An important physical phenomenon, quasinondestructive reading, has been observed for the first time in a photorefractive polymeric material, PMMA (poly-methylmethacrylate):DTNBI (1,3-dimethyl-2,2-tetramethylene-5-nitrobenzimidazoline):${\mathrm{C}}_{60}$. In addition, a maximum steady-state diffraction efficiency of 7% (125 μm sample thickness) and a net two-beam coupling gain of 16 ${\mathrm{cm}}^{-1\mathrm{}}$ are observed in this polymer. A two-trap-level model, in which the levels are populated sequentially, qualitatively mimics the intensity-dependent decay rate and the transition to quasinondestructive reading.

• Received 25 April 1994

DOI:https://doi.org/10.1103/PhysRevLett.73.2047