No abstract

Solid electrolyte memories utilizing voltage‐induced resistance change display the capability of multilevel switching, but understanding of the microscopic switching mechanism has been left incomplete. Here, in situ TEM observation of voltage‐induced changes in the microstructure of a solid electrolyte memory is reported, revealing that the multilevel switching originates from the growth of multiple conducting filaments with nanometer‐sized diameter and spacing.

Conductivity switching phenomena controlled by external voltages have been investigated for various NiO films deposited by dc reactive sputtering methods. Pt∕NiO∕Pt capacitor structures with top electrodes of different diameters have showed increasing off-state current with the diameter of a top electrode and nearly the same on-state current independent of the diameter. Local conductivity switching behaviors have been observed in a series structure consisting of two Pt∕NiO∕Pt capacitors with different resistance values. By reasoning out conductivity switching mechanisms from the switching characteristics and introducing multilayers consisting of NiO layers with different resistance values, we have reduced the reset current by two orders of magnitude.

During the last decade, the first autonomous under-In this paper, details of the development of ODIN-Ill are water robot Of the Autonomous system Laboratory Of the UNversity of Hawaii, ODIN (0"-Directional Intelligent Navigator) built in 1991 has produced a lot of valuable results in development control methods 11-51. Recently, ODIN was bo,.,, again in the 3rd eeneration with unioue features under recent techuoloeies described,-as well as the basic algorithm for the framework, and experimental results for a fine motion control scheme using a null motion solution considering practical issues such as energy consumption and thruster saturation. such-as abundant system resources owing to a PC104+, iew vehicle system software architectures with an object-oriented concept and its implementation, a graphical user interface and an independent algorithm module using a dynamic linking library (DLL) based on the Windows operating system. These give us an ideal enrimnment for developing various algorithms which are needed for developing an advanced underwater mbotic vehicle. This paper describes details of the development of ODIN-111 and presents Initial experimental results for fine motion control.

No abstract

No abstract

No abstract

Mach-Zehnder interferometers were fabricated from suspended membrane photonic crystal waveguides. Transmission spectra were measured and device operation was shown to be in agreement with theoretical predictions. © 2004 American Institute of Physics. ͓DOI: 10.1063/1.1642758͔ Planar photonic crystal waveguide ͑PCWG͒ technology has the potential to be a fundamental building block for future optical integrated circuits. Some of this potential arises from the ability to form small turning radius waveguide bends and wide angle Y branches 1 leading to the possibility of dense device integration. There have been many experimental demonstrations of two-dimensional photonic crystal waveguides recently including quantitative optical loss measurements.2-4 However, there have been few demonstrations published to date of photonic crystal waveguide bends and branches. [5][6][7] In this letter, we report on a demonstration of Mach-Zehnder interferometers formed in twodimensional photonic crystals.In this work we have fabricated Mach-Zehnder interferometers in two-dimensional photonic crystals with a range of path length differences between the arms of the interferometer. We expect therefore that the intensity transmitted through the interferometers will exhibit oscillations in the transmitted intensity as a function of the optical frequency with a period that depends on the path length difference and the propagation coefficient. The finite element method was used to calculate the band structure of the even guided mode for the PCWGs. Figure 1͑a͒ shows the calculated dispersion relations of guided modes of waveguides with ratios of the hole radius to lattice constant, r/a, of 0.27, 0.30, and 0.33. Only the lowest order guided mode is included in this figure. In this work, we intend to operate the fabricated MachZehnder interferometers in the spectral region in which there is very little chromatic dispersion. This simplifies the data analysis because we expect a fixed propagation coefficient and therefore a fixed oscillation period in the transmitted intensity over the wavelength range of operation. From the data in Fig. 1͑a͒, for an r/a value of 0.3 and a lattice constant value of 420 nm, this low chromatic dispersion region corresponds to the wavelength range of 1500-1550 nm and propagation coefficient in the range of 0.30-0.35. The experimental data in each case was taken in this low chromatic dispersion region. The group index can be obtained by differentiating the dispersion relation in Fig. 1͑a͒ and is plotted as a function of normalized wavelength in Fig. 1͑b͒ APPLIED PHYSICS LETTERS