Flat transformation optics graded-index (TO-GRIN) lenses

This paper illustrates the use of quasi-conformal (QC) transformation optics (TO) techniques to design flat gradient-index (GRIN) lenses as replacements for conventional optical lenses. Three flat TO lenses are considered to demonstrate the flexibility of the new design approach. Two dimensional (2D) Finite-Difference Time Domain (FDTD) simulations show equivalent performance between the original lenses and the flat TO lenses. Furthermore, a body of revolution (BOR) FDTD method was developed and employed to characterize the imaging properties of the three dimensional (3D) cylindrical lenses, validating the predictions of 2D simulations. These designs only require spatially-varying dielectric materials with no magnetic properties, facilitating low-loss, broadband operation in both the microwave and optical regimes.