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Acta Physica Sinica

Optical bistability in graded granular composites

Yamin Wu, Guoqing Chen, 江南大学理学院，无锡 214122

Published Jan 1, 2010• 0 citations
Publisher

Abstract

We studied the intrinsic optical bistability(OB) of coated spherical particles with graded dielectric profiles.According to Maxwell equations, we obtained the spatial average of the local field in the core as a function of the external applied field. Numerical results for power-law graded profiles show that the optical bistable behavior is dependent on the shell thickness and the power-laws exponent k. The interval of optical bistability increases with increasing shell thickness or increasing k. In addition, the field-dependent reflectance at normal incidence R in random composites is also investigated, and a hysteretic loop is observed.

DOI
10.7498/aps.59.592

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The intrinsic optical bistability (OB) of graded core-shell granular composites is investigated. The coated particles are made of cores with gradient dielectric function ∊ c (r) = A(r/a) k and nonlinear shells. In view of the exponential distribution of the core dielectric constant, the potential functions of each region are obtained by solving the Maxwell equations, and the mathematical expressions of electric field in the shells and cores are determined. Numerical study reveals that the optical bistable threshold and the threshold width of the composite medium are dependent on the shell thickness, core dielectric exponent, and power function coefficient. The optical bistable width increases with the decreasing shell thickness and the power exponent and with the increasing power function coefficient.
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