Igor Vurgaftman

6448642, Sep 10, 2002

Jan 27, 2000

09/492068

William W. Bewley - Falls Church VA, 22041
Edward A. Aifer - Arlington VA, 22207
Christopher L. Felix - Washington DC, 20002
Igor Vurgaftman - Pikesville MD, 21208
Jerry R. Meyer - Catonsville MD, 21228
John Glesener - Richardson TX, 75008

H01L 2340

257719, 257 99

This invention pertains to a method for removing heat from a heat source device and to a heat sink system characterized by a pressure bond having thermal resistance of less than about 5 K/kW-cm. The method is characterized by the steps of removing heat from a heat source device comprising the steps of placing a heat source device in contact with a heat source and applying a sufficient force to form a pressure bond between the heat source device and the heat sink wherein thermal resistance at the interface between the heat source device and the heat sink after the thermal bond is established is less than about 5 K/kW-cm. The heat sink system includes a heat source device and a heat sink in contact with the heat source device with thermal resistance at the interface of the heat source device and said heat sink is less than about 5 K/kW-cm.

6734043, May 11, 2004

Jul 17, 2002

10/196147

William W. Bewley - Falls Church VA
Edward A. Aifer - Arlington VA
Christopher L. Felix - Washington DC
Igor Vurgaftman - Pikesville MD
Jerry R Meyer - Catonsville MD
John Glesener - Richardson TX

The United States of America as represented by the Secretary of the Navy - Washington DC

H01L 2336

438122, 438 26

This invention pertains to a method for removing heat from a heat source device and to a heat sink system characterized by a pressure bond having thermal resistance of less than about 5 K/kW-cm. The method is characterized by the steps of removing heat from a heat source device comprising the steps of placing a heat source device in contact with a heat source and applying a sufficient force to form a pressure bond between the heat source device and the heat sink wherein thermal resistance at the interface between the heat source device and the heat sink after the thermal bond is established is less than about 5 K/kW-cm. The heat sink system includes a heat source device and a heat sink in contact with the heat source device with thermal resistance at the interface of the heat source device and said heat sink is less than about 5 K/kW-cm.

6826223, Nov 30, 2004

May 28, 2003

10/446259

Jerry Meyer - Pikesville MD
Igor Vurgaftman - Catonsville MD

The United States of America as represented by the Secretary of the Navy - Washington DC

H01S 308

372 96, 372102

A surface-emitting photonic crystal distributed feedback laser apparatus configured to emit an optical beam of light. The apparatus includes a laser cavity bounded by top and bottom optical claddings, an active region configured to produce optical gain upon receiving optical or electrical pumping, a periodic two-dimensional grating having an order higher than the fundamental and configured to induce modulation of a modal refractive index, and lateral pumped gain area contained within an area covered by the grating, the lateral pumped gain area configured to produce gain in one or more lasing modes having a modal index modulated by the grating. The lateral pumped gain area has a substantially circular shape of diameter D, and wherein the pumped gain area is enclosed by an unpumped region contained within the area covered by the grating but not receiving the optical or electrical pumping.

6868107, Mar 15, 2005

Mar 7, 2003

10/390255

Igor Vurgaftman - Pikesville MD, US
Jerry Meyer - Catonsville MD, US

The United States of America as represented by the Secretary of the Navy - Washington DC

H01S003/10
H01S003/098
H01S003/08

372 96, 372 18, 372 26, 372 9, 372 92, 372102

A method for calculating the beam quality and output wavelength spectrum of a photonic crystal distributed feedback laser includes the steps of calculating at least two coupling coefficients and forming a characteristic matrix; repeating the following steps at spaced increments of time until a steady state solution is reached: repeating the following steps for one of the incremental cavity lengths: calculating a gain change and a modal refractive index change for the laser waveguide structure for one incremental stripe width; calculating a spontaneous emission term for the gain change; calculating a gain roll-off term for the gain change; applying the gain change, the modal refractive index change, the spontaneous emission term, and the gain roll-off term to at least two forward-propagating beams and at least two backward-propagating beams for the one incremental stripe width; performing a Fourier transformation with respect to the one incremental stripe width to yield a plurality of diffraction terms; adding the diffraction terms to the characteristic matrix; propagating the two forward-propagating beams by the incremental cavity length from a first section to a succeeding and adjacent second section with the characteristic matrix; propagating the two backward-propagating beams by the incremental cavity length from the second section to the first section with the characteristic matrix; performing an inverse Fourier transformation with respect to the stripe width; and applying at least one boundary condition to a facet of the laser configuration for each time increment. The steady-state solution is used as the basis for evaluating the beam quality and output wavelength spectrum corresponding to the design parameters, the additional design parameters, and the photonic crystal geometry of the laser configuration. The invention provides scientists with an approach to designing and building lasers that eliminates much of the time and resources otherwise needed in the building and testing of unsuccessful designs.

6996152, Feb 7, 2006

Mar 7, 2003

10/385165

Igor Vurgaftman - Pikesville MD, US
Jerry Meyer - Catonsville MD, US

The United States of America as represented by the Secretary of the Navy - Washington DC

H01S 3/08

372 96, 372 20, 372 32, 372 501, 372 50124, 372 92, 372102

A photonic-crystal distributed-feedback laser includes a laser cavity with a waveguide structure that has a cavity length Land is bounded by two mirrors; an active region for producing optical gain upon receiving optical pumping or an input voltage; at least one layer having a periodic two-dimensional grating with modulation of a modal refractive index, the grating being defined on a rectangular lattice with a first period along a first axis of the grating and a second period along a second perpendicular axis of the grating, and wherein the grating produces three diffraction processes having coupling coefficients κ′, κ′, κ′; and a lateral gain area contained within a second area patterned with the grating that has substantially a shape of a gain stripe with a width W, with the gain stripe tilted at a first tilt angle relative to the two mirrors. The rectangular lattice of the grating is tilted at a second tilt angle substantially the same as the first tilt angle with respect to the gain stripe, and the ratio of the first and second grating periods is equal to the tangent of the first tilt angle, with the first tilt angle being between about 16 and about 23. The hexagonal lattice does not need to be tilted with respect to the two mirrors.

7256417, Aug 14, 2007

Feb 5, 2004

10/772573

Luke J. Mawst - Sun Prairie WI, US
Nelson Tansu - Bethlehem PA, US
Jerry R. Meyer - Catonsville MD, US
Igor Vurgaftman - Odenton MD, US

Wisconsin Alumni Research Foundation - Madison WI

H01L 29/205
H01S 3/103

257 14

Semiconductor optoelectronic devices such as diode lasers are formed on InP substrates with an active region with an InAsN or InGaAsN electron quantum well layer and a GaAsSb or InGaAsSb hole quantum well layer which form a type II quantum well. The active region may be incorporated in various devices to provide light emission at relatively long wavelengths, including light emitting diodes, amplifiers, surface emitting lasers and edge-emitting lasers.

7755828, Jul 13, 2010

Dec 14, 2007

11/956626

Marc Currie - Gaithersburg MD, US
Igor Vurgaftman - Odenton MD, US
Janet W Lou - Alexandria VA, US

The United States of America as represented by the Secretary of the Navy - Washington DC

G02F 1/01

359279

A method and system for modifying the detected phase of a signal by driving a photodetector into saturation. This system and method differs from current manual and electrical microwave phase modification by using saturation means for modifying the phase. The system and method may use a plurality of the signal generators for saturating the photodetector.

8125706, Feb 28, 2012

Mar 12, 2009

12/402627

Igor Vurgaftman - Odenton MD, US
Jerry R Meyer - Catonsville MD, US
Chadwick L. Canedy - Washington DC, US
William W. Bewley - Falls Church VA, US
James R. Lindle - Bowie MD, US
Chul-soo Kim - Springfield VA, US
Mijin Kim - Springfield VA, US

The United States of America as represented by the Secretary of the Navy - Washington DC

H01S 3/00

359344, 372 4301

A gain medium and an interband cascade laser, an interband cascade amplifier, and an external cavity laser having the gain medium are presented. The gain medium can include any one or more of the following features: (1) the active quantum well region includes a thick and In-rich GaInSb hole well; (2) the hole injector includes two or more GaSb hole wells having thicknesses in a specified range; (3) the electron and hole injectors are separated by a thick AlSb barrier to suppress interband absorption; (4) a first electron barrier of the hole injector region separating the hole injector region from an adjacent active quantum well region has a thickness sufficient to lower a square of a wavefunction overlap between a zone-center active electron quantum well and injector hole states to not more than 5%; (5) the thickness of the first InAs electron well in the electron injector, as well as the total thickness of the electron injector, is reduced; (6) the number of cascaded stages is reduced; (7) transition regions are inserted at the interfaces between the various regions of the gain medium so as to smooth out abrupt shifts of the conduction-band minimum; (8) thick separate confinement layers comprising Ga(InAlAs)Sb are disposed between the active gain region and the cladding to confine the optical mode and increase its overlap with the active stages; and (9) the doping profile of the cladding layers is optimized to minimize the overlap of the optical mode with the most heavily-doped portion of the InAs/AlSb SL cladding layers. An interband cascade laser, an interband cascade amplifier, or an external cavity laser employing a gain medium having these features can emit at a wavelength of about 2. 5 μm to about 8 μm at high temperatures.