Abstract
In this paper the focusing effect of flat metallic-slit array in micro-meter scale area is discussed and the role of surface plasmons waves inside slits is recognized. A proximate relationship between the equivalent focal length and slit material, slit geometrical parameters is built. The theoretically derived focal length and that from Finite Difference Time Domain (FDTD) simulation is proved to be in good agreement. Additionally, FWHM of focal point, focal depth and intensity of focal point for the slit array with invariant slit width and the slit array with variant slit width are compared as well. The slit array with varied slit width is found to have the better performance than slit array with invariant slit width.
(c) 2007 Optical Society of America.