The measurement sensitivity of microwave surface resistance, Rs, of high temperature superconducting (HTS) thin films using half-wavelength microstrip resonator with copper and HTS ground plane is analyzed for fundamental and higher order modes of the resonator. The estimated sensitivity of Rs-measurement is at least an order of magnitude greater at fundamental resonant frequency compared to when measured using higher order harmonic modes.

The vertical-cavity surface-emitting laser (VCSEL) is becoming a key device in high-speed optical local-area networks (LANs) and even wide-area networks (WANs). This device is also enabling ultra parallel data transfer in equipment and computer systems. In this paper, we will review its physics and the progress of technology covering the spectral band from infrared to ultraviolet by featuring materials, fabrication technology, and performances such as threshold, output power, polarization, modulation and reliability. Lastly, we will touch on its future prospects.

A 2D photonic crystal surface-emitting laser using a triangular lattice is developed, and current-injected lasing oscillation is demonstrated. From consideration of the Bragg diffraction condition in the 2D triangular-lattice structure, it is shown that the 2D coupling phenomenon occurs in the structure. As a result of the 2D periodicity of the structure, the longitudinal mode and lateral mode can be controlled, and stable single-mode oscillation is possible over a large 2D area. The lasing mode of the structure is analyzed by calculating the photonic band diagram by the 2D plane-wave expansion method, and we show that four band edges at which the lasing oscillation can occur exist at the Γ point. Current-injected lasing oscillation is successfully demonstrated at room temperature under pulsed conditions. The threshold current density is 3.2 kA/cm2 and the lasing wavelength is 1.285 µm. From the near-field and far-field patterns, it is shown that large-area 2D (diameter 480 µm) lasing oscillation occurs in the device and the divergence angle is very narrow (less than 1.8). We also demonstrate the correspondence between the measured lasing wavelengths and calculated band diagram by comparing the polarization characteristics with the calculated distribution of the electromagnetic field. The results indicate that 2D coherent lasing oscillation occurs due to the multi-directional coupling effect in the 2D photonic crystal. Finally, we show that the polarization patterns of the lasers can be controlled by introducing artificial lattice defects from the theoretical calculation.

We have developed a novel self-alignment process using the surface tension of the liquid resin for assembly of electronic or optoelectronic devices. Though the liquid resins have a characteristics as low as one tenth of the surface tension of solder in general, restoring forces for self-alignment capability can be produced by making it constrained on the 3-dimensional pads on chip and substrate. In this paper, its principle and characteristics are described and the relationship between process parameters and joint geometry were examined. And the possibility of self-alignment process was verified by analytic numerical method and scaled-up experiment. A self-alignment accuracy was examined experimentally and show that it became less than 0.4 µm. It can provide a useful information on various parameters involved in joint geometry and optimal design guideline to generate the proper profiles.

Bidirectional reflection distribution functions (BRDFs) of commercially pure titanium sheets with three different kinds of surface morphology were measured. Those experimental BRDFs were analyzed by using Phong's reflection model. Topographic measurements of the specimens' surfaces were performed with using a stylus-method. An explicit microfacet model based on topographic data was proposed. With using the explicit microfacet model and geometrical optics the calculated BRDFs were obtained and then compared with the experimental BRDFs. Both of them were in a good agreement. Through this comparison physical meanings of Phong's reflection model were discussed. We concluded that with using the explicit microfacet model it will be possible to calculate the BRDF of the materials' surface in arbitrary illumination conditions and that this modeling will be useful to develop new aesthetic surface appearance in material industries, computer graphics, architectural design and surface science.

We present an algorithm for computing the Minkowski sum of two surfaces of revolution with parallel axes, each defined as a rotational sweep of a slope-monotone closed curve. This result is an extension of that due to Sugihara et al., where the Minkowski sum for two slope-monotone closed curves in the plane is defined.

A periodic approach introduced previously is applied to the TM wave scattering from a finite periodic surface. A mathematical relation is proposed to estimate the scattering amplitude from the diffraction amplitude for the periodic surface, where the periodic surface is defined as a superposition of surface profiles generated by displacing the finite periodic surface by every integer multiple of the period . From numerical examples, it is concluded that the scattering cross section for the finite periodic surface can be well estimated from the diffraction amplitude for a sufficiently large .

Surface passivation process of GaN utilizing electron-cyclotron-resonance (ECR) excited plasma has been characterized and optimized for realization of stable operation in GaN-based high-power/high-frequancy electronic devices. From XPS analysis, the NH4OH treatment as well as the ECR-N2 and ECR-H2 plasma treatments were found to be effective in removing natural oxide and contaminants from the GaN surface. The SiNx/GaN structure prepared by the ECR excited plasma chemical vapor deposition (ECR-CVD) process showed better C-V behavior compared to the SiO2/GaN structure. Surface treatment process using the ECR plasma improved interface properties and achieved the Dit value of 21011 cm-2 eV-1 or less. An estimate of the valence band offset by XPS showed that the present SiNx/n-GaN structure has a type-I band lineup, suitable for the surface passivation of GaN-based devices. No pronounced stress remained at the SiNx/GaN interface, which was confirmed by Raman spectroscopy.

This paper proposes a precise method of realizing simultaneous measurement of microscopic defects and the macroscopic three-dimensional shapes of planar objects having specular reflection surfaces. The direction vector field of surface tilt is evaluated directly by the introduction of a moving slit-light technique based on computer graphic animation. A reflected image created by the moving slit-light is captured by a video camera, and the image sequence of the slit-light deformation is analyzed. The obtained direction vector field of the surface tilt recovers the surface shape by means of integration. Two sample objects, a concave mirror and a plane plastic injection molding, are tested to measure the performance of the proposed method. Surface anomalies such as surface dent and warpage are detected quantitatively at a high resolution (about 0.2 [µm]) and a high accuracy (about 95%) in a wide area (about 15 [cm]) of the test object.

Most of the current research is focused on the row-column scanning keyboard interface for English letter and number input. At the present time, there are insufficient methods to control the computer mouse effectively. In this study, a categorized row-column scanning computer interface is developed to improve the conventional single key-in row-column scanning method. The beneficial developments include: speed enhancement by categorizing radicals of keyboard, input control of mouse, and multiple selection of input methods such as surface electromyographic (SEMG) control, breath pressure sensibility control with puff, force sensibility control, infrared sensibility control and single key-in control. Meanwhile, an enhancement software package is developed to increase the row-column scanning keyboard capabilities and to upgrade the completeness of the computer mouse for the disabled persons to control the operation of data entry and the associated implementation better.

This paper first gives the exact surface integral representation for PO diffracted electromagnetic fields from bounded flat plate through the deformations of the original surface by using field equivalence principle. This exact representation with the surface integral can be approximately reduced to novel line integral along the boundary of the plate by the use of Maggi-Rubinowicz transformation, which keeps a high accuracy even in near zone. Numerical results for the scattering of the electric dipole wave from the square planar plate are presented for demonstrating the accuracy.

As a method of analyzing the wave scattering from a finite periodic surface, this paper introduces a periodic approach. The approach first considers the wave diffraction by a periodic surface that is a superposition of surface profiles generated by displacing the finite periodic surface by every integer multiple of the period . It is pointed out that the Floquet solution for such a periodic case becomes an integral representation of the scattered field from the finite periodic surface when the period goes to infinity. A mathematical relation estimating the scattering amplitude for the finite periodic surface from the diffraction amplitude for the periodic surface is proposed. From some numerical examples, it is concluded that the scattering cross section for the finite periodic surface can be well estimated from the diffraction amplitude for a sufficiently large .

The diffraction of a plane electromagnetic wave by an impedance wedge whose boundary is described in terms of the skew coordinate systems is treated by using the Wiener-Hopf technique. The problem is formulated in terms of the simultaneous Wiener-Hopf equations, which are then solved by using a factorization and decomposition procedure and introducing appropriate functions to satisfy the edge condition. The exact solution is expressed through the Maliuzhinets functions. By deforming the integration path of the Fourier inverse transform, which expresses the scattered field, the expressions of the reflected field, diffracted field and the surface wave are obtained. The numerical examples for these fields are given and the characteristics of the surface wave are discussed.

The present paper discusses several promising application areas for optical data links based on high-performance vertical-cavity surface-emitting laser diodes (VCSELs). Both 850 and 980 nm emission wavelength devices realized in the GaAs-AlGaAs or InGaAs-AlGaAs material systems are considered. We show data transmission results of 10 Gb/s signals at 830 nm wavelength over a new high-bandwidth multimode silica fiber of up to 1.6 km length. The same fiber type is employed to demonstrate the first 40 Gb/s transport over 300 m distance by means of a 4-channel coarse wavelength-division multiplexing approach. A first 1 10 linear VCSEL array capable of 10 Gb/s per channel operation is presented for use in next generation parallel optical modules. To improve the singlemode emission characteristics for output power in the 5 mW range we introduce a new device concept incorporating a long monolithic cavity. For low-cost short-distance data links we investigate graded-index polymer optical fibers and report on up to 9 Gb/s transmission over a length of 100 m. Polymer waveguides are also used in an optical layer of a hybrid electrical-optical printed circuit board. Transmitted 10 Gb/s optical data over a prototype board show the potential of this new technology. Finally we present two-dimensional VCSEL arrays for highly parallel data transport on a CMOS chip level. Both 980 and 850 nm bottom emitting devices with modulation capabilities up to 12.5 Gb/s are discussed.

The present paper discusses several promising application areas for optical data links based on high-performance vertical-cavity surface-emitting laser diodes (VCSELs). Both 850 and 980 nm emission wavelength devices realized in the GaAs-AlGaAs or InGaAs-AlGaAs material systems are considered. We show data transmission results of 10 Gb/s signals at 830 nm wavelength over a new high-bandwidth multimode silica fiber of up to 1.6 km length. The same fiber type is employed to demonstrate the first 40 Gb/s transport over 300 m distance by means of a 4-channel coarse wavelength-division multiplexing approach. A first 1 10 linear VCSEL array capable of 10 Gb/s per channel operation is presented for use in next generation parallel optical modules. To improve the singlemode emission characteristics for output power in the 5 mW range we introduce a new device concept incorporating a long monolithic cavity. For low-cost short-distance data links we investigate graded-index polymer optical fibers and report on up to 9 Gb/s transmission over a length of 100 m. Polymer waveguides are also used in an optical layer of a hybrid electrical-optical printed circuit board. Transmitted 10 Gb/s optical data over a prototype board show the potential of this new technology. Finally we present two-dimensional VCSEL arrays for highly parallel data transport on a CMOS chip level. Both 980 and 850 nm bottom emitting devices with modulation capabilities up to 12.5 Gb/s are discussed.

We have discussed a ray tracing method to estimate the scattering characteristics from random rough surface. It has been shown from the traced rays that the diffracted rays dominate over the reflected rays. For the field evaluation, we have used the Fresnel function for the diffracted coefficient and the Fresnel's reflection coefficients. Numerical examples have been carried out for the scattering characteristics of an ocean wave-like rough surface and the delay spared characteristics of a building-like surface. In the present work we have demonstrated that the ray tracing method is effective to numerical analysis of a rough surface scattering.

Modified Edge Representation (MER) empirically proposed by one of the authors is the line integral representation for computing surface radiation integrals of diffraction. It has remarkable accuracy in surface to line integral reduction even for sources very close to the scatterer. It also overcomes false and true singularities in equivalent edge currents. This paper gives the mathematical derivation of MER by using Stokes' theorem; MER is not only asymptotic but also global approximation. It proves remarkable applicability of MER, that is, to smooth curved surface, closely located sources and arbitrary currents which are irrelevant to Maxwell equations.

The finite volume time domain (FVTD) method is applied to electromagnetic wave scattering from random rough dielectric surfaces. In order to gain a better understanding of physics of backscattering of microwave from rough surface, this paper treats both horizontal and vertical polarizations especially at low- grazing angle. The results are compared with those obtained by the Integral equation method and the small perturbation method as well as with the experimental data. We have shown that the present method yields a reasonable solution even at LGA. It should be noted that the number of sampling points per wavelength for a rough surface problem should be increased when more accurate numerical results are required, which fact makes the computer simulation impossible at LGA for a stable result. However, when the extrapolation is used for calculating the scattered field, an accurate result can be estimated. If we want to obtain the ratio of backscattering between the horizontal and vertical polarization, we do not need the large number of sampling points.

In this paper we present a case study of a hierarchical statistical analysis. The method which we use here bridges the statistical information between process-level and system-level, and enables us to know the effect of the process variation on the system performance. We use two modeling techniques--intermediate model and response surface model--in order to link the statistical information between adjacent design levels. We show an experiment of the hierarchical statistical analysis applied to a Phase Locked Loop (PLL) circuit, and indicate that the hierarchical statistical analysis is practical with respect to both accuracy and simulation cost. Following three applications are also presented in order to show advantage of this linking method; these are Monte Carlo analysis, worst-case analysis, and sensitive analysis. The results of the Monte Carlo and the worst-case analysis indicate that this method is realistic statistical one. The result of the sensitive analysis enables us to evaluate the effect of process variation at the system level. Also, we can derive constraints on the process variation from a performance requirement.

Borehole radar is known as a powerful technique for monitoring of subsurface structures such as water flow. However, conventional borehole radar systems are operated in the frequency range lower than 100 MHz and the resolution is poor to measure a surface roughness and an inner structure of subsurface fractures directly. In order to monitor the water flow, these characteristics of subsurface fractures are important. We developed a polarimetric borehole radar system using dipole antennas and axial slot antennas and have found that this system can provide more information than conventional borehole radar. However, the relationship between the characteristic of subsurface fracture and the measured polarimetric radar information has not been clear. In this paper, we simulate electromagnetic wave scattering from subsurface fractures having a rough surface by Finite-Difference Time-Domain (FDTD) technique and discuss the relationship between a surface roughness of subsurface fracture and the polarimetric information. It is found that the subsurface fracture having strong cross-polarized components can be estimated to be rough surface fracture. The full polarimetric single-hole radar measurement was carried out at the Mirror Lake site, NH, USA. In this experiment, we found that subsurface fractures can be classified into some groups by an energy scattering matrix, and found that the subsurface fracture estimated to have a rough surface corresponds to that has higher water permeability.