The spatial distribution of chemical states in resistance-switching devices with a planar-type Pt/CuO/Pt structure has been studied by photoemission electron microscopy. It has been found that the change in resistance that occurs with the application of the first voltage is caused by the formation of a reduction path through the CuO channel between the Pt electrodes. A detailed analysis suggests that Joule-heat-assisted reduction induced by the current flowing through the device may play an important role in the formation of the conductive reduction path.

A polarization-stepping method for measurement of the Faraday rotation in magneto-active materials has been modified for evaluating the Verdet constant as a function of wavelength and temperature. It has been used for a comparison of wavelength and temperature dependent Verdet constant, dominant electronic transition wavelength, and Curie-Weiss temperature in terbium gallium garnet (TGG) single crystals and TGG ceramics samples. The room-temperature values of Verdet constant varied from 36.6 to 44.2 rad/T.m at 1.064 μm wavelength and from 122.4 to 155.5 rad/T.m at 0.632 μm wavelength for all samples under investigation. These results match very well the values obtained from single wavelength measurement in the literature and show the same measurement error for single crystal and ceramics, respectively. The Curie-Weiss temperature has been evaluated for the first time in TGG ceramics. This method could be used for the detailed characterization of magneto-optical properties of the materials over a wide range of wavelengths and temperatures which is of great importance for the proper design of Faraday devices.

A terbium gallium garnet (TGG) ceramic Faraday rotator (FR) with an isolation ratio of 33 dB was demonstrated at a laser radiation power of 257 W. This FR can be equipped with a large optical aperture by using ceramics technology to prevent laser damage at high-energy pulse operation. The thermal lens of a 257 W laser with a beam diameter of 2.6 mm had a focal length of 9.5 m, which is easily corrected using a spherical lens to suppress the undesirable effects of thermal lensing. The rotation angle of the FR was stabilized by water cooling. The results indicate that the TGG-ceramic-based FR is suitable for high-energy laser systems with high repetition rates.

The thermal-birefringence-induced depolarization in terbium gallium garnet (TGG) ceramics has been investigated experimentally. The depolarization ratio of $6.1\times {10}^{-4}$ has been observed at the maximum input power of 117 W cw, which corresponds to a normalized laser power of $p=0.14$. As predicted by the previously proposed theory, the amount of depolarization ratio and its slope with respect to the laser power of the ceramic TGG was approximately the same as that previously reported for high-quality-cut $〈111〉$ single crystal.

We report on the efficient high-power operation of a laser-diode-pumped Er³⁺-doped yttrium aluminum perovskite (Er:YAP) laser in the 3 μ m spectral region at room temperature. 6.9 W of continuous-wave (CW) output power was obtained at 2920 nm. The slope efficiency was as high as 30.6% with respect to the absorbed pump power, which is close to the quantum defect limit (33.4%). To the best of our knowledge, this is the highest CW output power generated from 3 μ m Er³⁺-doped solid state lasers at room temperature. Furthermore, our analysis has shown that more than 10 W of output power based on Er:YAP is possible by further mitigating the thermal lens effect.

The temperature dependence of the thermo-optic effects in single crystal and ceramic TGG were evaluated by using the Fizou interferometer method. The temperature dependence of the refractive index and thermal expansion are significantly improved at low temperature for both ceramics and single crystals. Our estimation using a figure of merit indicated that a TGG ceramics cooled to liquid nitrogen temperature can reduce thermal wave-front distortion by a factor of up to 4.7 with respect to that at 300 K, and can reduce thermal birefringence effects by up to a factor of 12 with respect to those at 300 K.