25 September 1989 Recent Advances In The Generation Of Picosecond Tunable Infrared Radiation
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We report recent progress in the generation of continuously tunable picosecond pulses by three-photon interaction in KTiOPO4. The system is based on a cw mode-locked Nd:LiYF4 laser, which synchronously pumps a dye laser and seeds a regenerative amplifier. Two different modes of operation are available simultaneously. Both operating regimes have equally large tunability : from 0.6 μm to 4.5 μm. In the high repetition rate mode, difference frequency mixing of the tunable output of the synchronously mode-locked dye laser and the Nd:LiYF4 laser generates a 100 MHz train of picosecond tunable IR pulses with typical average power in the milliwatt range. Substantially higher energy per pulse can be obtained over the full tuning range by subsequent amplification at lower repetition rates. For this purpose we use a KTiOPO4 parametric amplifier, pumped by the regenerative amplifier or its second harmonic. Typically, a single-pass gain of 106 is observed in this regime while maintaining the spatial, spectral and temporal characteristics of the seed beam. In the non-seeded configuration on the other hand, a parametric generator-amplifier consisting of two KTiOPO4 crystals operates in the saturation regime with energy conversion efficiencies of 10-20 % without pulse breakup and with very satisfactory pulse-to-pulse stability. However, in this configuration the spatial and spectral quality is traded for the ease of tunability.
© (1989) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Herman Vanherzeele "Recent Advances In The Generation Of Picosecond Tunable Infrared Radiation", Proc. SPIE 1104, Growth, Characterization, and Applications of Laser Host and Nonlinear Crystals, (25 September 1989); doi: 10.1117/12.960579; https://doi.org/10.1117/12.960579

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