Search Patents
  • System and method for using slow light in optical sensors
    Patent number: 7911622
    Abstract: An optical sensor includes at least one optical coupler and an optical waveguide in optical communication with the at least one optical coupler. The optical waveguide is configured to receive a first optical signal from the at least one optical coupler. The first optical signal has a group velocity and a phase velocity while propagating through at least a portion of the optical waveguide, the group velocity less than the phase velocity. An interference between the first optical signal and a second optical signal is affected by perturbations to at least a portion of the optical sensor.
    Type: Grant
    Filed: June 13, 2008
    Date of Patent: March 22, 2011
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Matthew A. Terrel, Michel J. F. Digonnet, Shanhui Fan
  • Optoelectronic semiconductor device and method of fabrication
    Patent number: 8896077
    Abstract: An optoelectronic device comprising an optically active layer that includes a plurality of domes is presented. The plurality of domes is arrayed in two dimensions having a periodicity in each dimension that is less than or comparable with the shortest wavelength in a spectral range of interest. By virtue of the plurality of domes, the optoelectronic device achieves high performance. A solar cell having high energy-conversion efficiency, improved absorption over the spectral range of interest, and an improved acceptance angle is presented as an exemplary device.
    Type: Grant
    Filed: October 21, 2010
    Date of Patent: November 25, 2014
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Yi Cui, Jia Zhu, Ching-Mei Hsu, Shanhui Fan, Zongfu Yu
  • Optical sensor having a non-negligible source coherence length
    Patent number: 8681339
    Abstract: An optical sensor, a method of configuring an optical sensor, and a method of using an optical sensor are provided. The optical sensor includes an optical loop having a length and a laser source optically coupled to the loop. The laser source has a coherence length. Light from the source is transmitted to the loop as a first signal and a second signal counterpropagating along the loop. The optical paths of the first signal and the second signal are substantially reciprocal with one another and the first signal and the second signal are combined together after counterpropagating through the loop to generate a third signal. A ratio of the coherence length to the length of the loop is greater than 1.
    Type: Grant
    Filed: March 25, 2013
    Date of Patent: March 25, 2014
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Michael J. F. Digonnet, Shanhui Fan, Seth Lloyd
  • RADIATIVE COOLING SYSTEMS
    Publication number: 20200333047
    Abstract: A material may be included in a cooling film or cooling panel to achieve cooling even under direct solar irradiation. The material includes one or more constituent materials and an outer surface configured to interact thermally with the atmosphere and with solar radiation. The material exhibits an emissivity of at least 0.8 in spectral range of 5 ?m to 15 um, an ultraviolet reflectivity of at least 0.5 in the spectral range of 275 nm to 375 nm, an ultraviolet absorptivity of at least 0.75 in the spectral range of 275 nm to 375 nm, or a combination thereof. A cooling film, or cooling panel, may be affixed to an exterior surface of a vehicle, structure, or system to provide cooling even under direct solar irradiance.
    Type: Application
    Filed: April 17, 2020
    Publication date: October 22, 2020
    Inventors: Aaswath Raman, Eli A. Goldstein, Shanhui Fan
  • Isotropic filters in spatial frequency domain by a photonic crystal slab
    Patent number: 10928551
    Abstract: An isotropic imaging filter is provided that includes a photonic crystal slab, where the photonic crystal slab includes a square lattice of air through holes, a dielectric constant, a thickness (d), a through hole radius (r), and a lattice constant (a), where the square lattice of air holes are separated according to a value of the lattice constant, where the thickness is configured according to d=M(a), where the through hole radii is configured according to r=N(a), where the thickness and the hole radii are configured to generate isotropic bands of guided resonances of an incident image.
    Type: Grant
    Filed: November 14, 2018
    Date of Patent: February 23, 2021
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Cheng Guo, Meng Xiao, Momchil Minkov, Yu Shi, Shanhui Fan
  • Optical fiber with a core ring
    Patent number: 7489848
    Abstract: An optical fiber includes a cladding with a material having a first refractive index and a pattern of regions formed therein. Each of the regions has a second refractive index lower than the first refractive index. The optical fiber further includes a core region and a core ring surrounding the core region and having an inner perimeter, an outer perimeter, and a thickness between the inner perimeter and the outer perimeter. The thickness is sized to reduce the number of ring surface modes supported by the core ring.
    Type: Grant
    Filed: January 8, 2008
    Date of Patent: February 10, 2009
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Hyang Kyun Kim, Shanhui Fan, Gordon S. Kino, Jonghwa Shin, Michel J. F. Digonnet, Vinayak Dangui
  • Space charge trap-assisted recombination suppressing layer for low-voltage diode operation
    Patent number: 11715809
    Abstract: Shockley-Read-Hall (SRH) generation and/or recombination in heterojunction devices is suppressed by unconventional doping at or near the heterointerface. The effect of this doping is to shift SRH generation and/or recombination preferentially into the wider band gap material of the heterojunction. This reduces total SRH generation and/or recombination in the device by decreasing the intrinsic carrier concentration ni at locations where most of the SRH generation and/or recombination occurs. The physical basis for this effect is that the SRH generation and/or recombination rate tends to decrease as ni around the depletion region decreases, so decreasing the effective ni in this manner is a way to decrease SRH recombination.
    Type: Grant
    Filed: June 25, 2021
    Date of Patent: August 1, 2023
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Parthiban Santhanam, Shanhui Fan
  • Photonic-bandgap fiber with a core ring
    Patent number: 7400806
    Abstract: A photonic-bandgap fiber includes a photonic crystal lattice with a material having a first refractive index and a pattern of regions formed therein. Each of the regions has a second refractive index lower than the first refractive index. The photonic-bandgap fiber further includes a core and a core ring surrounding the core and having an inner perimeter, an outer perimeter, and a thickness between the inner perimeter and the outer perimeter. The thickness is sized to reduce the number of ring surface modes supported by the core ring.
    Type: Grant
    Filed: April 19, 2007
    Date of Patent: July 15, 2008
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Hyang Kyun Kim, Shanhui Fan, Gordon S. Kino, Jonghwa Shin, Michel J. F. Digonnet, Vinayak Dangui
  • META-CRYTALS SLABS FOR GENERAL OPTICAL CONVOLUTION AND METHODS FOR DESIGNING META-CRYSTAL SLABS
    Publication number: 20230176248
    Abstract: A meta-crystal slab includes photonic structure with an input surface and an output surface, and a plurality of first voxels with a first permittivity and a plurality of second voxels with a second permittivity not equal to the first permittivity disposed between the input surface and the output surface. The photonic structure has a periodicity greater than an operating photonic wavelength ‘?’ for general convolution by the photonic structure and the photonic structure is configured to provide an output image with a convolution of an input image.
    Type: Application
    Filed: December 8, 2022
    Publication date: June 8, 2023
    Applicants: Toyota Motor Engineering & Manufacturing North America, Inc., Toyota Jidosha Kabushiki Kaisha, The Board of Trustees of the Leland Stanford Junior University
    Inventors: Shanhui Fan, Weiliang Jin, Cheng Guo, Nathan Zhao, Haiwen Wang, Sean P. Rodrigues
  • RADIATIVE COOLING SYSTEMS
    Publication number: 20220275973
    Abstract: A material may be included in a cooling film or cooling panel to achieve cooling even under direct solar irradiation. The material includes one or more constituent materials and an outer surface configured to interact thermally with the atmosphere and with solar radiation. The material exhibits an emissivity of at least 0.8 in spectral range of 5 ?m to 15 ?m, an ultraviolet reflectivity of at least 0.5 in the spectral range of 275 nm to 375 nm, an ultraviolet absorptivity of at least 0.75 in the spectral range of 275 nm to 375 nm, or a combination thereof. A cooling film, or cooling panel, may be affixed to an exterior surface of a vehicle, structure, or system to provide cooling even under direct solar irradiance.
    Type: Application
    Filed: May 18, 2022
    Publication date: September 1, 2022
    Inventors: Aaswath Raman, Eli A. Goldstein, Shanhui Fan
  • Low-loss resonator and method of making same
    Publication number: 20020097770
    Abstract: A method of making a low-loss electromagnetic wave resonator structure. The method includes providing a resonator structure, the resonator structure including a confining device and a surrounding medium. The resonator structure supporting at least one resonant mode, the resonant mode displaying a near-field pattern in the vicinity of said confining device and a far-field radiation pattern away from the confining device. The surrounding medium supports at least one radiation channel into which the resonant mode can couple. The resonator structure is specifically configured to reduce or eliminate radiation loss from said resonant mode into at least one of the radiation channels, while keeping the characteristics of the near-field pattern substantially unchanged.
    Type: Application
    Filed: June 19, 2001
    Publication date: July 25, 2002
    Inventors: Attila Mekis, Shanhui Fan, John D. Joannopoulos, Pierre Villeneuve
  • Thin film filters using omnidirectional reflectors
    Publication number: 20020135877
    Abstract: An electromagnetic wavelength filter that allows the transmission of electromagnetic energy within a narrow range of wavelengths while reflecting incident electromagnetic energy at other wavelengths. The filter includes at least one cavity region; and at least two reflectors surrounding the at least one cavity region, at least one of the reflectors being an omni-directional reflector. The omni-directional reflector includes a structure with a surface and an index of refraction variation perpendicular to the surface, and the omni-directional reflector is specifically configured to exhibit high omni-directional reflection for a predetermined range of frequencies of incident electromagnetic energy for any angle of incidence and any polarization.
    Type: Application
    Filed: February 12, 2001
    Publication date: September 26, 2002
    Inventors: Shanhui Fan, John D. Joannopoulos, George B. Kenney, Michal Lipson, Kevin M. Chen, Lionel C. Kimerling
  • Radiative cooling systems
    Patent number: 11841171
    Abstract: A material may be included in a cooling film or cooling panel to achieve cooling even under direct solar irradiation. The material includes one or more constituent materials and an outer surface configured to interact thermally with the atmosphere and with solar radiation. The material exhibits an emissivity of at least 0.8 in spectral range of 5 ?m to 15 ?m, an ultraviolet reflectivity of at least 0.5 in the spectral range of 275 nm to 375 nm, an ultraviolet absorptivity of at least 0.75 in the spectral range of 275 nm to 375 nm, or a combination thereof. A cooling film, or cooling panel, may be affixed to an exterior surface of a vehicle, structure, or system to provide cooling even under direct solar irradiance.
    Type: Grant
    Filed: May 18, 2022
    Date of Patent: December 12, 2023
    Assignee: SkyCool Systems, Inc.
    Inventors: Aaswath Raman, Eli A. Goldstein, Shanhui Fan
  • Radiative cooling systems
    Patent number: 11359841
    Abstract: A material may be included in a cooling film or cooling panel to achieve cooling even under direct solar irradiation. The material includes one or more constituent materials and an outer surface configured to interact thermally with the atmosphere and with solar radiation. The material exhibits an emissivity of at least 0.8 in spectral range of 5 ?m to 15 ?m, an ultraviolet reflectivity of at least 0.5 in the spectral range of 275 nm to 375 nm, an ultraviolet absorptivity of at least 0.75 in the spectral range of 275 nm to 375 nm, or a combination thereof. A cooling film, or cooling panel, may be affixed to an exterior surface of a vehicle, structure, or system to provide cooling even under direct solar irradiance.
    Type: Grant
    Filed: April 17, 2020
    Date of Patent: June 14, 2022
    Assignee: SkyCool Systems, Inc.
    Inventors: Aaswath Raman, Eli A. Goldstein, Shanhui Fan
  • Systems and Methods for Activation Functions for Photonic Neural Networks
    Publication number: 20210116781
    Abstract: Systems and methods for activation in an optical circuit in accordance with embodiments of the invention are illustrated. One embodiment includes an optical activation circuit, wherein the circuit comprises a directional coupler, an optical-to-electrical conversion circuit, a time delay element, a nonlinear signal conditioner, and a phase shifter. The directional coupler receives an optical input and provides a first portion to the optical-to-electrical conversion circuit and a second portion to the time delay element, the time delay element provides a delayed signal to the phase shifter, and the optical-to-electrical conversion circuit converts an optical signal from the directional coupler to an electrical signal used to activate the phase shifter to shift the phase of the delayed signal.
    Type: Application
    Filed: May 10, 2019
    Publication date: April 22, 2021
    Applicant: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Tyler William Hughes, Momchil Minkov, Ian Williamson, Shanhui Fan
  • Stopping and time reversing light in a waveguide with an all-optical system
    Patent number: 7116864
    Abstract: We introduce a new all-optical mechanism that can compress the bandwidth of light pulses to absolute zero, and bring them to a complete stop. The mechanism can be realized in a system consisting of a waveguide side-coupled to tunable resonators, which generates a photonic band structure that represents a classical analogue of the Electromagnetically Induced Transparency. The same system can also achieve a time-reversal operation. We demonstrate the operation of such a system by finite-difference time-domain simulations of an implementation in photonic crystals.
    Type: Grant
    Filed: November 30, 2004
    Date of Patent: October 3, 2006
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Mehmet Fatih Yanik, Wonjoo Suh, Zhang Wang, Shanhui Fan
  • Resonant microcavities employing one-dimensionally periodic dielectric waveguides
    Patent number: 5682401
    Abstract: The present invention provides a resonant microcavity which includes a periodic dielectric waveguide, and a local defect in the periodic dielectric waveguide which accommodates spacial confinement of radiation generated within the waveguide around the defect. In an alternative embodiment, the present invention provides a method of enhancing radiation confinement within a resonant microcavity and minimizing radiation losses into an associated substrate, the microcavity configured within a periodic dielectric waveguide as a local defect which exhibits spacial radiation confinement, the method including the step of increasing the refractive index contrast between the microcavity and the substrate.
    Type: Grant
    Filed: June 18, 1996
    Date of Patent: October 28, 1997
    Assignee: Massachusetts Institute of Technology
    Inventors: John D. Joannopoulos, Shanhui Fan, Pierre R. Villeneuve, Robert D. Meade
  • Training of Photonic Neural Networks Through in situ Backpropagation
    Publication number: 20210192342
    Abstract: Systems and methods for training photonic neural networks in accordance with embodiments of the invention are illustrated. One embodiment includes a method for training a set of one or more optical interference units (OIUs) of a photonic artificial neural network (ANN), wherein the method includes calculating a loss for an original input to the photonic ANN, computing an adjoint input based on the calculated loss, measuring intensities for a set of one or more phase shifters in the set of OIUs when the computed adjoint input and the original input are interfered with each other within the set of OIUs, computing a gradient from the measured intensities, and tuning phase shifters of the OIU based on the computed gradient.
    Type: Application
    Filed: May 10, 2019
    Publication date: June 24, 2021
    Applicant: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Tyler William Hughes, Momchil Minkov, Ian Williamson, Shanhui Fan
  • Tunable add/drop filter using side-coupled resonant tunneling
    Patent number: 6424763
    Abstract: A tunable electromagnetic field frequency filter having an input waveguide which carries a signal including at least one desired frequency, and an output waveguide. A resonator-system is coupled to the input and output waveguides and is operable for the selective transfer of the at least one desired frequency to the output waveguide. The resonator-system supports at least two system modes, and includes at least three reflectors with at least two different reflectivity spectra. At least one of the reflectivity spectra is tuned such that at least two of the system-modes have substantially the same frequency when the transfer occurs substantially.
    Type: Grant
    Filed: October 27, 2000
    Date of Patent: July 23, 2002
    Assignee: Massachusetts Institute of Technology
    Inventors: Pierre R. Villeneuve, Shanhui Fan, Gale S. Petrich, Leslie A. Kolodziejski, John D. Joannopoulos
  • Composite photonic crystals
    Patent number: 6134043
    Abstract: A composite photonic crystal structure comprising a guide crystal configured in a lane having a dielectric periodicity in at least a first direction in the plane; and barrier crystals configured above and below the guide crystal to confine light within the guide crystal, the barrier crystals having a dielectric periodicity in at least a second direction not in the plane. In another embodiment, there is provided a composite photonic crystal structure comprising a guide crystal configured in a plane having a dielectric periodicity in at least one dimension; and a barrier crystal configured adjacent the guide crystal to confine light within the guide crystal, the barrier crystal having a dielectric periodicity in at least two dimensions.
    Type: Grant
    Filed: August 11, 1998
    Date of Patent: October 17, 2000
    Assignee: Massachusetts Institute of Technology
    Inventors: Steven G. Johnson, Shanhui Fan, Pierre R. Villeneuve, Leslie Kolodziejski, John D. Joannopoulos
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