Atomically flat diamond (111) surface formation by homoepitaxial lateral growth

A process of homoepitaxial growth of diamond (111) films by microwave plasma-enhanced chemical vapor deposition has been investigated characterizing areas by ex-situ atomic force microscopy. The evolution of surface morphology during a lateral growth of (111) diamond was visualized utilizing a mesa structure as a marker. Lateral growth forms atomically flat surfaces, which show atomically flat terraces over several hundred nm widths and single bilayer steps of (111) diamond.     

Identifying rotation and oscillation in surface tension measurement using an oscillating droplet method

We proposed a new approach to identify the frequencies of droplet rotation and m=±2 oscillation that degrade the accuracy of surface tension measurement by an oscillating droplet method. Frequencies of droplet rotation and m=±2 oscillation can be identified by a phase unwrapping analysis of time dependence of the deflection angle for the maximum diameter of the droplet image observed from above. The present method was validated, using test data with given frequencies. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(7): 421–430, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20214     

Frequency Estimation in Intradyne Reception

We report on an optical intradyne receiver experiment with frequency estimation. Frequency estimation allows, if performed prior to block phase estimation or other phase recovery techniques, for a much higher frequency difference between transmit laser and local oscillator laser. We demonstrate the feasibility of our approach in a 20-Gb/s quadrature phase-shift keying experiment     

Dual voltage converter with improved power factor and enabling voltage control

In this paper, a novel version of the dual voltage converter is presented with improved voltage regulation and enabling a wide range of voltage control by using self-turn-off devices (power transistors) instead of diodes. Further, this system operates with unity displacement factor. We have obtained the analytical expressions of this circuit. The results are, however, quite complex. We could calculate values of the voltage and current waveforms by using a computer. The calculated values are essentially in agreement with the experimental values. Experimentally, an ideal load characteristic with null voltage regulation was obtained by the conduction angle control for power transistors. Further, a wide range of voltage from 220 V to 39 V was obtained. A disadvantage for this system is the requirement for snubber circuits with a larger value of capacitor in order to suppress the surge voltages at turn-off periods.     

Photon probe fault locator for single-mode optical fiber using an acoustooptical light deflector

A new backscattering technique for diagnosing the attenuation characteristics, spatial imperfections with length (fault location), and splice loss in a single-mode optical fiber has been developed by using a TeO2acoustooptical light deflector operating at 120 MHz. Due to the small insertion loss and high extinction ratio of the deflector, the dynamic range of the backscattered signal has been increased by at least 10 dB, which corresponds to the extension of 5 km in measurable length for fiber loss of 1 dB/km, compared with the conventional back-scattering technique in which the beam splitter and polarizer-analyzer combination are utilized. Another advantage of this technique is in that the saturation of the amplifier is avoided by arbitrarily cutting off a large power in the early stage of the Rayleigh scattering signal. A single-mode fiber of 19.2 km in length has been examined, and the distance for fault location up to 18.4 km was obtained.     

Marked extension of diagnosis length in optical time domain reflectometry using 1.32 ?m YAG laser

An optical time domain reflectometer was newly constructed by using a high power Nd:YAG laser operating at a wavelength of 1.32 ?m and a TeO2 acousto-optical light deflector. As a result, the maximum detectable fault location length of 34 km for single-mode fibre and that of 60 km for multimode graded-index fibre were successfully attained.     

Amplitude fluctuation in laser signal transmitted through a long multimode fiber

Theoretical investigation has been made on fluctuation in detected signal at the end of a multimode fiber. It has been predicted that the fluctuation is caused by oscillation frequency fluctuation of a laser diode in association with interference, taking place at the detector surface, among nonorthogonal axial Components of field vectors for different modes. The prediction has been confirmed using a two-mode fiber and multimode graded-index fibers, by measuring amplitude and frequency of the signal fluctuation at the output end of the fiber. A method to suppress the amplitude fluctuation has been proposed for transmission characteristics measurement on long fibers.     

Recovery of gold from the plating rinse by adsorption with nylon fibers

Taking note of the affinity of some reverse osmosis membranes to Au(CN)^-₂ in the citrate buffered gold plating rinse, we accomplished the recovery of gold by the adsorption to some polymers. Among several polymers, tested nylon fibre had the most excellent characteristics of adsorption. The amount of adsorption of gold on nylon fiber increased with a decrease in pH value of the solution, and 7.5 mg of gold was adsorbed on 1 g of nylon fiber at pH 3, 25°C. The rate of adsorption increased with an increase in temperature. In the case of desorption, the solution containing cyanide ions at a pH as high as 10 was desirable to be employed as an eluant. By passing the simulated plating rinse through a column of nylon fiber, the adsorption and desorption of gold was successfully accomplished. The maximum concentration of gold in the eluant was approximately 600 ppm.