Scattering approach to two-colour light forces and self-ordering of polarizable particles

S Ostermann, M Sonnleitner and H Ritsch

Collective coherent scattering of laser light by an ensemble of polarizable point particles creates long-range interactions, whose properties can be tailored by the choice of injected laser powers, frequencies, and polarizations. We use a transfer matrix approach to study the forces induced by non-interfering fields of orthogonal polarization or different frequencies in a 1D geometry, and find long-range self-ordering of particles without a prescribed order. Adjusting the laser frequencies and powers allows one to tune the inter-particle distances and provides a wide range of possible dynamical couplings not accessible in usual standing wave geometries with prescribed order. In this work, we restrict the examples to two frequencies and polarizations, but the framework also allows one to treat multicolour light beams with random phases. These dynamical effects should be observable in existing experimental setups with effective 1D geometries, such as atoms or nanoparticles coupled to the field of an optical nanofibre or transversely trapped in counter-propagating Gaussian beams.

DOI