Ba0.6Sr0.4TiO3 thin films doped with K were deposited on Pt/Ti/SiO2/Si substrates by the chemical solution deposition method. The structure, surface morphology and the dielectric and tunable properties of Ba0.6Sr0.4TiO3 thin films have been studied in detail. The K content in Ba0.6Sr0.4TiO3 thin films has a strong influence on the material's properties including surface morphology and the dielectric and tunable properties. It was found that the Curie temperature of K-doped Ba0.6Sr0.4TiO3 films shifts to a higher value compared with that of undoped Ba0.6Sr0.4TiO3 thin films, which leads to a dielectric enhancement of K-doped Ba0.6Sr0.4TiO3 films at room temperature. At the optimized content of 0.02 mol, the dielectric loss tangent is reduced significantly from 0.057 to 0.020. Meanwhile, the tunability is enhanced obviously from 26% to 48% at the measured frequency of 1 MHz and the maximum value of the figure of merit is 23.8. This suggests that such films have potential applications for tunable devices.

Effects of magnetic field and light illumination on the electrical transport properties of La 7/8 Sr 1/8 MnO3 thin film grown on a Si substrate are investigated. The film shows an insulator-metal transition at 𝑇𝑃 ≈ 191.9 K and a low-temperature resistance minimum at 𝑇min ≈ 48 K in darkness. Both magnetic field and light illumination shift the insulator-metal transition temperature 𝑇𝑃 to be higher, while the low-temperature transport properties of the film induced by them show different trends. That is, the magnetic field and light illumination make the 𝑇min shift to lower and higher temperatures, respectively. The enhancement of both 𝑇𝑃 and 𝑇min under light illumination could be explained in terms of photoinduced hole-doping and demagnetization effects of La 7/8 Sr 1/8 MnO3.

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Polycrystalline bulk samples of BaSn1-xMnxO3 with x=0, 0.05, 0.10 and 0.13 are prepared by the conventional solid state reaction method. The effects of Mn concentration on crystal structural, optical and magnetic properties of BaSn1-xMnxO3 are investigated systematically. Powder X-ray diffraction (XRD) shows that each of these compounds presens a perovskite structure (with the space group Pm3m) without the secondary crystalline phase. The Mn ions take the Sn sites which is revealed by the XRD, diffusion reflectance spectrum (DRS) and Raman scattering. With the increase of doping level x, the optical absorption edge shifts towards higher wavelength and is smoothened gradually, meanwhile the Raman spectrum shows that Raman mode is also changed. The photoluminescence spectrum under magnetic field shows that near-infrared luminescence is probably related to Sn ions. The magnetization measurement demonstrates that Mn-doped BaSnO3 system exhibits ferromagnetism at low temperature, which can be explained by the F-center exchange (FCE) mechanism.

A theoretical model for the laser which can produce femtosecond squeezed state has been developed. The stability of the cavity has been analyzed in detail by numerical computation. A stable mode-locked pulse train with pulse width of 160 fs and repetition rate of 67MHz has been obtained, which afforded a new important means for the realization of femtosecond squeezed state.