Patents by Inventor Paul H. Shen

Paul H. Shen 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: 8269200
    Abstract: A method and device for generating terahertz radiation comprising a substrate; a plurality of segments of polar crystal material formed on the substrate, the segments having an internal electric polarization; each segment comprising at least two edges oriented substantially perpendicular to the polar axis such that the electric polarization terminates at the edges and the segment comprises a majority of positive charges on one edge and a majority of negative charges on the opposite edge thereby leading to creation of an internal electric field; whereby when irradiated by a pulsed source of duration less than one picosecond, electron-hole pairs are generated within the segments and the internal electric field separates and accelerates the electron-hole pairs to thereby produce terahertz radiation.
    Type: Grant
    Filed: March 8, 2011
    Date of Patent: September 18, 2012
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Michael Wraback, Paul H Shen
  • Patent number: 8203127
    Abstract: A method and device for generating terahertz radiation comprising a plurality of layers of polar crystal material operative to emit terahertz radiation; the plurality of layers comprising transport layers and divider layers, the plane of the layers being not parallel to the polar axis, the interface between the transport layers and divider layers forming boundaries at which the internal electric polarization terminates leading to charges accumulating at the boundaries, and creation of internal electric fields oriented along the polar axis.
    Type: Grant
    Filed: April 4, 2011
    Date of Patent: June 19, 2012
    Assignee: The United States of America, as represented by the Secretary of the Army
    Inventors: Michael Wraback, Paul H Shen
  • Publication number: 20110291109
    Abstract: An avalanche photodetector comprising a multiplication layer formed of a first material having a first polarization; the multiplication layer having a first electric field upon application of a bias voltage; an absorption layer formed of a second material having a second polarization forming an interface with the multiplication layer; the absorption layer having a second electric field upon application of the bias voltage, the second electric field being less than the first electric field or substantially zero, carriers created by light absorbed in the absorption layer being multiplied in the multiplication layer due to the first electric field; the absorption layer having a second polarization which is greater or less than the first polarization to thereby create an interface charge; the interface charge being positive when the first material predominately multiplies holes, the interface charge being negative when the first material predominately multiplies electrons, the change in electric field at the inte
    Type: Application
    Filed: May 26, 2011
    Publication date: December 1, 2011
    Applicant: U.S. Government as represented by the Secretary of the Army
    Inventors: MICHAEL WRABACK, Paul H. Shen, Anand V. Sampath
  • Publication number: 20110291108
    Abstract: A detection device comprising a photodetector comprising a first semiconductor layer through which light first enters the photodetector; the first semiconductor layer to semiconductor material crystal lattice which terminates at an interface; the discontinuity of the semiconductor crystal lattice at the interface creating a first interface charge; the first semiconductor layer being an absorption layer in which photons in a predetermined wavelength range are absorbed and create photogenerated carriers; and a second polar semiconductor layer deposited on the crystal lattice of the first semiconductor layer, the second polar semiconductor being substantially transparent to light in the predetermined wavelength range, the second polar semiconductor layer having a total polarization different from the first semiconductor layer so that a second interface charge is induced at the interface between the first and second semiconductor layers; the induced second interface charge reduces or substantially cancels the fir
    Type: Application
    Filed: May 24, 2011
    Publication date: December 1, 2011
    Applicant: U.S. Government as represented by the Secretary of the Army
    Inventors: Paul H. Shen, Michael Wraback, Anand V. Sampath
  • Publication number: 20110198515
    Abstract: A method and device for generating terahertz radiation comprising a substrate; a plurality of segments of polar crystal material formed on the substrate, the segments having an internal electric polarization; each segment comprising at least two edges oriented substantially perpendicular to the polar axis such that the electric polarization terminates at the edges and the segment comprises a majority of positive charges on one edge and a majority of negative charges on the opposite edge thereby leading to creation of an internal electric field; whereby when irradiated by a pulsed source of duration less than one picosecond, electron-hole pairs are generated within the segments and the internal electric field separates and accelerates the electron-hole pairs to thereby produce terahertz radiation.
    Type: Application
    Filed: March 8, 2011
    Publication date: August 18, 2011
    Applicant: U.S. Government as represented by the Secretary of the Army
    Inventors: MICHAEL WRABACK, PAUL H. SHEN
  • Publication number: 20110180733
    Abstract: A method and device for generating terahertz radiation comprising a plurality of layers of polar crystal material operative to emit terahertz radiation; the plurality of layers comprising transport layers and divider layers, the plane of the layers being not parallel to the polar axis, the interface between the transport layers and divider layers forming boundaries at which the internal electric polarization terminates leading to charges accumulating at the boundaries, and creation of internal electric fields oriented along the polar axis; whereby when irradiated by a pulsed source of duration less than one picosecond, a time-varying and spatially nonuniform distribution of carriers is created in the growth direction of the polar crystal material thereby generating a first time-varying current due to diffusion of the carriers; the internal electric fields accelerating the carriers generated by the pulsed radiation source operating to produce a second time-varying current that is additive with the first time-v
    Type: Application
    Filed: April 4, 2011
    Publication date: July 28, 2011
    Applicant: U.S. Government as represented by the Secretary of Army
    Inventors: MICHAEL WRABACK, PAUL H. SHEN
  • Patent number: 7411662
    Abstract: A system and method for performing high-resolution imagery of a target are provided. One embodiment is a method of performing high-resolution imagery of a target comprising: generating a chirped waveform that modulates a light signal transmitted toward a target for performing active LADAR of the target; generating a low-frequency local oscillator waveform for performing active imaging; and simultaneously performing passive imaging and active LADAR.
    Type: Grant
    Filed: October 20, 2005
    Date of Patent: August 12, 2008
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: William C. Ruff, Barry L. Stann, Paul H. Shen, Brian C. Redman, Keith M. Aliberti
  • Patent number: 6844924
    Abstract: A high range resolution ladar includes a chirp generator for producing a chirp signal waveform that is used by a laser diode to propagate a divergent laser light waveform. The reflected light signals from the target are directed to a self mixing detector that is coupled to the chirp generator where the responsivity of the detector varies in accordance with the chirp waveform for converting reflected light signals from the target to electrical signals and for mixing the converted electrical signal with the chirp waveform to produce an output electrical signal whose frequency is proportional to the range to the target. The self-mixing detector includes at least one detector having a semiconductor substrate and first and second electrodes deposited on the substrate and spaced from each other, wherein the first set of electrodes is connected to the chirp generator and the second set of electrodes is connected to a memory for storing a plurality of frames of image data.
    Type: Grant
    Filed: June 28, 2002
    Date of Patent: January 18, 2005
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: William C. Ruff, Barry L. Stann, Paul H. Shen
  • Publication number: 20030076485
    Abstract: A high range resolution ladar includes a chirp generator for producing a chirp signal waveform that is used by a laser diode to propagate a divergent laser light waveform. The reflected light signals from the target are directed to a self mixing detector that is coupled to the chirp generator where the responsivity of the detector varies in accordance with the chirp waveform for converting reflected light signals from the target to electrical signals and for mixing the converted electrical signal with the chirp waveform to produce an output electrical signal whose frequency is proportional to the range to the target. The self-mixing detector includes at least one detector having a semiconductor substrate and first and second electrodes deposited on the substrate and spaced from each other, wherein the first set of electrodes is connected to the chirp generator and the second set of electrodes is connected to a memory for storing a plurality of frames of image data.
    Type: Application
    Filed: June 28, 2002
    Publication date: April 24, 2003
    Inventors: William C. Ruff, Barry L. Stann, Paul H. Shen
  • Patent number: 6366389
    Abstract: A high contrast ultrahigh speed optically-addressed ultraviolet light modulator exploits the optical anisotropy in a ZnO film epitaxially grown on (01 {overscore (1)}2) sapphire. This device, which could also be realized in a ZnO bulk crystal or similar wide bandgap material, achieves both high contrast and high speed by exploiting the anisotropic bleaching of the anisotropic absorption and concomitant ultrafast polarization rotation near the lowest exciton resonances produced by femtosecond ultraviolet pulses. The resultant modulation in a preferred embodiment is characterized by a contrast ratio of 70:1, corresponding to a dynamic polarization rotation of 12°, and decays to a quasi-equilibrium value within 100 ps.
    Type: Grant
    Filed: August 15, 2000
    Date of Patent: April 2, 2002
    Inventors: Michael Wraback, Paul H. Shen, Shaohua Liang, Chandrasekhar R. Gorla, Yicheng Lu
  • Patent number: 6188808
    Abstract: An optical signal processor is implemented as a monolithically integrated semiconductor structure having optical waveguide devices forming beam splitters, optical amplifiers and optical phase shifters. The monolithic structure photonically controls a phased-array microwave antenna. Phase-locked master and slave lasers generate orthogonal light beams having a difference frequency that corresponds to the microwave carrier frequency of the phased-array antenna. The lasers feed the signal processor, which performs beam splitting, optical amplifying and phase shifting functions. A polarizer and an array of diode detectors convert optical output signals from the signal processor into microwave signals that feed the phased-array antenna. The optical waveguides of the signal processor are fabricated in a single selective epitaxial growth step on a semiconductor substrate.
    Type: Grant
    Filed: May 20, 1999
    Date of Patent: February 13, 2001
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Weimin Zhou, Paul H. Shen, Mitra Dutta, Jagadeesh Pamulapati
  • Patent number: 6075254
    Abstract: A semiconductor waveguide modulator that is polarization insensitive/independent at bias variations for any chosen wavelength. The modulator of the present invention employs a novel type of strained semiconductor quantum well (QW) structure that exhibits bias independent, heavy-hole and light hole degeneracy. This effect is achieved by inserting one or two thin layers of highly tensile, strained materials in a specific position within the QW. By adjusting the thickness and the position of the highly tensile strained layers, the quantum confined Stark effect (QCSE) for the heavy hole and light hole can be engineered separately to control the bias dependent polarization properties. The present invention has applications, for example, in optoelectronic devices in the areas of telecommunications, optical signal processing, scanning and displays.
    Type: Grant
    Filed: March 24, 1998
    Date of Patent: June 13, 2000
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Paul H. Shen, Jagadeesh Pamulapati, Mitra Dutta
  • Patent number: 5953362
    Abstract: A vertical cavity surface emitting laser is formed by eutectically bonding a laser cavity, defined by an active layer disposed between first and second, stacked mirror assemblies, to a host substrate which has a predetermined anisotropic coefficient of thermal expansion. During the forming process, a uniaxial strain is induced within the laser cavity. With this arrangement, large arrays of vertical cavity surface emitting lasers can be formed with predetermined polarization states that are based on the selected anisotropic host substrate.
    Type: Grant
    Filed: December 15, 1997
    Date of Patent: September 14, 1999
    Inventors: Jagadeesh Pamulapati, Paul H. Shen
  • Patent number: 5930031
    Abstract: An optical signal processor is implemented as a monolithically integrated semiconductor structure having optical waveguide devices forming beam splitters, optical amplifiers and optical phase shifters. The monolithic structure photonically controls a phased-array microwave antenna. Phase-locked master and slave lasers generate orthogonal light beams having a difference frequency that corresponds to the microwave carrier frequency of the phased-array antenna. The lasers feed the signal processor, which performs beam splitting, optical amplifying and phase shifting functions. A polarizer and an array of diode detectors convert optical output signals from the signal processor into microwave signals that feed the phased-array antenna. The optical waveguides of the signal processor are fabricated in a single selective epitaxial growth step on a semiconductor substrate.
    Type: Grant
    Filed: April 8, 1998
    Date of Patent: July 27, 1999
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Weimin Zhou, Paul H. Shen, Mitra Dutta, Jagadeesh Pamulapati
  • Patent number: 5847435
    Abstract: An MQW is fabricated such that at a particular level of purely mechanical ress/strain the optical properties of the MQW are altered by breaking the heavy and light hole degeneracy (splitting of the heavy and light holes in the valence band) of the MQW in the E-k domain. In a preferred embodiment of the invention ring electrical contacts are disposed on the MQW and the entire MQW structure, including electrical contacts is mounted on a piezoelectric substrate, with the proper crystallographic orientation and strain induced orientation, via an epoxy.In operation, a bias is applied to the MQW structure and the piezoelectric substrate. The bias causes quantum decoupling of the heavy and light holes; however, the bias also will cause the piezoelectric material to move, which will induce a strain on the MQW structure.
    Type: Grant
    Filed: August 9, 1996
    Date of Patent: December 8, 1998
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Arthur Ballato, Richard H. Wittstruck, Yicheng Lu, Mitra Dutta, Jagadeesh Pamulapati, Paul H. Shen
  • Patent number: 5770472
    Abstract: An optical signal processor is implemented as a monolithically integrated semiconductor structure having optical waveguide devices forming beam splitters, optical amplifiers and optical phase shifters. The monolithic structure photonically controls a phased-array microwave antenna. Phase-locked master and slave lasers generate orthogonal light beams having a difference frequency that corresponds to the microwave carrier frequency of the phased-array antenna. The lasers feed the signal processor, which performs beam splitting, optical amplifying and phase shifting functions. A polarizer and an array of diode detectors convert optical output signals from the signal processor into microwave signals that feed the phased-array antenna. The optical waveguides of the signal processor are fabricated in a single selective epitaxial growth step on a semiconductor substrate.
    Type: Grant
    Filed: September 9, 1996
    Date of Patent: June 23, 1998
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Weimin Zhou, Paul H. Shen, Mitra Dutta, Jagadeesh Pamulapati
  • Patent number: 5748359
    Abstract: An imaging system for transferring an infrared (IR) image to a visible image. The imaging system includes a polarization rotator that rotates the polarization of a visible light beam in response to absorptions of radiation from the IR image. A polarizer outputs components of the visible light beam as a function of the amount of absorbed radiation from the IR image. The polarization rotator is formed from a multiple quantum well structure grown on a semiconductor substrate with a thermally induced uniaxial, in-plane, compressive strain. The multiple quantum well structure includes a heterostructure of undoped barrier layers and doped quantum well layers. The strain causes the quantum well layers to have anisotropic radiation absorption characteristics. In particular, orthogonal components of the visible light parallel to and perpendicular to the strain will experience different degrees of absorption.
    Type: Grant
    Filed: November 21, 1996
    Date of Patent: May 5, 1998
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Paul H. Shen, Mitra Dutta, Michael Wraback, Jagadeesh Pamulapati
  • Patent number: 5579331
    Abstract: A quantum-well semiconductor laser/amplifier mounted on a highly conductive semiconductor substrate. Inactive regions include a highly doped N-region and a highly doped P-region. The N-region is composed of semiconductor material mounted on the substrate. The active region includes a quantum-well heterostructure of intrinsic semiconductor material that mounts on the N-region. The quantum-well structure includes a series of quantum wells, each having barrier layers, quantum-well layers, and a delta-strained layer mounted near the center of the quantum wells. The delta-strained layers are very thin, being formed from a number of mono-layers of semiconductor material. There is a large lattice mismatch between each of the delta-strained layers and its adjacent quantum-well layers. The band edges of the quantum-well layers and the delta-strained layers are located at substantially the same level. The P-region is composed of a semiconductor material that mounts on the quantum-well structure.
    Type: Grant
    Filed: May 31, 1995
    Date of Patent: November 26, 1996
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Paul H. Shen, Paul W. Cooke, Wayne H. Chang
  • Patent number: 5488226
    Abstract: An thermal imaging device having a transparent substrate, an active multiple quantum well (MQW) epilayer with bottom electrical contacts bonded to the substrate, wherein the substrate is cut such that its thermal expansion coefficient is matched or roughly matched to that of the MQW epilayer in the direction parallel to the long axis of the bottom contacts and so that the thermal expansion coefficient of the substrate is mismatched in a direction normal to the long axis of the bottom contacts. Infrared radiation incident on each unit cell of the n.times.m array will produce a temperature change .DELTA.T in the MQW which will produce stress normal to the long axis of the bottom contacts. The uniaxial stress produced by the temperature changes .DELTA.T breaks the rotation symmetry in the plane of the MQW structure.
    Type: Grant
    Filed: November 18, 1994
    Date of Patent: January 30, 1996
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Gerald J. Iafrate, Mitra Dutta, Paul H. Shen, Michael A. Stroscio