PT-Symmetric Optical Materials and Structures

The objective of this program was to pursue basic research that could potentially lead to new opportunities in science and engineering by harnessing parity-time (PT) symmetry concepts in optics and other fields of physics, engineering, and chemistry. As indicated in studies by our groups and others, PT symmetry and non-Hermiticity in general can provide a new avenue for molding the flow of light by judiciously incorporating both optical gain and loss in photonic structures and materials. In such settings, this non-Hermitian symmetry can lead to unusual and previously unattainable light propagation characteristics. Along these lines, optical active devices have been investigated that could respond with enhanced sensitivities to external signals, and strategies have been developed to exploit non-Hermitian singularities-better known as exceptional points. One of the goals of this effort was to investigate optical materials that exhibit substantial amount of optical gain, needed to implement PT-symmetric configurations. In this regard, special emphasis was given to polymeric materials and active semiconductor systems that in principle can exhibit very high optical amplification coefficients.