Abstract

In spectroscopy, photochemistry, biology and environmental applications, narrow-band pulsed laser radiation sources, tunable in the UV. VIS and IR spectrum regions, are normally required. In the recent years, optical parametric oscillators (OPO), in particular OPOs on BBO crystals, covering the 0.4 - 2.2 μm spectrum interval by tunable radiation, have been extensively used for this purpose. Such OPOs, however, require single-mode Nd:YAG lasers for pump, and if proper measures are not taken, generate radiation whose spectral width is wavelength-dependent and equals to 0.2 - 3.0 nm, thus imposing heavy restrictions on their application range. Utilization of spectral selectors and/or injection of dye-laser narrow-band radiation, will permit this disadvantage to be avoided, but at the same time will inevitably involve a very complicated OPO optical construction, narrowed tunability range and enhanced expenses. On the other hand, relatively simple narrow-band lasers on Ti:Sapphire and LiF:F₂-crystals are being extensively used at present. These lasers provide a linewidth as narrow as ~ 10^-1 cm^-1 and do not require single-mode Nd:YAG-lasers for pump.

© 1998 IEEE