利用平面波展开方法计算了波状结构二维光子晶体(2DPC)的等频面,对等频面内矩形轮廓的等频线进行研究,提出了波状结构2DPC的自准直特性,运用时域有限差分(FDTD)方法模拟了波状结构2DPC在不同入射角情况下对所入射高斯光束的自准直作用.将波状结构2DPC的自准直特性运用到近场亚波长成像,模拟了波状结构2DPC的自准直亚波长成像效果,单光源的成像分辨率达到0.28λ,且随着光源逐渐远离近场范围而降低.
The equal-frequency surface of wavy two-dimensional (2D) photonic crystals (PC) is obtained by virtue of plane wave expansion method. From the equal-frequency surface, we find a iso-frequency contour of rectangular form. A flat dispersion relation exists at this frequency, which is suitable for the self-collimation. The finite-difference time-domain (FDTD) method is used to simulate the self-collimation in wavy 2DPC on which a Gaussian beam is incident at different angles. Subwavelength lensing by self-collimation is also available in wavy 2DPC. The resolution of 0. 283, is achieved when single source is employed in simulation. The resolution will gradually degrade as the source moves beyond the near-field domain.