Bifurcated overtones of one-way localized Fabry–Pérot resonances in parity-time symmetric optical lattices

Gaafer Fatma Nafaa¹, Shen Yaxi¹, Peng Yugui¹, Wu Aimin^{2, †}, Zhang Peng^{3, ‡}, Zhu Xuefeng^{1, 2, 4, §}

(color online) Field distributions at FP resonances in the PT resonator. (a) Electric field distributions for the light propagating from the left and the right through the PT resonator at FP resonances (n = 0, , , ), where the field is observed to be unidirectionally localized. The blue and red curves of field distributions in panels (b), (c), and (d) present the spatial modal degeneracy for , , and , respectively.