Gain saturation dependence on signal wavelength in a travelling-wave semiconductor laser amplifier

Gain saturation dependence on signal wavelength in a 1.5 ?m InGaAsP travelling-wave semiconductor laser amplifier is experimentally studied. Saturation output powers were 6.9dBm, 8.3dBm and 10.6dBm for signal wavelengths of 1490 nm, 1510 nm and 1540 nm, respectively. This saturation dependence on wavelength, i.e. higher saturation output power for longer signal wavelength, results from signal gain peak shift towards longer wavelength with increasing input power.     

Using precise data sets on farming and pesticide properties to verify a diffuse pollution hydrological model for predicting pesticide concentration.

Verification of a diffuse pollution model involves comparing results actually observed with those predicted by precise model inputs. Acquisition of precise model inputs is, however, problematic. In particular, when the target catchment is large and substantial estimation uncertainty exists, not only model verification but also prediction is difficult. Therefore, in this study, rice-farming data were collected for all paddy fields from all farmers in a catchment and pesticide adsorption and degradation rates in paddy field soil samples were measured to obtain precise model inputs. The model inputs successfully verified the model's capability to predict pesticide concentrations in river water. Sensitivity analyses of the model inputs elucidated the processes significantly affecting pesticide runoff from rice farms. Pesticide adsorption and degradation rates of the soil did not significantly affect pesticide concentrations, although pesticide discharge to river water accounted for less than 50% of the total quantity of pesticide applied to fields, possibly owing to pesticide adsorption and degradation. The timing of increases in pesticide concentrations in river water was affected mostly by the farming schedule, including the time of pesticide application and irrigation, and secondarily by rainfall events.     

Chirp reduction in wavelength conversion using a laser diode byinjection locking

The authors demonstrate that an injection locking technique suppresses the chirp in wavelength conversion using a laser diode. Waveform patterns of a 2.5 Gbit/s intensity-modulated signal after 128 km transmission through a normal dispersion singlemode fibre were improved by the injection locking technique     

Silicon nitride thin-film deposition by LPCVD with in situ HF vaporcleaning and its application to stacked DRAM capacitor fabrication

Silicon nitride film deposited by LPCVD with newly developed in situ HF vapor cleaning has been studied and applied to fabricate dielectric films for stacked DRAM capacitors. Using this method, an oxide-free surface of underlaid poly-Si can be obtained. Silicon nitride film deposited on this surface has been verified by FTIR measurement to have the stoichiometrically proper composition of Si₃N₄ . However, the film was found to be selectively deposited on poly-Si electrodes. This selective deposition degrades the reliability of the stacked capacitor, because the silicon nitride can not completely cover the periphery of poly-Si electrodes on SiO₂. We propose a simple process that avoids the problem making it possible to apply silicon nitride film to stacked-capacitor fabrication. Stacked capacitors fabricated by this process exhibit very low leakage current and high electrical reliability even for ultra-thin silicon nitride films less than 5 nm thick     

Design of electrofusion joints and evaluation of fusion strength using fusion simulation technology

Fusion simulation is one of the key techniques in designing and producing electrofusion (EF) joints for gas distribution and in evaluating fusion joint integrity. This paper describes the result of a numerical simulation of a thermal fusion process, using the finite element method. A nonlinear heat transfer computer program was used to obtain the temperature profile of a large electrofusion joint at fusion. The effects of applied voltage, heating time, wire pitch, and ambient temperature were examined for designing a 150-mm EF joint. A method to shorten the cooling time was also investigated. The fusion condition range suitable for a 150-mm EF joint was found to be slightly narrower than that suitable for a 50-mm EF joint. Examination of the effect of wire pitch revealed that if the pitch is extremely large, thermal degradation starts in the resin close to the wire before the fusion-interface strength reaches the maximum value. We have developed a program to simulate the process of closing the gap between the pipe and the joint due to resin expansion and melting after the power is supplied.     

Monoclonal antibody analysis of phosphatidylserine and protein kinase C localizations in developing rat cerebellum

Understanding the topographical relationships between phosphatidylserine (PS) and protein kinase C (PKC) within neurons can provide clues about the mechanism of translocation and activation of PKC. For this purpose we applied monoclonal antibodies (Abs) of PS and PKC to sections of developing rat cerebellum. The anti-PKC Ab immunohistochemical pattern showed homogeneous staining of Purkinje cells over various postnatal ages, whereas the anti-PS Ab staining showed a heterogeneous localization over these ages. Purkinje cells did not stain well between postnatal day 14 (PND 14) and PND 21, suggesting that the PS was lost from the membrane during preparation of the sections during this period. These data imply that interactions between PS and PKC vary in Purkinje cells during postnatal development.     

A 64-Mb DRAM with meshed power line

A 64-Mb dynamic RAM (DRAM) has been developed with a meshed power line (MPL) and a quasi-distributed sense-amplifier driver (qDSAD) scheme. It realizes high speed, t_RAS=50 ns (typical) at V_cc=3.3 V, and 16-b input/output (I/O). This MPL+qDSAD scheme can reduce sensing delay caused by the metal layer resistance. Furthermore, to suppress crosstalk noise, a V_SS shield peripheral layout scheme has been introduced, which also widens power line widths. This 64-Mb DRAM was fabricated with 0.4-μm CMOS technology using KrF excimer laser lithography. A newly developed memory cell structure, the tunnel-shaped stacked-capacitor cell (TSSC), was adapted to this 64-Mb DRAM