Self-excitation of lasing in lithium niobate during recording of dynamic phase gratings by circular photogalvanic currents

Lasing in plane-parallel lithium niobate samples doped with 0.03 wt. % Fe was observed and investigated for the first time. It was excited by focused radiation from a helium-cadmium laser with the ordinary polarization. It was found that lasing was a consequence of formation of a volume phase holographic grating by the excitation of circular photogalvanic currents oscillating in space. Measurements of the threshold angles of lasing yielded the maximum gain and internal losses in the resonator of such a lithium niobate laser.