Other

US Government As Represented by the Secretary of the Army

The University of Alabama

Time Domain Corporation

Michael Scalora

Mark J Bloemer

Charles M Bowden

Michael D Tocci

Jonathan P Dowling

Giuseppe D'Aguanno

Marco Centini

Maria Antonietta Vincenti

Domenico De Ceglia

Concita Sibilia

Mirko Giuseppe Cappeddu

William C Pittman

Richard L Fork

Giovanni Bruno

Salvatore Baglio

Michael E Crenshaw

Marco Grande

Rachel J Flynn

Senter B Reinhardt, Jr

Pio Capezzuto

Nadia Mattiucci

Giusseppe V Bianco

Antonella D'Orazio

Evgenl Y Poliakov

An optically transparent graphene-based wire-grid polarizer for operating at microwave frequencies (X band) has a glass substrate having multiple strips or layers of SOCldoped graphene. The strips are separated by portions of the glass substrate such that the strips are arranged in parallel. The SOCldoped graphene strips have a quasi-metallic quality allowing for the transmission of an electric field with horizontal polarization in the horizontal direction while reflecting the vertical portion of the electric field.

Optically transparent microwave polarizer based on quasi-metallic graphene

A photonic bandgap structure having multiple stacked layers has a thickness from the top of its top layer to the bottom of its bottom layer of less than one micron. Metal conducting layers having negative real dielectric constants are positioned between semiconductor layers having positive dielectric constants. The layers are arranged and stacked, and the thicknesses and materials for the semiconductor layers and conductive layers are selected to realize desired absorption, transmission, and reflection characteristics.

Photonic bandgap structure

A photovoltaic cell having multiple stacked layers has a thickness from the top of its top layer to the bottom of its bottom layer of less than one micron. Metal conducting layers are positioned between semiconductor layers with semiconductor layers having higher bandgaps being located above semiconductor layers having lower band gaps. The layers of the photovoltaic cell are arranged and stacked, and the thicknesses and materials for the semiconductor layers and conductive layers are selected to realize desired absorption, transmission, and reflection characteristics. The geometry and thicknesses of the respective layers of the cell allows incident light of various angles to be absorbed by all of the semiconductor layers of the cell.

Photonic bandgap solar cells

We have shown that a single layer of a 3D Zero Index Material (ZIM) has omnidirectional reflection properties. In the range between the electric plasma frequency and the magnetic plasma frequency, ZIM reflect radiation for all angles of incidence and polarization with reflectivities of &#x2dc;99%. In addition, with increasing angles of incidence, the reflecting band does not shift in frequency but actually widens. The operational bandwidth can be 100% or greater by increasing the separation between the electric and magnetic plasma frequencies. We have also shown that in the spectral region that allows the omnidirectional gap, ZIM can be used as the cladding of hollow waveguides with better performance than traditional hollow waveguides.

Zero index material omnireflectors and waveguides

A waveguide has upper and lower cladding regions. A core of the waveguide made of a non-linear optical polymer is positioned between the upper and lower cladding regions. A first electrode is connected to the upper cladding region and a second electrode is connected to the lower cladding region. The upper cladding region and the lower cladding region are made of photonic band gap materials and have multiple periods of cladding layers with each period having a first layer having a linear refractive index of nand each period having a second layer having a linear refractive index of n. The waveguide allows for minimal distances to exist between the electrodes while allowing for virtual lossless cm-long transmission of propagating light. By applying a voltage to the electrodes, the propagated light can be modulated.

Photonic crystal-based optical waveguide modulator

An LCD device for displaying an image includes pixel control electrodes constructed as a transparent metal stack having a photonic band gap (PBG) structure that transmits a visible range of wavelengths and suppresses a non-visible range of wavelengths. A liquid crystal layer between the pixel control electrodes controls the transmission of light in response to a voltage applied across the pixel control electrodes. A light emitting structure (LES), such as a light emitting diode (LED) or light emitting polymer (LEP) device includes a cathode electrode, a substrate, an active layer for emitting visible light, and a transparent anode electrode having a PBG structure.

Liquid crystal display device and light emitting structure with photonic band gap transparent electrode structures

A photonic band gap (PBG) device is provided for frequency up and/or down-converting first and second photonic signals incident on the device to produce a down-converted output photonic signal. When the first and second incident photonic signals have respective first and second frequencies &ohgr; and &ohgr; , the down-converted photonic signal has a third frequency &ohgr; &equals;&ohgr; &minus;&ohgr; . When the first incident field has a frequency &ohgr; , the first up-converted photonic signal has a second frequency &ohgr; . The second up-converted photonic signal has a third frequency &ohgr; &equals;&ohgr; &plus;&ohgr; . Thus, the PBG device can be used to generate coherent near- and mid-IR signals by frequency down-converting photonic signals from readily available photonic signal sources, or red, blue, and ultraviolet signals by up-converting the same readily available photonic signal sources.

Photonic signal frequency up and down-conversion using a photonic band gap structure

A device is provided for generating a photonic signal having a phase different from an input photonic signal that is incident on the device. The input photonic signal has an signal frequency, signal bandwidth, and a signal intensity. The device comprises a plurality of material layers. The material layers are arranged such that the device exhibits a photonic band gap structure. The photonic band gap structure exhibits a transmission band edge that corresponds to the input photonic signal frequency. A second photonic signal is generated at a second photonic frequency preferably close to a second band edge. The interaction of the input photonic signal with the second photonic signal generates a phase shift of order &pgr; for relatively small input intensities.

Efficient non-linear phase shifting using a photonic band gap structure

Non-linear reflectivity and non-linear transmissivity of a first photonic signal incident on a photonic band gap (PBG) structure are controlled by applying a second photonic signal to the PBG structure while the first photonic signal is incident on the PBG structure. The first and second photonic signals have respective frequencies near a low frequency, first order band gap edge and a high frequency, second order band gap edge resonance peak of the PBG structure. The first photonic signal undergoes enhanced non-linear gain near the band gap edges when a predetermined phase difference is imposed between the first and second photonic signals, resulting in dramatic reflectivity and transmissivity changes for a band gap structure of only a few microns in length.

Photonic signal reflectivity and transmissivity control using a photonic band gap structure

A photonic band gap structure device and method for delaying photonic signals of a predetermined frequency and a predetermined bandwidth by a predetermined delay is provided. A Fabry-Perot delay line device has several regions of periodically alternating refractive material layers which exhibit a series of photonic band gaps and a periodicity defect region, interposed between the regions of periodically alternating refractive material layers. The Fabry-Perot delay line device imparts a predetermined delay to photonic signals that pass therethrough. The introduction of the periodicity defect region into this photonic band gap structure creates a sharp transmission resonance within the corresponding photonic band gap of the structure and causes at least an order of magnitude improvement in photonic signal delay for a band-edge delay line device of similar size. Variable photonic delays to multiple photonic signals are also generated by this Fabry-Perot delay line device. In addition, a photonic signal delay device based on an optical fiber grating structure is provided. A defect layer doped with a gain medium increases the density of modes thereby increasing the density of photons at a particular frequency. The introduction of gain automatically causes an increase in the photon density, and therefore, a narrowing of the density of modes. This allows tuning of the group velocity, just as if periods were being added. This also enables larger delays.

Photonic band gap device and method using a periodicity defect region doped with a gain medium to increase photonic signal delay

The photonic band gap (PBG) dual-spectrum sensor utilizes the frequency-selective properties of a photonic band gap device constructed in accordance with this invention to separate incident electromagnetic wave into two frequency bands. The parameters of the PBG device are chosen so that one frequency band is transmitted through the device with low attenuation while the second band is reflected with low attenuation from the front face of the device. This separation of the two frequency bands allows separate detection processes to be performed to recover the information content of the two signals before the information is fused in subsequent signal processing operation. Such a PBG device would be useful in missile seekers that seek to distinguish a target object from its background.

Photonic band gap dual-spectrum sensor

A photonic band gap structure device and method for delaying photonic signals of a predetermined frequency and a predetermined bandwidth by a predetermined delay is provided. A Fabry-Perot delay line device has several regions of periodically alternating refractive material layers which exhibit a series of photonic band gaps and a periodicity defect region, interposed between the regions of periodically alternating refractive material layers. The Fabry-Perot delay line device imparts a predetermined delay to photonic signals that pass therethrough. The introduction of the periodicity defect region into this photonic band gap structure creates a sharp transmission resonance within the corresponding photonic band gap of the structure and causes at least an order of magnitude improvement in photonic signal delay for a band-edge delay line device of similar size. Variable photonic delays to multiple photonic signals are also generated by this Fabry-Perot delay line device. In addition, a photonic signal delay device based on an optical fiber grating structure is provided.

Photonic band gap device and method using a periodicity defect region to increase photonic signal delay

A device and method of optics propagation and signal control integrated with micro-electro-mechanical-switches (MEMS). This device modifies optical transmission properties of a transparent multilayer metal stack by mechanically varying the thickness of an air gap between layers in the stack This is accomplished by utilizing MEMS coupled with the stack to change the optical path in a given layer of the transparent multilayer metal stack. This can be accomplished by developing a hybrid combination of transparent multilayer stacks and MEMS, wherein an air gap is used as one of the dielectric layers. The air gap thickness can be controlled by the MEMS device thereby enabling dramatic control of the optical path.

Apparatus and method for controlling optics propagation based on a transparent metal stack

A novel SH generator based on a photonic band gap (PBG), mixed half-quarter-wave, periodic structure is described. Both energy output and conversion efficiencies are nearly three orders of magnitude greater than for bulk, phase-matched devices of comparable lengths. Similar results for a GaAs/AlAs semiconductor periodic structure are also found. These results have immediate applications in frequency up- and down-conversion lasers, higher and lower harmonic generation, and Raman-type lasers, where either Stokes or anti-Stokes resonances can be enhanced or suppressed near the band edge. In general, the underlying mechanism requires the fields to be strongly confined, allowing for longer interaction times, increased effective gain lengths, and enhanced conversion efficiencies, although strong pump confinement alone can also result in significantly enhanced SH generation.

Photonic signal frequency conversion using a photonic band gap structure

A transparent metal structure permits the transmission of light over a tunable range of frequencies, for example, visible light, and shields ultraviolet light and all other electromagnetic waves of lower frequencies, from infrared to microwaves and beyond. The transparent metal structure comprises a stack of alternating layers of a high index material and a low index material, at least one of the materials being a metal. By carefully choosing the thickness of the second material, the transparent window can be tuned over a wide range of frequencies.

Growing community of inventors

Huntsville, AL, United States of America

Michael Scalora