This paper presents circuit models for the description of the frequency-dependent behavior of coils for horizontal deflection in CRTs. This enables CRT circuit designers to use circuit simulation programs to predict the high-frequency behavior of the interaction between the deflection coils and the drive circuit. An overview is given of the major phenomena that occur in CRT deflection coils at various frequencies. Models are presented for the dissipative, the capacitive, and the resonant behavior in successive frequency intervals. With these models, phenomena such as power dissipation and ringing can not only be related to design parameters, but can also be calculated from impedance characteristics which are relatively easy to measure.

This paper chronicles the leaky-mode leakages in a corner-fed square patch. First, the measured peak RPA (relative power absorbed, 1-|S11|2-|S21|2) values of the two-port corner-fed square patch (two-port test circuit) are reported. These are 21.1%, 52.3%, 89.8% and 81.3% at 5.68 GHz, 11.76 GHz, 16.68 GHz and 22.29 GHz, respectively. Such periodicity of frequencies and the phenomenon of increasing losses at higher frequencies enable us to link these peak frequencies to leaky-mode excitations. The modal spectra of the higher-order leaky modes with a strip width of 630 mil, equal to the side length of the square patch, are obtained by the well-known space-domain integral equation method. The maximum available power gain (GA,max), obtained by simultaneously complex conjugate matched impedance at the referenced two ports of the test circuit, depicts that (1) nearly loss-free transmission parameter outside the leaky-mode regions and (2) substantial losses inside the leaky-mode regions. This result suggests that the leaky modes are the main sources causing losses for the two-port test circuit. Furthermore, the valley points of the measured and theoretical GA,max are about -7.5 dB, -9.7 dB and -12.0 dB at 10.13 GHz, 16.68 GHz and 22.29 GHz, respectively, and all are in the leaky-mode regions of the modal spectra. The one-port properties of the two-port patch with the second port opened are then investigated. The degenerated (0,N) and (N,0) modes (N=1, 2, 3 and 4), calculated by the cavity model method, fall into the strong leakage regions from the first to the fourth higher-order leaky modes. The well-known leaky line's frequency-scanning characteristics also appear in the one-port test circuit, with the angle of the main beam moving from θ=30 to θ=40 as the operating frequency is increased from 22.50 GHz to 23.75 GHz. Lastly, a two-dimensional (2-D) transmission-line model of the one-port test circuit is proposed. This model uses two orthogonal modal currents as excitations to stimulate the corner-fed square patch. At 22.60 GHz, in the fourth higher-order leaky mode (EH4) region, the current distributions obtained by the 2-D transmission-line model closely agree with those of the full-wave simulation. This consistency shows that the damped-oscillation current distributions of the corner-fed square patch at 22.60 GHz are caused significantly by the multiple reflections of the leaky mode. Furthermore, at the resonant frequencies of the patch, the tangled bound-mode resonance of the EH0 mode can enhance the leaky-mode leakages.

This paper describes how the symmetry of a three-phase circuit prevents the symmetric modes of several subharmonic oscillations. First, we make mathematically it clear that the generation of symmetrical 1/3l-subharmonic oscillations (l=1,2,) are impossible in the three-phase circuit. As far as 1/(3l+1)-subharmonic oscillations (l=1,2,) and 1/(3l+2)-subharmonic oscillations (l=0,1,) are concerned, the former in negative-phase sequence and the latter in positive-phase sequence are shown to be impossible. Further, in order to confirm the above results, we apply the method of interval analysis to the circuit equations and obtain all steady state solutions with unsymmetric modes.

Spatiotemporal chaos in a multidomain regime in a Gunn-effect device is numerically investigated as an example of collective domain oscillations under global constraints. The dynamics of carrier densities are computed using a set of model partial differential equations. Numerical results reveal some distinctive and chaotic clustering features caused by the global coupling and boundary effects. The chaotic regime is then characterized in terms of a Lyapunov spectrum and Lyapunov dimension, the latter increasing with the size of the system.

We have measured the temperature dependence of the gain characteristics in 1.3-µm AlGaInAs/InP strained multiple-quantum-well (MQW) semiconductor lasers using Hakki-Paoli method. By measuring the temperature dependences of the peak gain value and the gain peak wavelength, we evaluated the temperature dependences of the threshold current and the oscillation wavelength, respectively. The small temperature dependence of the threshold current in AlGaInAs/InP lasers is caused by the small temperature dependence of the transparency current density, which is represented by the characteristic temperature TJtr of 116 K. In AlGaInAs/InP high T0 lasers, the temperature dependence of the oscillation wavelength is slightly larger than that in GaInAsP/InP lasers because of the larger temperature dependence of bandgap wavelength 0.55 nm/K.

We have measured the temperature dependence of the gain characteristics in 1.3-µm AlGaInAs/InP strained multiple-quantum-well (MQW) semiconductor lasers using Hakki-Paoli method. By measuring the temperature dependences of the peak gain value and the gain peak wavelength, we evaluated the temperature dependences of the threshold current and the oscillation wavelength, respectively. The small temperature dependence of the threshold current in AlGaInAs/InP lasers is caused by the small temperature dependence of the transparency current density, which is represented by the characteristic temperature TJtr of 116 K. In AlGaInAs/InP high T0 lasers, the temperature dependence of the oscillation wavelength is slightly larger than that in GaInAsP/InP lasers because of the larger temperature dependence of bandgap wavelength 0.55 nm/K.

We present calculations of the linear-response conductance of a SiGe based single-electron transistor (SET). The conductance and the discrete charging of the quantum dot are calculated by free-energy minimization. The free-energy calculation takes the discrete level-spectrum as well as complex many-body interactions into account. The tunneling rates for tunneling through the source and lead barrier are calculated using Bardeen's transfer Hamiltonian formalism. The tunneling matrix elements are calculated for transitions between the zero-dimensional states in the quantum dot and the lowest subband in the one-dimensional constriction. We compare the results for the conductance peaks with those from calculations with a constant tunneling rate where the shape of the peaks is only due to energetic arguments.

The orbital portrait of quasi-periodic oscillation shows transition like change with the amplitude of external force in periodically forced van der Pol oscillator. This phenomenon originates from frequency pulling between self-sustained and periodic external oscillations induced by the frequency shift of former. We estimate this shift and succeed in deriving the transition points at which the portrait changes.

Our recent progress in GaN-based nanostructures for quantum dot (QD) lasers and vertical microcavity surface emitting lasers (VCSELs) is discussed. We have grown InGaN self-assembled QDs on a GaN epitaxial layer, using atmospheric-pressure metalorganic chemical vapor deposition. The average diameter of the QDs was as small as 8.4 nm and strong photoluminescence emission from the QDs was observed at room temperature. Furthermore, we found that InGaN QDs could be formed even after 10 QD layers were stacked, thus increasing the total QD density. Using these growth results, we fabricated a laser structure with InGaN QDs embedded in the active layer. A clear threshold was observed in the dependence of the emission intensity on the excitation energy at room temperature under optical excitation. We succeeded in demonstrating in lasing action in vertical cavity surface emitting lasers at room temperature with a cavity finesse of over 200.

In this study, wave propagation phenomena of phase states are observed at van der Pol oscillators coupled by inductors as a ladder. For the case of 17 oscillators, interesting wave propagation phenomena of phase states are found. By using the relationship between phase states and oscillation frequencies, the mechanisms of the propagation and the reflection of wave are explained. Circuit experimental results agree well with computer calculated results qualitatively.

The analysis of the Takens-Bogdanov bifurcation of the equilibrium at the origin in the Chua's equation with a cubic nonlinearity is carried out. The local analysis provides, in first approximation, different bifurcation sets, where the presence of several dynamical behaviours (including periodic, homoclinic and heteroclinic orbits) is predicted. The local results are used as a guide to apply the adequate numerical methods to obtain a global understanding of the bifurcation sets. The study of the normal form of the Takens-Bogdanov bifurcation shows the presence of a degenerate (codimension-three) situation, which is analyzed in both homoclinic and heteroclinic cases.

This paper presents the several bifurcation phenomena generated in nonlinear three-phase circuit with symmetry. The circuit consists of delta-connected nonlinear inductors, capacitors and three-phase symmetrical voltage sources. Particular attention is paid to the subharmonic oscillations of order 1/2. We analyze the bifurcations of the oscillations from both theoretical and experimental points. As a tool of analysis, we use the homotopy method. Additionally, by comparing with single-phase and single-phase-like circuits, the special feature of the three-phase circuit is revealed.

In this paper we study the evolution of the resonance zones that appear in connection with a Hopf-pitchfork bifurcation exhibited by a Z2-symmetric electronic circuit. These regions, bounded by curves of folds (saddle-node bifurcations) may be closed or open depending on the values of the parameters. An angular degeneracy on the torus bifurcation curve originates the banana shape of Arnold's tongues. The presence of homoclinic bifurcations is also pointed out.

A photorefractive ring resonator with self-pumped four-wave mixing (PRRR-SPFWM) in which the Cat mirror region and the four-wave mixing region are formed in a single photorefractive crystal is proposed, and the steady-state analysis of this unknown device is first performed. Since the backward pump beam is generated as a phase conjugate of the forward pump beam in the Cat mirror region, counterpropagation of both pump beams is spontaneously obtained. We analyze its oscillation intensities in steady state, and show that the threshold coupling strength of oscillation depends on the cavity mirror reflectivity and the reflectivity of the Cat mirror region. We also show interesting property of PRRR-SPFWM, the possibility to switch over between unidirectional and bidirectional oscillation by controlling the amplitude of coupling strength.

We investigate the relaxation oscillation characteristics of an actively mode-locked fiber laser and a novel stabilizing method of the laser theoretically and experimentally. The stabilizing method controls cavity length to suppress the rf power of the relaxation oscillation frequency of the laser output, and can directly monitor the stability of the laser to ensure the most stable operation. With this method, the rf power ratio between mode-locking frequency and the background noise can be kept to more than 70 dB, and highly stable transform-limited pulse generation is achieved. Bit-error-free operation at 6. 3 GHz over 10 hours is successfully demonstrated. The stability of the center wavelength of the laser output and the required accuracy of cavity control for high-speed laser operation are also discussed.

Widely tunable coherent terahertz (THz)-wave generation was successfully demonstrated based on the laser light scattering from the lowest A1-symmetry polariton mode by using a Q-switched Nd:YAG laser pumping. This method exhibits multiple advantages like wide tunability (frequency: 0. 9-2. 2 THz), coherency and compactness of its system. In this paper, the general performances of this THz-wave generator, as well as the recent development of the system and its application are reported. Measurements of tunability, coherency, power, polarization, radiation angle, and divergence are shown. The cryogenic cooling of the crystal was performed in addition, and a more than one hundred times higher THz-wave output was observed. A spectroscopic application of our wave source is demonstrated by measuring the water vapor absorption.

Gate performance for observing Coulomb oscillations and Coulomb diamonds are compared for two types of gated sub-µm double-barrier heterostructures. The first type of device contains modulation-doped barriers, whereas the second type of device contains a narrower band gap material for the well and no barriers with doped impurities. Both the Coulomb oscillations and Coulomb diamonds are modified irregularly as a function of gate voltage in the first type of device, while in the second type of device they are only systematically modified, reflecting atom-like properties of a quantum dot. This difference is explained in terms of the existence of impurities in the first type of device, which inhomogeneously deform the rotational symmetry of the lateral confining potential as the gate voltage is varied. The absence of impurities is the reason why we observe the atom-like properties only in the second type of device.

In this study, we show how changing a frequency in one of N chaotic circuits coupled by a resistor effects our system by means of both circuit experiment and computer calculation. In these N chaotic circuits, N-1 circuits are completely identical, and the remaining one has altered the value of the oscillation frequency. It is found that for the case of N = 3 when a value of a coupling resistor is gradually increased, only one circuit with different frequency exhibits bifurcation phenomena including inverse period-doubling bifurcation, and for larger value of coupling resistor, the chaotic circuit with different frequency suddenly stops oscillating and the remaining two chaotic circuits exhibit completely anti-phase synchronization.

This paper presents the several bifurcation phenomena of harmonic oscillations occurred in nonlinear three-phase circuit. The circuit consists of delta-connected nonlinear inductors, capacitors and three-phase symmetrical voltage sources. We analyze the bifurcations of the oscillations by the homotopy method. Additionally, we confirm the bifurcation phenomena by real experiments. Furthermore, we reveal the effect of nonlinear couplings of inductors by the comparison of harmonic oscillations in a single-phase circuit.

Periodic solutions of slow-fast systems called "canards," "ducks," or "lost solutions" are examined in a second order autonomous system. A characteristic feature of the canard is that the solution very slowly moves along the negative resistance of the slow curve. This feature comes from that the solution moves on or very close to a curve which is called slow manifolds or "rivers." To say reversely, solutions which move very close to the river are canards, this gives a heuristic definition of the canard. In this paper, the generation mechanism of the canard is examined using a piecewise linear system in which the cubic function is replaced by piecewise linear functions with three or four segments. Firstly, we pick out the rough characteristic feature of the vector field of the original nonlinear system with the cubic function. Then, using a piecewise linear model with three segments, it is shown that the slow manifold corresponding to the less eigenvalue of two positive real ones is the river in the segment which has the negative resistance. However, it is also shown that canards are never generated in the three segments piecewise linear model because of the existence of the "nodal type" invariant manifolds in the segment. In order to generate the canard, we propose a four segments piecewise linear model in which the property of the equilibrium point is an unstable focus.