A Novel Design of Photonic Crystal Lens Based on Negative Refractive Index

In this study a concave lens based on two dimensional photonic crystal platform with negative refractive index is presented. The proposed lens is employed as a spot-size con- verter to facilitate coupling of the light from a single mode flbre with a large spot-size area into photonic crystal waveguide with a very small spot-size area, even smaller than the operating wavelength. Optimisation of the lens and its integration with the single mode flbre and photonic crystal waveguide into a single optical chip was performed by employing 2D Finite-Difierence Time-Domain (FDTD). A signiflcant reduction of the optical chip dimensions and high cou- pling e-ciency have been achieved by optimizing each device (the lens and the photonic crystal waveguide).