Zehui Du

Influence of crystal phase and transparent substrates on electro-optic properties of lead zirconate titanate films

Pb(ZrxTi1−x)O3 [x=0.52, PZT(52) near morphotropic phase boundary], tetragonal PZT(65), and rhombohedral PZT(20) thin films have been fabricated on different transparent substrates by radio frequency sputtering. The optical studies show that the band gap energies and refractive indices of the PZT thin films are crystal phase dependent. The largest electro-optic (EO) coefficient of 219.6 pm/V has been achieved by controlling the crystal phase of the PZT thin films. The linear EO coefficients of PZT(52) films on the (Pb0.86La0.14)TiO3-coated glass, indium tin oxides, and MgO substrates are also studied. Such study could contribute to the crystal phase and substrate dependent PZT films for electro-optic devices and multifunctional integrated circuits.

Growth mode of sol-gel derived PLT seeding layers on glass substrates and its effect on templating the oriented growth of PLZT thin films

Highly (100) oriented PLT (La/Zr/Ti: 14/0/100) seeding layers have been developed on glass substrates by the optimized sol-gel process. The early growth stages of the seeding layers have been studied by continuously decreasing film thickness to tens of atomic layers (∼8 nm thick) from ∼50 nm and Volmer–Weber growth mode has been observed. The seeding layers consist of islandlike clusters inside which the grains were radially assembled. The mechanisms for the oriented growth of the seeding layers were then explained. The seeding layers with different island densities could induce distinct orientation degree and perovskite formation for the subsequently deposited PLZT (9/65/35) films. The PLZT films grown on continuous seeding islands exhibited the highest orientation degree and desirable optical and electro-optic properties.

Optical and electro-optic properties of micrometric thick lead zirconate titanate films on (Pb0.86,La0.14)TiO3/glass

Highly (100)-oriented Pb(Zr0.52,Ti0.48)O3 (PZT) films of up to ∼2.4 μm are deposited on the (Pb0.86,La0.14)TiO3 (PLT)-coated amorphous substrate by one cycle of sputtering and annealing. The films possess fibrous columnar nanostructures and vertically grow on the PLT/glass substrate. Microstructure analysis and property characterization indicate that the films possess very promising optical, waveguiding, and electro-optic (EO) properties, as well as low propagation loss. The transparency of >80% in the range of λ=400–1200 nm and the linear EO coefficient of 341.4 pm/V have been measured in the films. Due to the large EO coefficient and the micrometric thickness, a giant phase retardation of 2.93 rad has been measured under an electric field of 50 kV/mm.

Defect enhanced optic and electro-optic properties of lead zirconate titanate thin films

Pb(Zr1-xTix)O3 (PZT) thin films near phase morphotropic phase boundary were deposited on (Pb0.86La0.14)TiO3-coated glass by radio frequency sputtering. A retrieved analysis shows that the lattice parameters of the as-grown PZT thin films were similar to that of monoclinic PZT structure. Moreover, the PZT thin films possessed refractive index as high as 2.504 in TE model and 2.431 in TM model. The as-grown PZT thin film had one strong absorption peak at 632.6 nm, which attributed to lead deficiency by quantitative XPS analysis. From the attractive properties achieved, electro-optic and photovoltaic characteristic of the films were carried out.

Modeling of multilayer electrode performance in transverse electro-optic modulators

For some electro-optic (EO) modulators, lowering the driving voltage is necessary to reduce the power consumption of the modulators. There are four significant factors influencing the driving voltage of the EO modulators: geometrical parameters of wafer and electrodes, surface and embedded electrodes, material properties of wafer, and structure of modulators. Using the superposition method and surface charge technique, the electric fields, halfwave voltages, switching times and optical transmissions of EO modulators with two-layer, three-layer, and four-layer electrodes are calculated, respectively. It is found that the halfwave voltage decreases while the switching time increase slightly as the number of layers increases. Such study demonstrates that using multilayer electrodes is an effective technique of lowering the halfwave voltage, which may have implication of EO modulator design.