Optical switching due to whispering gallery modes in dielectric microspheres coated by a Kerr material

We numerically evaluated the optical responses of a nonlinear microsphere put on prisms, i.e. in prism-coupling geometry where the incident light excites the WGM through near-field coupling. As numerical calculations, we employed the finite-difference time-domain method taking into account Kerr nonlinearity. The sphere was coated by a Kerr material with 160 nm thick. The third-order nonlinear susceptibility of the Kerr material chi(3) was assumed to be 7 x 10(-14)[m(2) V(-2)]. The diameter of the sphere was assumed to be 1 micro m. The numerical results have shown that the control and/or the signal lights can induce the optical switching-like variation in the reflectance. Such a nonlinear response of the sphere has been interpreted by the variation in the dielectric constant of the sphere due to a Kerr nonlinearity.