Efficient uni- and bi-directional oscillations in photorefractive ring resonators

We have demonstrated efficient amplification of 830 nm and 1.06 micrometers light in a ring resonator using Rh:BaTiO3. The power oscillating inside the ring exceeded the pump power by up to a factor of 2.3 at 1.06 micrometers . We have also showed that such an efficiently working photorefractive cavity is also sensitive to nanometer changes in its cavity length. We have also observed simultaneous, bi-directional and counterpropagating oscillations in a resonator pumped by a single 647 nm pump beam. The intensity of one oscillation beam was up to two orders of magnitude higher than the intensity of the other oscillation beam.