PT symmetric phase transition and photonic transmission in an optical trimer system

Parity-time (PT) symmetric structures have exhibited potential applications in developing various robust quantum devices. In an optical trimer with balanced loss and gain, we analytically study the PT symmetric phase transition by investigating the spontaneous symmetric breaking. We also illustrate the asymmetric photonic transmission behaviors in both of the PT symmetric and PT symmetry broken phases. We find (i) the non-periodical dynamics of photonic transmission in the PT symmetry broken phase instead of PT symmetric phase can be regarded as a signature of phase transition; and (ii) it shows asymmetric photonic transmission behavior in both of the phases but comes from different underlying physical mechanisms. The obtained results may be useful to implement the photonic devices based on coupled-cavity system. (C) 2017 Optical Society of America