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.
Highlights
Nonlinear optics induced by strong field has become a study hotspot, such as second or high harmonic [1,2,3,4,5], four-wave mixing [6], optical solitons [7,8,9,10], and optical bistability (OB) [11,12,13,14]
We explore the nonlinear optical properties in the aperiodic PT-symmetric lattices that were constructed by the Fibonacci sequence dielectrics
The gain in Fibonacci sequence dielectrics might be realized by doping Ge/Cr or nonlinear two-wave mixing [43,47,58,59], and the loss of material could result from acoustic modulators [60]
Summary
Nonlinear optics induced by strong field has become a study hotspot, such as second or high harmonic [1,2,3,4,5], four-wave mixing [6], optical solitons [7,8,9,10], and optical bistability (OB) [11,12,13,14]. Sci. 2019, 9, 5125 materials to form periodic distribution, it can achieve specific optical properties, such as the localization of light field [30,31,32], unidirectional transmission [33,34], directional cloaking [35], and solitons [36,37]. In the past, it mainly focused on the control of the real part for the index of refraction in periodic. We investigate the modulating of graphene chemical potential in the threshold of OB
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