Improving the imaging intensity of a photonic crystal flat lens by an antireflection method |
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Authors: | J Sun YF Shen LG Wang J Zhou Y Zhang YC Wang J Chen K Han G Tang |
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Institution: | 1. School of Sciences, China University of Mining and Technology, Xuzhou 221116, People’s Republic of China;2. Surface Physics Laboratory, Fudan University, Shanghai 200433, People’s Republic of China;3. Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117546, Singapore |
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Abstract: | In this paper, a two-dimensional photonic crystal (PC) consisting of a triangular lattice of silicon rods in air is studied theoretically. Equal-frequency contours (EFCs) analysis shows that this PC structure exhibits an effective refractive index neff = −1 at a normalized frequency ω=0.30×2πc/a. A superlens effect is demonstrated using this PC structure by the finite-difference time-domain (FDTD) simulation. An antireflection layer (ARL) is introduced into the PC slab surface in order to achieve a high-intensity image. Two point sources imaging process is also simulated both in the case of a perfect PC structure and in the case of a PC structure with an ARL. The results show that the method of introducing the ARL into the PC surface is effectual for improving both the intensity of the image and the capability of the super-resolution of two sources, which are in accord with the coupled-mode theory analysis. Theoretical study implies that the surface defect modes play an important role in enhancing the transmitted intensity of energy flow. |
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Keywords: | Photonic crystals Negative refraction Coupled-mode theory Super-resolution |
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