Frequency tuning in generation of picosecond secondharmonic pulses

A tunable spectral component was observed in the 500–600 nm range when picosecond second-harmonic pulses were generated in LiNbO₃ and LiIO₃ crystals. One such component, tunable by variation of the orientation of the crystal was observed in LiIO₃, but two components appeared in KDP. Thermal frequency tuning of the additional component was observed in lithium niobate. Moreover, the application of an electric field also caused frequency tuning.