Search

Optical systems obeying non-Hermitian dynamics have been the subject of intense and concerted investigation over the last two decades owing to their broad implications in photonics, acoustics, electronics as well as atomic physics. A vast majority of such investigations rely on a dissipative, balanced loss-gain system which introduces unavoidable noise and consequently, this limits the coherent control of propagation dynamics. Here, we show that an all-dielectric, non-dissipative photonic crystal (PC) could host, at least two exceptional points in its eigenvalue spectrum. By introducing optimum apodization in the PC architecture, namely 1D-APC, we show that such a configuration supports a spectrum of exceptional points which distinctly demarcates the PT-symmetric region from the region where PT -symmetry is broken in the parameter space. The analytical framework allows us to estimate the geometric phase of the reflected beam and derive the constraint that governs the excitation of topologically-protected optical Tamm-plasmon modes in 1D-APCs.

Adiabatic following has been an widely-employed technique for achieving near-complete population transfer in a two-level quantum mechanical system. The theoretical basis, however, could be generalized to a broad class of systems exhibiting SU(2) symmetry. In the present work, we present an analogy of population transfer dynamics of two level system with that of light propagation in a classical one-dimensional photonic crystal, commonly known as distributed-Bragg-reflector (DBR).This formalism facilitates in adapting the idea of adiabatic following, more precisely the rapid adiabatic passage (RAP) which is usually encountered in a broad class of quantum-mechanical systems.We present two different DBR configurations in which the adiabatic constraints are obeyed along the DBR length by virtue of optimum design. The reflection spectrum for both the configurations exhibit broadening of photonic bandgap (PBG) in addition to a varying degree of suppression of sharp transmission resonances. The inter modal coupling between counter-propagating modes as well as their phase-mismatch, for both the DBR configuration, exhibits a longitudinal variation which is usually observed in Allen-Eberly scheme of adiabatic population transfer in two-level atomic systems.

Supplementary document S1