Takakazu YONEZAWA^*, Masahiro DAIBO, and Norio TAYAMA

Graduate School of Engineering, Iwate University, Morioka 020-8551, Japan

(Received January 29, 2007; Accepted August 29, 2007)

In a planar lens made of left-handed material (LHM), the rays converge to a focal point in the material and once again in free space. The problems exhibited by the planar lens are its great thickness, the long optical path length, and energy concentration in the LHM. We examine a bowl-shaped LHM lens with an index n = -1. In this lens, the back is a concave hemispherical surface and the rays never converge in the LHM, but in free space only. We also designed a quantized bowl-shaped LHM lens composed of multiple layers of thin LHM plates of uniform thickness. A bowl-shaped LHM lens quantized with more than 4 bits has a lens function similar to that of a smooth curved lens. The bowl-shaped lens is characterized by its thinness, its short optical path length, and the absence of energy concentration in the LHM. Furthermore, the quantized bowl-shaped LHM lens can be fabricated. Wave propagation through these lenses is numerically simulated using the finite difference time domain (FDTD) method.

Key words: left-handed material (LHM), planar lens, concave hemispherical surface, power density, quantized lens, finite difference time domain (FDTD) method

^*E-mail address: yonezawa@pipe.elc.iwate-u.ac.jp