Unique multistable states in periodic structures with saturable nonlinearity. I. Conventional case and unbroken $\mathcal{PT}$-symmetric regime

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Auteurs principaux: Raja, S. Vignesh, Govindarajan, A., Lakshmanan, M.
Format: Preprint
Publié: 2024
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author Raja, S. Vignesh
Govindarajan, A.
Lakshmanan, M.
author_facet Raja, S. Vignesh
Govindarajan, A.
Lakshmanan, M.
contents In this work, we predict that periodic structures without gain and loss do not exhibit an S-shaped hysteresis curve in the presence of saturable nonlinearity (SNL). Instead, the input-output characteristics of the system admit ramp-like optical bistability (OB) and multistability (OM) curves that are unprecedented in the context of conventional periodic structures in the literature. An increase in the nonlinearity (NL) or the gain-loss parameter increases the switch-up and down intensities of different stable branches in a ramp-like OM curve. Revival of the typical S-shaped hysteresis curve requires the device to work under the combined influence of frequency detuning and $\mathcal{PT}$-symmetry. An increase in the detuning, NL and gain-loss parameters reduces the switching intensities of the S-shaped OB (OM) curves. During the process, mixed OM curves that feature a fusion between ramp-like and S-shaped OM curves emanate at low values of the detuning parameter in the input-output characteristics. The detuning parameter values for which ramp-like, S-shaped, and mixed OM appear varies with the NL coefficient. For a given range of input intensities, the number of stable states admitted by the system increases with the device length or NL. When the laser light enters the device from the opposite end of the grating, nonreciprocal switching occurs at ultra-low intensities via an interplay between NL, detuning, and gain-loss parameters.
format Preprint
id arxiv_https___arxiv_org_abs_2404_13724
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Unique multistable states in periodic structures with saturable nonlinearity. I. Conventional case and unbroken $\mathcal{PT}$-symmetric regime
Raja, S. Vignesh
Govindarajan, A.
Lakshmanan, M.
Optics
Pattern Formation and Solitons
In this work, we predict that periodic structures without gain and loss do not exhibit an S-shaped hysteresis curve in the presence of saturable nonlinearity (SNL). Instead, the input-output characteristics of the system admit ramp-like optical bistability (OB) and multistability (OM) curves that are unprecedented in the context of conventional periodic structures in the literature. An increase in the nonlinearity (NL) or the gain-loss parameter increases the switch-up and down intensities of different stable branches in a ramp-like OM curve. Revival of the typical S-shaped hysteresis curve requires the device to work under the combined influence of frequency detuning and $\mathcal{PT}$-symmetry. An increase in the detuning, NL and gain-loss parameters reduces the switching intensities of the S-shaped OB (OM) curves. During the process, mixed OM curves that feature a fusion between ramp-like and S-shaped OM curves emanate at low values of the detuning parameter in the input-output characteristics. The detuning parameter values for which ramp-like, S-shaped, and mixed OM appear varies with the NL coefficient. For a given range of input intensities, the number of stable states admitted by the system increases with the device length or NL. When the laser light enters the device from the opposite end of the grating, nonreciprocal switching occurs at ultra-low intensities via an interplay between NL, detuning, and gain-loss parameters.
title Unique multistable states in periodic structures with saturable nonlinearity. I. Conventional case and unbroken $\mathcal{PT}$-symmetric regime
topic Optics
Pattern Formation and Solitons
url https://arxiv.org/abs/2404.13724