Low Threshold Optical Bistability in Aperiodic PT-Symmetric Lattices Composited with Fibonacci Sequence Dielectrics and Graphene

Abstract

We explore the optical bistability in aperiodic parity–time-symmetric (PT-symmetric) photonic lattices that are composed of Fibonacci sequence dielectrics and graphene at terahertz frequencies. Two Fibonacci sequence dielectrics, viz. aperiodic photonic lattices, are utilized for enhancing band-edge resonances and achieving the electric field localization that can enhance the nonlinearity of graphene. Modulating the gain-loss factor of dielectrics in the PT symmetry lattices further strengthens the nonlinearity effect and, consequently, low threshold bistability is realized. The interval between the upper and lower bistability thresholds enlarges as the momentum relaxation time of graphene changes. Moreover, we show that the bistability threshold can also be flexibly tuned by modulating the graphene chemical potential. The study might be applied in photomemories and optical switches.

Tunable and giant spatial Goos–Hänchen shifts in a parity-time symmetric Cantor photonic crystals incorporated with a centered graphene layer

“…Several maiden ideas in the scope of parity-time metamaterials are inspiring the researchers in the past few years [5]. Many significant characteristics have been discovered and miscellaneous features have been widely studied in photonic crystals and heterostructures, such as weak localization of light [6][7][8], optical transparency and nonreciprocal propagation [9][10][11], coherent perfect absorber (CPA) laser and exceptional points [12][13][14], interacting graphene multilayers and quasiperiodic structures [6,[15][16][17][18][19] and giant Goos-Hänchen (GH) lateral shift [20][21][22][23][24][25][26]. Graphene which is a flat and a lossy monolayer of carbon material has a prominent optical and electronic properties.…”

Exceptional Points in Non-Hermitian Photonic Crystals Incorporated With a Defect

“…In recent years, complex photonic crystals (PCs) have provided a new opportunity to explore the non-Hermitian optical properties and other nonlinearities theoretically and experimentally [22][23][24][25][26][27][28]. Many significant optical characteristics have been discovered in PCs, such as solitons [29][30][31][32][33], topological modes [34,35], and strong absorptions [36][37][38][39].…”