Patents by Inventor Rodney C. Alferness

Rodney C. Alferness 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: 5627925
    Abstract: Wavelength division multiplexing, spatial switching cross-connect structures which may be deployed as intermediate nodes of an all optical network to route any input channel on any source fiber to any destination fiber at any available wavelength to achieve full connectivity between the nodes of the network. The non-blocking cross-connect structure comprises a wavelength division demultiplexer for receiving multiple wavelength channels from each source fiber and for separating received channels into N wavelengths so that the wavelengths are organized according to a corresponding fiber of origin, a nonblocking optical structure for spatially and independently rearranging the received wavelengths so that wavelengths having a common destination fiber are grouped together, and a wavelength division multiplexer for multiplexing together wavelengths having the same destination fiber.
    Type: Grant
    Filed: April 7, 1995
    Date of Patent: May 6, 1997
    Assignee: Lucent Technologies Inc.
    Inventors: Rodney C. Alferness, Adel A. M. Saleh
  • Patent number: 5495543
    Abstract: A double-periodic grating is described for obtaining polarization-independent filtering and coupling. The grating may be viewed as a combination of two gratings with slightly different grating periods. The two periods are carefully chosen to match the difference in propagation constants of the TE and TM polarization modes such that both modes are coupled at the same wavelength.A novel method of obtaining a double-periodic grating is described.
    Type: Grant
    Filed: January 13, 1995
    Date of Patent: February 27, 1996
    Assignee: AT&T Corp.
    Inventors: Rodney C. Alferness, Fred L. Heismann
  • Patent number: 5253314
    Abstract: Various optical functions are generated in accordance with the present invention of a novel broadly tunable monolithic wavelength selective coupler which can be integrated with a gain medium to form a broadly tunable laser. The tunable wavelength selective coupler supports a pair of asynchronous waveguides, an upper waveguide and a lower waveguide, in combination with a phase match course grating for coupling optical energy between said waveguides. One end of the lower waveguide terminates at an output facet. The corresponding end of the upper waveguide terminates in an optical signal absorbing medium. The other end of the lower waveguide is terminated to prevent optical energy from entering the waveguide; and, the corresponding end of the upper waveguide terminates at an input facet.
    Type: Grant
    Filed: January 31, 1992
    Date of Patent: October 12, 1993
    Assignee: AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Lawrence L. Buhl, Thomas L. Koch, Uziel Koren
  • Patent number: 5243669
    Abstract: Polarization rotation is achieved in an exemplary embodiment in an optical waveguide by augmenting the waveguide structure with a plurality of spaced-apart sections for loading the refractive index of the waveguide to cause a lateral asymmetry in the refractive index profile of the waveguide viewed in the plane transverse to the waveguide longitudinal axis. Each spaced-apart section induces non-zero coupling between the principal orthogonal polarization modes. Phase matched coupling between the principal orthogonal polarization modes is achieved by spacing the sections periodically by a distance .LAMBDA. equal to .lambda./.DELTA.N where .lambda. is the propagation wavelength in the waveguide and .DELTA.N is the difference between the effective refractive indices for the principal orthogonal polarization modes. Realizations of the waveguide structure are shown using Group III-V semiconductor rib waveguide structures.
    Type: Grant
    Filed: April 7, 1992
    Date of Patent: September 7, 1993
    Assignee: AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Thomas L. Koch, Yosi Shani
  • Patent number: 5009477
    Abstract: An arrangement for butt coupling of waveguide electrooptic plates to form a crossbar switch. The arrangement includes a stack of M splitter plates, each of which routes an injected optical signal to one of N outputs, and a stack of N combiner plates, each of which routes the signal of a selected one of M inputs to a common output. The stack of splitter plates is rotated with respect to the stack of combiner plates and the output signal ports of the splitter plates are coupled to the input signal ports of the combiner plates, so that each output of an splitter plate is connected to a different combiner plate. Within each splitter plate there is a fan-out network of waveguide electrooptic couplers and each coupler, under electric control, routes signals from one input to either one of two outputs. With j levels of such interconnected couplers 2.sup.j output are developed. The combiner plates have an identical architecture but with a signal flow in the reverse direction.
    Type: Grant
    Filed: May 12, 1989
    Date of Patent: April 23, 1991
    Assignee: AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Zigmantas L. Budrikis, David W. Hagelbarger, Herwig W. Kogelnik, Arun N. Netravali
  • Patent number: 4991975
    Abstract: Disclosed is a time division multiplexed optical communication system that is capable of operation at relatively high bit rates and that is relatively stable and immune to crosstalk and noise. The system comprises receiver means wherein the timing signal for demultiplexing is derived from the fully multiplexed optical pulse stream by means that comprise a narrow band receiver and timing means that produce a lower-frequency timing signal from the output of the narrow band receiver. The timing signal is used to drive one or more optical switches. In one embodiment of the invention the receiver means have a binary-tree architecture and the timing signals are substantially sinusoidal. In another embodiment the receiver means have a linear-bus architecture and the timing signals are pulse-like.
    Type: Grant
    Filed: November 22, 1988
    Date of Patent: February 12, 1991
    Assignee: AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Gadi Eisenstein, Steven K. Korotky, Rodney S. Tucker
  • Patent number: 4955028
    Abstract: Wavelength tunability and single frequency output are achieved in a coherent light source employing an adjustably controllable reflector. The light source includes a gain medium coupled to a single-mode fiber having a partially reduced cladding region at a predetermined distance from the gain medium. A Bragg reflector is either formed on the reduced cladding region of the single-mode fiber or formed on an external element in close proximity to the reduced cladding region. A single resonant optical cavity is formed by placing another reflector on the side of the gain medium opposite the gain medium-to-fiber coupling. Wavelength tuning of the light source is accomplished by controllably adjusting the period or the Bragg reflector element.
    Type: Grant
    Filed: March 25, 1988
    Date of Patent: September 4, 1990
    Assignee: AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Gadi Eisenstein, Uziel Koren, Ping K. Tien, Rodney S. Tucker, Matthew S. Whalen
  • Patent number: 4904045
    Abstract: A grating coupler is combined with a quantum well index modulator and an optical waveguide to alter the reverse or forward coupling characteristics between two different propagation modes of the system.
    Type: Grant
    Filed: March 25, 1988
    Date of Patent: February 27, 1990
    Assignees: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Thomas L. Koch, Uziel Koren, Jane E. Zucker
  • Patent number: 4883335
    Abstract: An optical power tap is disclosed which allows effectively nonreciprocal injection and removal of power at each node of a single-mode optical fiber local area network. The power tap uses a wavelength-selective directional coupler to inject and remove power from the bus, and a nonlinear converter in the bus to convert light from one wavelength to another. In the specific embodiment disclosed a neodymium-doped silica fiber is used as a nonlinear material to convert light from one wavelength to another.
    Type: Grant
    Filed: January 20, 1988
    Date of Patent: November 28, 1989
    Assignees: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Thomas H. Wood
  • Patent number: 4852960
    Abstract: Highly frequency-selective reflectivity is realized in an optical device including a waveguide and an evanescent-field coupled grating resonator cavity. The device may include a light source and serve as a low-chirp, narrow-linewidth communications laser for use, e.g., for transmission over a fiber having non-negligible dispersion and also in wavelength-multiplexed coherent systems.
    Type: Grant
    Filed: September 23, 1988
    Date of Patent: August 1, 1989
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Charles H. Henry, Rudolf F. Kazarinov, Nils A. Olsson, Kenneth J. Orlowsky
  • Patent number: 4826282
    Abstract: A structure of first and second grating sections separated by a phase-shift section serves as a narrow-band resonator filter. Such structure may be optically coupled to a semiconductor laser cavity, and the resulting assembly can serve as a tunable narrow-linewidth laser, e.g., in wavelength-multiplexed and coherent-lightwave communications systems.
    Type: Grant
    Filed: July 21, 1987
    Date of Patent: May 2, 1989
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventor: Rodney C. Alferness
  • Patent number: 4751555
    Abstract: Low loss semiconductor waveguides for supporting propagation of optical signals over a wide range of wavelengths are achieved by growing at least two epitaxial layers of dopant material contiguous along a major surface of each layer to form a heterointerface therebetween. At least one of the epitaxial layers includes a sufficient concentration of semiconductor material to cause strain via lattice mismatch substantially at and near the heterointerface. The strain induces a change in refractive index such that the heterointerface exhibits a substantially higher refractive index than a portion of each epitaxial layer proximate to the heterointerface. The resulting waveguide is capable of supporting propagation of optical signals substantially along the heterointerface. In one example, contiguous epitaxial layers of InP and InGaP form a waveguide for optical signals at wavelengths greater than 0.93 .mu.m. The concentration of Ga in the InGaP epitaxial layer is varied from 10.sup.18 to 10.sup.20 cm.sup.
    Type: Grant
    Filed: May 11, 1987
    Date of Patent: June 14, 1988
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Andrew G. Dentai, Charles H. Joyner, Jr.
  • Patent number: 4750801
    Abstract: An optical filter using first and second grating sections separated by a changed refractive index section operates as a narrowband grating resonator.
    Type: Grant
    Filed: September 30, 1985
    Date of Patent: June 14, 1988
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventor: Rodney C. Alferness
  • Patent number: 4737007
    Abstract: Narrow band, wavelength selective optical coupling is achieved in a device including first and second optical transmission media and a filter. The first and second optical transmission media are in substantially close proximity of each other in a predetermined interaction region to provide evanescent coupling therebetween. The filter is positioned on the first optical transmission medium in the predetermined region for causing the coupling to be wavelength selective and contradirectional from the first optical transmission means to the second optical transmission means. One exemplary embodiment of the coupler includes optical fibers as the transmission media and a Bragg reflection grating integrally formed on the first transmission medium as the filter. Other embodiments include the use of semiconductor waveguides as the optical transmission media.
    Type: Grant
    Filed: February 24, 1986
    Date of Patent: April 12, 1988
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Matthew S. Whalen
  • Patent number: 4728168
    Abstract: Optical functions such as Q-switching, mode locking, cavity dumping, and modulation are generated by a simple laser arrangement which includes a gain medium and an electrically controllable, optical waveguide device optically coupled to the gain medium. The gain medium and waveguide device are either interposed between two reflective surfaces or coupled by a waveguide in order to form a single composite cavity laser structure.
    Type: Grant
    Filed: November 26, 1986
    Date of Patent: March 1, 1988
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Gadi Eisenstein, Steven K. Korotky
  • Patent number: 4711515
    Abstract: An electrooptic polarization multiplexer/demultiplexer incorporates an electrooptic, directional coupler switch structure. The multiplexer/demultiplexer includes a substrate of birefringent, electrooptic material, a pair of phase matched, dielectric waveguides embedded in the substrate and spaced closely together over a distance L (the coupler or device length), a buffer layer of insulating material positioned over the substrate and the pair of electrodes, and a plurality of metallic electrodes positioned on the buffer layer in the vicinity of the waveguides. Electrodes are arranged in a multi-section, reversed .DELTA..beta. configuration. The distance L is selected such that 1.ltoreq.L/1.sub.TE .ltoreq.2 and L/1.sub.TM .ltoreq.0.5, where 1.sub.TE and 1.sub.TM are transfer lengths for the TE and TM modes, respectively.
    Type: Grant
    Filed: May 29, 1984
    Date of Patent: December 8, 1987
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventor: Rodney C. Alferness
  • Patent number: 4667331
    Abstract: Optical functions such as Q-switching, mode locking, cavity dumping, and modulation are generated by a simple laser arrangement which includes a gain medium and an electrically controllable, optical waveguide device optically coupled to the gain medium. The gain medium and waveguide device are either interposed between two reflective surfaces or coupled by a waveguide in order to form a single composite cavity laser structure.
    Type: Grant
    Filed: January 20, 1984
    Date of Patent: May 19, 1987
    Assignee: AT&T Company and AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Gadi Eisenstein, Steven K. Korotky
  • Patent number: 4553810
    Abstract: Prior art techniques for velocity matching the optical wave and the modulating electrical wave in traveling wave, electrooptic devices includes the use of phase reversals and intermittent interaction. This results in a device whose frequency response includes a single peak. It has been discovered that by reducing the length of the interaction intervals between the electrical and optical systems, a multiplicity of harmonically related frequency peaks can be obtained. Furthermore, by combining the phase reversal and intermittent interaction techniques in a common device, the available bandwidth can be doubled.
    Type: Grant
    Filed: April 21, 1983
    Date of Patent: November 19, 1985
    Assignee: AT&T Bell Laboratories
    Inventors: Rodney C. Alferness, Steven K. Korotky, Enrique A. J. Marcatili
  • Patent number: 4533207
    Abstract: An improved wavelength tunable TE to TM optical mode converter is provided by confining the electric fields for mode conversion and wavelength tuning to non-overlapping regions of a bi-refringent waveguide. Several electrode configurations for providing this spatial separation are disclosed.
    Type: Grant
    Filed: June 21, 1983
    Date of Patent: August 6, 1985
    Assignee: AT&T Bell Laboratories
    Inventor: Rodney C. Alferness
  • Patent number: 4448479
    Abstract: A simulated velocity match between a traveling optical wave and a traveling electrical modulating wave is obtained in traveling wave, velocity mismatched electrooptic devices by introducing, at longitudinally spaced intervals along the electrical signal wavepath, means for producing the equivalent of a 180 degree phase shift in the effect of the modulating signal upon the operative electrooptic parameter of said device. This technique is employed to minimize the effect of walk-off due to velocity mismatch in modulators, phase shifter and mode converters.
    Type: Grant
    Filed: November 16, 1981
    Date of Patent: May 15, 1984
    Assignee: Bell Telephone Laboratories, Incorporated
    Inventor: Rodney C. Alferness