Reconfigurable coupler-based metallic photonic crystal lens and nematic liquid crystal

In this paper, a new design for a lens built around a two-dimensional (2D) metallic photonic crystal (PhC) platform with negative refractive index is proposed. The proposed lens has been composed of a silver layer with a triangular array of circular air holes. A three-dimensional geometric study performed with the aid of 2D finite element method results in focusing the light rays with intensity and FWHM of 10.5 and 1.7 mu m, respectively. The suggested lens is used to efficiently couple the light from a planar waveguide with a large spot size area into another PhC waveguide with a subwavelength spot size area. Additionally, filling the drilled holes in the proposed lens with nematic liquid crystal allows obtaining a reconfigurable lens with significant wave FWHM shaping with extinction ratios of about 8 dB. The proposed reconfigurable lens is used to couple two different waveguides with different coupling ratios. (c) 2018 Optical Society of America.