The influence of various heat-treatment on the viscosity, transformation temperature and electric conductivity of some soda-silica glasses in the immiscibility region was investigated. Two distinct temperature regions were found for several glasses. In one of the regions, heat-treatment leads to the " droplet " structure, whereas in the other it leads to the " two-framework " structure. The boundary between these regions was attributed to the boundary line of the spinodal region. A noticeable decrease in the transformation temperature of low-viscosity phase was found for the glass with a discontinuous low-viscosity phase. The uniform tension in droplets was assumed to be the cause of this effect.

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This paper reports on the laser emission properties of Pyrromethene 580, Pyrromethene 597, Pyrromethene 650and Rhodamine 1 lB in the novel matrix polymer-filled microporous glass (PFMPG). This host material combines the advantages of an organic environment for the dye with the superior thermooptical and mechanical properties of an inorganic glass. Laser efficiency was measured as a function of pump flux for different dye concentrations, resonator feedback, and locations on the sample. Service life, defined as the number of pulses for the output to drop to the 70% point, was recorded at 5 Hzfor the higher dye concentrations. The highest efficiencies were observed for Pyrromethene 597 (7O%), which had a service life of 6O,OOO shots at 25 MW/cm2 and 45,OOO shots at 50MW/cm2. The longest service life was measured for Rhodamine 1 lB (l 10,000 pulses at 25 MW/cm2), but this dye had somewhat lower efficiency (5O -55%). Thermal lensing measurements were made for dye-doped PFMPG and MPMMA, and showed that the lensing is much lower in the hybrid matrix. The agreement with the theoretical modeling is very good.

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