Polarization switching in a ring cavity with resonantly drivenJ=1/2 toJ=1/2 atoms

We have solved within the mean field limit for the steady state behaviour of a gas ofJ=1/2 toJ=1/2 model atoms in a ring cavity excited by an incident laser field of arbitrary polarization. Results are presented for the case of zero applied magnetic field and exact resonance between the laser frequency, the atomic transition and a cavity resonance (pure absorptive case). We find that the behaviour of the polarization switching between ⁺ and ^– outputs depends on the values of the upper and lower state collisional relaxation rates, expressed via a single parameter . The case of linearly polarized input is of particular interest since optical bistability is found to occur for 2, being pre-empted by polarization switching for >2. The results are discussed in terms of an atomic feedback mechanism coupling the ⁺ and ^– modes.