Negative refraction and subwavelength focusing in two-dimensional photonic crystals

Abstract

We experimentally and theoretically demonstrate negative refraction and focusing on electromagnetic (EM) waves by using two-dimensional photonic crystal slabs at microwave frequencies. Negative refraction is observed both for transverse magnetic (TM) and transverse electric (TE) polarized incident EM waves. Gaussian beam shifting method is used to verify negative refractive index. Subwavelength imaging and flat lens behavior of photonic crystals are successfully demonstrated. We have been able to overcome the diffraction limit and focus the EM waves to a spot size of 0.21θ. Metallodielectric photonic crystals are employed to increase the range of angles of incidence that results in negative refraction. Experimental results and theoretical calculations are in good agreement throughout the work.