Spontaneous Oscillation and Self-Pumped Phase Conjugation in a Photorefractive Polymer Optical Amplifier

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

Optical processing with photorefractive polymers depends upon achieving high optical gain, which depends exponentially upon the product of the interaction length and the gain coefficient. By using several polymer layers to increase the overall interaction length and a new high-performance photorefractive polymer composite, the overall optical one-pass gain becomes as large as a factor of 5. For a two-layer sample placed in an optical cavity made with two concave mirrors, spontaneous oscillation due to two-beam coupling gain has been observed. Because only one pumping beam is required, this configuration also acts as a self-pumped phase conjugating mirror with a reflectivity of 13% for an applied electric field of 75 Volts per micrometer, marking a crucial milestone for this growing class of optoelectronic materials.