Local parity-time symmetry functional devices for integrated optics

We address the potential of a system with gain and loss featuring a PT-symmetric configuration for the realization of tunable, reconfigurable and non-reciprocal devices. By using PT-symmetric coupled waveguides and Bragg reflectors as fundamental building blocks, it is possible to build a wide variety of functional optical devices such as switches, unidirectional Bragg gratings, reconfigurable modal demultiplexers etc. The use of nonuniform coupling or gain-loss modulation profiles further brings a number of advantages as compared to the uniform PT-symmetric structures. The disruptive paradigm of the PT-symmetry could thus provide a major boost to integrated optics and is expected to foster a new generation of tunable, reconfigurable and non-reciprocal devices.