FIBEROPTIC TRANSMISSION OF STRETCHED PULSES FROM A Q-SWITCHED RUBY-LASER

Fiber-optic transmission of Q-switched ruby laser pulses is limited by fiber damage owing to the high laser-beam intensities. Pulse stretchi ng with a semiconductor-based control circuit for the Pockels cell of the ruby laser to reduce the peak intensities is described. Pulses wit h durations from 200 ns to 1 mu s and a coherence length of similar to 3 m were generated. These pulses were coupled into multimode optical fibers to investigate the transmission characteristics and the limits of transmittable pulse energies. Stretched pulses can be transmitted i n quartz fibers with a 600-mu m core diameter to pulse energies of 300 mJ, which is an increase by a factor of 4 compared with standard Q-sw itched pulses. I It is expected that beam guiding of ruby laser pulses by fiber optics will significantly facilitate the use of holographic interferometry in technical applications such as vibration analysis. ( C) 1996 Optical Society of America