Beat-like frequency pattern of extraordinary transmission and reflection in PT-symmetric Fibonacci aperiodic optical networks of waveguide rings

In parity-time-symmetric (PT-symmetric) Fibonacci ordered-aperiodic optical networks of waveguide rings, the beat-like pattern of the frequencies corresponding to maximum extraordinary transmission and reflection is investigated. It is found that, resembling acoustic resonance and optical beat, when these frequencies between two contiguous Fibonacci generations are sufficiently close and within a certain limit, the transmission and reflection of the following generation become stronger than those of the previous two; otherwise, they are weakened. These properties are the combined results of the optical PT symmetry and the inherent self-repeating pattern of the Fibonacci ordering, which might deepen the understandings and provide a fresh perspective on the PT-symmetric ordered-aperiodic and disordered systems. (C) 2019 Elsevier B.V. All rights reserved.