Measurements of Radiation Pressure owing to the Grating Momentum

The force from radiation pressure owing to the grating momentum was measured for a thin transmissive fused silica grating near the Littrow angles at wavelengths of 808 nm and 447 nm. A significant magnitude of force was measured in the direction parallel to the grating surface. We also confirmed that the component of force normal to the grating surface may vanish. This forcing law is characteristically different from radiation pressure on a reflective surface, and thus, opens new opportunities for light-driven applications such as solar or laser driven sailcraft, or the transport of objects in liquids.