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Search Results: 1 - 10 of 23246 matches for " Sailing He "
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Can Maxwell's Fish Eye Lens Really Give Perfect Imaging?
Fei Sun;Sailing He
PIER , 2010, DOI: 10.2528/PIER10091003
Abstract: Both explicit analysis and FEM numerical simulation are used to analyze the field distribution of a line current in the so-called Maxwell's fish eye lens [bounded with a perfectly electrical conductor (PEC) boundary]. We show that such a 2D Maxwell's fish eye lens cannot give perfect imaging due to the fact that high order modes of the object field can hardly reach the image point in Maxwell's fish eye lens. If only zeroth order mode is excited, a good image of a sharp object may be achieved in some cases, however, its spot-size is larger than the spot size of the initial object field. The image resolution is determined by the field spot size of the image corresponding to the zeroth order component of the object field. Our explicit analysis consists very well with the FEM results for a fish eye lens. Time-domain simulation is also given to verify our conclusion. Multi-point images for a single object point are also demonstrated.
Create a Uniform Static Magnetic Field Over 50 T in a Large Free Space Region
Fei Sun;Sailing He
PIER , 2013, DOI: 10.2528/PIER13012802
Abstract: We propose a compact passive device as a super-concentrator to obtain an extremely high uniform static magnetic field over 50 T in a large two-dimensional free space in the presence of a uniform weak background magnetic field. Our design is based on transformation optics and metamaterials for static magnetic fields. Finite element method (FEM) is utilized to verify the performance of the proposed device.
High-subwavelength-resolution imaging of multilayered structures consisting of alternating negative-permittivty and dielectric layers with flattened transmission curves
Yi Jin,Sailing He
Physics , 2008,
Abstract: Multilayered structures consisting of alternating negative-permittivity and dielectric layers are explored to obtain high-resolution imaging of subwavelength objects. The peaks with the smallest |ky| (ky is the transverse wave vector) on the transmission curves, which come from the guided modes of the multilayered structures, can not be completely damped by material loss. This makes the amplitudes of the evanescent waves around these peaks inappropriate after transmitted through the imaging structures, and the imaging quality is not good. To solve such a problem, the permittivity of the dielectric layers is appropriately chosen to make these sharp peaks merge with their neighboring peaks. Wide flat upheavals are then generated on the transmission curves so that evanescent waves in a large range are transmitted through the structures with appropriate amplitudes. In addition, it is found that the sharp peaks with the smallest |ky| can be eliminated by adding appropriate coating layers and wide flat upheavals can also be obtained.
On subwavelength imaging of Maxwell's fish eye lens
Fei Sun,Sailing He
Physics , 2010,
Abstract: Both explicit analysis and FEM numerical simulation are used to analyze the field distribution of a line current in the so-called Maxwell's fish eye lens, which has been claimed recently to be able to achieve perfect imaging. We show that such a Maxwell's fish eye lens cannot give perfect imaging due to the fact that high order modes of the object field can hardly reach the image point in the Maxwell's fish eye. If only zero order mode is excited, a subwavelength image can be achieved, however, its spot-size is larger than the spot size of the source field. The image resolution is determined by the field spot size of the image corresponding to the zeroth order component of the object field. Our explicit analysis consists very well with the FEM results for a modified fish eye bounded with perfectly electrical conductor (PEC). Explicit condition is given for achieving a subwavelength image. When this condition is not satisfied, a single line current source may give multiple image spots.
90 degree polarization rotator using a bilayered chiral metamaterial with giant optical activity
Yuqian Ye,Sailing He
Physics , 2010, DOI: 10.1063/1.3429683
Abstract: A bilayered chiral metamaterial (CMM) is proposed to realize a 90 degree polarization rotator, whose giant optical activity is due to the transverse magnetic dipole coupling among the metallic wire pairs of enantiomeric patterns. By transmission through this thin bilayered structure of less than \lambda/30 thick, a linearly polarized wave is converted to its cross polarization with a resonant polarization conversion efficiency (PCE) of over 90%. Meanwhile, the axial ratio of the transmitted wave is better than 40 dB. It is demonstrated that the chirality in the propagation direction makes this efficient cross-polarization conversion possible. The transversely isotropic property of this polarization rotator is also experimentally verified. The optical activity of the present structure is about 2700 degree/\lambda, which is the largest optical activity that can be found in literature.
Enhancing extraordinary transmission of light through a metallic nano slit with a nano cavity antenna
Yanxia Cui,Sailing He
Physics , 2008,
Abstract: The extraordinary transmission of light through a nano slit in a metal film is enhanced by introducing a nano cavity antenna formed by a nearby metallic nano-strip over the slit opening. For a fixed wavelength, the width of the metallic nano-strip should be chosen to make the horizontal metal-insulator-metal waveguide of finite length resonant as a Fabry-Perot cavity. When such a cavity antenna is used to enhance the transmission through a non-resonant nano slit, the slit should be opened at a position with maximal magnetic field in the horizontal resonant cavity. It is shown that an optimized cavity antenna can enhance greatly the transmission of light through a non-resonant nano slit (by about 20 times) or a resonant nano slit (by 124%). The transmission spectrum of the nano slit can also be tuned by adjusting the width of the metallic nano-strip. Such a transmission enhancement with a nano cavity antenna is studied for the first time and the physical mechanism is explained.
A theoretical revisit of giant transmission of light through a metallic nano-slit surrounded with periodic grooves
Yanxia Cui,Sailing He
Physics , 2009, DOI: 10.1364/OE.17.013995
Abstract: The giant transmission of light through a metallic nano-slit surrounded by periodic grooves on the input surface is revisited theoretically. It is shown that the influence to the transmission comes from three parts: the groove-generated surface plasmon wave (SPW), the nano-slit-generated SPW and the incident wave. The groove-generated SPW is the main factor determining the local field distribution around the nano-slit opening, which is directly related to the transmission through the nano-slit. The nano-slit-generated SPW can be considered as a disturbance to the light distribution on the input surface. The influence of the incident wave can be strongly reduced when strong surface plasmon wave is generated on the input surface by many periods of deep grooves. Our study shows that the slit-to-groove distance for a maximal transmission through the nano-slit surrounded with periodic grooves can not be predicted by several previous theories, including the magnetic field phase theory of a recent work (Phys. Rev. Lett. 99, 043902, 2007). A clear physical explanation is given for the dependence of the transmission on the slit-to-groove distance.
Optical Magnetic Response in a Single Metal Nanobrick
Jianwei Tang,Sailing He
Physics , 2011,
Abstract: Anti-symmetric localized surface plasmons are demonstrated on a single silver nanostrip sandwiched by SiC layers. By employing the resonance of anti-symmetric localized surface plasmons, we enable single metal nanobricks to produce optical magnetism, in the blue and violet light range, as well as in a part of the ultraviolet light range. The physical mechanism is explained.
Degeneracy analysis for a super cell of a photonic crystal and its application to the creation of band gaps
Liang Wu,Sailing He
Physics , 2002, DOI: 10.1103/PhysRevE.67.026612
Abstract: A method is introduced to analyze the degeneracy properties of the band structure of a photonic crystal making use of the super cells. The band structure associated with a super cell of a photonic crystal has degeneracies at the edge of the Brillouin zone if the photonic crystal has some kind of point group symmetry. Both E-polarization and H-polarization cases have the same degeneracies for a 2-dimensional (2D) photonic crystal. Two theorems are given and proved. These degeneracies can be lifted to create photonic band gaps by changing the transform matrix between the super cell and the smallest unit cell. The existence of the photonic band gaps for many known 2D photonic crystals is explained through the degeneracy analysis.
Imaging Studies of Characteristics for a Slab of a Lossy Left-handed Material
Linfang Shen,Sailing He
Physics , 2003, DOI: 10.1016/S0375-9601(03)00168-3
Abstract: The characteristics of an imaging system formed by a slab of a lossy left-handed material (LHM) are studied. The transfer function of the LHM imaging system is written in an appropriate product form with each term having a clear physical interpretation. A tiny loss of the LHM may suppress the transmission of evanescent waves through the LHM slab and this is explained physically. An analytical expression for the resolution of the imaging system is derived. It is shown that it is impossible to make a subwavelength imaging by using a realistic LHM imaging system unless the LHM slab is much thinner than the wavelength.
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