Patents Represented by Attorney Richard D. Laumann

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  • Thermal stable optical logic element
    Patent number: 4701030
    Abstract: An optical logic element in which energy absorption is approximately constant is described.
    Type: Grant
    Filed: March 15, 1985
    Date of Patent: October 20, 1987
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventor: Jack L. Jewell
  • Sawtooth photodetector
    Patent number: 4694318
    Abstract: A structure having a sawtooth graded bandgap region between two layers having the same conductivity type is useful as a photodetector.
    Type: Grant
    Filed: December 5, 1984
    Date of Patent: September 15, 1987
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Federico Capasso, Won-Tien Tsang
  • Heterojunction semiconductor devices having a doping interface dipole
    Patent number: 4686550
    Abstract: Heterojunction devices having doping interface dipoles near the heterojunction interface are disclosed. The doping interface dipoles comprise two charge sheets of different conductivity type which are positioned within a carrier mean free path of the heterojunction interface.
    Type: Grant
    Filed: December 4, 1984
    Date of Patent: August 11, 1987
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Federico Capasso, Alfred Y. Cho
  • Apparatus for simultaneous molecular beam deposition on a plurality of substrates
    Patent number: 4681773
    Abstract: Apparatus is described which is especially well suited for simultaneous molecular beam epitaxy of materials, such as silicon, on a plurality of substrates.
    Type: Grant
    Filed: April 4, 1986
    Date of Patent: July 21, 1987
    Assignee: American Telephone and Telegraph Company AT&T Bell Laboratories
    Inventor: John C. Bean
  • Superlattice photoconductor
    Patent number: 4679061
    Abstract: Photoconductive gain is observed in a device comprising a superlattice having well and barrier layers, and cladding layers on the opposite sides of the superlattice with the barrier layers of the superlattice having an energy bandgap greater than the bandgap of the cladding layers.
    Type: Grant
    Filed: June 14, 1985
    Date of Patent: July 7, 1987
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Federico Capasso, Alfred Y. Cho, Albert L. Hutchinson, Khalid Mohammed
  • Device using ordered semiconductor alloy
    Patent number: 4661829
    Abstract: An ordered-disordered transition is observed in semiconductor alloys which enables either the ordered or disordered structure to be produced.
    Type: Grant
    Filed: June 5, 1985
    Date of Patent: April 28, 1987
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: John C. Bean, Abbas Ourmazd
  • High speed intensity modulated light source
    Patent number: 4638483
    Abstract: A semiconductor laser is frequency modulated and the output is put through an FM to IM converter. Intensity modulation is obtained at high frequency with the use of low switching current and minimal chirping oscillations.
    Type: Grant
    Filed: July 30, 1984
    Date of Patent: January 20, 1987
    Assignee: AT&T Bell Laboratories
    Inventor: John E. Bowers
  • Selective area III-V growth and lift-off using tungsten patterning
    Patent number: 4637129
    Abstract: A method of device fabrication using selective area regrowth Group III-V compound semiconductors with tungsten patterning is described.
    Type: Grant
    Filed: July 30, 1984
    Date of Patent: January 20, 1987
    Assignee: AT&T Bell Laboratories
    Inventors: Gustav E. Derkits, Jr., James P. Harbison
  • Double active layer semiconductor laser
    Patent number: 4627065
    Abstract: A double active layer semiconductor laser having single longitudinal mode operation is described. The laser comprises first and second active layers which are separated from each other by an intermediate barrier layer but are optically coupled to each other so that, effectively, single mode operation results.
    Type: Grant
    Filed: June 10, 1983
    Date of Patent: December 2, 1986
    Assignee: AT&T Bell Laboratories
    Inventors: Ralph A. Logan, Won-Tien Tsang
  • Heteroepitaxial ridge overgrown laser
    Patent number: 4622673
    Abstract: A ridge waveguide laser with the ridge being grown through a stripe opened in an oxide layer covering one of the cladding layers is described. In one embodiment, the cladding layer is corrugated and the ridge waveguide laser is a distributed feedback laser.
    Type: Grant
    Filed: May 24, 1984
    Date of Patent: November 11, 1986
    Assignee: AT&T Bell Laboratories
    Inventor: Won-Tien Tsang
  • Multicavity optical device
    Patent number: 4622671
    Abstract: Semiconductor lasers having cleaved optically coupled cavities operating electrically isolated produce output of a single longitudinal mode. Wavelength tuning of the single longitudinal mode is possible.
    Type: Grant
    Filed: April 8, 1983
    Date of Patent: November 11, 1986
    Assignee: AT&T Bell Laboratories
    Inventor: Won-Tien Tsang
  • Method of selective area epitaxial growth using ion beams
    Patent number: 4622093
    Abstract: A method of selective area epitaxial growth using a scanning ion beam is described.
    Type: Grant
    Filed: January 8, 1986
    Date of Patent: November 11, 1986
    Assignee: AT&T Bell Laboratories
    Inventor: Won-Tien Tsang
  • Spectral control arrangement for coupled cavity laser
    Patent number: 4608697
    Abstract: Control circuits stabilize and maintain coupled-cavity lasers in a single longitudinal mode. The laser is electrically connected and mutually and optically coupled to a control means responsive to a light output signal from the laser for controlling the laser by generating a control signal to the laser to produce single longitudinal mode output. The single mode output is maintained even during high speed modulation in which the current or ambient conditions vary.
    Type: Grant
    Filed: June 16, 1983
    Date of Patent: August 26, 1986
    Assignee: AT&T Bell Laboratories
    Inventor: Larry A. Coldren
  • Optical fiber having in-line polarization filter
    Patent number: 4606605
    Abstract: A device using a birefringent optical fiber having periodic integral perturbations with the period equal to the birefringence beat length being useful as, for example, a polarization rotator and an optical filter.
    Type: Grant
    Filed: June 29, 1984
    Date of Patent: August 19, 1986
    Assignee: AT&T Bell Laboratories
    Inventors: Arthur Ashkin, Rogers H. Stolen
  • Large optical cavity laser having a plurality of active layers
    Patent number: 4602370
    Abstract: A large optical cavity injection laser having a plurality of active layers within the large optical cavity. The active layers having a thickness great enough so that quantum effects are not significant.
    Type: Grant
    Filed: May 12, 1983
    Date of Patent: July 22, 1986
    Assignee: AT&T Bell Laboratories
    Inventor: Won-Tien Tsang
  • Multi-quantum well laser emitting at 1.5 .mu.m
    Patent number: 4599728
    Abstract: A multi-quantum well laser having a Ga.sub.0.47 In.sub.0.53 As/Al.sub.0.48 In.sub.0.52 As active region emitting at 1.55 .mu.m and well layers having a thickness less than 150 Angstroms.
    Type: Grant
    Filed: July 11, 1983
    Date of Patent: July 8, 1986
    Assignee: AT&T Bell Laboratories
    Inventors: Kambiz Alavi, Alfred Y. Cho, Thomas P. Pearsall, Henryk Temkin
  • Photodetector with graded bandgap region
    Patent number: 4599632
    Abstract: A photodetector having a graded bandgap region is an ultrahigh speed photodetector when operated at zero bias.
    Type: Grant
    Filed: August 30, 1982
    Date of Patent: July 8, 1986
    Assignee: AT&T Bell Laboratories
    Inventors: Clyde G. Bethea, Federico Capasso, Albert L. Hutchinson, Barry F. Levine, Won-Tien Tsang
  • Wavelength division multiplexing optical communications systems
    Patent number: 4592043
    Abstract: A wavelength division multiplexing optical communications system and components thereof capable of using as many as 10.sup.4 channels are described. The system uses a waveguide resonator which is evanescently coupled to an optical fiber or waveguide. There is also an intracavity element optically coupled to the waveguide resonator and the control circuit element which is capable of tuning the frequency of either the intracavity element or the waveguide resonator, or both, to specific frequencies. There may be a plurality of devices optically coupled to each other through the system waveguide to form an optical communications system.
    Type: Grant
    Filed: April 24, 1984
    Date of Patent: May 27, 1986
    Assignee: AT&T Bell Laboratories
    Inventor: Gareth F. Williams
  • Superlattice geometry and devices
    Patent number: 4591889
    Abstract: Semiconductor devices having submonolayer superlattices are described. These devices may have periodic compositional variations in a direction parallel to the substrate surface as well as in the perpendicular direction. Such superlattices are useful in numerous types of devices including lasers, transistors, etc.
    Type: Grant
    Filed: September 14, 1984
    Date of Patent: May 27, 1986
    Assignee: AT&T Bell Laboratories
    Inventors: Arthur C. Gossard, Pierre M. Petroff
  • Variable gap devices
    Patent number: 4590507
    Abstract: A device having a selectively doped varying bandgap region with pyroelectric characteristics is described which is useful as a photodetector or temperature sensor. A plurality of selectively doped regions forming a superlattice may also be used. Ferroelectric devices are also described.
    Type: Grant
    Filed: July 31, 1984
    Date of Patent: May 20, 1986
    Assignee: AT&T Bell Laboratories
    Inventors: Federico Capasso, Arthur C. Gossard, Michael J. Stavola