Patents by Inventor Seng-Tiong Ho

Seng-Tiong Ho 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).

  • Publication number: 20040008948
    Abstract: An oval resonator device is provided which includes an oval resonator having straight portions for coupling signals from external sources. The straight portions of the oval resonator minimize phase mismatch in a coupled signal. The oval resonator device can be used in various devices including channel-dropping filters, switches, tunables filters, phase modulators, and 1×N multiplexers/demultiplexers.
    Type: Application
    Filed: May 27, 2003
    Publication date: January 15, 2004
    Inventors: Mee-Koy Chin, Seng-Tiong Ho
  • Publication number: 20040005105
    Abstract: A new electro-optic (EO) phase modulator constructed from a combination of a low-loss passive polymer waveguide and a self-assembled chromophore superlattice (SAS) with an intrinsically polar microstructure. In contrast to typical polymer-based modulators, the present invention utilizes a siloxane SA methodology that enables the acentric alignment of constituent chromophores during film growth without the need for post-deposition electric field poling. The guiding layer is constructed of the SAS and the glassy polymer Cyclotene™. The use of SiO2, Cytop™ and Cyclotene™ glassy polymers, results in a straightforward device fabrication process that is compatible with the thermally and photochemically robust SAS. Thus, nanoscale control of the film architecture results in greatly simplified macroscopic device fabrication. The present invention provides a SAS-based electro-optic modulator demonstrating excellent electro-optic response properties and a &pgr; phase shift.
    Type: Application
    Filed: April 15, 2003
    Publication date: January 8, 2004
    Inventors: Tobin J. Marks, Seng-Tiong Ho, Milko E. van der Boom, Yi-Guang Zhao, Wei-Kang Lu
  • Patent number: 6636669
    Abstract: A nanophotonic directional coupler is disclosed for transferring light from one waveguide to a second waveguide. The directional coupler is formed within relatively small dimensional parameters and can be formed to accommodate light signals of both transverse electric (TE) and transverse magnetic (TM) polarizations.
    Type: Grant
    Filed: May 19, 2000
    Date of Patent: October 21, 2003
    Assignee: Northwestern University
    Inventors: Mee Koy Chin, Seng-Tiong Ho
  • Patent number: 6549685
    Abstract: A new electro-optic (EO) phase modulator constructed from a combination of a low-loss passive polymer waveguide and a self-assembled chromophore superlattice (SAS) with an intrinsically polar microstructure. In contrast to typical polymer-based modulators, the present invention utilizes a siloxane SA methodology that enables the acentric alignment of constituent chromophores during film growth without the need for post-deposition electric field poling. The guiding layer is constructed of the SAS and the glassy polymer Cyclotene™. The use of SiO2, Cytop™ and Cyclotene™ glassy polymers, results in a straightforward device fabrication process that is compatible with the thermally and photochemically robust SAS. Thus, nanoscale control of the film architecture results in greatly simplified macroscopic device fabrication. The present invention provides a SAS-based electro-optic modulator demonstrating excellent electro-optic response properties and a &pgr; phase shift.
    Type: Grant
    Filed: January 31, 2001
    Date of Patent: April 15, 2003
    Assignee: Northwestern University
    Inventors: Tobin J. Marks, Seng-Tiong Ho, Milko E. van der Boom, Yi-Guang Zhao, Wei-Kang Lu
  • Publication number: 20030053785
    Abstract: A light transfer device is provided that includes a first light pathway having a first input and a first output and a second light pathway having a second output. The second light pathway is coupled to the first light pathway, and light from the first input is transferable between the first and second light pathways. An active medium is positioned along one of the first and second light pathways, and the active medium is capable of receiving optical energy that modifies the active medium so that the active medium controls the transfer of light between the first and second pathways.
    Type: Application
    Filed: July 18, 2002
    Publication date: March 20, 2003
    Inventor: Seng-Tiong Ho
  • Publication number: 20030044118
    Abstract: Composite optical waveguide structures or mode transformers and their methods of fabrication and integration are disclosed, wherein the structures or mode transformers are capable of bi-directional light beam transformation between a small mode size waveguide and a large mode size wavguide. One aspect of the present invention is directed to an optical mode transformer comprising a waveguide core having a high refractive index contrast between the waveguide core and the cladding, the optical mode transformer being configured such that the waveguide core has a taper wherein a thickness of the waveguide core tapers down to a critical thickness value, the critical thickness value being defined as a thickness value below which a significant portion of the energy of a light beam penetrates into the cladding layers surrounding the taper structure thereby enlarging the small mode size.
    Type: Application
    Filed: October 19, 2001
    Publication date: March 6, 2003
    Applicant: PHOSISTOR TECHNOLOGIES, INC.
    Inventors: Yan Zhou, Seng-Tiong Ho
  • Patent number: 6473541
    Abstract: A light transfer device is provided that includes a first light pathway having a first input and a first output and a second light pathway having a second output. The second light pathway is coupled to the first light pathway, and light from the first input is transferable between the first and second light pathways. An active medium is positioned along one of the first and second light pathways, and the active medium is capable of receiving optical energy that modifies the active medium so that the active medium controls the transfer of light between the first and second pathways.
    Type: Grant
    Filed: September 14, 2000
    Date of Patent: October 29, 2002
    Inventor: Seng-Tiong Ho
  • Publication number: 20020131663
    Abstract: A new electro-optic (EO) phase modulator constructed from a combination of a low-loss passive polymer waveguide and a self-assembled chromophore superlattice (SAS) with an intrinsically polar microstructure. In contrast to typical polymer-based modulators, the present invention utilizes a siloxane SA methodology that enables the acentric alignment of constituent chromophores during film growth without the need for post-deposition electric field poling. The guiding layer is constructed of the SAS and the glassy polymer Cyclotene™. The use of SiO2, Cytop and Cyclotene™ glassy polymers, results in a straightforward device fabrication process that is compatible with the thermally and photochemically robust SAS. Thus, nanoscale control of the film architecture results in greatly simplified macroscopic device fabrication. The present invention provides a SAS-based electro-optic modulator demonstrating excellent electro-optic response properties and a &pgr; phase shift.
    Type: Application
    Filed: January 31, 2001
    Publication date: September 19, 2002
    Inventors: Tobin J. Marks, Seng-Tiong Ho, Milko E. van der Boom, Yi-Guang Zhao, Wei-Kang Lu
  • Patent number: 6436614
    Abstract: A method for the formation of a thin optical crystal layer (e.g., a thin LiNbO3 optical single crystal layer) overlying a low dielectric constant substrate (e.g., a low dielectric constant glass substrate). The method includes implanting ions (e.g., He+) through a surface of an optical crystal substrate. The implanting of the ions defines, in the optical crystal substrate, a thin ion-implanted optical crystal layer overlying a bulk optical crystal substrate. A low dielectric constant substrate is subsequently bonded to the surface, using either a direct or an indirect bonding technique, to form a bonded structure. The bonded structure is thermally annealed at a temperature in the range of 300° C. to 600° C. for 30 minutes to 300 minutes.
    Type: Grant
    Filed: June 19, 2001
    Date of Patent: August 20, 2002
    Inventors: Feng Zhou, Seng-Tiong Ho
  • Publication number: 20020072142
    Abstract: A process for shifting the bandgap energy of a quantum well layer (e.g., a III-V semiconductor quantum well layer) without inducing complex crystal defects or generating significant free carriers. The process includes introducing ions (e.g., deep-level ion species) into a quantum well structure at an elevated temperature, for example, in the range of from about 200 ° C. to about 700 ° C. The quantum well structure that has had ions introduced therein includes an upper barrier layer, a lower barrier layer and a quantum well layer. The quantum well layer is disposed between the upper barrier layer and the lower barrier layer. The quantum well structure is then thermally annealed, thereby inducing quantum well intermixing (QWI) in the quantum well structure and shifting the bandgap energy of the quantum well layer. Also, a photonic device assembly that includes a plurality of operably coupled photonic devices monolithically integrated on a single substrate using the process described above.
    Type: Application
    Filed: July 26, 2001
    Publication date: June 13, 2002
    Inventors: Boon-Siew Ooi, Seng-Tiong Ho
  • Publication number: 20020048728
    Abstract: A method for the formation of a thin optical crystal layer (e.g., a thin LiNbO3 optical single crystal layer) overlying a low dielectric constant substrate (e.g., a low dielectric constant glass substrate). The method includes implanting ions (e.g., He+) through a surface of an optical crystal substrate. The implanting of the ions defines, in the optical crystal substrate, a thin ion-implanted optical crystal layer overlying a bulk optical crystal substrate. A low dielectric constant substrate is subsequently bonded to the surface, using either a direct or an indirect bonding technique, to form a bonded structure. The bonded structure is thermally annealed at a temperature in the range of 300° C. to 600° C. for 30 minutes to 300 minutes.
    Type: Application
    Filed: June 19, 2001
    Publication date: April 25, 2002
    Inventors: Feng Zhou, Seng-Tiong Ho
  • Publication number: 20020048727
    Abstract: A process for forming a refractive-index-patterned film for use in optical device manufacturing. The process includes forming a photosensitive lead-silicate-containing film on a substrate (e.g., a silicon, quartz or glass substrate) using, for example, a conventional and inexpensive sol-gel process. A predetermined portion of the lead-silicate-containing film is subsequently exposed to ultra-violet (UV) light through a patterned mask (e.g., a patterned amplitude mask, patterned phase mask or patterned gray scale mask). The UV exposure modifies the refractive index of the predetermined portion, thereby forming a refractive-index-patterned lead-silicate-containing film suitable for use in optical device manufacturing. The use of a photosensitive lead-silicate-containing film enables a relatively large refractive index modification upon exposure to UV light.
    Type: Application
    Filed: June 19, 2001
    Publication date: April 25, 2002
    Inventors: Yan Zhou, Seng-Tiong Ho
  • Patent number: 6341184
    Abstract: An optical modulator that includes a resonator near one arm of a Mach-Zehnder interferometer and that increases the optical length of that arm so as to introduce a phase-shift in an optical signal propagating in that arm when compared to an optical signal propagating in the other arm of the interferometer. The resonator also increases the electro-optic interaction between an electrical signal (i.e., the source of information in a modulated signal) and the optical devices (e.g., waveguides). A modulator constructed in accordance with the present invention is thus physically small than prior art modulators and requires a significantly reduced drive voltage to impart information on an optical signal.
    Type: Grant
    Filed: September 8, 2000
    Date of Patent: January 22, 2002
    Assignees: Nannovation Technologies, Inc., Northwestern University
    Inventors: Seng-Tiong Ho, Mee Koy Chin
  • Publication number: 20010025826
    Abstract: A semiconductor dry etching process that provides deep, smooth, and vertical etching of InP-based materials using a chlorinated plasma with the addition of nitrogen (N2) gas. Etching of InP-based semiconductors using an appropriate Cl2/N2 mixture without any additional gases provides improved surface morphology, anisotropy and etch rates.
    Type: Application
    Filed: February 28, 2001
    Publication date: October 4, 2001
    Inventors: Thomas E. Pierson, Christopher T. Youtsey, Seng-Tiong Ho, Seoijin Park
  • Patent number: 6298180
    Abstract: A light transfer device is provided that includes a first light pathway having a first input and a first output and a second light pathway having a second output. The second light pathway is coupled to the first light pathway, and light from the first input is transferable between the first and second light pathways. An active medium is positioned along one of the first and second light pathways, and the active medium is capable of receiving light that modifies the active medium so that the active medium controls the transfer of light between the first and second pathways.
    Type: Grant
    Filed: September 15, 1999
    Date of Patent: October 2, 2001
    Inventor: Seng-Tiong Ho
  • Patent number: 6118571
    Abstract: Electro-optic modulator comprises a substrate having an epitaxial, preferentially oriented, low scattering loss thin ferroelectric film waveguide deposited by metalorganic chemcial vapor deposition on the substrate, and first and second strip electrodes on the waveguide with the electrodes spaced apart to establish an electric field effective to render the waveguide modulating to light in response to applied bias or voltage.
    Type: Grant
    Filed: March 2, 1998
    Date of Patent: September 12, 2000
    Assignee: Northwestern University
    Inventors: Bruce W. Wessels, Seng Tiong Ho, Gregory M. Ford, Douglas M. Gill
  • Patent number: 6069729
    Abstract: High speed electro-optic modulator designs are presented. One design includes first and second electrodes offset from each other and further includes a substrate supporting a laterally confined ferroelectric material, for example, LiNbO.sub.3. The confined ferroelectric material, in turn, supports first and second optical waveguides. In a second design, a thin ferroelectric film is fabricated on a substrate that supports first and second electrodes. The thin ferroelectric film has a first thickness in which the first and second optical waveguides are supported, and a second thickness under a portion of the electrodes. The second thickness, for example, may be zero. A third design includes a thin ferroelectirc film fabricated on a substrate and supporting first and second electrodes. The thin ferroelectric film has a reduced thickness in at least one electrode gap region.
    Type: Grant
    Filed: January 20, 1999
    Date of Patent: May 30, 2000
    Assignee: Northwestern University
    Inventors: Douglas M. Gill, Seng-Tiong Ho
  • Patent number: 6009115
    Abstract: An optical, semiconductor micro-resonator device includes a microcavity resonator and a pair of adjacent waveguides. The microcavity resonator may be formed as a disk, a ring or closed loop with arbitrarily curved circumference with a diameter of approximately 56000.lambda..sub.lg /n.sub.res or less where .lambda..sub.lg is the longest operating wavelength of light and n.sub.res is the propagating refractive index. A portion of each of the waveguides is disposed adjacent to the microcavity resonator wherein the adjacent portion may be either tangential to the microcavity resonator or curve about a respective portion of the microcavity resonator. Light propagating in the first waveguide with a wavelength on resonance with the microcavity resonator is coupled thereto via resonant waveguide coupling and from the microcavity resonator the light is coupled to the second waveguide for output therefrom.
    Type: Grant
    Filed: May 4, 1999
    Date of Patent: December 28, 1999
    Assignee: Northwestern University
    Inventor: Seng-Tiong Ho
  • Patent number: 5926496
    Abstract: An optical, semiconductor micro-resonator device includes a microcavity resonator and a pair of adjacent waveguides. The microcavity resonator may be formed as a disk, a ring or closed loop with arbitrarily curved circumference with a diameter of approximately 56000 .lambda..sub.lg /.sub.res or less where .lambda..sub.lg is the longest operating wavelength of light and n.sub.res is the propagating refractive index. A portion of each of the waveguides is disposed adjacent to the microcavity resonator wherein the adjacent portion may be either tangential to the microcavity resonator or curve about a respective portion of the microcavity resonator. Light propagating in the first waveguide with a wavelength on resonance with the microcavity resonator is coupled thereto via resonant waveguide coupling and from the microcavity resonator the light is coupled to the second waveguide for output therefrom.
    Type: Grant
    Filed: May 20, 1997
    Date of Patent: July 20, 1999
    Assignee: Northwestern University
    Inventors: Seng-Tiong Ho, Deana Rafizadeh
  • Patent number: 5878070
    Abstract: A photonic light emitting device comprising a relatively high refractive index photonic-wire semiconductor waveguide core in the form of an arcuate shape, linear shape and combinations thereof. The waveguide core is formed into a closed loop cavity for a light-emitting device or laser. The waveguide core is surrounded on all transverse sides by relatively low refractive index medium and comprises an active medium having major and minor sides and semiconductor guiding layers proximate the major sides. The active medium and the guiding layers are so dimensioned in a transverse direction relative to the path of light propagation through the core to provide dramatically increased spontaneous-emission coupling efficiency, leaading to low lasing threshold and high intrinsic modulation rates.
    Type: Grant
    Filed: May 24, 1996
    Date of Patent: March 2, 1999
    Assignee: Northwestern University
    Inventors: Seng-Tiong Ho, Jian P. Zhang