By means of the three-dimensional (3D) finite-difference time domain (FDTD) method, we have investigated in detail the optical properties of a two-dimensional photonic crystal (PC) surface-emitting laser having a square-lattice structure. The 3D-FDTD calculation is carried out for the finite size PC slab structure. The device is based on band-edge resonance, and plural band edges are present at the corresponding band edge point. For these band edges, we calculate the mode profile in the PC slab, far field pattern (FFP) and polarization mode of the surface-emitted component, and photon lifetime. FFPs are shown to be influenced by the finiteness of the structure. Quality (Q) factor, which is a dimensionless quantity representing photon lifetime, is introduced. The out-plane radiation loss in the direction normal to the PC plane greatly influences the total Q factor of resonant mode and is closely related with the band structure. As a result, Q factors clearly differ among these band edges. These results suggest that these band edges include resonant modes that are easy to lase and resonant modes that are difficult to lase.

We propose a novel optical signal processing using an optically pumped vertical-cavity surface-emitting laser (VCSEL) with an external light input. The mode transition between a fundamental and a 1st-high-order transverse mode is induced by an external light injection. Since a single mode fiber (SMF) spatially selects a fundamental transverse mode as an output signal, we are able to realize a nonlinear transfer function, which will be useful in future photonic networks. The mode transition characteristic of a 1.55 µm optically pumped two-mode VCSEL has been simulated by using a two-mode rate equation, which includes the effects of spatial hole burning and spectral hole burning as gain saturation coefficients. We focus on the detuning effect in the injection locking. When the wavelength of an input light with a fundamental mode is slightly longer than that of a VCSEL operating in a 1st-high-order transverse mode, the transverse mode of the VCSEL is switched to a fundamental mode at a critical input power level. This gives us an ideal transfer function for 2R (reamplification and reshaping) regeneration. Also, the proposed scheme may enable polarization insensitive signal processing, which is a unique feature in surface emitting lasers.

The formation of single monolayer of liquid crystalline molecules, 4-n-pentyl-4-cyanobiphenyl (5CB), deposited by the evaporation method in the air, was confirmed with the surface potential measurement. The surface potential increased with the time of evaporation, and the 3- or 4-minute evaporation at a source temperature of 110 gave the saturated potential, indicating the formation of single monolayer. Single monolayer formation was also supported by the comparison of the UV-visible absorption for evaporated film with LB monolayer. Positive potentials were built at the surface, indicating that CN group faces the substrate.

The deposition conditions of Y0.9Ba1.9La0.2Cu3Oy (La-YBCO) and (LaAlO3)0.3-(SrAl0.5Ta0.5O3)0.7 (LSAT) thin films were studied with the aim of fabricating ramp-edge Josephson junctions on a superconducting ground plane. These films were deposited by a magnetron sputtering method and utilized as a base electrode and an insulating layer under the electrode, respectively. YBa2Cu3Oy thick films grown by liquid phase epitaxy (LPE-YBCO) were used for a ground plane. Insertion of a SrTiO3 buffer layer between LSAT and LPE-YBCO significantly improved the flatness of the film surface. La-YBCO films with a flat surface and Tc (zero) of 87K were reproducibly obtained by DC sputtering. We have fabricated ramp-edge Josephson junctions using these films. Resistively and capacitively shunted junction (RCSJ)-like characteristics were observed in them. An Ic spread of 10.2% (at 4.2K, average Ic = 0.5 mA) was obtained for a 1000-junction series-array.

In the past decade, significant effort has been made toward increasing the accuracy and robustness of three-dimensional scanning methods. In this paper, we present a new prototype vision system named 3D Model Studio, which has been built to reconstruct a complete 3D model in as less as a few minutes. New schemes for a probe calibration and a 3D data merging (axis consolidation) are employed. We also propose a new semi-automatic contour registration method to generate accurate contour model from 3D data points, along with a contour triangulation based surface reconstruction. Experimental result shows that our system works well for reconstructing a complete 3D surface model of a human body.

We propose using SQP (Sequential Quadratic Programming) to directly recover 3D quadratic surface parameters from multiple views. A surface equation is used as a constraint. In addition to the sum of squared reprojection errors defined in the traditional bundle adjustment, a Lagrangian term is added to force recovered points to satisfy the constraint. The minimization is realized by SQP. Our algorithm has three advantages. First, given corresponding features in multiple views, the SQP implementation can directly recover the quadratic surface parameters optimally instead of a collection of isolated 3D points coordinates. Second, the specified constraints are strictly satisfied and the camera parameters and 3D coordinates of points can be determined more accurately than that by unconstrained methods. Third, the recovered quadratic surface model can be represented by a much smaller number of parameters instead of point clouds and triangular patches. Experiments with both synthetic and real images show the power of this approach.

Based on an experimental fact that surface wave plasmas excited by strongly coupled microwave through thin dielectric windows show nearly perfect absorption of microwave and, after diffusion, form a widely uniform dense plasma. A plasma with an uniformity of 5% over an area of 50 cm 60 cm was produced. The plasma produced by application of 2400 W total microwave power gives 1 1011 cm-3 in density and 1.5 eV in electron temperature.

26 GHz bandpass filter and duplexer using TM11δ rectangular-mode dielectric cavity resonators are proposed. These have a configuration compact and suitable for mounting on circuit boards. The resonators consisting of the Ba(Mg,Ta)O3 ceramic material showed a high quality factor value of 2600, which is roughly comparable to that of conventional E-plane waveguide filters. The dielectric losses of the ceramic material were experimentally evaluated from the viewpoint of the high frequency operation and the dielectric loss tangent of 7.410-5 was observed at 20 GHz. A three-stage Tchebyscheff bandpass filter with 0.4% relative bandwidth was fabricated and the passband insertion loss was 1.7 dB. A duplexer designed with two TM11δ mode filters and a microstrip T-junction is also presented.

This article describes a new method for converting an arbitrary topology mesh into one having subdivision connectivity. First, a base mesh is produced by applying a sequence of edge collapse operations to the original mesh with irregular connectivity. Then, the base mesh is iteratively subdivided. Each subdivided mesh is optimized to reduce its distance from the original mesh and to improve its global smoothness and compactness. A set of corresponding point pairs, which is required to compute the distance from the original mesh to the subdivided mesh, is determined by combining the initial parameterization and the multi-resolution projection. Experimental results show that the proposed method yields good performance in terms of global smoothness, small distortion, and good compactness, compared with conventional methods.

In order to clarify the mechanism of gate leakage in AlGaN/GaN heterostructure field effect transistors (HFETs), temperature (T)-dependent current-voltage (I-V) characteristics of Ni/n-AlGaN Schottky contact were measured in detail. Large deviations from the thermionic emission transport were observed in I-V-T behavior with anomalously large reverse leakage currents. An analysis based on the thin surface barrier (TSB) model showed that the nitrogen-vacancy-related near-surface donors play a dominant role in the leakage through the AlGaN Schottky interface. As a practical scheme for suppressing the leakage currents, use of an insulated gate (IG) structure was investigated. As the insulator, Al2O3 was selected, and an Al2O3 IG structure was formed on the AlGaN/GaN heterostructure surface after an ECR-N2 plasma treatment. An in-situ XPS analysis exhibited successful formation of an ultrathin stoichiometric Al2O3 layer which has a large conduction band offset of 2.1 eV at the Al2O3/Al0.3Ga0.7N interface. The fabricated Al2O3 IG HFET achieved pronounced reduction of gate leakage, resulting in the good gate control of drain currents up to VGS = +3 V. The maximum drain saturation current and transconductance were 0.8 A/mm and 120 mS/mm, respectively. No current collapse was observed in the Al2O3 IG-HFETs, indicating a remarkable advantage of the present Al2O3-based insulated gate and passivation structure.

RF diamond FETs have been realized on a hydrogen-terminated diamond surface conductive layer. By utilizing the self-aligned gate fabrication process which is effective for the reduction of the parasitic resistance, the transconductance of diamond FETs has been greatly improved. Consequently, the high frequency operation of 22 GHz has been realized in 0.2 µ m gate diamond MISFETs with a CaF2 gate insulator. This value is the highest in diamond FETs and is comparable to the maximum value of SiC MESFETs at present.

We have developed a novel self-alignment process using the surface tension of the liquid resin for assembly of electronic and optoelectronic devices. Due to their characteristics of low surface tension, however, the parametric design guidelines are necessary for resin self-alignment capability. In this paper, a shape prediction mathematical model and a numerical method are developed. The developed system is capable of achieving the liquid joint geometry and the parametric design for self-alignment capability. The influences of geometric parameters such as liquid volume, component weight, pad radius, liquid surface tension on the shape of liquid joint are investigated. Furthermore, the parametric design guidelines considered the process-related practical matters of misalignment level, distribution of the supplied liquid volumes and coplanarity deviation includes difference of the height between the pads are provided.

In this paper, the time-frequency separation algorithm (TFS) proposed by Belouchrani and Amin is applied to ground penetrating radar (GPR) data to reduce ground clutter, that hides reflected waves from a near-surface planar interface. We formulated the problem with several assumptions so that narrow band signals, whose center frequency and baseband signal depend on propagation paths, are received at the receiver, when a wideband signal is radiated from a transmitter. These phenomena can be clearly seen in time-frequency distribution (TFD) of the received signal. In this paper, we adopted the TFS utilizing the TFD signature as a blind separation technique to separate the ground clutter from the target signals. We show numerical and experimental results in order to verify the validity of the problem formulation and the TFS. We carried out GPR measurements to measure permafrost in Yakutsk, Russia. We found the difference in TFD signatures between the ground clutter and the target signal in the experimental data. We could detect the upper boundary of the permafrost with the TFS in spite of the unstable ground clutter.

Accurately segmenting and quantifying pulmonary nodule structure is a key issue in three-dimensional (3-D) computer-aided diagnosis (CAD) schemes. This paper presents a nodule segmentation method from 3-D thoracic CT images based on a deformable surface model. In this method, first, a statistical analysis of the observed intensity is performed to measure differences between the nodule and other regions. Based on this analysis, the boundary and region information are represented by boundary and region likelihood, respectively. Second, an initial surface in the nodule is manually set. Finally, the deformable surface model moves the initial surface so that the surface provides high boundary likelihood and high posterior segmentation probability with respect to the nodule. For the purpose, the deformable surface model integrates the boundary and region information. This integration makes it possible to cope with inappropriate position or size of an initial surface in the nodule. Using the practical 3-D thoracic CT images, we demonstrate the effectiveness of the proposed method.

The new hybrid antenna structures having external high-impedance-plane (HIP) shield are proposed. These antennas consist of normal patch or dipole antenna, working as a radiator, and HIP shield working as a reflector. The external HIP shield helps to reduce the undesired backward radiation. Generally, metal shield should be placed a quarter wavelengths apart from the antenna, but HIP shield can be placed close to the antenna and low profile structure can be obtained. In addition, compared with single-layer HIP antennas, having a patch surrounded by HIP structure, these hybrid antennas have the advantage of installation because the shielding effect can be obtained by attaching the external shield under the existing antenna. We fabricated HIP boards and combined with a microstrip patch or a regular dipole. The hybrid patch antenna with HIP shield improves the front-to-back radiation ratio (F/B ratio) similar to the single-layer HIP antenna or the hybrid patch with metal shield. But the dipole antenna with HIP shield, the F/B ratio is worse than the dipole with metal shield. These results indicate the TM mode antenna is suitable for the HIP shield in terms of the F/B ratio improvement.

The frequency dependence of surface resistance Rs of high temperature superconductor (HTS) films are measured by a novel measurement method using four TE0mp modes in a sapphire rod resonator. At first, a loss tangent tan δ of the sapphire rod and Rs of the HTS films are evaluated separately from the results measured for the TE021 and TE012 modes with close resonant frequencies. Secondly, Rs values at two different resonant frequencies for the TE011 and TE022 modes are measured using a well-known relation for sapphire tan δ/f = constant, where f is a frequency. Rs values of HoBa2Cu3O7-x thin films were measured in the frequency range of 10 to 43 GHz by using four sapphire rod resonators with different sizes. As a result, it is found that these measured results of Rs have a characteristic of frequency square.

This paper newly proposes a hollow ferrite waveguide which consists of a microstrip line loaded on two ferrite slabs with adjacent air gap. Dispersion relation of magnetostatic surface wave in the waveguide is derived by the two dimensional analysis, and reciprocal behavior for parallel bias magnetic field and nonreciprocal behavior for antiparallel bias magnetic field are shown. Propagation characteristic of magnetostatic surface wave in the hollow ferrite waveguide are experimentally demonstrated under both parallel and antiparallel bias magnetic field directions. Strong nonreciprocal behavior in the hollow guide was found for case of antiparallel bias field configuration. These experimental results are mostly in agreement with the dispersion diagram. A nonreciprocal four port junction is demonstrated as an application of the hollow ferrite waveguide.

The joint histogram of second order scale space differential invariants of natural images (including textures) is typically clustered about parabolic surface patches, whereas symmetrical elliptical patches (local convexities or concavities) are very rare and symmetrical hyperbolical patches also occur less frequently than parabolic patches. We trace the origin of this striking effect in the context of Gaussian random noise. For this case one may derive the joint histogram of curvedness and shape index analytically. The empirical observations are fully corroborated. In deriving these results we introduce a polar coordinate system in the space of second order scale space derivatives that turns out to be particularly useful in the study of the statistics of local curvature properties. The empirical observations apply also to non-Gaussian noise (e.g., Brownian noise) as well as to photographs of natural scenes. We discuss general arguments that help explain these observations.

The key elements of sub-100 nm MOSFET modeling for circuit simulation are accurate representation of new physical phenomena arising from advancing technologies and numerical efficacy. We summarize the history of MOSFET modeling, and address difficulties faced by conventional methods. The advantage of the surface-potential-based approach will be emphasized. Perspectives for next generations will be also discussed.

This paper presents a review of volumetric erosion studies applied to electrical contacts. The numerical methods presented are generic and could equally be applied to a number of areas where surfaces have been eroded or damaged. Equally there is no scale limitation of the surfaces to which the numerical methods can be applied. The paper starts with an introduction of the issues associated with the measurement of contact erosion, and then presents a summary of various hardware system for making 3D measurements of surfaces such as electrical contacts. This is followed by a review of the generic form fitting methods and also volume calculation methods. The paper concludes with a review of results taken from a test system for contact studies and from contact samples taken from commercial relays.