The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Yeo-taek Yoon - One of the best experts on this subject based on the ideXlab platform.
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polarization independent visible wavelength filter incorporating a symmetric metal dielectric Resonant Structure
Optics Express, 2012Co-Authors: Chang-hyun Park, Yeo-taek YoonAbstract:A nanophotonic polarization-independent visible wavelength filter is presented, incorporating a symmetric metal-dielectric Resonant Structure on quartz substrate, where a sub-wavelength grating, made up of a two-dimensional array of Al square sheets, is integrated with a Si3N4 slab waveguide via an oxide layer. Incident light is orthogonally diffracted by the symmetric grating towards two directions of the grating groove, and then Resonantly coupled to both transverse electric and transverse magnetic guided modes associated with the underlying waveguide, irrespective of light polarization. Polarization independent bandpass filtering was thus achieved around specific wavelengths, determined by the grating pitch and the effective index of the waveguide. Three devices, operating in the blue, green and red spectral bands, were built through design and analysis drawing upon the finite-difference time-domain method. The devices, DEV I, II, and III, were constructed with grating pitches of 285, 355 and 395 nm, respectively, while the core was 100 nm thick. They were inspected to function as an efficient bandpass filter, centered at 460, 560 and 610 nm, with bandwidths of about 13, 14 and 17 nm, respectively; the peak transmission efficiencies were consistently over 85%. Furthermore, the transfer characteristics, insensitive to light polarization, were satisfactorily confirmed for normal incidence.
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Polarization-independent visible wavelength filter incorporating a 2D metal-dielectric Resonant Structure
2012 17th Opto-Electronics and Communications Conference, 2012Co-Authors: Chang-hyun Park, Yeo-taek YoonAbstract:A visible wavelength filter has been built based on a two-dimensional (2D) metal-dielectric Resonant Structure, featuring a polarization-independent operation and a high transmission over 90%.
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highly efficient color filter incorporating a thin metal dielectric Resonant Structure
Applied Physics Express, 2012Co-Authors: Yeo-taek Yoon, Chang-hyun ParkAbstract:A highly efficient color filter that takes advantage of an ultrathin metal (Al)-dielectric (TiO2) Resonant Structure, where a subwavelength metallic grating is deposited as cladding in a planar dielectric waveguide, is demonstrated. A selective spectral response was obtained by virtue of the guided mode resonance between the diffracted mode and waveguide mode. The center wavelengths for the blue, green, and red filters were found to be 430, 520, and 630 nm, and the corresponding 3 dB bandwidths were 67, 84, and 80 nm, respectively. All three filters provided an overall transmission exceeding 70% and a satisfactory color image.
Chang-hyun Park - One of the best experts on this subject based on the ideXlab platform.
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polarization independent visible wavelength filter incorporating a symmetric metal dielectric Resonant Structure
Optics Express, 2012Co-Authors: Chang-hyun Park, Yeo-taek YoonAbstract:A nanophotonic polarization-independent visible wavelength filter is presented, incorporating a symmetric metal-dielectric Resonant Structure on quartz substrate, where a sub-wavelength grating, made up of a two-dimensional array of Al square sheets, is integrated with a Si3N4 slab waveguide via an oxide layer. Incident light is orthogonally diffracted by the symmetric grating towards two directions of the grating groove, and then Resonantly coupled to both transverse electric and transverse magnetic guided modes associated with the underlying waveguide, irrespective of light polarization. Polarization independent bandpass filtering was thus achieved around specific wavelengths, determined by the grating pitch and the effective index of the waveguide. Three devices, operating in the blue, green and red spectral bands, were built through design and analysis drawing upon the finite-difference time-domain method. The devices, DEV I, II, and III, were constructed with grating pitches of 285, 355 and 395 nm, respectively, while the core was 100 nm thick. They were inspected to function as an efficient bandpass filter, centered at 460, 560 and 610 nm, with bandwidths of about 13, 14 and 17 nm, respectively; the peak transmission efficiencies were consistently over 85%. Furthermore, the transfer characteristics, insensitive to light polarization, were satisfactorily confirmed for normal incidence.
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Polarization-independent visible wavelength filter incorporating a 2D metal-dielectric Resonant Structure
2012 17th Opto-Electronics and Communications Conference, 2012Co-Authors: Chang-hyun Park, Yeo-taek YoonAbstract:A visible wavelength filter has been built based on a two-dimensional (2D) metal-dielectric Resonant Structure, featuring a polarization-independent operation and a high transmission over 90%.
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highly efficient color filter incorporating a thin metal dielectric Resonant Structure
Applied Physics Express, 2012Co-Authors: Yeo-taek Yoon, Chang-hyun ParkAbstract:A highly efficient color filter that takes advantage of an ultrathin metal (Al)-dielectric (TiO2) Resonant Structure, where a subwavelength metallic grating is deposited as cladding in a planar dielectric waveguide, is demonstrated. A selective spectral response was obtained by virtue of the guided mode resonance between the diffracted mode and waveguide mode. The center wavelengths for the blue, green, and red filters were found to be 430, 520, and 630 nm, and the corresponding 3 dB bandwidths were 67, 84, and 80 nm, respectively. All three filters provided an overall transmission exceeding 70% and a satisfactory color image.
Charles R. Sullivan - One of the best experts on this subject based on the ideXlab platform.
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Wireless Power Transfer Utilizing a High-$Q$ Self-Resonant Structure
IEEE Transactions on Power Electronics, 2019Co-Authors: Aaron L. F. Stein, Phyo Aung Kyaw, Charles R. SullivanAbstract:The range and efficiency of a wireless power transfer (WPT) system is limited by the quality factor of the Resonant coils. Conventional Resonant coils are made from solid or Litz wire. At megahertz frequencies solid wire is not utilized well due to skin effect, and Litz wire is very lossy due to proximity effect. We present a multilayer self-Resonant Structure as a low-cost method for creating high-Q coils. This Structure uses thin foil layers that are separated by a dielectric material in order to form an LC resonator, while also forcing equal current sharing between conductors. The self-Resonant Structure makes it feasible to achieve advantages similar to Litz wire, but at multi-megahertz frequencies where effective Litz wire is not commercially available. These Structures are made with foil layers much thinner than a skin depth, which can make handling these thin layers a challenge. To solve this problem, we also present a modified self-Resonant Structure in which the layered conductors are made with flex-PCB substrates with no vias. The PCB substrates provide a relatively inexpensive way to handle thin conductive layers, and the modified self-Resonant Structure ensures that the poor dielectric properties of the PCB substrates do not impact the quality factor of the Structure. A prototype of the modified self-Resonant Structure has a quality factor of 1183 at 7.09 MHz, despite only being 6.6 cm in diameter, which is more than 6.5x larger than other coils presented in the literature with a similar diameter. An experimental WPT setup utilizing two self-Resonant Structures achieves 94% efficiency at a distance of 5.0 cm, which is more than twice the distance as similarly sized conventional coils can achieve while maintaining the same efficiency.
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Thin self-Resonant Structures with a high-Q for wireless power transfer
2018 IEEE Applied Power Electronics Conference and Exposition (APEC), 2018Co-Authors: Aaron L. F. Stein, Phyo Aung Kyaw, Jesse Feldman-stein, Charles R. SullivanAbstract:The range, efficiency, and size of Resonant coils in an inductive wireless charging system is determined by the quality factor Q of the Resonant coils. The multi-layer self-Resonant Structure is a new Resonant coil technology that has been demonstrated to have a Q 6× larger than conventional coils. However, to date, implementations of this Structure have been thick, which limits their practical applications. In this paper, we explore the relationship between the thickness of a self-Resonant Structure and its performance. A computationally efficient 2-D optimization algorithm is proposed to design thin Resonant Structures and illustrate the trade-offs in the design. A new magnetic core shape is proposed which shapes the magnetic field lines to be parallel to the conductive layers and reduces current crowding. Finally, a prototype 3.5 mm thick self-Resonant Structure is constructed, which has a measured quality factor of 560 despite having a diameter of only 6.6 cm; this provides a 3.03× improvement over the state-of-the-art wireless power transfer coils in the literature.
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High-Q self-Resonant Structure for wireless power transfer
2017 IEEE Applied Power Electronics Conference and Exposition (APEC), 2017Co-Authors: Aaron L. F. Stein, Phyo Aung Kyaw, Charles R. SullivanAbstract:The range and efficiency of wireless power transfer systems are limited by the quality factor of the transmit and receive coils used. Multi-layer self-Resonant Structures have been proposed as a low-cost method for creating high-Q coils for high-frequency wireless power transfer. In these Structures thin foil layers are separated by a dielectric material in order to form a capacitance that resonates with the inductance of the Structure, while also forcing equal current sharing between conductors. In order to reduce winding loss, these Structures are made with foil layers much thinner than a skin depth, which makes the layers of the Structure extremely difficult to handle. In this paper, we present a modified self-Resonant Structure in which the layered conductors are made from standard PCB substrates with no vias. The PCB substrates provide an inexpensive way to handle thin conductive layers, and the modified self-Resonant Structure ensures that the poor dielectric properties of the PCB substrates do not impact the quality factor of the Structure. The modified self-Resonant Structure makes it feasible to achieve advantages similar to litz wire, but at multi-MHz frequencies where effective litz wire is not commercially available. Experimental results show that the Structure has a quality factor of 1177 at 7.08 MHz, despite only being 6.6 cm in diameter. The quality factor normalized by the diameter is more than 6.5x larger than other coils presented in the literature.
Yu-jiang Wu - One of the best experts on this subject based on the ideXlab platform.
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low profile printed octa band lte wwan mobile phone antenna using embedded parallel Resonant Structure
IEEE Transactions on Antennas and Propagation, 2013Co-Authors: Jin-hua Chen, Shun Yang, Joshua Le-wei Li, Yu-jiang WuAbstract:A simple low-profile antenna for octa-band LTE/WWAN operation in the internal mobile phone application is proposed and studied in this article. Consisting of a feeding strip and a coupling strip mainly, the presented antenna can be easily printed on the no-ground area of the top of a FR4 substrate, yet it occupies only a size of 15 × 40 mm2 and has a height of 3.5 mm. In this scheme, a chip inductor (L1 = 20 nH) is loaded in the long inductive strip, which can form a parallel Resonant Structure together with the coupling strip section close to the feeding strip. With these presences, a double-resonance mode (λ/4 Resonant mode) is successfully generated at about 720 and 900 MHz to cover the lower band of LTE700/GSM850/900 (704-960 MHz). While the desired upper band of DCS1800/PCS1900/UMTS2100/LTE2300/2500 (1710-2690 MHz) can be obtained with the help of second two Resonant modes, including a high-order λ/2 Resonant mode at 1800 MHz and a λ/4 Resonant mode at 2550 MHz. That is to say that those two wide operating bandwidths are achieved to cover all the octa-band LTE/WWAN operation. Good radiation efficiency and antenna gain for frequencies over the desired operating bands is obtained. Detailed design considerations of the proposed antenna are described, and both experimental and simulation results are also presented and discussed.
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Low-Profile Printed Octa-Band LTE/WWAN Mobile Phone Antenna Using Embedded Parallel Resonant Structure
IEEE Transactions on Antennas and Propagation, 2013Co-Authors: Jin-hua Chen, Shun Yang, Joshua Le-wei Li, Yu-jiang WuAbstract:A simple low-profile antenna for octa-band LTE/WWAN operation in the internal mobile phone application is proposed and studied in this article. Consisting of a feeding strip and a coupling strip mainly, the presented antenna can be easily printed on the no-ground area of the top of a FR4 substrate, yet it occupies only a size of 15 × 40 mm2 and has a height of 3.5 mm. In this scheme, a chip inductor (L1 = 20 nH) is loaded in the long inductive strip, which can form a parallel Resonant Structure together with the coupling strip section close to the feeding strip. With these presences, a double-resonance mode (λ/4 Resonant mode) is successfully generated at about 720 and 900 MHz to cover the lower band of LTE700/GSM850/900 (704-960 MHz). While the desired upper band of DCS1800/PCS1900/UMTS2100/LTE2300/2500 (1710-2690 MHz) can be obtained with the help of second two Resonant modes, including a high-order λ/2 Resonant mode at 1800 MHz and a λ/4 Resonant mode at 2550 MHz. That is to say that those two wide operating bandwidths are achieved to cover all the octa-band LTE/WWAN operation. Good radiation efficiency and antenna gain for frequencies over the desired operating bands is obtained. Detailed design considerations of the proposed antenna are described, and both experimental and simulation results are also presented and discussed.
Aaron L. F. Stein - One of the best experts on this subject based on the ideXlab platform.
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Wireless Power Transfer Utilizing a High-$Q$ Self-Resonant Structure
IEEE Transactions on Power Electronics, 2019Co-Authors: Aaron L. F. Stein, Phyo Aung Kyaw, Charles R. SullivanAbstract:The range and efficiency of a wireless power transfer (WPT) system is limited by the quality factor of the Resonant coils. Conventional Resonant coils are made from solid or Litz wire. At megahertz frequencies solid wire is not utilized well due to skin effect, and Litz wire is very lossy due to proximity effect. We present a multilayer self-Resonant Structure as a low-cost method for creating high-Q coils. This Structure uses thin foil layers that are separated by a dielectric material in order to form an LC resonator, while also forcing equal current sharing between conductors. The self-Resonant Structure makes it feasible to achieve advantages similar to Litz wire, but at multi-megahertz frequencies where effective Litz wire is not commercially available. These Structures are made with foil layers much thinner than a skin depth, which can make handling these thin layers a challenge. To solve this problem, we also present a modified self-Resonant Structure in which the layered conductors are made with flex-PCB substrates with no vias. The PCB substrates provide a relatively inexpensive way to handle thin conductive layers, and the modified self-Resonant Structure ensures that the poor dielectric properties of the PCB substrates do not impact the quality factor of the Structure. A prototype of the modified self-Resonant Structure has a quality factor of 1183 at 7.09 MHz, despite only being 6.6 cm in diameter, which is more than 6.5x larger than other coils presented in the literature with a similar diameter. An experimental WPT setup utilizing two self-Resonant Structures achieves 94% efficiency at a distance of 5.0 cm, which is more than twice the distance as similarly sized conventional coils can achieve while maintaining the same efficiency.
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Thin self-Resonant Structures with a high-Q for wireless power transfer
2018 IEEE Applied Power Electronics Conference and Exposition (APEC), 2018Co-Authors: Aaron L. F. Stein, Phyo Aung Kyaw, Jesse Feldman-stein, Charles R. SullivanAbstract:The range, efficiency, and size of Resonant coils in an inductive wireless charging system is determined by the quality factor Q of the Resonant coils. The multi-layer self-Resonant Structure is a new Resonant coil technology that has been demonstrated to have a Q 6× larger than conventional coils. However, to date, implementations of this Structure have been thick, which limits their practical applications. In this paper, we explore the relationship between the thickness of a self-Resonant Structure and its performance. A computationally efficient 2-D optimization algorithm is proposed to design thin Resonant Structures and illustrate the trade-offs in the design. A new magnetic core shape is proposed which shapes the magnetic field lines to be parallel to the conductive layers and reduces current crowding. Finally, a prototype 3.5 mm thick self-Resonant Structure is constructed, which has a measured quality factor of 560 despite having a diameter of only 6.6 cm; this provides a 3.03× improvement over the state-of-the-art wireless power transfer coils in the literature.
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High-Q self-Resonant Structure for wireless power transfer
2017 IEEE Applied Power Electronics Conference and Exposition (APEC), 2017Co-Authors: Aaron L. F. Stein, Phyo Aung Kyaw, Charles R. SullivanAbstract:The range and efficiency of wireless power transfer systems are limited by the quality factor of the transmit and receive coils used. Multi-layer self-Resonant Structures have been proposed as a low-cost method for creating high-Q coils for high-frequency wireless power transfer. In these Structures thin foil layers are separated by a dielectric material in order to form a capacitance that resonates with the inductance of the Structure, while also forcing equal current sharing between conductors. In order to reduce winding loss, these Structures are made with foil layers much thinner than a skin depth, which makes the layers of the Structure extremely difficult to handle. In this paper, we present a modified self-Resonant Structure in which the layered conductors are made from standard PCB substrates with no vias. The PCB substrates provide an inexpensive way to handle thin conductive layers, and the modified self-Resonant Structure ensures that the poor dielectric properties of the PCB substrates do not impact the quality factor of the Structure. The modified self-Resonant Structure makes it feasible to achieve advantages similar to litz wire, but at multi-MHz frequencies where effective litz wire is not commercially available. Experimental results show that the Structure has a quality factor of 1177 at 7.08 MHz, despite only being 6.6 cm in diameter. The quality factor normalized by the diameter is more than 6.5x larger than other coils presented in the literature.