Modeling nonlinear optical effects in arbitrary nanoparticles by the boundary element method

We present an accurate and versatile boundary element formulation to model nonlinear optical effects in nanoparticles. The nanoparticle shape is represented by triangular patches, which allows the use of very realistic geometrical models. The material may be piece-wise homogeneous, which is often the case in practice. The boundary-integral formulation allows the unknowns to be reduced to compact boundary surfaces, which then results in many desirable properties for the method. Consequently, surface and bulk second-order nonlinear effects can be conveniently modeled in the undepleted-pump approximation. We present results on second-harmonic imaging of gold nanobumps with focused radially polarized beam.