Patents by Inventor Abhishek Kumar Srivastava
Abhishek Kumar Srivastava 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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Publication number: 20240110101Abstract: A ferroelectric liquid crystal (FLC) material in a vertically aligned liquid crystal cell, comprising at least one chiral compound and at least one non-chiral liquid crystal compound, with a sub-micron scale helix pitch less than 300 nm, spontaneous polarization greater than 100 nC/cm2, and a tilt angle greater than 38 degrees. The ferroelectric liquid crystal (FLC) material provides an extremely large Kerr constant in a vertically aligned liquid crystal cell at the communication band of the light and therefore reduces the driving voltage and response time.Type: ApplicationFiled: November 8, 2023Publication date: April 4, 2024Inventors: VALERII VLADIMIROVICH VASHCHENKO, OLENA V. VASHCHENKO, ABHISHEK KUMAR SRIVASTAVA
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Patent number: 11880114Abstract: Techniques for using ferroelectric liquid crystals Dammann grating (FLCDG) for light detection and ranging devices are disclosed. In LiDAR devices, accuracy, response time, and cost performance can be limited by some factors, such as laser pulse width, time resolution of a time-to-digital conversion chip, detector bandwidth, shot noise, and time error generated by electronic circuits. A FLCDG-based architecture can improve a LiDAR device, and provide for one-shot capturing due to the high switching speed at very low driving voltage provided by ferroelectric liquid crystals and the equal diffracting ability of Dammann grating.Type: GrantFiled: August 27, 2020Date of Patent: January 23, 2024Assignee: THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGYInventors: Zhengnan Yuan, Abhishek Kumar Srivastava, Zhibo Sun, Hoi Sing Kwok
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Publication number: 20230250338Abstract: There is provided a ferroelectric liquid crystal (FLC) material for the deformed helix FLC (DHFLC) electro-optical mode devices and shows optimum electro-optical properties including high tilt angle (>38°), and short helix pitch (<120 nm), and spontaneous polarization (>100 nC/cm2) comprising at least two components, wherein at least one FLC component is a chiral compound of Formula (I): particularly: wherein W1 and W2 are chiral groups with polar substituent at chiral centre, A and B are independently N atom or CH groups providing that at least one of A or B is N atom. Other various groups are as defined herein.Type: ApplicationFiled: February 7, 2023Publication date: August 10, 2023Inventors: Valerii Vladimirovich VASHCHENKO, Olena V. VASHCHENKO, Abhishek Kumar SRIVASTAVA, Zhibo SUN, Zhengnan YUAN, Hoi Sing KWOK
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Publication number: 20230244102Abstract: One or more devices, systems, methods and/or apparatus to facilitate suppression of fringe field effect, such as for diffraction grating and/or display purposes. In one embodiment, a ferroelectric liquid crystal (FLC) element can comprise a pair of conductive substrates, a FLC layer having a helical pitch and positioned between the conductive substrates, one or more spacers fixedly positioned between the conductive substrates, and an alignment layer positioned between the FLC layer and one of the conductive substrates. The alignment layer can be disposed at least partially contiguous with the FLC layer. The FLC layer can comprise a chiral smectic C* liquid crystal layer having at least one of a helical pitch smaller than an average cell gap of the FLC layer, or an average helical pitch of the FLC layer being smaller than an average thickness of the FLC layer between the conductive substrates.Type: ApplicationFiled: September 10, 2021Publication date: August 3, 2023Inventors: Zhibo Sun, Zhengnan Yuan, Abhishek Kumar Srivastava, Hoi-Sing Kwok
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Patent number: 11441074Abstract: A nanoparticle film is disclosed. The nanoparticle film comprises a plurality of polymerized liquid crystal monomers having an axis of alignment, and a plurality of nanoparticles disposed in the polymerized liquid crystal monomers. Each of the nanoparticles has a surface modified by a plurality of first ligands and a long axis aligned with the axis of alignment through the plurality of first ligands.Type: GrantFiled: August 7, 2020Date of Patent: September 13, 2022Assignee: THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGYInventors: Maksym Fedorovich Prodanov, Valerii Vladimirovich Vashchenko, Abhishek Kumar Srivastava, Swadesh Kumar Gupta, Chengbin Kang, Maksym Diakov
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Patent number: 11294241Abstract: A composite photoalignment layer for aligning liquid crystal molecules includes: a monomeric material; a photoinitiator or a thermal initiator; and an azo dye material. A method for preparing a composite photoalignment layer for aligning liquid crystal molecules includes: mixing, in solution form, a monomeric material, a photoinitiator or a thermal initiator, and an azo dye material; coating the mixed solution onto a substrate to form a thin film; exposing the thin film to polarized light; and, with a thermal initiator, heating the thin film to polymerize the monomeric material and form a solid thin film.Type: GrantFiled: September 22, 2020Date of Patent: April 5, 2022Assignee: THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGYInventors: Man Chun Tseng, Abhishek Kumar Srivastava, Cuiling Meng, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok, Yue Shi, Yeuk Lung Jacob Ho, Chenxiang Zhao
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Publication number: 20220089949Abstract: A method for production of quantum rods is semiconductor luminescent nanoparticles of elongated shape. The semiconductor luminescent nanoparticles are core-shell nanoparticles, where core is CdSe coated with CdS shell. At the current state of the art, mass production of this type of quantum rods is challenging because of extremely fast growth of wurtzite CdSe seeds serving as the core, especially when the seeds size is below 3.0 nm that is required for synthesis of green emitting QRs. We propose the non-injection method for CdSe-seeds which comprises: preparation of single reaction mixture containing both Cd- and Se-precursors, which is liquid at room temperature: pumping the reaction mixture through the heating zone specially designed to provide highly reproducible and well-controllable residential time (0.1-60 seconds) in a heating chamber, thereby resulting in CdSe seeds with low size distribution and narrow emission bandwidth; synthesis of quantum rods using the prepared CdSe seeds.Type: ApplicationFiled: September 21, 2021Publication date: March 24, 2022Inventors: Maksym F. Prodanov, Valerii Vladimirovich Vashchenko, Abhishek Kumar Srivastava
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Patent number: 11056613Abstract: A method for fabricating quantum rods includes: preparing a Cd-precursor; preparing a S-precursor and CdSe seeds; preparing a Zn-precursor; mixing the S-precursor and the CdSe seeds with the Cd-precursor in a reaction mixture; adding the Zn-precursor to the reaction mixture; stopping the reaction; and performing a purification process to obtain the quantum rods.Type: GrantFiled: April 10, 2019Date of Patent: July 6, 2021Assignee: THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGYInventors: Maksym F. Prodanov, Valerii Vladimirovich Vashchenko, Abhishek Kumar Srivastava, Hoi Sing Kwok
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Publication number: 20210178795Abstract: Various photo-luminescent films and associated methods are enabled. For instance, a photo-luminescent film comprises a substrate layer comprising a plurality of pores, and a composite comprising luminescent nanoparticles disposed in the plurality of pores.Type: ApplicationFiled: December 11, 2020Publication date: June 17, 2021Inventors: Swadesh Kumar Gupta, Maksym Fedorovich Prodanov, Valerii Vladimirovich Vashchenko, Abhishek Kumar Srivastava, Chengbin Kang, Yiyang Gao
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Patent number: 11015120Abstract: A low birefringence ferroelectric liquid crystal (FLC) mixture composed of at least two components shows birefringence in the range 0.05 to 0.14, which is suitable for the modern display and photonic devices. The cell gap can be tuned from 1.5 ?m to 4 ?m to reduces the fabrication complexity and chromatic distortion by electro-optical modulation. The FLC mixtures can be employed in a wide temperature range. The characteristics of the said FLC mixture can be tuned by tuning the concentration of the constituents of the mixture. The helical pitch of the FLC mixtures can be varied from 100 nm to 10 ?m. A smectic tilt angle can be varied between 17° to 45° and the spontaneous polarization can be tuned over a wide range to meet requirements of different electro-optical modes, and the FLC mixture is applicable for a wide variety of electro-optical effects.Type: GrantFiled: January 30, 2018Date of Patent: May 25, 2021Assignee: The Hong Kong University of Science and TechnologyInventors: Valerii Vladimirovich Vashchenko, Evgenii Pavlovich Pozhidaev, Abhishek Kumar Srivastava, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok
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Patent number: 10948774Abstract: A photoaligned quantum rod enhancement film (QREF) includes: a substrate (802, 805); a photoalignment layer deposited on the substrate (802, 805); and a polymer layer deposited on the photoalignment layer, the polymer layer comprises a plurality of quantum rods, the plurality of quantum rods are configured to emit one or more wavelengths of light in response to pumping light, and are aligned to an alignment axis based on the photoalignment layer.Type: GrantFiled: May 10, 2017Date of Patent: March 16, 2021Assignee: THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGYInventors: Abhishek Kumar Srivastava, Wanlong Zhang, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok
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Publication number: 20210063841Abstract: Techniques for using ferroelectric liquid crystals Dammann grating (FLCDG) for light detection and ranging devices are disclosed. In LiDAR devices, accuracy, response time, and cost performance can be limited by some factors, such as laser pulse width, time resolution of a time-to-digital conversion chip, detector bandwidth, shot noise, and time error generated by electronic circuits. A FLCDG-based architecture can improve a LiDAR device, and provide for one-shot capturing due to the high switching speed at very low driving voltage provided by ferroelectric liquid crystals and the equal diffracting ability of Dammann grating.Type: ApplicationFiled: August 27, 2020Publication date: March 4, 2021Inventors: Zhengnan Yuan, Abhishek Kumar Srivastava, Zhibo Sun, Hoi Sing Kwok
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Publication number: 20210040389Abstract: A nanoparticle film is disclosed. The nanoparticle film comprises a plurality of polymerized liquid crystal monomers having an axis of alignment, and a plurality of nanoparticles disposed in the polymerized liquid crystal monomers. Each of the nanoparticles has a surface modified by a plurality of first ligands and a long axis aligned with the axis of alignment through the plurality of first ligands.Type: ApplicationFiled: August 7, 2020Publication date: February 11, 2021Inventors: Maksym Fedorovich Prodanov, Valerii Vladimirovich Vashchenko, Abhishek Kumar Srivastava, Swadesh Kumar Gupta, Chengbin Kang, Maksym Diakov
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Publication number: 20210011343Abstract: A composite photoalignment layer for aligning liquid crystal molecules includes: a monomeric material; a photoinitiator or a thermal initiator; and an azo dye material. A method for preparing a composite photoalignment layer for aligning liquid crystal molecules includes: mixing, in solution form, a monomeric material, a photoinitiator or a thermal initiator, and an azo dye material; coating the mixed solution onto a substrate to form a thin film; exposing the thin film to polarized light; and, with a thermal initiator, heating the thin film to polymerize the monomeric material and form a solid thin film.Type: ApplicationFiled: September 22, 2020Publication date: January 14, 2021Inventors: Man Chun TSENG, Abhishek Kumar SRIVASTAVA, Cuiling MENG, Vladimir Grigorievich CHIGRINOV, Hoi Sing KWOK, Yue SHI, Yeuk Lung Jacob HO, Chenxiang ZHAO
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Patent number: 10816855Abstract: A composite photoalignment layer for aligning liquid crystal molecules includes: a monomeric material; a photoinitiator or a thermal initiator; and an azo dye material. A method for preparing a composite photoalignment layer for aligning liquid crystal molecules includes: mixing, in solution form, a monomeric material, a photoinitiator or a thermal initiator, and an azo dye material; coating the mixed solution onto a substrate to form a thin film; exposing the thin film to polarized light; and, with a thermal initiator, heating the thin film to polymerize the monomeric material and form a solid thin film.Type: GrantFiled: October 17, 2017Date of Patent: October 27, 2020Assignee: The Hong Kong University of Science and TechnologyInventors: Man Chun Tseng, Abhishek Kumar Srivastava, Cuiling Meng, Hoi Sing Kwok, Yeuk Lung Jacob Ho
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Publication number: 20190312175Abstract: A method for fabricating quantum rods includes: preparing a Cd-precursor; preparing a S-precursor and CdSe seeds; preparing a Zn-precursor; mixing the S-precursor and the CdSe seeds with the Cd-precursor in a reaction mixture; adding the Zn-precursor to the reaction mixture; stopping the reaction; and performing a purification process to obtain the quantum rods.Type: ApplicationFiled: April 10, 2019Publication date: October 10, 2019Applicant: The Hong Kong University of Science and TechnologyInventors: Maksym F. Prodanov, Valerii Vladimirovich Vashchenko, Abhishek Kumar Srivastava, Hoi Sing Kwok
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Patent number: 10281731Abstract: A 2D/3D switchable liquid crystal lens device includes: a polarization-dependent lens array, configured to provide a focusing effect for impinging light having a first plane of polarization of the impinging light and to provide no focusing effect for impinging light have a second plane of polarization orthogonal to the first plane of polarization; a switchable polarization rotating stage, comprising bi-stable liquid crystals, wherein the switchable polarization rotating stage is configured to output light having the first plane of polarization to the polarization-dependent lens array while the bi-stable liquid crystals are in a first state, and to output light having the second plane of polarization to the polarization-dependent lens array while the bi-stable liquid crystals are in a second state; and a driving system, configured to switch the bi-stable liquid crystals of the switchable polarization rotating stage between the first state and the second state.Type: GrantFiled: May 15, 2015Date of Patent: May 7, 2019Assignee: THE HONG KONG UNIVERSITY OF SCIENCE & TECHNOLOGYInventors: Abhishek Kumar Srivastava, Vladimir Grigorievich Chigrinov, Hoi-Sing Kwok
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Publication number: 20190129252Abstract: A photoaligned quantum rod enhancement film (QREF) includes: a substrate (802, 805); a photoalignment layer deposited on the substrate (802, 805); and a polymer layer deposited on the photoalignment layer, the polymer layer comprises a plurality of quantum rods, the plurality of quantum rods are configured to emit one or more wavelengths of light in response to pumping light, and are aligned to an alignment axis based on the photoalignment layer.Type: ApplicationFiled: May 10, 2017Publication date: May 2, 2019Applicant: The Hong Kong University of Science and TechnologyInventors: Abhishek Kumar SRIVASTAVA, Wanlong ZHANG, Vladimir Grigorievich CHIGRINOV, Hoi Sing KWOK
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Publication number: 20180216004Abstract: A low birefringence ferroelectric liquid crystal (FLC) mixture composed of at least two components shows birefringence in the range 0.05 to 0.14, which is suitable for the modern display and photonic devices. The cell gap can be tuned from 1.5 ?m to 4 ?m to reduces the fabrication complexity and chromatic distortion by electro-optical modulation. The FLC mixtures can be employed in a wide temperature range. The characteristics of the said FLC mixture can be tuned by tuning the concentration of the constituents of the mixture. The helical pitch of the FLC mixtures can be varied from 100 nm to 10 ?m. A smectic tilt angle can be varied between 17° to 45° and the spontaneous polarization can be tuned over a wide range to meet requirements of different electro-optical modes, and the FLC mixture is applicable for a wide variety of electro-optical effects.Type: ApplicationFiled: January 30, 2018Publication date: August 2, 2018Inventors: VALERII VLADIMIROVICH VASHCHENKO, EVGENII PAVLOVICH POZHIDAEV, ABHISHEK KUMAR SRIVASTAVA, VLADIMIR GRIGORIEVICH CHIGRINOV, HOI SING KWOK
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Patent number: 9946133Abstract: An electrically suppressed helix (ESH) ferroelectric liquid crystal (FLC) display cell with fast response includes: a liquid crystal layer, disposed between two transparent substrates, wherein helix pitch of chiral smectic liquid crystals of the liquid crystal layer is less than the thickness of the liquid crystal layer; at least one polarizer; and a voltage source, configured to apply electrical driving voltage pulses to electrodes of the display cell with amplitude greater than a critical voltage for helix unwinding of the chiral smectic liquid crystals.Type: GrantFiled: March 10, 2016Date of Patent: April 17, 2018Assignee: THE HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGYInventors: Abhishek Kumar Srivastava, Vladimir Grigorievich Chigrinov, Hoi Sing Kwok