Scattering Forces within a Left-Handed Photonic Crystal.

Electromagnetic waves are known to exert optical forces on particles through radiation pressure. It was hypothesized previously that electromagnetic waves inside left-handed metamaterials produce negative radiation pressure. Here we numerically examine optical forces inside left-handed photonic crystals demonstrating negative refraction and reversed phase propagation. We demonstrate that even though the direction of force might not follow the flow of energy, the positive radiation pressure is maintained inside photonic crystals.