Light Diffraction of Aligned Polymer Fibers Periodically Dispersed by Phase Separation of Liquid Crystal and Polymer

We have confirmed light diffraction of aligned polymer fibers obtained by a phase separation of an anisotropic-phase solution of liquid crystal and polymer. He—Ne laser light passing through the polymer fibers was scattered in the axis vertical to the fibers, and had two peaks of light intensity symmetrical to the center of the transmitting laser spot. The two peaks were found to be caused by light diffraction due to the periodic polymer-fiber dispersion because the peaks corresponded to values calculated by intervals between the fibers. The periodical fiber networks are considered to be formed by anisotropic spinodal decomposition. This effect can be used to measure the dispersion order of the polymer fibers. © 2004 The Optical Society of Japan     

Large-volume injection electrothermal AAS combined with tungsten-treated pyrolytic graphite furnace: determination of cadmium in tap, snow and river water samples with phosphate modifier.

A large-volume (100 microl) injection-ETAAS with W-treated PG furnace combined with a phosphate modifier was applied to the determination of unpolluted levels of Cd in tap, snow and river-water samples. The limit of detection of 1.1 ng l(-1) was observed for a 4 w/v% NH4H2PO4 modifer. Matrix interference studies were tested for major ion species well found in fresh water. The direct determination of Cd in certified river water (12 +/- 2 ng l(-1)) was carried out and the observed value was in agreement with the certified one. The good recoveries of Cd added to real environmental water samples were also observed. This method was applied to the determination of Cd in unpolluted environmental water samples.     

Cerasome as an Organic-Inorganic Vesicular Nanohybrid: Characterization of Cerasome-Forming Lipids having a Single or a Dual Trialkoxysilyl Head

Morphological characterization of the organic-inorganic vesicular nanohybrids, Cerasomes, was performed in aqueous media from two aspects. Firstly, a novel Cerasome-forming lipid having two triethoxysilyl groups in the head moiety was synthesized and the physical property of the Cerasome was investigated. While the morphological stability of the Cerasomes, as evaluated from the vesicular collapse behavior against a micelle-forming nonionic surfactant, Triton-X 100, was extremely higher than that of the conventional phospholipid liposome, the stabilities were comparable to each other for the Cerasomes derived from the dual- and single-head lipids. On the other hand, the surface property of the Cerasome formed with the dual-head lipid more closely resembled the colloidal silica particles rather than that derived from the single-head lipid, as suggested by zeta-potential measurements. Secondly, the effect of the media pH on the morphological stability of the Cerasome formed with the single-head lipid was evaluated and appeared as a time difference in obtaining the morphological stability of the Cerasome. These morphological characteristics of the Cerasomes could be mainly owing to the development of the siloxane network on the vesicular surface.     

Non-destructive rapid analysis of brominated flame retardants in electrical and electronic equipment using Raman spectroscopy.

Using Raman spectroscopy without any preparation, we analyzed the brominated flame retardant, polybromodiphenyl ethers (PBDEs), which has been prohibited by the European Union. The typical Raman bands of PBDEs, which are clearly different from those of other brominated flame retardants, are from 100 to 300 cm(-1). In our analysis, the detection limit was about 100 ppm, and the analysis took about 1 min, whereas the usual method of solvent extraction using gas chromatography/mass spectroscopy takes 50 h.     

Chaos control and noise suppression in external-cavitysemiconductor lasers

Feedback-induced chaos and intensity noise enhancement in a laser diode with external optical feedback are studied by computer simulations. The enhancement of relative intensity noise (RIN) that is often observed in experiments is considered as a result of the feedback-induced deterministic chaos and the intensity noise suppression is treated from the viewpoint of chaos control. Especially, the conventional noise suppressing technique known as a high-frequency injection modulation is turned into a problem of stabilizing chaos through parameter modulations. We developed an analytical method which allows to optimize the modulation frequency from the linear stability analysis of the dynamical model that describes the laser diode with external feedback. The robustness of the modulation with respect to the modulation frequency and depth is verified and the results suggest the feasibility of applying our method to actual noise suppression. The RIN in the low-frequency region (up to 100 MHz) is shown to be reduced to the solitary laser level when the feedback-induced chaos is effectively controlled with the optimized modulation frequency     

Structural characterization of polypyrrole in the solid state by high resolution 15N NMR spectroscopy [II]

The solid-state ¹⁵N CP/MAS NMR spectra and ¹⁵N spin-lattice relaxation times (T₁) of doped and dedoped ¹⁵N-labeled polypyrroles prepared by electrochemical polymerization, have been measured by means of high-resolution solid-state ¹⁵N NMR. The ¹⁵N signal of polypyrrole consists of four peaks decomposed by line shape analysis. The four peaks obtained have been assigned to the various structures of polypyrrole. Further, the half-width of the ¹⁵N NMR spectra of polypyrroles is discussed as related to the electrical conductivity. © 1995 John Wiley & Sons, Inc.     

Fibre Bragg grating compression-tuned over 110 nm

A fibre Bragg grating with a tuning range covering beyond the C- and L-bands has been realised, which represents the broadest tuning range reported of any Bragg grating. The device exhibits constant spectral response and polarisation mode dispersion within these bands.     

Analytical evaluation technique of self-phase-modulation effect onthe performance of cascaded optical amplifier systems

We propose an approximate analytical evaluation technique of self-phase-modulation (SPM) in cascaded optical amplifier systems. The effect of SPM on optical pulse distortion is represented by the increase in the α-parameter of the transmitter. The waveform distortion is approximated by assuming that the pulse is transmitted over a dispersive fiber without nonlinearity. This technique greatly reduces the calculation time, and is especially useful in designing cascaded amplifier systems, evaluating theoretical maximum transmission distance     

A 1.8 Gb/s GaAs optoelectronic universal switch LSI withmonolithically integrated photodetector and laser driver

A high-speed monolithic optical interface switch LSI is developed using a GaAs MSM photodetector and large-scale integrated electric circuits. This LSI operates universally as a 1.8 Gb/s optical-input/optical-output four-channel time-division switch, a 1.8 Gb/s optical-input/electrical-output 1:4 demultiplexer, a 2.0 Gb/s electrical-output 4:1 multiplexer, and a 2.8 Gb/s electrical-input/electrical-output 4×4 space-division switch. It uses a new multistage 2×2 switch block with small hardware and high-speed operation. It can be expanded to a 16×16 optical-input/optical-output time-division switch operating at up to 1.8 Gb/s for broadband-ISDN