Design and analysis of superlens based on complex two-dimensional square lattice photonic crystal

Abstract

We theoretically demonstrate the imaging properties of a complex two-dimensional (2D) face-centered square lattice photonic crystal (PC) made from germanium cylinders in air background. The finitedifference time-domain (FDTD) method is employed to calculate the band structure and simulate image construction. The band diagram of the complex structure is significantly compressed. Negative refraction occurs in the second energy band with negative phase velocity at a frequency of 0.228 (2πc/a), which is lower than results from previous studies. Lower negative refraction frequency leads to higher image resolution. Numerical results show that the spatial resolution of the system reaches 0.7296λ, which is lower than the incident wavelength.