Sodium bismuth titanate (Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub>, NBT) is considered to be an excellent candidate for a lead-free piezoelectric material from the viewpoint of environmental protection. The optimum temperature of crystallinity is 650°C. The films exhibit a well-defined hysteresis loop with a remnant polarization 2Pr of about 1 μC/cm<sup>2</sup> and a coercive voltage V<sub>c</sub> of approximately 0.9V. The films also show good insulating property at room temperature. The high frequency C-V curve is indicative of good film/substrate interface characteristic. The fixed charge density (N<sub>fc</sub>) and the surface state density (N<sub>ss</sub>) are considered to be adequate for a ferroelectric field effect transistor operation. Electrical measurements results show that this kind of films have a potential practice for device applications such as memory and switching devices.
A mixed laser crystal of Nd<sub>0.0053</sub>(Gd<sub>0.42</sub>Y0.58)<sub>0.9947</sub>VO<sub>4</sub> has been successfully grown by the Czochralski method. The special properties of this crystal have also been measured. Formed with a simple concave-plano resonator, passive Q-switching operation of a diode-pumped Nd<sub>0.0053</sub>(Gd<sub>0.42</sub>Y<sub>0.58</sub>)<sub>0.9947</sub>VO<sub>4</sub> laser with Cr<sup>4+</sup>:YAG has been demonstrated. For Q-switched operation, the maximum average power was measured to be 1.11W with the corresponding repetition rate of 10 kHz, the pulse width of 10 ns when the initial transmission of Cr<sup>4+</sup>:YAG crystal was 60%. Meanwhile, the largest pulse energy of 111 μJ and the highest peak power of 14.61 kW were obtained.
We report on the experimental studies of a diode-end-pumped CW Nd:GdVO<sub>4</sub> laser. CW output power of 19.8 W at 1064 nm and a slope efficiency of 58.5% were obtained under the pump power of 39.5 W. The beam quality M<sup>2</sup> at maximum output power was measured to be around 2.62. The thermal focal length in Nd:GdVO<sub>4</sub> crystal under the pump power from 22 W to 40.6 W was measured.
The laser properties of Nd:YxGd1–xVO4 crystal are investigated. The continuous-wave (cw) laser performance of diode-pumped Nd:YxGd1–xVO4 crystal operating at 1.06 µm and that intracavity second-harmonic generation (SHG) with a KTP crystal into the green spectral range at 532 nm are studied. Also the pulse characteristics of Nd:YxGd1–xVO4 laser crystal are reported. A diode-pumped compact and efficient Cr4+:YAG passively Q-switched Nd:YxGd1–xVO4 laser formed by a simple flat-flat resonator is demonstrated. The dependence of the operational parameters on the pump power is also investigated experimentally.