Generation of 312 nm, femtosecond pulses using a poled copolymer film

A 2.5- mu m-thick corona-poled copolymer film was used to double approximately 13-fs-long, 50-nJ-energy, 625-nm-wavelength pulses at a 8-kHz repetition rate. The large effective d coefficient results in a relatively high conversion efficiency for such a thin film. A maximum efficiency of 0.13% has been measured. Long-term stable operation was obtained with efficiencies of 0.025% at the damage threshold of approximately 160 GW/cm/sup 2/. The damage threshold is remarkably high for organic materials and was found to be peak intensity rather than average intensity dependent.>