A strong interest has been attracted on nanocrystalline Si (NSi) since it was found to show efficient luminescence at room temperature. In addition, NSi has the thermal conductivity much smaller than that of Si. Therefore, the NSi has been expected to be applied to light emitting devices, thermal insulators, and optical devices. But there are few reports about the thermal property of NSi. In particular, the mechanism of thermal conductive process in the NSi adsorbed with molecules and/or quantum dots is not clear. In this paper, we report our experimental results on the measurements of thermal properties of NSi film adsorbed with CdSe quantum dots using photoacousic technique.

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High quality epitaxial KNbO_3 films were successfully grown on (100)SrRuO_3//(100)SrTiO_3 substrates by hydrothermal method. The KNbO_3 or KNbO_3-based materials are one of the promising lead-free piezoelectric materials as an environmental friendly material; however, the main interest in the KNbO_3-based piezoelectric materials have limited on bulk ceramics materials owing to the difficulty in thin or thick films preparation. Therefore the hydrothermal method has utilized for the growth of KNbO_3 films. Because, hydrothermal method has number of advantages for fabrication method of ultrasonic transducers; low deposition temperature, good conformability, high-purity deposition on a substrate. In this study, epitaxial SrRuO_3 film was used as bottom electrodes, which were grown on (100) SrTiO_3 substrate by sputter method. KNbO_3 films were prepared on (100) SrRrO_3//SrTiO_3 substrates at 210 ℃ by hydrothermal method. The KNbO_3 films were 7.5 μm thicknesses, and the K/Nb ratio measured by EDS was 50/50. The piezoelectric performance and material constants of the prepared KNbO_3 thick film were measured.

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In vibration sensing by use of a FBG based on intensity modulation, light incident on a FBG is narrow-band light tuned to the slope in a transmittance spectrum of the FBG. Since the sensor sensitivity is proportional to the slope of the spectrum curve, enhancement of the sensitivity requires steeper slope of the curve. In this paper, vibration sensing by use of Fabry-Perot interferometer with FBG reflectors (FBG-FPI) is numerically investigated. Because a transmittance spectrum of an FBG-FPI has steeper slope, the FBG-FPI can yield improvement in sensitivity of the sensing.

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When Lamb wave propagates in a crystal, the photo-elastic effect induces a refractive index change in a crystal and makes phase grating in a crystal. Therefore optical mode conversion occurs in the crystals which Lamb wave propagating. Using this phenomenon, it can be expect the Lamb wave type crystal substrate apply to the optical communication system. In this study, we had theoretically examined the optical mode conversion during refractive index period structure. The theoretical calculation result predicted a least power for the mode conversion at a model in various modes. Furthermore, when Lamb wave Λ =270μm and substrate thickness H=20μm in mode 1, Lamb wave power P_<100> to need for 100% optical mode conversion was 12.8mW. Which is very small power for the optical mode converter.

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A method of detecting targets present in the shadow area of an obstacle like a seamount by applying a time reversal is described. Transmission signals of two types with a different phase are used. First, the signal of a normal phase is transmitted in the propagation environment without a target, and the signal received with each element of a transducer array is preserved. Next, the signal of an anti-phase is transmitted in the propagation environment with the target, and the signals received with each element of the transducer array are preserved. The received signals of two types are added in the vector. The time reversal sound field (TRSF) to the target is formed by time-reversing and re-emitting the added signal.

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The line-focus-beam ultrasonic material characterization system can perform material characterization by accurately measuring the propagation characteristics (viz., phase velocity V_<LSAW> and attenuation α_<LSAW>) of leaky surface acoustic waves (LSAWs) excited on the water-loaded specimen surface. In the conventional theoretical calculations, water was treated as an ideal fluid and the shear-wave component was not considered for the boundary conditions. In this paper, we studied an exact measurement model of LSAW propagation characteristics for synthetic silica glass and borosilicate glass, considering the shear-wave component in the water-loading effect and viscosities of longitudinal and shear waves for both specimen and water. The calculated results for this advanced measurement model exhibit dispersion for both LSAW velocities and normalized attenuation coefficient factors. This is mainly caused by the effect of shear-wave component of water.

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We investigate the vibrational modes of GaAs nanopillars of hexagonal cross section on a GaAs substrate using an ultrafast optical technique. The motions of the pillars after excitation with visible light pulses are detected using a time-delayed infrared light pulses. Thickness modes of the pillars are detected in the 10-30 GHz range.

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In the present work, we theoretically studied the acoustic phonon modes in a NWSL composed of cubic materials. Based on the group theory, the acoustic phonon modes were classified. We found there exist four independent phonon modes in the rectangular cross-section GaAs/AlAs NWSLs. Using the XYZ algorithm, we calculated dispersion relations for each mode. The overall structure of the phonon dispersion relations can be understood by the folding of the dispersion curves in the subband structure of a homogeneous plain wire. Phononic band gaps are generated at the center and edges of the mini-BZ. Here, we note that dispersion relations depend on the shape of the cross-section of a NWSL. The results for square and circular cross-section NWSLs will be given elsewhere. Furthermore, it would be interesting to consider a phononic crystal consisting of two-dimensional arrays of NWSLs.

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A transverse ultrasonic vibration was employed to bond the Cu flip chip bump with Cu finished glass substrate. This study was focused on the atmospheric pressure plasma treatment conditions on the ultrasonic bonding strength between the Cu bump and Cu finished substrate because the cleanness and roughness of the bonding surface strongly affected the joint integrity. The optimized ultrasonic conditions greatly enhanced the joint strength bonded using ultrasonic energy, while the excessive plasma treatment degraded the joint integrity. In this study, the mechanisms why the joint strength was determined by the treatment conditions were examined and discussed using X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES).

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The purpose of this paper is to find bonding parameters of electrodes between the glass and flexible printed circuit board (FPCB) using ultrasonic vibration. The electrodes of FPCB and were electroless-plated with Sn and the glass substrate was sputtered with Cu. The peel strengths of the joints were investigated with various parameters, such as bonding pressure and time. This study showed that the electrodes between the glass and FPCB were successfully bonded without any adhesive at a low temperature during a short time, compared to other bonding methods: adhesive bonding and thermo-compression bonding.

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In this paper, relationships among acoustic properties, fictive temperatures, and chlorine concentrations were discussed for silica glasses. Hereafter, we will investigate relationships between the acoustic properties and OH concentrations.

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