A. Grunnetjepsen et al., SPONTANEOUS OSCILLATION AND SELF-PUMPED PHASE-CONJUGATION IN A PHOTOREFRACTIVE POLYMER OPTICAL AMPLIFIER, Science, 277(5325), 1997, pp. 549-552
Optical processing with photorefractive polymers depends on achieving
high optical gain, which depends exponentially on the product of the i
nteraction length and the gain coefficient. By use of several polymer
layers to increase the overall interaction length and a new high-perfo
rmance 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 oscil
lation due to two-beam coupling gain was observed. Because only one pu
mping beam is required, this configuration also acts as a self-pumped
phase-conjugating mirror with a reflectivity of 13 percent for an appl
ied electric field of 75 volts per micrometer, marking a milestone for
this growing class of optoelectronic materials.