Optical bistability of a nondilute suspension of nonlinear coated particles

摘要

The intrinsic optical bistability (OB) of a nondilute suspension of coated spherical particles is investigated. We assume both the core and the shell to be nonlinear with third-order nonlinear susceptibilities chi(c) and chi(s) respectively, and thus the local field in the nonlinear core is not uniform and cannot be obtained exactly. In this connection, we establish the self-consistent mean field approximation, and obtain the spatial average of the local field squared in the nonlinear core (or the shell) as a function of the external applied field. We show that an optical bistable behavior exists only when the structure parameter (lambda) is less than the critical one lambda(c), which is dependent on the magnitude of both chi(c) and chi(s). Moreover, the bistable curves depend strongly on chi(c) and are weakly dependent on chi(s). In addition. the threshold intensity decreases with increasing lambda, and it can be lowered further by using a nondilute volume fraction. The field-dependent effective dielectric function is also studied, and the hysteretic loops are again found. (c) 2005 Elsevier B.V. All rights reserved.