Gain Enhancement by Moving Gratings in a Photorefractive Polymer

A. Grunnet-Jepsen, C. L. Thompson, and W. E. Moerner

The use of moving gratings allows dramatic enhancement of the two-beam coupling gain in a photorefractive polymer. The advantage of using multi-layer structures to increase the effective interaction length is also demonstrated and a small signal optical amplification as large as 500 is achieved using a three-layer sample, the highest reported to date in a photorefractive polymer. From an investigation of the time dependence and detuning frequency dependence, we determine that hole conduction is dominant and that the mobility life-time product reaches mt=3x10^-10 cm²/V at an applied electric field E_o=71 V/mm.