Improving unrestricted imaging quality of a triangular lattice photonic crystal slab by modifying surface configuration |
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Authors: | J Sun YF Shen J ChenLG Wang J ZhouY Zhang K HanG Tang |
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Institution: | a School of Sciences, China University of Mining and Technology, Xuzhou 221116, People''s Republic of China b Surface Physics Laboratory, Fudan University, Shanghai 200433, People''s Republic of China c Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117546, Singapore |
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Abstract: | We propose a photonic crystal (PC) structure only by replacing square lattice Luo et al. (2002) 12]] with triangular lattice to obtain an unrestricted imaging. Equal-frequency contours (EFCs) analysis shows that this triangular lattice two-dimensional PC exhibits an effective isotropic refractive index neff=−1 at a normalized frequency ω=0.291×2πc/a. Imaging quality of this triangular lattice PC slab involving both power intensity and full-width at half-maximum intensity of the image is studied using the finite-difference time-domain (FDTD) simulation. In order to achieve a high-quality image, an appropriate surface termination is chosen. In addition, by adjusting the surface air-hole radius of the PC slab, the imaging quality can be further improved. Coupled-mode theory analysis shows that the optimized surface termination and the adjusted surface air-hole can excite two kinds of surface modes that can couple with the Bloch wave in the PC. With the help of these surface modes, both the intensity of image and the super-resolution capacity of this triangular lattice PC slab can be improved greatly. |
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Keywords: | Photonic crystals Negative refraction Coupled-mode theory Super-resolution |
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