Patents by Inventor Hoi Wai Choi
Hoi Wai Choi 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).
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Patent number: 11688833Abstract: A nanostructure fabricated on a semiconductor light-emitting device induces strain in the active region. The active device includes at least one quantum heterostructure, in which the strain changes the extent of Quantum Confined Stark Effect, and thus modifies the wavelength of light emission. By mixing strain relaxation and strain induction effects there is a spectral broadening of the light emission, providing polychromatic light emission.Type: GrantFiled: May 17, 2021Date of Patent: June 27, 2023Assignee: VERSITECH LIMITEDInventors: Hoi Wai Choi, Wai Yuen Fu
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Publication number: 20210273140Abstract: A nanostructure fabricated on a semiconductor light-emitting device induces strain in the active region. The active device includes at least one quantum heterostructure, in which the strain changes the extent of Quantum Confined Stark Effect, and thus modifies the wavelength of light emission. By mixing strain relaxation and strain induction effects there is a spectral broadening of the light emission, providing polychromatic light emission.Type: ApplicationFiled: May 17, 2021Publication date: September 2, 2021Applicant: VERSITECH LIMITEDInventors: Hoi Wai CHOI, Wai Yuen FU
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Patent number: 11094855Abstract: A nanostructure fabricated on a semiconductor light-emitting device induces strain in the active region. The active device includes at least one quantum heterostructure, in which the strain changes the extent of Quantum Confined Stark Effect, and thus modifies the wavelength of light emission. By mixing strain relaxation and strain induction effects there is a spectral broadening of the light emission, providing polychromatic light emission.Type: GrantFiled: March 12, 2018Date of Patent: August 17, 2021Assignee: Versitech LimitedInventors: Hoi Wai Choi, Wai Yuen Fu
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Publication number: 20200135982Abstract: A nanostructure fabricated on a semiconductor light-emitting device induces strain in the active region. The active device includes at least one quantum heterostructure, in which the strain changes the extent of Quantum Confined Stark Effect, and thus modifies the wavelength of light emission. By mixing strain relaxation and strain induction effects there is a spectral broadening of the light emission, providing polychromatic light emission.Type: ApplicationFiled: March 12, 2018Publication date: April 30, 2020Applicant: Versitech LimitedInventors: Hoi Wai CHOI, Wai Yuen FU
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Patent number: 10615222Abstract: Methods of fabricating flexible, free-standing LED structures are provided. An LED structure can be formed on a sapphire substrate, and the surface of the LED structure can then be coated with epoxy and attached to a rigid supporting substrate. A laser lift-off process can be performed using an ultraviolent beam from a high-power pulsed-mode laser and a shadow mask, causing at least a portion of the LED structure to separate from the sapphire substrate. The structure can then be immersed in an acetone bath to dissolve the epoxy and separate the structure from the supporting substrate.Type: GrantFiled: August 20, 2015Date of Patent: April 7, 2020Assignee: The University of Hong KongInventors: Hoi Wai Choi, Kwai Hei Li, Yuk Fai Cheung
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Publication number: 20190157508Abstract: A device includes a light-emitting diode (LED) integrated with a photodetector on the same semiconductor platform, such that the photocurrent generated by the photodetector can be used to monitor the optical output of the LED, which is located adjacent to the photodetector. The device provides a compact, robust, reliable and low-cost way of monitoring LED emission.Type: ApplicationFiled: May 17, 2016Publication date: May 23, 2019Applicant: The University of Hong KongInventors: Hoi Wai CHOI, Kwai Hei LI, Haitao LU
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Publication number: 20160233269Abstract: Methods of fabricating flexible, free-standing LED structures are provided. An LED structure can be formed on a sapphire substrate, and the surface of the LED structure can then be coated with epoxy and attached to a rigid supporting substrate. A laser lift-off process can be performed using an ultraviolent beam from a high-power pulsed-mode laser and a shadow mask, causing at least a portion of the LED structure to separate from the sapphire substrate. The structure can then be immersed in an acetone bath to dissolve the epoxy and separate the structure from the supporting substrate.Type: ApplicationFiled: August 20, 2015Publication date: August 11, 2016Inventors: Hoi Wai Choi, Kwai Hei Li, Yuk Fai Cheung
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Patent number: 9401453Abstract: A nano-LED containing an array of nano-pillars of different diameters that are distributed over an emission area of an LED chip is capable of emitting broadband and white or nearly white light. Since each pillar emits light at a different wavelength according to its diameter and strain state, the overall emission spectral characteristics of the device is a combination of individual spectrum, giving rise to broadband emission. The spectral shape can be tailored for different shades of white emission, by controlling the distribution of the different diameter nano-pillars. The nano-pillars are patterned by nanosphere lithography.Type: GrantFiled: May 24, 2013Date of Patent: July 26, 2016Assignee: THE UNIVERSITY OF HONG KONGInventor: Hoi Wai Choi
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Publication number: 20130313517Abstract: A nano-LED containing an array of nano-pillars of different diameters that are distributed over an emission area of an LED chip is capable of emitting broadband and white or nearly white light. Since each pillar emits light at a different wavelength according to its diameter and strain state, the overall emission spectral characteristics of the device is a combination of individual spectrum, giving rise to broadband emission. The spectral shape can be tailored for different shades of white emission, by controlling the distribution of the different diameter nano-pillars. The nano-pillars are patterned by nanosphere lithography.Type: ApplicationFiled: May 24, 2013Publication date: November 28, 2013Applicant: THE UNIVERSITY OF HONG KONGInventor: Hoi Wai Choi
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Publication number: 20120292788Abstract: Methods and systems are provided to utilize and manufacture a stacked chip assembly. Microelectronic or optoelectronic chips of any dimensions are directly stacked onto each other. The chips can be of substantially identical sizes. To enable forming the stacked chip assembly, trenches are laser micro-machined onto the bottom surface of a chip to accommodate the bond wedge/ball and wire path of the chip beneath it. Consequently, chips can be tightly integrated without a gap and without having to reserve space for the bond wedges/balls.Type: ApplicationFiled: May 18, 2012Publication date: November 22, 2012Applicant: The University of Hong KongInventor: Hoi Wai Choi
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Patent number: 7982228Abstract: Methods and systems are provided that may be used to utilize and manufacture a light sources apparatus. A first light emitting diode emits light having a first wavelength, and a second light emitting diode for emitting light having a second wavelength. Each of the first and second light emitting diodes may comprise angled facets to reflect incident light in a direct toward a top end of the first light emitting diode. The second light emitting diode comprising angled facets may reflect incident light in a direction toward a top end of the second light emitting diode. A first distributed Bragg reflector is disposed between the top end of the first light emitting diode and a bottom end of the second light emitting diode to allow light from the first light emitting diode to pass through and to reflect light from the second light emitting diode.Type: GrantFiled: October 2, 2009Date of Patent: July 19, 2011Assignee: Versitech LimitedInventors: Hoi Wai Choi, Kwun Nam Hui, Xianghua Wang
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Publication number: 20100084668Abstract: Methods and systems are provided that may be used to utilize and manufacture a light sources apparatus. A first light emitting diode emits light having a first wavelength, and a second light emitting diode for emitting light having a second wavelength. Each of the first and second light emitting diodes may comprise angled facets to reflect incident light in a direct toward a top end of the first light emitting diode. The second light emitting diode comprising angled facets may reflect incident light in a direction toward a top end of the second light emitting diode. A first distributed Bragg reflector is disposed between the top end of the first light emitting diode and a bottom end of the second light emitting diode to allow light from the first light emitting diode to pass through and to reflect light from the second light emitting diode.Type: ApplicationFiled: October 2, 2009Publication date: April 8, 2010Inventors: Hoi Wai CHOI, Kwun Nam HUI, Xianghua WANG
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Patent number: 7598149Abstract: An array of light emitting devices, each device comprising a sloped wall mesa (24) of luminescent semiconductor material. Extending over the sloped wall mesas (24) is a metal contact (30). The array can be arranged as a parallel addressable system so that all devices (24) can be stimulated to emit light simultaneously. Alternatively, the array can be arranged as a matrix addressable array, in which case individual devices can be selectively stimulated.Type: GrantFiled: February 2, 2004Date of Patent: October 6, 2009Assignee: University of StrathclydeInventors: Martin David Dawson, Hoi Wai Choi, Chan-Wook Jeon
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Publication number: 20080043798Abstract: A vertical-cavity device comprises: (a) a chip comprising an active semiconductor layer for providing optical gain; (b) a first mirror arranged on a first side of the active layer; (c) a second mirror arranged on a second side of the active layer, opposite to the first mirror, and forming with at least the first mirror an optically resonant cavity that passes through the active layer in a direction out of the plane of the active layer; (d) a heatspreader for removing heat from the active layer, the heatspreader being arranged inside the cavity and having a first surface adjacent to the chip and a second surface opposite to the first surface, the heatspreader being transparent to light of wavelengths in an operating bandwidth of the device. In addition to removing heat from the active layer, the heatspreader also has one or more further selected property that has a further selected effect on light output from the device.Type: ApplicationFiled: March 24, 2004Publication date: February 21, 2008Applicant: The University of StrathclydeInventors: Stephane Luc Dominique Calvez, John-Mark Hopkins, David Burns, Martin David Dawson, Chan Wook Jeon, Hoi Wai Choi
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Publication number: 20080023715Abstract: A light emitting diode comprising of a fluorescent microsphere coating is proposed. The coating consists of fluorescent microspheres which fluoresce at green and red wavelengths, excited by a shorter wavelength LED. Due to the micron-scale dimension of the spheres, they are non-resolvable to the human eye and the overall optical output appears as color mixed. By varying the proportions of green and red fluorescent microspheres and the wavelength of the excitation source, the color of the optical output can be tuned. If the optical output has of blue, green and red components in the correct proportions, white color emission can be achieved. The light emitting diode can be sectioned into multiple individually-addressable regions. Each section can emit at a different wavelength according to the type of fluorescent microspheres coated. By varying the intensity of the blue, green and red regions by changing the bias voltage, the output wavelength (color) can be continuously tuned (varied).Type: ApplicationFiled: July 19, 2007Publication date: January 31, 2008Inventor: Hoi Wai CHOI