  We present the design and simulation of a three-dimensional photonic crystal
waveguide for linear laser-driven acceleration in vacuum. The structure
confines a synchronous speed-of-light accelerating mode in both transverse
dimensions. We report the properties of this mode, including sustainable
gradient and optical-to-beam efficiency. We present a novel method for
confining a particle beam using optical fields as focusing elements. This
technique, combined with careful structure design, is shown to have a large
dynamic aperture and minimal emittance growth, even over millions of optical
wavelengths.
