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Metamaterials: Detailed parametric studies on cut-wire pair and combined structure
Lam, Vu Dinh,Tung, Nguyen Thanh,Van Hong, Le,Lee, Young Pak Institute of Physics 2009 Journal of physics. Conference series Vol.187 No.1
<P>We studied the electromagnetic behavior of cut-wire pair structure, which is considered as a magnetic metamaterial for designing the left-handed material. It was found that the lattice constant of cut-wire pair structure provides subtle effects not only on the electric resonance but also on the magnetic one. In addition, we also investigated on how this affects the left-handed behavior of combined structures of cut-wire pair and continuous wire. These structures were designed, fabricated, and measured in the microwave frequency regime.</P>
Biomedical and Environmental Applications of Chitosan-based Nanomaterials
( Jae Kweon Park ),( Lam Dai Tran ),( Hoang Vinh Tran ),( Trang Thu Mai ),( Thu Phuong Ha ),( Binh Hai Nguyen ),( Hoang Thai ),( Hoang Dinh Vu ),( Dien Gia Pham ),( Phuc Xuan Nguyen ) 한국키틴키토산학회 2011 한국키틴키토산학회지 Vol.16 No.1
Being naturally abundant resources and having many interesting physicochemical and biological properties, chitin/chitosan have been found useful in many fields. This paper describes the strategy to design a multifunctional, chitosan based nanomaterials and their biomedical and environmental applications. Different physicochemical methods including FESEM/TEM, PPMS were used to characterize the obtained nanomaterials. For each application, a series of specific characterizing methods were used for evaluating the applicability/capacity of materials.
Dual-band isotropic metamaterial absorber based on near-field interaction in the Ku band
The Linh Pham,Hong Tiep Dinh,Dinh Hai Le,Xuan Khuyen Bui,Son Tung Bui,Hong Luu Dang,Anh Duc Phan,Dac Tuyen Le,Dinh-Lam Vu 한국물리학회 2020 Current Applied Physics Vol.20 No.2
We numerically and experimentally investigate single-band and dual-band isotropic metamaterial absorbers (IMAs) based on metallic disks. By optimizing the diameter of the metallic disks and the thickness of the dielectric substrate, the single-band IMA is observed at 16.2 GHz with absorptivity of 97%. When adding one diskpair to the structure, the dual-band IMA is obtained at 12.8 and 15.5 GHz due to the symmetry breaking. The physical mechanics is explained by near-field coupling effect and equivalent LC circuit model. The measurement results performed in the range 12–18 GHz show a good agreement with simulation and theoretical analysis. Our findings demonstrate a new approach to achieve dual-band and multi-band IMAs.
Excitation of Resistive States in Superconducting Films by Using Electrical and Light Pulses
Jean-Paul Maneval,Fran cois-Ren e Ladan,J.C. Villegier,Vu Dinh Lam,Phan Hong Khoi 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5
The resistance induced by nanosecond pulses of electric currrent or of light has been studied in superconducting Nb and NbN thin lms. Narrow bridges exhibit the features expected from quasi-1D transport, namely, localized phase-slip centers (PSC) and hot spots (HS), depending upon the prescribed conditions of temperature and applied current. PSC and HS are clearly identied from their characteristic delay and their evolution in time. We then analyze the response to combined pulsed illumination and current. Using very thin (4 nm) niobium-nitride lms, it was possible to detect the visible light delivered photon by photon. The resistance induced by nanosecond pulses of electric currrent or of light has been studied in superconducting Nb and NbN thin lms. Narrow bridges exhibit the features expected from quasi-1D transport, namely, localized phase-slip centers (PSC) and hot spots (HS), depending upon the prescribed conditions of temperature and applied current. PSC and HS are clearly identied from their characteristic delay and their evolution in time. We then analyze the response to combined pulsed illumination and current. Using very thin (4 nm) niobium-nitride lms, it was possible to detect the visible light delivered photon by photon.
Nguyen Van Dung,유영준,이영백,Nguyen Thanh Tung,Bui Son Tung,Vu Dinh Lam 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.1
The influence of lattice constants on the electromagnetic behavior of a cut-wire-pair (CWP)structure has been elucidated. In this report, we performed both simulations and experiments todetermine the influence of polarization on the metamagnetic resonance of the CWP structure. Thekey finding is the result of an investigation on the plasmon hybridization between the two CWs,which showed that the polarization of the incident wave was affected. Good agreement betweennumerical simulation and measurement is achieved.
Ultra-broadband and flexible metamaterial absorber based on MoS2 cuboids with Mie resonances
Ha Duong Thi,Nam Man Hoai,Tung Bui Son,Khuyen Bui Xuan,Lam Vu Dinh,Le-Van Quynh 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.11
In this work, we present a type of fexible and broadband metamaterial absorber operating in the GHz range. The proposed structure consists of three layers: a periodic square-shaped array made of molybdenum disulfde (MoS2) on the top, a continuous polyimide layer in the middle and a continuous copper layer at the bottom. For fat model, the proposed absorber exhibits a broadband absorption in the frequency range of 10.1–17.6 GHz with an absorption of more than 90% under normal incidence. Due to the symmetry of structure, the absorption feature is polarization-insensitive. The absorption remains above 80% in the frequency range of 11.1–15.6 GHz when the incident angle is up to 60° for TE-polarized wave, while the absorption is higher than 90% in the frequency range of 13.5–18 GHz for incident angles up to 60° for TM-polarized wave. For bending model, the absorption is signifcantly expanded when the bending radius decreases to under 100 mm. The physical mechanism of the absorption properties is explained in detail by the electric feld distribution, the magnetic feld distribution following the Mie resonance theory and infuence of the loss of MoS2. Obtained results in the work might contribute to the development of potential applications based on metamaterials in the microwave region such as imaging, protecting and light emitting devices.
Reversibly-propagational metamaterial absorber for sensing application
Tung, Bui Son,Khuyen, Bui Xuan,Yoo, Young Joon,Rhee, Joo Yull,Kim, Ki Won,Lam, Vu Dinh,Lee, Young Pak World Scientific Publishing Company 2018 Modern physics letters. B, Condensed matter physic Vol.32 No.4
<P>We investigated a reversibly-propagational metamaterial perfect absorber (MPA) for <I>X</I> band using two separated identically-patterned copper layers, which were deposited on continuous dielectric FR-4 layers. By adjusting oblique incidence, two separated resonances are excited, then come close to each other and is finally merged to be a perfect absorption peak at 10.1 GHz. The nature of resonance is the quadrupole mode instead of the fundamental resonances in common MPAs. The mechanism of perfect absorption is the coupling of two quadrupole resonances at their superposition, leading to an enhancement of energy absorption. Finally, we numerically presented the capability of sensing thin resonant substance using the proposed MPA. The characteristic resonance of substance, which does not appear on the absorption spectrum at the limited thickness of bare substance layer, is detected with a great magnitude of signal by exploiting the absorption resonance of MPA. Our work provides another way to obtain the reversibly-propagational absorption by controlling the incident angle instead of the geometrical structure, and might be useful for the potential devices based on MPA such as detectors and sensors.</P>
Metamaterial Perfect Absorber Using the Magnetic Resonance of Dielectric Inclusions
Nguyen Van Dung,Bui Son Tung,Bui Xuan Khuyen,Young Joon Yoo,YoungPak Lee,Joo Yull Rhee,Vu Dinh Lam 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.8
In this report, we introduce a stable metamaterial perfect absorber at GHz frequency based on a novel design of a Mie-type resonance. A single perfect absorption peak is achieved at 9.54 GHz, and the influence of the structural parameters on the absorption behavior is studied; the results were consistent with dielectric-resonator theory. The absorption is demonstrated to be polarizationinsensitive; furthermore, the absorber structure can work for a wide incident angle without any change in the resonance peak. Our absorber structure can also control 47% of the resonance peak’s position by changing the temperature of the dielectric layer. Our absorber structure can also be applied as an electromagnetic-wave absorber for wide-incident-angle, thermally-controllable devices.