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We theoretically investigated the physical mechanism of significant bandwidth enhancement in injection-locked semiconductor lasers with strong light injection. Strong light injection can increase the semiconductor laser bandwidth to several times the free-running relaxation oscillation bandwidth. We focused on the fact that an injection-locked semiconductor laser can operate at an optical frequency different from its cavity resonance condition. Resonance is shifted from solitary resonance through the carrier-induced refractive-index change due to strong optical injection. We then framed a theory in which the enhanced resonance can be generated by transient interference between the injection-locked field and the field corresponding to the shifted cavity resonance. To examine the theory, we numerically investigated the rate equations and found that the numerical and theoretical results agree well over a wide range for strong injection. A stability analysis for the rate equations revealed that there is a mode transition from relaxation oscillation to interference-induced oscillation with increased injection, and the relaxation oscillation can become suppressed for higher injection levels. We believed that negligibly small fluctuations of the carrier suppressed the relaxation oscillation and examined it numerically. We also predict that, at strong injection levels, semiconductor lasers can be lower-dimensional systems because of the possibility of adiabatic elimination of the carrier. We further conclude that such low-dimensional systems can generate a high-frequency interference beat in the laser cavity and the resultant enhanced resonance.

In this paper, we present for the first time general analytical solutions of the static Green's functions for shielded and open arbitrarily multilayered media. The analytical formulas for the static Green's functions, which are expressed in the form of the Fourier series or the Fourier integrals, have simple form and are applicable to arbitrary number of the dielectric layers. The derivation of the formulas is primarily based on a technique by which a recurrence relation between L layers and L+1 layers is developed. Green's functions for a three-layered dielectric structure are given as an example of the general formulas. These general analytical solutions will provide a new and efficient tool to the analysis of the multilayered medium structures.

A new method of analysis called the partial-boundary element method (p-BEM) is proposed for the analysis of striplines with arbitrary cross-sectional dielectric in multi-layered media. By using a Green's function that satisfies the boundary conditions of a relevant structure with multi-layered media and introducing a concept of the equivalent charge density, the p-BEM formulates a potential integral and boundary integral equations only on partial-boundaries such as the surface of the arbitrary cross-sectional dielectric. The number of the equations needed to be formulated is much less than in the conventional BEM. Numerical results of analysis are presented for two kinds of striplines: 1) with a rectangular dielectric ridge and 2) with an embedded rectangular dielectric in three-layered media. >

The propagation and dispersion characteristics of picosecond electrical pulses in a suspended coplanar waveguide (SCPW) are investigated, and it is shown that the SCPW is a very promising transmission structure for ultrashort pulses. Numerical results for the modal dispersion of the SCPW are presented and compared to those of the conventional CPW, and a field-coupling theory is used to explain the evolution in the dispersion behavior. An evaluation based on the numerical analysis shows that a SCPW with properly controlled dispersion can exhibit a five times improvement in pulse transmission capability compared to the conventional CPW. Both computer simulations and experimental measurements show a substantial suppression in pulse distortion as well, compared to conventional CPWs. >

A new modal analysis method based on the combination of a point-matching method and a group theoretic approach is proposed by which optical fibers having symmetrically distributed multiple cores on a circumference can be studied. The case of sextet cores is treated. The results of numerical calculations and microwave model experiments are compared.

The use of suspended strip lines is becoming a powerful transmission technique at millimeter wavelengths because of low attenuation, weak dispersion, and various merits in manufacturing processes. This paper estimates effects of side-wall grooves of these lines on transmission characteristics within the TEM wave approximation.

Quatenary dielectric waveguide systems, which could be applied to optical fibers and dielectric image lines, are analyzed with an extended point-matching method. Theoretical results are confirmed with microwave experiments.

A simple approximate formula for the CAD of the dispersion property of microstrip lines is reported in this paper which well fits the calculated curves based on a rigorous method.

The proximity effects of microstrip lines near a substrate edge are estimated by using the rectangular boundary division method for effectively designing high-packing-density MMICs (monolithic microwave integrated circuits). Simple CAD (computer-aided design) formulas of edge-compensated microstrip lines (ECM lines) are introduced which can be applied to circumvent the proximity effects on the characteristic impedance. The practical design parameters of the ECM lines are given in the form of numerical data and simple polynomials for CAD work with a curve-fitting procedure. Results of capacitance measurements are compared with this theory. >

The propagation and dispersion characteristics of picosecond pulses in a suspended coplanar waveguide (SCPW) are presented. An evaluation based on numerical analysis shows that the SCPW can result in an improvement of about five times in pulse transmission capability over conventional CPWs. Pulse propagation along the SCPW is studied by simulations and experiments, both of which show a substantial suppression in pulse distortion. It is concluded that the SCPW should be a promising transmission structure for ultrashort pulses with picosecond and subpicosecond durations. >

In this paper, an analysis of traveling-wave optical modulator with thick trapezoidal cross-sectional electrodes on multilayered dielectric substrate is presented. The method of analysis uses a combination of the conformal mapping technique and the variational principle.

In this paper, we propose two low loss microstrip lines with side-grooves which can weaken the concentration of the current density at the edges of the strip conductor. A method called partial-boundary element method (p-BEM) is employed in our analysis. Theoretical results for these lines demonstrate significant effects on the conductor loss reduction by the side-grooves and inlaid dielectric material.

This, paper describes an effective analysis method suited to generalized suspended striplines, that is, planar transmission lines having multiple conductor sheets on multiple substrates, and multiple supporting grooves or pedestals. Two example striplines structures are analyzed based on this method. Some experimental results are also shown.

The use of suspended striplines is becoming an important transmission-line technique at millimeter wavelengths because of low attenuation, weak dispersion, and various merits in manufacturing processes. This paper estimates the effects of side-wall grooves of these lines on transmission characteristics within the TEM wave approximation.

Composite dielectric waveguides, or a class of dielectric waveguides made of a few dielectric materials, are described. A composite circular dielectric waveguide (CCDW) is treated with the the point-matching method. Computed values of the propagation constant of the CCDW are compared with those of the homogeneous circular dielectric waveguides (HCDW). Microwave experiments carried out to comfirm the theory are discribed.

The modal characteristics of homogeneous optical fibers with several types of deformed boundaries are analyzed by a numerical method on the point-matching principle. The propagation constants of various modes are given. The separation of degeneracy in the dominant is discussed. The results of microwave-model experiments show good agreement with those of calculation.

Modulation electric fields in a class of planar, lumped-parameter circuit or traveling-wave-type electrooptic modulators in integrated optics are analyzed by applying a simple transformation of variables to presently available formulas on microwave integrated circuits (MIC's). Example calculations are shown.

The nonuniform discretization of the integral equation on the tangential electromagnetic (EM) field on the boundary surface is proposed as a numerically efficient method to analyze the microstrip-like transmission lines. The calculated results of the propagation constant of the microstrip line based on this method are compared with other published analytical results. Various types of planar striplines are treated by the same formulas. The dominant and higher order modes of shielded microstrip line are discussed and compared with the longitudinal-section electric (LSE) and linear synchronous motor (LSM) modes of a two-medium waveguide.

The proximity effects of microstrip lines near a substrate's edge present a problem for effectively designing high-packing-density MMICs (monolithic microwave integrated circuits). Proximity effects of this type are analyzed using the rectangular boundary division method. It is assumed that the cross-sectional dimensions of transmission lines in the MMICs are small compared with the wavelengths to allow the use of the quasi-TEM-wave approximation. Then, the concept of edge-compensated microstrip lines to keep the characteristic impedance constant near a substrate edge is introduced to circumvent the proximity effects and to expand the interconnection flexibility of microstrip lines on MMIC substrates. The practical design parameters of edge-compensated 50- Omega microstrip lines are given in the form of numerical data and simple polynomials for CASD (computer-aided design) work with a curve-fitting procedure. Results of capacitance measurements are compared with this theory with errors of about 1% resulting. >

This paper proposes a two-layer traveling-wave type electrooptic modulator structure to maximize modulation bandwidth from transmission line aspects. This structure can be designed to satisfy the velocity matching and impedance matching condition simultaneously. A design method for this structure is discussed.

The purpose of this paper is to present an effective modal analysis method for a class of recently developed optical fibers with multiple cores. The main feature of the method is to combine the point-matching procedure with group theory to solve such complicated boundary value problems. The results of the numerical computations are compared with those of microwave simulation experiments.

The methods of modal and coupling field analysis for optical fibers with circularly distributed cores and a central core are presented. The point-matching technique combined with group theory is used for the modal analysis. The coupling field characteristics are analyzed by the superposition of eigenmode fields thus obtained.

Wir untersuchten den Verlauf der grundsatzlichen Veredelungsmethoden des gebleichten Buchenzellstoffs, der fast nor aus Zellulose und Pentosan besteht, in besonderer Rucksicht der Beziehung zwischen α-Zellulose und Pentosan.Kaltes Alkali lost nur β- und γ-Zellulose heraus, aber greift nicht α-Zellulose an, weshalb der α-Zellulosegelialt ansteigt. Es entfernt Pentosan in β+γ Zellulose gut, aber nur ein Drittel von Pentosan in α-Zellulose.Da heisses Alkali ferner α-Zellulose angreift, verbessert sich der α-Zellulosegehalt nicht so und die Ausbeute ist kleiner. Wegen der wenigeren Entfernung von Pentosan in β+γ Zellulose ist das gesamte Pentosan auch viel.Bei der Behandlung mit Saure verringert sich Pentosan in α-Zellulose mit dem Verlust der Zellulose einhergehend, sodass das Verhaltnis nicht kleiner als 2% wird. Da Pentosan in β+γ Zellulose etwas zunimmt, so verkleinert sich das gesamte Pentosan nicht so.Bei der Zweistufenbehandlung mit Alkali und Saure beeinflusst die Vorbehandlung ziemlich stark α-Zellulose, aber kaum Pentosan.Kochen mit Salzen, wie Na2SO3, Na2S2O3, CH3COONH4 und (CH3COO)Pb2, ergibt our eineAbnahme von Pentosan in α-Zellulose und in β+γ Zellulose.Die Behandlung mit. kaltent Alkali oder mit Saure ubte geringen Einfluss auf die Verarbeitung zur Kunstseide und deren Eigenschaften ans. Bei der Verarbeitung wird die Entstehung sekundarer Furfuroide vermutet.In jedem Falle bleibt immer 2% Pentosan in α-Zellulose stark verbunden, obwohl nicht alles das wahre Pentosan ist.Besonderen Dank schulden wir Herrn N. Negishi fur seine Hilfe beim Spinnen der Kunstseide.

A general method is proposed for analyzing the transmission line characteristics of strip lines with rectangular outer conductor and multidielectric layers within a TEM wave approximation. This method uses Green's function for formulating the problem and a variational principle for obtaining practical solutions. The case of the microstrip line is first discussed, and numerical results are found to be consistent with other theories and experiments. The case of strip lines with a rectangular outer conductor and three dielectric layers is examined for various combinations of dielectric materials. Other applications of Green's function and the theoretical limitation of this method are also described.

A simple approximate formula for the computer-aided design of the dispersion property of microstrip lines is reported in this paper which well fits the calculated curves based on a rigorous analysis.

This short paper describes a proposed structure of a broad-band electrooptical modulator and an application of existing microstrip analysis programs to determine dimensions of the structure for a broad-band property. Results of numerical computations indicate that it is possible to obtain a broad-band modulator by using LiNbO/sub 3/ or LiTaO/sub 3/.

A method for analyzing general thick-strip transmission lines is reported. Calculated characteristic impedances based on this method are consistent with other theory and experiment in the case of thick-strip microstrip lines. The case of thick-strip lines with three dielectric layers and shielding is also presented.

An experimental modulator was fabricated to test a design principle of broadband traveling-wave electrooptic light modulators proposed in a previous paper. The measured value of modulation bandwidth, 10 GHz, appears to confirm the design principle.

An analytical method is described which determines the distributed capacitance of a thin-film electrooptic light modulator with parallel-strip electrodes. The capacitance is expressed in a variational form. The anisotropy of the crystal and the presence of surrounding air are considered. Numerical examples for the case of Li-Nb-O/sub 3/ are given.

The dispersion property of microstrip lines was measured in a frequency range from 2 to 50 GHz and compared with that estimated by an approximate formula in a previous paper.