Lithium niobate laser with frequency-degenerate pumping

White et al. (1982) and Cronin-Golomb et al. (1982) have obtained self-pumped oscillation in BaTiO3 in an external resonator with one coherent beam. The present investigation is concerned with a similar oscillation achieved in iron-doped lithium niobate crystals pumped with a CW beam from a He-Cd laser. It is found that oscillations can be obtained by using either transmission or reflection dynamic gratings. A necessary condition for achieving oscillation is found to be positive feedback and compensation for the loss by amplification. Attention is given to the threshold condition for a holographic laser, the gain in photorefractive crystals, and oscillations in three different setups.