${ \mathcal P }{ \mathcal T }$-symmetric transport in non-${ \mathcal P }{ \mathcal T }$-symmetric bi-layer optical arrays

J Ramirez-Hernandez, F M Izrailev, N M Makarov, D N Christodoulides
2016 Journal of Optics  
We study transport properties of an array created by alternating (a,b) layers with balanced loss/gain characterized by the key parameter γ. It is shown that for non-equal widths of (a,b) layers, i.e., when the corresponding Hamiltonian is non-PT-symmetric, the system exhibits the scattering properties similar to those of truly PT-symmetric models provided that without loss/gain the structure presents the matched quarter stack. The inclusion of the loss/gain terms leads to an emergence of a
more » ... e number of spectral bands characterized by real values of the Bloch index. Each spectral band consists of a central region where the transmission coefficient T_N ≥ 1, and two side regions with T_N ≤ 1. At the borders between these regions the unidirectional reflectivity occurs. Also, the set of Fabry-Perrot resonances with T_N=1 are found in spite of the presence of loss/gain.
doi:10.1088/2040-8978/18/9/09lt01 fatcat:h2n4lkjojzhopimh5bf7btutvu