Tohru Kineri

Preparation and optical properties of gold-dispersed (Pb, La)TiO3 thin films by sol-gel process

Abstract Gold-dispersed Pb 1−1.5x La x TiO 3 (PLT[x × 100]) thin films were prepared by a sol-gel process. Volume fraction of Au and La content x of the films were varied from 0 to 10 vol.% and from 0 to 0.3, respectively. Refractive index of the matrix increased with increasing crystal size of PLT. Not only the refractive index of matrix but also the static dipole electric field of the matrix was considered to affect the optical properties of the films. χ (3) of 5 vol.% gold-dispersed PLT20 film was 1.0 × 10 −7 esu at 532 nm that was far from the plasma resonance wavelength of the film.

Hybrid optical circulator using garnet-quartz composite embedded in planar waveguides

A novel hybrid configuration of optical circulator is presented. A Garnet-Quartz composite (GQC), which is comprised of four quarter-wave plates and Faraday rotator, is embedded into a groove formed across the branching waveguides pair of Mach-Zehnder interferometer. Optical path difference of the pair is 0 rad for forward path, whereas /spl pi/ for backward path with the GQC, realizing nonreciprocal operation. The forward-to-reverse isolation of 16.2-29.8 dB and the insertion loss of 8.8-9.4 dB are obtained.

Preparation and optical properties of gold-dispersed BaTiO3 thin films by sol-gel process

Gold-dispersed BaTiO3 thin films, which will be used for third-order nonlinear optical devices, were prepared by sol-gel method with spin-coating using HAuCl4 (DOT) 4H2O, Ba(CH3COO)2 and Ti [O(CH2)3CH3]4 as starting materials. The thin films were heat-treated in air at temperatures ranging from 400 degree(s)C to 800 degree(s)C for 1 h. Thin films with different volume fractions of fine gold particles were successfully prepared. The peak position of the surface plasmon resonance of gold particles shifted toward the long wavelength as the heat-treatment temperature and the volume fraction of gold increased. The BaTiO3 matrix was amorphous up to 400 degree(s)C, but became crystallized at temperatures above 500 degree(s)C. The fine gold particles became coarse between 600 degree(s)C and 800 degree(s)C. The mean particle size of gold was 20 nm at 800 degree(s)C. The nonlinear optical property of these thin films was measured by the degenerate four-wave mixing (DFWM) method using a frequency-doubled Nd:YAG laser with 20 ps pulse duration. Third-order nonlinear susceptibility (Chi) (3) of gold-dispersed BaTiO3 thin film with 10 vol% of gold was 2.5 X 10-8 esu.

Preparation and optical properties of gold-dispersed BaTiO3, PGO (Pb5Ge3O11) and PLT (Pb1–1.5xLaxTiO3) thin films by sol-gel process

Gold-dispersed BaTiO3, PGO and PLT thin films, which will be used for third-order nonlinear optical devices, were prepared by sol-gel process with spin-coating using HAuCl44H2O, Ba(CH3COO)2, Ti[O(CH2)3CH3]4, Pb(CH3COO)23H2O, Ge[O-n-C4H9]4, La(CH3COO)31.5 H2O as starting materials. The thin films were heat-treated in air at temperatures ranging from 400 to 800 for 1 h. The nonlinear optical property of these thin films was measured by the degenerate four-wave mixing (DFWM) method using a frequency-doubled Nd: YAG laser with 20 ps pulse duration. Third-order nonlinear susceptibility χ(3) of gold-dispersed BaTiO3, PGO and PLT thin films with 5 vol% of gold were 1.410−6 esu, 3.510−7 esu respectively. The large χ(3) may be ascribed to the high dielectric constant of the films.