation to sub-wavelength dimensions in the near field.

Growing community of inventors

Ann Arbor, MI, United States of America

Anthony Grbic