Subwavelength focusing by a micro/nanofiber array

Utilizing the diffraction property of the output light from micro/nano fibers (MNFs), a new scheme based on a MNF array to focus optical beams with subwavelength resolution in the far field is proposed. By using the three-dimensional finite-difference beam-propagation method (FD-BPM), we investigated the diffraction interference effect of the MNFs during light propagation. The numerical stimulation demonstrates a focusing spot with FWHM of 0.43 lambda at a distance of 9 lambda from the output endface of MNF array. The effects of the characteristics of the array, the MNFs, and the input optical field on focusing are analyzed in detail.