Low photoelastic and optical properties in RO-SnO-P2O5 (R = Zn, Ba, Sr) glasses.

We report transparent RO-SnO-P2O5 (R=Zn, Ba, Sr) glasses with low photoelastic constant less than ∼1 B (1×10(-12) Pa(-1)) and high refractive index more than ∼1.65. The BaO or SrO substitution effect of SnO on optical properties is nearly the same as ZnO substitution of the ternary zinc tin-phosphate glass without hazardous oxide. A new series of BaO-SnO-P2O5 glass characterized with a very low photoelastic constant of ∼0.08 B, high refractive index (∼1.66), and better water durability is a candidate for precise polarization control devices such as optical filters and beam splitters.

Extraordinary anisotropy of ultrafast laser writing in glass.

The unusual dependence of femtosecond laser writing on the light polarization and direction of raster scanning is demonstrated in silica and chalcogenide glasses. Two different mechanisms contributing to the observed anisotropy are identified: the chevron-shaped stress induced by the sample movement and the pulse front tilt of ultrashort light pulse. Control of anisotropies associated with the spatio-temporal asymmetry of an ultrashort pulse beam and scanning geometry is crucial in the ultrafast laser machining of transparent materials.

Zero photoelastic zinc tin phosphate glass without lead oxide.

The photoelastic constant (PEC) is evaluated for 15 zinc tin phosphate glasses in a series of xZnO-(67-x)SnO-33P(2)O(5) where x is 0-30 mol. % at 0.5-7 mol. % intervals. The phase retardation of polarized light, passing through a disk sample with applying various uniaxial loads, was measured for PEC determinations by using a frequency stabilized transverse Zeeman He-Ne laser as a polarized light source. The substitution of ZnO for SnO results in the increase of PEC from negative to positive values in the range of -1.43 and +1.45×10(-12) Pa(-1). The minimum PEC value of 0.04±0.02×10(-12) Pa(-1) was experimentally obtained in the 18.5 mol. % ZnO-48.5 mol. % SnO-33 mol. % P(2)O(5) glass.

Imprinted optical pattern of low-softening phosphate glass.

Thermal imprinting of transparent tin phosphate glass was performed at 250 degrees C using a fine-patterned silica mold. The glass sample was prepared by a conventional melt-quenching method and polished with a roughness of < or =10 nm for imprinting experiments. The imprinting temperature is optimized based on experimental viscosity data. Scanning electron microscope and atomic force microscope observations revealed that a square grid pattern has a surface roughness of < or =10 nm and 5 microm x 5 microm squares with ~1 microm intervals and 90-100 nm depth. Diffraction spots due to the micropattern are demonstrated by illuminating He-Ne laser light.