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Wei Z.,Tongji University | Wei Z.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology | Li H.,Tongji University | Li H.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology | And 11 more authors.
Optics Express | Year: 2010

We report for the first time that an ultra-thin hybrid metamaterial slab can reflect an incident plane wave in -1st diffraction order, giving rise to anomalous reflection in a "negative" way. The functionality is derived from the hybridized surface resonant states of the slab. The retro-directive reflection is demonstrated numerically for a Gaussian beam at oblique incidence and verified experimentally at microwave frequencies. © 2010 Optical Society of America.


Wu C.,Tongji University | Wu C.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology | Li H.,Tongji University | Wei Z.,Tongji University | And 4 more authors.
Physical Review Letters | Year: 2010

We developed a theory to compute and interpret the photonic band structure of a periodic array of metallic helices. Interesting features of the band structure include longitudinal and circularly polarized eigenmodes and wide polarization gap. The helical symmetry also implies unusual features such as negative group velocity bands at both sides of the polarization gap and band crossings pinned at the zone boundary. A direct proof of negative refraction via a chiral route is achieved for the first time by measuring the spatial beam shift through a slab of the three-dimensional helices. © 2010 The American Physical Society.


Gao W.,Hong Kong University of Science and Technology | Leung H.M.,Hong Kong University of Science and Technology | Li Y.,Hong Kong University of Science and Technology | Li Y.,Tongji University | And 4 more authors.
Journal of Optics | Year: 2011

We report on the fabrication of double-layer gold crossed-gratings consisting of a convoluted top gold grating superposed on a bottom gold grating by using an e-beam direct write technique together with a lift-off process. The crossed-gratings exhibit, in the visible range, strong circular dichroism which is dependent upon the incident direction due to the convoluted top gold grating and also the substrate. Resonance dips in the transmittance of circularly polarized light are also observed. The experimental results are explained qualitatively by simulations using a finite-integration technique. The simulations confirm that the dips in the transmittance are electromagnetic resonances corresponding to parallel and anti-parallel current flows in the crossed-gratings. © 2011 IOP Publishing Ltd.


Zhang Z.,Tongji University | Du G.,Tongji University | Du G.,Shandong University | Jiang H.,Tongji University | And 7 more authors.
Journal of the Optical Society of America B: Optical Physics | Year: 2010

We theoretically demonstrate that complete absorption of light can be realized in a heterostructure composed of a thick metal film and truncated photonic crystals with a lossy dielectric defect. Because of the coupling between the interface mode and the defect mode, all of the light can enter the heterostructure. Meanwhile, the fields are enhanced remarkably in the defect, so the light is fully absorbed by the lossy defect. When the coupling between two different localized modes is strong, two absorption peaks are obtained, while a weak coupling leads to a narrow absorption band due to the degeneracy of two localized modes. © 2010 Optical Society of America.


Jiao H.,Tongji University | Jiao H.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology | Ding T.,Tongji University | Ding T.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology | And 2 more authors.
Optics Express | Year: 2011

A comparative study of laser induced damage of HfO2/SiO 2 and TiO2/SiO2 mirrors at 1064 nm has been carried out. One TiO2/SiO2 mirror with absorption of 300 ppm and two HfO2/SiO2 mirrors with absorption of 40 and 4.5 ppm were fabricated using electron beam evaporation method. For r-on-1 test, all HfO2/SiO2 mirrors with low average absorption are above 150 J/cm2 at 10ns. However, the TiO2/SiO2 mirrors with high average absorption are just 9.5 J/cm2, which are probably due to the rather high absorption and rather low band gap energy. Meanwhile, all the samples were irradiated from front and back side respectively using the raster scan test mode. In case of front side irradiation, it is found that: for TiO2/SiO2 high reflectors, the representative damage morphologies are shallow pits that were probably caused by absorbing centers. However, for HfO2/SiO2 high reflectors, the dominant damage morphologies are micrometer-sized nodules ejected pits and the delamination initiating from the pits. The absorption of HfO2/ SiO2 coatings is low enough to have minor influence on the laser damage resistance. In case of backside irradiation, the morphology of TiO 2/SiO2 mirrors is mainly center melted pits that are thermal melting induced damage. Meanwhile, HfO2/SiO2 mirrors with isometrical fracture rings damage morphology are thermal induced stress damage. © 2011 Optical Society of America.


Wang Z.-L.,Tongji University | Wang Z.-L.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology | Jiang H.-T.,Tongji University | Jiang H.-T.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology | And 4 more authors.
Optics Express | Year: 2010

Self-collimations are found in one-dimensional (ID) photonic crystals consisting of two kinds of single-negative materials that effectively cancel each other out. Compared to the self-collimations in all-dielectric photonic crystals or ID photonic crystals with negative-index materials, this kind of structure can amplify both far and near fields greatly during collimation. © 2010 Optical Society of America.


Jinlong Z.,Tongji University | Jinlong Z.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology | Xinbin C.,Tongji University | Xinbin C.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology | And 6 more authors.
Applied Optics | Year: 2011

A HfO2/SiO2 chirped mirror was manufactured by electron beam evaporation to increase the laser resistance. The hybrid monitoring strategy utilizing both monochromatic monitoring and quartz crystal monitoring was applied to the deposition compared to the single optical monitoring method. The coatings were characterized by transmission spectrophotometer and white light interferometry, and the experimental results showed that the chirped mirror monitored with the hybrid strategy possessed high reflectivity (>99:7%) and tolerable group delay dispersion oscillation (-50 ± 20 fs2) in the spectra range of 740-860nm. © 2011 Optical Society of America.


Wang X.,Tongji University | Wang X.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology | Zheng H.,Tongji University | Zheng H.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology
Journal of Solution Chemistry | Year: 2011

In order to obtain the electronic structure of leucine (Leu) in aqueous solution, we studied three systems: Leu+7H2O, Leu+8H2O and Leu+9H2O. The results indicated that the system Leu +8H2O was the only choice which was both acceptable and doable: its computational effort was affordable, and it could simulate a main part of the solvent effect on the electronic structure of Leu in solution. Based on the system Leu+8H 2O, all-electron, ab initio calculations were performed to construct an equivalent potential of water for the electronic structure of Leu with dipoles. The results showed that the main effect of water on the electronic structure of Leu was raising the occupied states about 0.0824 Ry on average, and broadening the energy gap by 11%. The water effect on the electronic structure of Leu could be well simulated by the dipole potential. The obtained equivalent potential can be applied directly to the electronic structure calculation of proteins in solution. © Springer Science+Business Media, LLC 2011.


Zhang J.,China Jiliang University | Zhang J.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology | Liu J.,China Jiliang University | Huang X.,China Jiliang University | And 2 more authors.
Physica Status Solidi (A) Applications and Materials Science | Year: 2012

Ba0.4Sr0.6Ti1-yCoyO3 ceramics show a diphase of Ba1-xSrxTiO3 and 6H-hexagonal BaTi1-yCoyO3. As y increases, Ba0.4Sr0.6Ti1-yCoyO3 ceramics experience a transformation from ferroelectric to relaxor-like behavior. For the samples with y ≥ 0.10, the dielectric constant exhibits relaxor-like behavior with the frequency-dependent temperature of the dielectric peak Tm following an Arrhenius law, accompanying a giant dielectric response. The dielectric relaxation with an extremely high dielectric peak is attributed to charge ordering and defects. The samples with low Co levels (y ≤ 0.05) exhibit dielectric nonlinear behavior, whereas those with high Co levels (y ≥ 0.10) have ferromagnetic properties. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Li X.,Tongji University | Li X.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology | Shen J.,Tongji University | Shen J.,Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology
Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams | Year: 2010

The mechanism of laser induced damage on optical films, and the methods to improve the laser-induced damage threshold(LIDT) were reviewed in two respects including theory and experiment. We summarized the existing theory models and their applicable scope, and also discussed the problems about defects from various aspects. The characteristics of different coating technics and after-treatment ways were compared in detail. By gathering the achievements of our own and peer institutions at home and abroad, we generalized the sol-gel technics which could be used to improve the LIDT. We also pointed out the direction of future work considering some newly emerging problems such as contamination in vacuum and the subsurface damage.

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