Opto-mechanical measurement of micro-trap via nonlinear cavity enhanced Raman scattering spectrum

High-gain resonant nonlinear Raman scattering on trapped cold atoms within a high-fineness ring optical cavity is simply explained under a nonlinear opto-mechanical mechanism, and a proposal using it to detect frequency of micro-trap on atom chip is presented. The enhancement of scattering spectrum is due to a coherent Raman conversion between two different cavity modes mediated by collective vibrations of atoms through nonlinear opto-mechanical couplings. The physical conditions of this technique are roughly estimated on Rubidium atoms, and a simple quantum analysis as well as a multi-body semiclassical simulation on this nonlinear Raman process is conducted.Comment: 7 pages, 2 figure

A Vlasov approach to bunching and selfordering of particles in optical resonators

We develop a Vlasov type continuum density description for the coupled nonlinear dynamics of polarizable particles moving in the light field of a high Q optical resonator. The intracavity light field, which exerts optical forces on the particles, depends itself on the dynamics of the particle density, which constitutes a time dependent refractive index. This induces mode frequency shifts, losses and coupling. For typical geometries we find solid analytic criteria for the stability of an initial homogeneous particle density for a wide class of initial velocity distributions including thermal distributions. These agree with previously found bunching and self-ordering instabilities but are extended to a wider range of parameters and initial conditions. Using a linear perturbation expansion we calculate the growth exponents of small density perturbations in the parameter region beyond this instability threshold. Numerical solutions of the full equations as well as simulations of the underlying many particle trajectories confirm these results. In addition the equations allow to extract analytical scaling laws to extrapolate cavity cooling and selfordering dynamics to higher particle numbers