Interaction of Q-Switched & Modelocked YAG Laser Pulses with Perspex.

We report the experimental observations made during interaction of a train of multiple 30 ps durations Nd:YAG laser pulses with acrylic glass. The laboratory built Q-switched and modelocked Nd:YAG laser was cavity dumped at right angle giving average output energy of about 28.5µJ at the Perspex glass. Focusing of the converted (532 nm) and unconverted (1.06µm) pulses on the Perspex surface led electric field enhanced immense dark green output. This fantastic observation may be caused by higher order harmonics generation, thermoluminescence, space charge electric field acceleration, green Perspex fluorescence or self superposition of inter-pulse period delayed pulses due to nonlinear optical distances traversed by green pulses during reflection from the heated surface of the Perspex. Unconverted IR pulses may produce a nonlinear refractive index profile. This work analyses different aspects of the scenario. [ABSTRACT FROM AUTHOR]