Luneburg lens composed of sunflower-type graded photonic Crystals

Sunflower-type graded photonic crystals (GPCs) are investigated and used to design the Luneburg lens for transverse electric (TE) and transverse-magnetic (TM) polarizations. Our investigation suggests that these novel structures present better focusing characteristics as well as wider transmission bandwidth for TM polarization than that for TE polarization. It is envisaged that these sunflower-type GPCs can be potentially used in optical system where compact and powerful focusing elements are required such as the Luneburg lens.