No abstract

We report new experimental results on the spectral, thermal, and orientational characteristics of stoichiometry-dependent mid-IR absorption in AgGaSe(2) crystals. In currently available material, this absorption poses an obstacle to the power scaling of the 2-µm-pumped AgGaSe(2) optical parametric oscillator (OPO). Preliminary experiments have indicated that this absorption could be substantially reduced by optimization of the process parameters during crystal growth and annealing. OPO output powers approaching 10 W may be achievable by using optimized material.

The electrical conductivity and chlorine ion diffusion in KC1 and KCl:SrC12 single crystals have been analyzed by least-squares methods, using as a model a perfect crystal perturbed by five defects: isolated anion vacancies, isolated cation vacancies, divalent cation impurities, divalent cation-impurity-cationvacancy complexes, and vacancy pairs. The transport equations were derived from this five-defect model using a simple theory for noninteracting particles, except for the nearest-neighbor binding to form complexes and vacancy pairs, and using the same theory including long-range Coulomb interactions between the isolated defects. This latter theory yielded the better description of the experimental results. However, the analyses showed that significant nonrandom deviations exist between theory and experiment. These deviations exist in both the intrinsic and extrinsic regions of conductivity. The failure of existing concepts for these transport properties is discussed in terms of possible additional mechanisms, i.e., electrons, cationic Frenkel defects, or trivacancies, and in terms of more complete theoretical treatment.

The first successful operation of a AgGaSe2 infrared parametric oscillator is reported. Continuous tuning ranges of 1.6–1.7 μm, 6.7–6.9 μm, and 2.65–9.02 μm were achieved using 1.34-μm neodymium and 2.05-μm holmium pump lasers. Pulse energies exceeding 3 mJ, peak powers near 100 kW, and conversion efficiencies of 18% were obtained. Operation of the parametric oscillator was possible well below the 13–40 MW/cm2 surface damage threshold of this nonlinear material.

No abstract