  We consider a model of a particle trapped in a harmonic optical trap but with
the addition of a non-conservative radiation induced force. This model is known
to correctly describe experimentally observed trapped particle statistics for a
wide range of physical parameters such as temperature and pressure. We
theoretically analyse the effect of non-conservative force on the underlying
steady state distribution as well as the power spectrum for the particle
position. We compute perturbatively the probability distribution of the
resulting non-equilibrium steady states for all dynamical regimes, underdamped
through to overdamped and give expressions for the associated currents in phase
space (position and velocity). We also give the spectral density of the trapped
particle's position in all dynamical regimes and for any value of the
non-conservative force. Signatures of the presence non-conservative forces are
shown to be particularly strong for in the underdamped regime at low
frequencies.
