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 χ⁽³⁾ was assumed to be 7 × 10^?14m² V^?2]. The diameter of the sphere was assumed to be 1 µm. 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.