Opt. Express 20, 8907–8914 (2012)

Light typically exerts a positive radiation pressure (a pushing force) on an object. Jonathan Nemirovsky, Mikael Rechtsman and Mordechai Segev from Technion in Israel have proposed a new technique that could be used to achieve negative radiation pressure in a medium with antiparallel group and phase velocities. Realizing this phenomenon has proved difficult because the media explored so far are either solids, which prohibit particle motion, or structured on a subwavelength level and therefore exhibit large electromagnetic losses. The researchers propose the use of a dielectric slab waveguide structure that has a large (up to tens of wavelengths in length) gap in the middle to allow particles to propagate. The structure consists of a gap sandwiched between two biaxial slabs, followed by uniaxial layers and clad with a Bragg grating. The layers can then be designed so that the light energy (and group velocity) moves in one direction but the phase velocity, inside the central gap layer, moves in the opposite direction. Particles in the gap should experience a force in the direction of the phase velocity, in a direction opposite to the energy flow.