Bottle-shaped second harmonic generation with adjustable locations

Nonlinear photonic crystals (NPCs) have been widely used for studying nonlinear wave behaviors and in many applications requiring generation of light at new frequencies. In particular, the nonlinear photonic structures can be smartly designed to facilitate multiple functions in a single crystal. Here we show how to design a two-dimensional NPC to realize bottle-shaped second harmonic generation from a fundamental Gaussian beam with adjustable converging properties. The influences of structural parameters on the bottle beam generation are also investigated. These results are important for playing full potentials of NPCs and provide a convenient way to generate special beam at new frequencies with controllable properties.