PICOSECOND ND-YLF LASER-MULTIPASS AMPLIFIER SOURCE PUMPED BY PULSED DIODES FOR THE OPERATION OF POWERFUL OPOS

Picosecond pulse trains from a quasi cw Nd:YLF oscillator are amplifie d by a multipass system pumped by a pulsed 100 W peak power laser diod e. Gain factors in the order of 100 are achieved with input pulses of 100 nJ energy and 2 ps duration. The high power of the amplified pulse trains allows the operation of a quasi-cw synchronously pumped KTP op tical parametric oscillator (OPO) at high output coupling. Pumping by the second harmonic provides OPO pulses of 2.1 ps duration in trains c onsisting of 25 pulses with a noteworthy flat top of the envelope. The conversion efficiency of 13% corresponds to a total energy of 50 mu J in the trains. The parameters promise wide applications of the system in ultrafast spectroscopy.