A laser system capable of efficient production of high energy sub-nanosecond pulses in the 2-15 .mu.m spectral region is disclosed. Diode pumped solid state lasers are used as pump sources. The system design is simple, reliable and compact allowing for easy integration. The laser system includes a combination of compact solid-state .about.1 micron laser sources, producing high power picosecond pulses, with optical parametric amplification and a quasi-continuous wave laser for seeding the amplification process that enables the efficient conversion of the high power .about.1 micron laser radiation to tuneable mid-infrared sub-ns pulses. New parametric processes are presented for achieving high gains in bulk nonlinear crystals. Furthermore, a method of exceeding the fundamental conversion efficiency limit of direct three wave mixing is presented. The compact and robust nature of this novel laser system opens up the use of high power and high peak power mid-infrared laser pulses to a wide variety of important medical and dental applications.