Stability of Information Readout by Self-pumped Phase Conjugation in Barium Titanate

For real-time optical image storage and processing, we have systematically studied self-pumped phase conjugation (SPPC) [1] in barium titanate (BaTiO3) crystals (from Sanders Associates Inc., Merrimack, NH) in terms of the incident angle θ, the impact position l on the crystal surface, the distance L between the imaging lens and the impact point on the crystal face [Figure 1], the argon-ion laser power P (p-wave with various wavelengths), and the ambient temperature T. We found that the stability of the temporal SPPC intensity IPC (t) strongly depends on these geometrical parameters, θ, l, and L. The objective in this paper is to identify optimal conditions in order to stablize and maximize the temporal evolution of the SPPC reflectivity R(t) which is defined as the ratio of IPC (t) to the intensity IM retro-reflected by a mirror at the position of the crystal to the detector. We have defined the optimal (or stable) condition for the SPPC as |Rmax-R(t)|/Rmax ≤ 0.1, where Rmax is the maximum value of R(t) (recorded within 10 minutes to 1 hour) and also the maximum value in terms of the above geometrical and physical parameters.