GAIN ENHANCEMENT BY MOVING GRATINGS IN A PHOTOREFRACTIVE POLYMER

The use of moving gratings allows dramatic enhancement of the two-beam coupling gain in a photorefractive polymer. The advantage of using mu lti-layer structures to increase the effective interaction length is a lso demonstrated and a small signal optical amplification as large as 500 is achieved using a three-layer sample, the highest reported to da te in a photorefractive polymer. From an investigation of the time dep endence and detuning frequency dependence, we determine that hole cond uction is dominant and that the mobility life-time product reaches mu tau = 3 x 10(-10) cm(2)/V at an applied electric field E-0 = 71 V/mu m . (C) 1998 Elsevier Science B.V.