Patents Assigned to Fox-Tek
  • Semiconductor optical amplifier with electronically controllable polarization dependent gain
    Patent number: 6891666
    Abstract: An optical amplifier has two amplifying sections formed in a semiconductor structure. The two amplifying sections have different ratios of gain for two polarization states (e.g., TE and TM). Thus the amplifier as a whole has a gain ratio determined by the gains of the two amplifying sections. The two amplifying sections are separately electronically controllable so as to control the gains of the two amplifying sections and thus the gain ratio of the amplifier as a whole. Such an amplifier can be made by quantum well intermixing.
    Type: Grant
    Filed: March 11, 2003
    Date of Patent: May 10, 2005
    Assignee: Fox-Tek, Inc.
    Inventors: Geoff Darling, Ted Sargent
  • Semiconductor optical amplifier with electronically controllable polarization dependent gain
    Publication number: 20040196541
    Abstract: An optical amplifier has two amplifying sections formed in a semiconductor structure. The two amplifying sections have different ratios of gain for two polarization states (e.g., TE and TM). Thus the amplifier as a whole has a gain ratio determined by the gains of the two amplifying sections. The two amplifying sections are separately electronically controllable so as to control the gains of the two amplifying sections and thus the gain ratio of the amplifier as a whole. Such an amplifier can be made by quantum well intermixing.
    Type: Application
    Filed: March 11, 2003
    Publication date: October 7, 2004
    Applicant: Fox-Tek, Inc.
    Inventors: Geoff Darling, Ted Sargent
  • Single-waveguide integrated wavelength demux photodetector and method of making it
    Patent number: 6731850
    Abstract: A photodetector has a spatially varying absorption spectrum formed in a monolithic InGaAsP structure whose quantum well active structure has modified effective bandgap properties. A waveguide couples light to the quantum well active structure. The spatially varying absorption spectrum allows wavelength-division demultiplexing. The effective bandgap properties can be modified by rapid thermal annealing to cause the diffusion of defects from one or two InP defect layers into the quantum well active structure.
    Type: Grant
    Filed: November 16, 2001
    Date of Patent: May 4, 2004
    Assignee: Fox-Tek
    Inventor: Edward H. Sargent
  • Integrated multi-wavelength and wideband lasers
    Patent number: 6628686
    Abstract: A laser has a spatially varying absorption spectrum formed in a monolithic InGaAsP structure whose quantum well active structure has modified effective bandgap properties. The spatially varying emission spectrum allows emission at multiple wavelengths or emission in a broad band. The effective bandgap properties can be modified by rapid thermal annealing to cause the diffusion of defects from one or two InP defect layers into the quantum well active structure. The laser can be implemented variously as a Fabry-Perot laser and a laser array.
    Type: Grant
    Filed: November 16, 2001
    Date of Patent: September 30, 2003
    Assignee: Fox-Tek, Inc
    Inventor: Edward H. Sargent
  • Semiconductor laser with disordered and non-disordered quantum well regions
    Patent number: 6594295
    Abstract: In a semiconductor laser, non-disordered quantum well active region functions as a lasing region. Surrounding the non-disordered quantum well active region is a disordered quantum well active region which prevents diffusion of injected carriers from the non-disordered quantum well active region or provides a lateral heterobarrier. The disordered quantum well active region is formed by rapid thermal annealing in which defects from one or two InP defect layers diffuse into the parts of the quantum well active region to be disordered.
    Type: Grant
    Filed: November 16, 2001
    Date of Patent: July 15, 2003
    Assignee: Fox-Tek, Inc.
    Inventor: Edward H. Sargent
  • Quantum well intermixing in InGaAsP structures induced by low temperature grown InP
    Publication number: 20030071265
    Abstract: A quantum well structure having an indium gallium arsenide phosphide (InGaAsP) quantum well active region has a low temperature grown indium phosphide (LT-InP) cap layer grown on it. Defects in the cap layer are intermixed into the quantum well active region by rapid thermal annealing to produce a blue shift in the active region. The blue shift increases as the growth temperature of the LT-InP cap layer decreases or as the phosphine flow rate during production of the LT-InP layer increases.
    Type: Application
    Filed: October 4, 2002
    Publication date: April 17, 2003
    Applicant: FOX TEK
    Inventors: David A. Thompson, Bradley J. Robinson, Gregory J. Letal, Alex S.W. Lee, Brooke Gordon