We present an analysis of what is called parametric oscillation in photorefractive media. It is shown theoretically that when a running grating and a constant electric field are applied to a photorefractive medium it is possible for two secondary gratings to grow spontaneously. These theoretical predictions are subsequently verified experimentally in the crystal Bi<sub>12</sub>SiO<sub>20</sub>, and excellent qualitative agreement is obtained. In previous subharmonic experiments, only grating vectors <i>K</i>/2, <i>K</i>/3, and <i>K</i>/4 were observed. Now, however, a whole continuum of grating vectors has been observed. Thus subharmonic generation in photorefractive materials is simply a special case of parametric oscillation in which the two secondary gratings are identical.
© 1995 Optical Society of America
Henrik C. Pedersen and Per Michael Johansen, "Parametric oscillation in photorefractive media," J. Opt. Soc. Am. B 12, 1065-1073 (1995)