We design an on-chip single mode photon to surface-plasmon coupler. Our coupler consists of a tapered dielectric waveguide and a V-shaped plasmonic part. In contrast to other concepts designated to minimized-loss coupling into long-ranging waveguides, we focus on an easy-to-fabricate structure working in the visible spectral range. The air-cladded design provides full experimental access to the evanescent fields emerging from the plasmonic stripe guide. An adaptive finite element method for full three dimensional simulations is used combined with the Taguchi method for optimization, which makes our procedure extremely time-efficient and executable on standard personal computers.