High-energy single pulse and multi-spike operation with a passive polymer Q-switch

Stable highly efficient polymer passive switch based on a polyurethane composite and organic dye BDN were developed for the neodymium lasers. The maximum energy of 0.98 J was obtained for a single pulse at passive Q-switching of these lasers. Repetition of single pulses at 50 Hz was possible. Repetitively pulsed operation with a peak output power up to 2 MW and an energy of train of nanosecond pulses 14.1 J were achieved in an yttrium aluminate laser for the first time. Variation of the initial switch transmittance made it possible to vary the pulse (spike) duration in the range 28–90 ns. The maximum pulse repetition rate in a train was 350 kHz when the Q-switching efficiency was 98%. The damage threshold of the investigated polymer matrix was achieved 14 and 18 J/cm² for single pulse duration (15 and 35 ns correspondingly) and 52 J/cm² in multi-spike generation regime (duration 80 ns).