Subwavelength optical imaging through a silver nanorod

We numerically investigated subwavelength imaging in a silver nanorod of 50-nm height and 20-nm diam buried in dielectric background (SiO₂) with a finite-difference time-domain (FDTD) method in the three dimensions. The near-field components of the Gaussian incident beam were plasmonically transferred through the input end of a silver nanorod to reproduce the light distributions of the incident wave at the output end. The field distributions were calculated at the different sectional planes of the rods, and it was found that the spatial resolution was less than 40 nm given by the rod size, which is much beyond the diffraction limit of the conventional imaging system. The field intensity in the image plane was well resolved due to the collection of surface plasmon polaritons. The behaviors of the three components of field distribution at entrance and exit from the nanorod and the influences of the optical field distribution generated by some factors are also discussed in detail. The proposed structure possesses a deep transfer of super-resolution image and can be used with image transfer. © 2007 Society of Photo-Optical Instrumentation Engineers.