Sub-50 ps pulses at 620 nm obtained from frequency doubled 1240 nm diamond Raman laser

We report a monolithic 1240 nm diamond Raman laser producing pulses with duration of 42–62 ps at 100 kHz repetition rate, and maximum average power of 246 mW. The Raman laser is formed by a 0.5-mm thick planar diamond, coated on both sides and pumped by ~100 ps pulses from a Q-switched 1064 nm laser. The maximum conversion efficiency from 1064 nm to 1240 nm was about 25%. The 1240 nm signal was frequency-doubled in single-pass configuration through a 10-mm long LBO crystal, enabling generation of pulses with a duration of 29–46 ps at 620 nm. The maximum average power at 620 nm was 128 mW, and the maximum conversion efficiency from 1240 nm to 620 nm was 50%. The Raman laser provides an efficient and flexible way to extend short pulse operation to wavelengths in spectral domains difficult to reach, such as 620 nm and in addition provides a simple pulse shortening mechanisms.