The thermal conductivities of Y2O3, Y2O3:Nd3+, Y3Al5O12:Nd3+, and LaF3 have been measured from 77°–300°K by a steady-heat-flow method. The densities of these crystals and of LaF3:Nd3+ have been determined in the same temperature range, using x-ray methods. Using this information and specific heat data from a variety of sources, the thermal diffusivities of these materials have been calculated. Although the diffusivity of pure yttrium oxide is somewhat higher than that of pure yttrium aluminum garnet, introduction of about 1 mole % of neodymium into both these compounds leads to crystals with diffusivities approximating that of undoped YAG. The diffusivity of doped yttrium oxide and YAG (about 0.05–0.06 cm2/sec at room temperature) is about three times that found for undoped lanthanum fluoride. The relative ease with which heat may be removed from Nd-doped Y2O3 and YAG suggests their use in lasers to diminish time variations in the width of the beam.

Laser emission at 172 nm has been produced by pumping a Nd:LaF3 crystal with incoherent Kr*2 radiation at 146 nm. The 5-ns pulse contained approximately 20–30 μJ of energy. Fluorescence measurements indicate potential for tuning from 170–175 nm, which should be observable with OH−-free crystals.

We use infrared reflectance from 400 to 4000 cm−1 to evaluate cubic SiC films grown by chemical vapor deposition on Si substrates. From different regions of the spectra we determine precise film thicknesses, estimate carrier concentrations in highly doped specimens, observe roughness at both film surfaces, and detect conducting regions at the interface. We show how the roughness and the interfacial conducting region introduce nonideality into the spectra. The method is nondestructive and the information can be obtained in less than 1 h after film growth.

Optical mode measurements have been used to determine the anisotropic diffusion coefficient and surface index changes for planar Ti : LiNbO3 waveguides at 0.633 μm. Measured values for the diffusion coefficient at 1000 °C are 𝒟y=9.4×10−13 and 𝒟z=1.4×10−12 cm2/sec. The ratio of the extraordinary to the ordinary surface index change (Δne/Δn0) was found to vary between 1.3 and 1.8, depending on diffusion temperature and Ti film thickness. Ti and Li concentration profiles were measured by secondary-ion mass spectrometry. Additional high concentration peaks, 0.2–0.3 μm wide for both ions, were found superimposed on otherwise well-behaved diffusion profiles. This observation is interpreted to result from a tendency towards Li-Ti-O compound (Li2TiO3 or Li2Ti3O7) formation at the diffusion temperature in a dilute mixture with LiNbO3. Such compound formation has the effect of impeding the Ti diffusion into the LiNbO3 substrate. Electron microprobe measurements were used to measure lateral diffusion from channel waveguides. Under nominally identical conditions, lateral diffusion coefficients varying by as much as a factor of 3 have been observed. The minimum lateral diffusion coefficients observed at 1000 °C were 𝒟y=9.7×10−13 and 𝒟z=1.4×10−12 cm2/sec.

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