The optimization of near infrared CW Gd3Ga5O12:Nd-,YAIO3:Nd- AND YVO4:Nd- microlasers
The modeling of CW GGG:Nd- (1.4237 mum), YAP:Nd- (1.34 mum), YVO4:Nd-microlasers (1.0643 mum) is carried out. At that for the each fixed value of the incident pumping power and the laser beam divergence the optimal values of the activator concentration, the active medium length and the reflectivity of the output mirror, i.e. the values that maximize the laser power, are determined.
Concentration distribution of Nd3+ In Nd:Gd3Ga5O12 crystals studied by optical absorption method
Nd:Gd3Ga5O12 crystals with different concentrations of Nd3+ were grown by Czochralski method, their absorption spectra were measured at room temperature. By using the optical absorption method, the effective distribution coefficient keff for Nd3+ in GGG was fitted to be 0.40±0.01, which is higher than that of Nd3+ in YAG. The 808nm absorption cross‐section was calculated to be 4.0±0.2×10‐20cm‐2. The lengthways and radial concentration distribution of Nd3+ in the crystals were also analyzed and discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Genetic Effects of Acute and Chronic Ionizing Irradiation on Pinus sylvestrisL. Inhabiting the Chernobyl Meltdown Area
The main results of the 12-year radiation-genetic monitoring of radiobiological, cytogenetic, and genetic parameters in Pinus sylvestrisforest plantation from the Chernobyl meltdown area are presented. The acute ionizing irradiation at doses > 1 Gy was shown to induce formation of morphoses and depressed growth; at doses >2 Gy, the reproductive ability of the trees declined. The radiobiological parameters showed a linear or close to linear dose-dependence relationship. The acute irradiation at a dose of 0.5 Gy induced cytogenetic and genetic effects that were significantly higher than the corresponding control values. The relationship between the cytogenetic effects and the absorbed dose was exponential. The dependence of the mutation frequency at specific loci on the absorbed dose was described by a nonlinear curve. The results of cytogenetic analysis of seedlings obtained from seeds annually collected in zones of slight, moderate, and strong damage of Pinus sylvestrisL. are presented.