Patents by Inventor Alexandre Bratkovski

Alexandre Bratkovski has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 8983238
    Abstract: An optical resonator configured to be tuned using piezoelectric actuation, includes a core, the core being configured to transmit light; a piezoelectric layer; a first electrode and a second electrode. The piezoelectric layer is interposed between the first electrode and the second electrode. A voltage difference across the first and second electrodes alters a geometric dimension of the piezoelectric layer such that physical force is applied to the core and a resonant optical frequency of the resonator is changed. A method of utilizing mechanical stress to tune an optical resonator includes applying physical force to the resonator by subjecting a piezoelectric material to an electric field, the physical force changing a resonant frequency of the resonator.
    Type: Grant
    Filed: October 28, 2008
    Date of Patent: March 17, 2015
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventors: Alexandre Bratkovski, Sagi Mathai, Duncan Stewart
  • Publication number: 20140176942
    Abstract: A surface enhanced Raman spectroscopy (SERS) apparatus employs a nanorod in an indentation in a surface of a substrate. The SERS apparatus includes the nanorod having a tip at a free end opposite to an end of the nanorod that is supported by the substrate indentation. The indentation has a tapered profile and supports the nanorod at a bottom of the indentation. The free end of the nanorod extends away from the indentation bottom. The SERS apparatus further includes a Raman-active material at a surface of one or both of the nanorod and the indentation. The indentation and the nanorod facilitate one or both of production and detection of a Raman scattering signal emitted by an analyte in a vicinity of the nanorod and indentation.
    Type: Application
    Filed: July 27, 2011
    Publication date: June 26, 2014
    Inventors: Alexandre Bratkovski, Zhiyong Li
  • Patent number: 8693894
    Abstract: A gain clamped optical device includes a semiconductor stack and a resonant cavity configured to emit stimulated light. A window created in the optical device is configured to emit the stimulated light in an LED mode.
    Type: Grant
    Filed: October 28, 2008
    Date of Patent: April 8, 2014
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventors: Shih-Yuan Wang, Michael Tan, Alexandre Bratkovski, Sagi Mathai
  • Patent number: 8604897
    Abstract: Various embodiments of the present invention are directed to metamaterial-based devices and to methods of fabricating metamaterial-based devices. In one embodiment, a metamaterial-based device comprises a channel layer, a top metallic layer, and a bottom metallic layer. The channel layer has a top and a bottom surfaces, and at least one channel configured to transmit at least one material. The top metallic layer has a top surface and a bottom surface attached to the top surface of the channel layer and has a first lattice of openings extending between the top and bottom surfaces of the top metallic layer. The bottom metallic layer has a top surface and a bottom surface, wherein the top surface of the bottom metallic layer is attached to the bottom surface of the channel layer.
    Type: Grant
    Filed: July 26, 2007
    Date of Patent: December 10, 2013
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventors: Alexandre Bratkovski, Wei Wu
  • Patent number: 8546898
    Abstract: An optoelectronic memory cell has a transparent top electrode, a photoactive layer, a latching layer, and a bottom electrode. The photoactive layer absorbs photons transmitted through the top electrode and generates charge carriers. During light exposure, the latching layer changes its resistance under an applied electric field in response to the generation of charge carriers in the photoactive layer.
    Type: Grant
    Filed: September 29, 2009
    Date of Patent: October 1, 2013
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventors: Lars Thylen, Alexandre Bratkovski, Shih-Yuan Wang, R. Stanley Williams
  • Patent number: 8519372
    Abstract: A nanoscale switching device is constructed such that an electroforming process is not needed to condition the device for normal switching operations. The switching device has an active region disposed between two electrodes. The active region has at least one switching layer formed of a switching material capable of transporting dopants under an electric field, and at least one conductive layer formed of a dopant source material containing dopants that can drift into the switching layer under an electric field. The switching layer has a thickness about 6 nm or less.
    Type: Grant
    Filed: July 30, 2009
    Date of Patent: August 27, 2013
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventors: Jianhua Yang, Shih-Yuan Wang, R. Stanley Williams, Alexandre Bratkovski, Gilberto Ribeiro
  • Patent number: 8327721
    Abstract: A sensor fabric has a plurality of flakes of a flexoelectric material and electrodes as threads for connecting the flakes together. Each flake has at least one pair of opposite edges connected by two separate electrodes. When the sensor fabric is placed in contact with the surface of an object, the flake is bent along the contour of the object surface. The bending of the flexoelectric flake generates a polarization voltage between its opposite edges, which can be measured via the electrodes to determine the local surface contour of the object.
    Type: Grant
    Filed: October 26, 2009
    Date of Patent: December 11, 2012
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventors: Alexandre Bratkovski, Ivan Naumov
  • Publication number: 20120223286
    Abstract: A nanoscale switching device is constructed such that an electroforming process is not needed to condition the device for normal switching operations. The switching device has an active region disposed between two electrodes. The active region has at least one switching layer formed of a switching material capable of transporting dopants under an electric field, and at least one conductive layer formed of a dopant source material containing dopants that can drift into the switching layer under an electric field. The switching layer has a thickness about 6 nm or less.
    Type: Application
    Filed: July 30, 2009
    Publication date: September 6, 2012
    Inventors: Jianhua Yang, Shih-Yuan Wang, R. Stanley Williams, Alexandre Bratkovski, Gilberto Ribeiro
  • Publication number: 20120136631
    Abstract: Apparatus and systems are provided for data signaling between a centralized transceiver and a plurality of sensor nodes. Subordinate sensor nodes transmit data corresponding to sensed physical variables to a master node within a group. The master node within the group transmits the data on to a data acquisition transceiver. Data communications are performed by free-space signaling. Large areas can be monitored by a vast array of such sensors, organized as plural neighborhoods, without the need for wiring, optical fibers or other tangible interconnections.
    Type: Application
    Filed: January 29, 2010
    Publication date: May 31, 2012
    Inventors: Alexandre Bratkovski, Marco Fiorentino, Raymond Beausoleil
  • Publication number: 20120122394
    Abstract: Apparatus and systems are provided for data signaling between a centralized transceiver and a plurality of sensor nodes. Each sensor node independently generates electrical power from one or more renewable sources. Each sensor node transmits data corresponding to sensed physical variables to the transceiver by free-space signaling. Large areas can be monitored by a vast array of such sensors without the need for wiring, optical fibers or other tangible interconnections.
    Type: Application
    Filed: January 29, 2010
    Publication date: May 17, 2012
    Inventors: Alexandre Bratkovski, R. Stanley Williams
  • Publication number: 20120120059
    Abstract: A display device for displaying 3D holographic images has multiple pixels, each having a set of coupled optical resonators. The optical paths of the coupled optical resonators can be adjusted to impart a desired phase shift to light passing through the coupled optical resonators. The transmission amplitude and phase of each pixel of the display can be dynamically and individually adjusted for displaying 3D holographic images.
    Type: Application
    Filed: October 27, 2009
    Publication date: May 17, 2012
    Inventors: Alexandre Bratkovski, Lars Thylen, Jinging Li
  • Publication number: 20120074378
    Abstract: A memory element is provided that includes a first electrode, a second electrode, and an active region disposed between the first electrode and the second electrode, wherein at least a portion of the active region comprises an elastically deformable material, and wherein deformation of the elastically deformable material causes said memory element to change from a lower conductive state to a higher conductive state. A multilayer structure also is provided that includes a base and a multilayer circuit disposed above the base, where the multilayer circuit includes at least of the memory elements including the elastically deformable material.
    Type: Application
    Filed: September 23, 2010
    Publication date: March 29, 2012
    Inventors: Wei Wu, Jianhua Yang, Zhiyong Li, Shih-Yuan Wang, Dmitri Strukov, Alexandre Bratkovski
  • Publication number: 20120039114
    Abstract: A memcapacitor device (100) includes a first electrode (104) and a second electrode (106) and a memcapacitive matrix (102) interposed between the first electrode (104) and the second electrode (106). Mobile dopants (111) are contained within the memcapacitive matrix (102) and are repositioned within the memcapacitive matrix (102) by the application of a programming voltage (126) across the first electrode (104) and second electrode (106) to alter the capacitance of the memcapacitor (100). A method for utilizing a memcapacitive device (100) includes applying a programming voltage (126) across a memcapacitive matrix (102) such that mobile ions (111) contained within a memcapacitive matrix (102) are redistributed and alter a capacitance of the memcapacitive device (100), then removing the programming voltage (126) and applying a reading voltage to sense the capacitance of the memcapacitive device (100).
    Type: Application
    Filed: June 18, 2009
    Publication date: February 16, 2012
    Inventors: Alexandre Bratkovski, R. Stanley Williams
  • Publication number: 20120035057
    Abstract: Methods and apparatus characterized by distinct operating modes are provided. A thin graphite material defined by graphene layers is supported on a silicon substrate. The graphite material is defined by edge sites at the interface with the silicon. The graphite material is characterized by electrical superconductive-like behavior at room-temperatures while electrical current flows there through in a first direction. The graphite material is further characterized by a transition to Ohmic behavior while electrical current flows there through in a second direction opposite to the first. Devices exhibiting diode-like behavior can be formed accordingly.
    Type: Application
    Filed: August 3, 2010
    Publication date: February 9, 2012
    Inventors: Alexandre Bratkovski, Iakov Kopelevitch
  • Publication number: 20120012810
    Abstract: An optoelectronic memory cell has a transparent top electrode, a photoactive layer, a latching layer, and a bottom electrode. The photoactive layer absorbs photons transmitted through the top electrode and generates charge carriers. During light exposure, the latching layer changes its resistance under an applied electric field in response to the generation of charge carriers in the photoactive layer.
    Type: Application
    Filed: October 29, 2009
    Publication date: January 19, 2012
    Inventors: Lars Thylen, Alexandre Bratkovski, Shih-Yuan Wang, R. Stanley Williams
  • Patent number: 8098971
    Abstract: An electromagnetic resonance device includes an input reflector, an output reflector, and a periodic dielectric medium (PDM) disposed between the input reflector and the output reflector. The input reflector and output reflector are configured to be reflective to radiation having a wavelength of interest. The PDM includes a periodic structure having a dielectric periodicity between a first surface and a second surface. The dielectric periodicity is configured with a negative refraction for the wavelength of interest. A first radiation is reflected by the input reflector toward the first surface of the PDM, passes through the PDM, and is focused on the output reflector as a second radiation. The second radiation is reflected by the output reflector toward the second surface of the PDM, passes through the PDM, and is focused on the input reflector as the first radiation.
    Type: Grant
    Filed: September 19, 2005
    Date of Patent: January 17, 2012
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventors: Alexandre Bratkovski, Raymond G. Beausoleil, Shih-Yuan Wang
  • Patent number: 8053982
    Abstract: One embodiment of the present invention relates to a light-emitting diode having one or more light-emitting layers, a pair of electrodes disposed on the light-emitting diode so that an operating voltage can be applied to generate light from the one or more light-emitting layers, and at least one external electrode in electronic communication with the one or more light-emitting layers. Applying an appropriate voltage to the at least one external electrodes at about the time the operating voltage is terminated extracts excess electrons from the one or more light-emitting layers and reduces the duration of electron-hole recombination during the time period over which the operating voltage is turned off.
    Type: Grant
    Filed: October 1, 2008
    Date of Patent: November 8, 2011
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventors: Alexandre Bratkovski, Shih-Yuan Wang, Michael Tan, Theodore I. Kamins
  • Publication number: 20110267048
    Abstract: Methods and apparatus pertaining to magnetically sensitive devices are provided. A device includes a graphite containing-material (GCM) supported in contact with respective pairs of electrodes. The GCM is subject to a magnetic field. Various levels of electric current are driven through the GCM, while corresponding voltage measurements are taken. Resulting current-versus-voltage data pairs are compared to calibration data for the device. Magnetic field intensities, operating states of the device or other determinations can be made according to the comparison.
    Type: Application
    Filed: April 29, 2010
    Publication date: November 3, 2011
    Inventors: Alexandre Bratkovski, Iakov Kopelevitch
  • Patent number: 8009943
    Abstract: Various embodiments of the present invention are directed to photonic switches and switch fabrics employing the photonic switches. In one embodiment of the present invention, a photonic switch comprises a first waveguide disposed on a surface of a substrate in proximity to an opening in the substrate, and a second waveguide crossing the first waveguide and positioned in proximity to the opening in the substrate. The photonic switch includes a tunable microring resonator disposed on the surface of the substrate adjacent to the first waveguide and the second waveguide and configured with an opening aligned with the opening in the substrate. The photonic switch also includes a wire having a first end and a second end and configured to pass through the opening in the microring and the opening in the substrate.
    Type: Grant
    Filed: October 20, 2008
    Date of Patent: August 30, 2011
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventors: Alexandre Bratkovski, Michael Tan, Raymond Beausoleil
  • Patent number: 8009937
    Abstract: An optical resonator configured to be tuned using a charge-based memory cell includes an optical cavity configured to transmit light and receive injected charge carriers; a charge-based memory cell in proximity to or within the optical cavity, the memory cell containing a number of trapped charges which influence the resonant optical frequency of the optical resonator. A method of tuning an optical resonator includes applying a voltage or current to a charge-based memory cell to generate a non-volatile charge within the memory cell, the nonvolatile charge changing a resonant frequency of the optical resonator.
    Type: Grant
    Filed: October 28, 2008
    Date of Patent: August 30, 2011
    Assignee: Hewlett-Packard Development Company, L.P.
    Inventors: Sagi Mathai, Alexandre Bratkovski, Duncan Stewart