Single frequency semiconductor laser exploiting the concept of Parity-Time symmetry

The principle of gain-loss modulation lying in the heart of Parity-Time symmetric optics is exploited for realization of single frequency DFB lasers. Due to the “unidirectional” gain discrimination mechanism induced by the complex refractive index Bragg grating, it is expected that the coherence of such a laser would be highly tolerant with respect to the optical feedback.