中文摘要：

Flat lenses are designed by means of graded negative refractive index-based photonic crystals(PCs) constructed using air-holes tuned with different shapes.By gradually modifying the filling factor along the transverse direction,we obtain the graded negative index-based lenses for the purpose of focusing an incident plane wave.The finite-difference and timedomain(FDTD) algorithm is adopted for numerical calculation.Our calculation results indicate that these lenses can finely focus incident plane waves.Moreover,for the same size of air-holes,the focusing properties of the lens with rectangular air-holes are better than those with the other shaped air-holes.The graded negative index PCs lenses could possibly enable new applications in optoelectronic systems.

英文摘要：

Flat lenses are designed by means of graded negative refractive index-based photonic crystals （PCs） constructed using air-holes tuned with different shapes. By gradually modifying the filling factor along the transverse direction, we obtain the graded negative index-based lenses for the purpose of focusing an incident plane wave. The finite-difference and timedomain （FDTD） algorithm is adopted for numerical calculation. Our calculation results indicate that these lenses can finely focus incident plane waves. Moreover, for the same size of air-holes, the focusing properties of the lens with rectangular air-holes are better than those with the other shaped air-holes. The graded negative index PCs lenses could possibly enable new applications in optoelectronic systems.