We fabricated a terahertz (THz) band-pass filter using multilayer ceramic technology. The filter design is based on an interference multilayer filter composed of three resonant cavities. The filter exhibited insertion loss as low as 1.5 dB at a center frequency of 0.15 THz. The bandwidth of the passband was modified by changing the optical length of the cavity. A demonstrated tuning of the full width at half maximum (FWHM) ranged from 12.5 to 6.9%. No significant change in transmission intensity was observed when the optical length of the cavity was changed. At a frequency of approximately 0.8 THz, filter insertion loss increased from 1.5 to 6 dB. The influence of dielectric losses of the ceramic materials on the filter insertion loss is also discussed.

Three‐dimensional photonic crystals with a diamond structure composed of YSZ (3 mol% Y2O3‐stabilized ZrO2) spheres in a resin matrix were fabricated by using stereolithography. The lattice constant was 12 mm and the diameter of the spheres was 5 mm. These photonic crystals made of ceramic spheres showed complete photonic band gaps at around 12 GHz between the eighth and ninth bands. The propagation characteristics of microwaves agreed well with the calculated results using the plane wave expansion method.

B arium titanate and/or barium strontium titanate thin films have been in increasing demand as ferroelectric materials for the fabrication of ferroelectric memory devices, 1 multilayer capacitors, 2 optical modulators, 3 and other devices. Paraelectric thin films are attractive dielectrics for use in decoupling capacitors and high-frequency voltage-tunable microwave circuits, such as voltage-controlled oscillators (VCOs), tunable filters, and phase shifters. 4 In recent years, there has been increasing interest in the synthesis of artificial superlattices of oxide materials because they have the potential to drastically improve ferroelectric properties. 5 Many studies concerning the SrTiO 3 /Ba-TiO 3 system 6À9 have succeeded in fabricating artificial superlattices. Their superlattices have shown behaviors different from those of solid solution Ba x Sr 1Àx TiO 3 (BST).Artificial superlattices of oxide materials have been prepared by various vapor deposition techniques, such as RF sputtering, 10,11 pulsed laser deposition, 12,13 and molecular beam epitaxy. 14,15 To improve the dielectric properties of perovskite-type artificial superlattices, the thickness of the layer must be less than 10 nm, and each layer must grow highly epitaxially. Vapor deposition techniques are suitable for preparing thin films with thicknesses of less than 10 nm because these techniques can deposit at the atomic level. Nevertheless, to our knowledge, there has been no report on highly oriented SrTiO 3 /BaTiO 3 artificial superlattices with a thickness of less than 10 nm prepared by the chemical solution deposition (CSD) method. CSD of BaTiO 3 or SrTiO 3 at temperatures of approximately 600À800 °C typically results in a polycrystalline, granular film because of the trend toward homogeneous nucleation in the pyrolyzed precursor. 16À18 The CSD method utilized for the

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In a study of electroless indium plating with titanium trichloride as a reducing agent, indium film was directly deposited onto Pd-catalyzed aluminum substrate at a rate of 1.56mg • cm -2 • h -1 , and it was possible to continue plating by renewing the bath at 30minute intervals.