Los Alamos National Security, LLC

The Trustees of Boston College

Boston University

Tufts University

Willie John Padilla

Richard Douglas Averitt

John F O'Hara

Xin Zhang

Eric A Shaner

Sameer Sonkusale

Hu Tao

Saroj Rout

Mark Lee

Andrew Strikwerda

Hou-Tong Chen

Houtong Chen

An apparatus for controlling propagation of an electromagnetic wave includes a metamaterial having an array of cells, each cell containing a metallic structure having a resonant frequency; a plurality of devices integrated in the metamaterial, each of said devices being in electrical communication with a metallic structure in a cell in the array of cells; and a controller for electrically activating each of said plurality of devices to cause said resonant frequency to change, thereby causing at least one of a permeability and permittivity of the metamaterial to change.

Active manipulation of electromagnetic wave propagation in metamaterials

A geometrically modifiable resonator is comprised of a resonator disposed on a substrate, and a means for geometrically modifying the resonator. The geometrically modifiable resonator can achieve active optical and/or electronic control of the frequency response in metamaterials and/or frequency selective surfaces, potentially with sub-picosecond response times. Additionally, the methods taught here can be applied to discrete geometrically modifiable circuit components such as inductors and capacitors. Principally, controlled conductivity regions, using either reversible photodoping or voltage induced depletion activation, are used to modify the geometries of circuit components, thus allowing frequency tuning of resonators without otherwise affecting the bulk substrate electrical properties. The concept is valid over any frequency range in which metamaterials are designed to operate.

Dynamic frequency tuning of electric and magnetic metamaterial response

An apparatus and method are disclosed for detecting terahertz radiation at room temperature. A detecting pixel includes a sub-wavelength split-ring resonator, and is mechanically coupled to (but thermally decoupled from) a substrate via a cantilever formed from two materials that have a significant mismatch in their thermal expansion coefficients. Incident radiation causes the split-ring resonator to resonate, thereby generating heat that is transferred to the cantilever, causing the cantilever to flex. An optical readout system includes a secondary light source, such as a laser, that shines on a reflective surface on the pixel, whereby a photodiode detects the reflected light and permits calculation of a relative deflection of the pixel in the nanometer range. An exemplary detector has a noise equivalent power rating of approximately 60 pW/&#x221a;Hz.

Thermal imager using metamaterials

Metamaterial structures are taught which provide for the modulation of terahertz frequency signals. Each element within an array of metamaterial (MM) elements comprises multiple loops and at least one gap. The MM elements may comprise resonators with conductive loops and insulated gaps, or the inverse in which insulated loops are present with conductive gaps; each providing useful transmissive control properties. The metamaterial elements are fabricated on a semiconducting substrate configured with a means of enhancing or depleting electrons from near the gaps of the MM elements. An on to off transmissivity ratio of about 0.5 is achieved with this approach. Embodiments are described in which the MM elements incorporated within a Quantum Cascade Laser (QCL) to provide surface emitting (SE) properties.

Active terahertz metamaterial devices

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Newton, MA, United States of America

Willie John Padilla