Generation of Novel Wavelengths by Means of Raman Conversion

摘要

Raman converters and a Difference Frequency Mixer have been developed for near and mid IR range along with excitation system based on 1053-nm Nd:YLF MOPA laser generating 2 types of nanosecond pulses (10 ns and 20 ns). We used a flash-lamp pumped amplifier following by a diode-pumped solid-state master oscillator with a passive Cr:YAG modulator. Usually such a passive Q-switch MOPA laser produces pulses with a long (over 10 ns) pre-pulse pedestal. This complicates an excitation of Raman generation in media where SBS threshold at nanosecond pumping is below the SRS threshold (liquids and gases as a rule, but also some solids as fused silica). The reduction of SRS threshold would be possible if we excite a Stokes Raman emission in a resonator. However, even in this case the long pre-pulse pedestal may favor the SBS excitation vs. the SRS.