Threshold reduction and mode selection with uncoated Raman crystal acting as a low-finesse cavity.

We report a stimulated Raman scattering threshold reduction by a factor of ∼4 using a simple uncoated SrWO crystal with plane/parallel faces pumped by 1.5 mJ, 11 ns single-frequency pulses at 532 nm. The weak etalon effect is sufficient to shape both the spatial and spectral characteristics of the output Raman beam.

87 fs pulse generation in a diode-pumped semiconductor saturable absorber mirror mode-locked Yb:YLF laser.

A Yb:YLF crystal has been investigated in a femtosecond oscillator pumped by two 400 mW single-mode fiber-coupled diodes emitting at 976 nm and mode locked with a semiconductor saturable absorber mirror. Almost Fourier transform-limited pulses with durations of 87 and 107 fs were demonstrated for extraordinary and ordinary polarizations, respectively. This is, to the best of our knowledge, the first demonstration of sub-100 fs pulses with Yb:YLF, and it proves the potential for ultrashort pulse generation and amplification with this material.