Efficient parametrical generation in the 1.8-2.5 micron spectral region by periodically poled KTP

Summary form only given. High power and efficient light sources operating in 2 /spl mu/m spectral region are important for a number of applications including biomedicine. Optical parametrical oscillators (OPOs) can generate high energy output pulses with high efficiency and can be a viable alternative to other laser sources in this spectral region. Usually the nanosecond OPO design involves balancing cavity losses against available gain in order to keep the oscillation threshold sufficiently low and avoid optical damage of the nonlinear crystal and optical coatings. In the work we demonstrate that large nonlinearity and high optical damage threshold of the periodically poled KTiOPO/sub 4/ (PPKTP) allows efficient extraction of nanosecond parametrical pulses in the mJ energy range from very low finesse optical cavities pumped at 1.064 /spl mu/m by the 3-times diffraction limited beam of the Q-switched Nd:YAG laser.