We discussed the cutoff characteristics of slab waveguide, and showed some numerical examples. We used the approximate dispersion equation which is valid in the frequency region near the cutoff, and is applicable not only to the lower modes but also to the higher modes.

We describe coherence multiplexing of ring interferometric fiber optic sensors using a short coherence length source. It is shown that the high finesse of the two ring interferometers with almost the same cavity length in the tandem arrangement may be exploited to yield a multiplexed system of increased sensitivity.

Single shot picosecond optical pulse waveform measurement has been investigated by an electro-optic sampling technique. An optical gate driven by an ultrafast photoconductive switch is employed as an optical sampler. Discrete sampled signals are coupled into an optical fiber array consisting of different length fibers to control the time delay. The output of the optical fiber array is detected by a photodetector and displayed on an oscilloscope with an expanded time scale. For measurement of 100 ps duration optical pulse, the time resolution of the system was estimated to be 14 ps.

An optical amplifier repeater using two-stage semiconductor laser amplifiers with automatic power control (APC) system was inplemented for the first time. The APC system was realized by the direct monitoring of the amplified signal power. The assessment of the optical amplifier repeater confirmed the usefulness of the APC syster.

In this paper considered is the problem of scheduling a large number of parallel tasks (tasks having the same release and due times) on parallel processors. It is assumed that tasks all require one unit processing time, and the release and due times are non-negative integers. Task sets each of which consists of parallel tasks are dealt with instead of individual tasks in the conventional manner. The minimum number of processors required to process the given task sets is obtained by increasing stepwise the number of processors. To this end the minimal subset of task sets which cannot be allocated to a certain fixed number of processors is determined by a linear-order breadth-first search using the result of task assignment in two different ways, one top-down and the other bottom-up. The time complexity of the overall procedure is O(min(n, m)(mn log n)) and the space complexity is O(nm), where n and m are the numbers of task sets and time slots respectively.

One of the most important factors indicating the effectiveness of a word clustering method is how commonly it can be applied to different languages. This paper evaluates the applicability of a new word clustering method to the English and Japanese languages using word sets edited from technical summaries. The method employs an iterative clustering routine which increases the number of clustered words. Thus, evaluations are achieved as a function of the number of iterations of the clustering routine from the aspects (a) clustering characteristics determined from the number of clustered words, the number of clusters formed, etc., and (b) performance determined from the average clustering ratio and the average cluster uniformity. Consequently, the applicability of the method to English and Japanese is obtained through evaluations indicating similarities between them for both clustering characteristics and performance. It is also clarified that about fifty percent of the target words can be clustered in less than five iterations of the clustering routine.

The transmission and reflection characteristics of a H-plane symmetrical T-junction having a reflector near the junction plane are theoretically studied. The reflector is an equilateral triangle post, and it is installed in contact with the wall of the through-guide facing the junction plane to improve the wave propagation from the truncated-guide to the through-guide. In case of equal cross section, we find an optimum reflector, the top angle of which triangle reflector is 0 degree and its height is about half of the guide width. Roughly speaking, the fin, that is, the reflector of 0 degree has the characteristic value of (transmission coefficient |S12| between the truncated-guide and the through-guide) 0.705 over a wide frequency range. This value is nearly equal to the upper limit value of |S12| 1/20.7071. Thus 99.4 percent (0.70522) of the energy fed from the truncated-guide transmits evenly into the other two arms, and 0.6 percent reflects. The problem is treated by a method of combining the boundary-element method and a hybrid-representation circuit equation.

Two algorithms are presented for a time-domain analysis of a switching converter which is replaceable with a piecewise-linear system. One of them is for the transient state analysis and the other is for the steady-state analysis. Both of them use the eigen-value and the eigen-vector calculations. The analysis based on these algorithms can be carried out more rapidly and accurately than the conventional analysis using standard fixed or variable step-size integration methods. On the uk converter, the results of the proposed method are compared with those of the Hamming method (a variable step integration method) and of SPICE2 (a general-purpose circuit analysis program using variable step-size integration method).

A new fabrication method for a laser-to-single-mode-fiber coupling module has been developed, where the first spherical (or ball) lens of a double confocal lens system is affixed by a new UV (ultraviolet light) curable adhesive. Temperature characteristics and preliminary reliability test results confirmed that the module is sufficiently stable for usage in fiber-optic communication systems and other applications.

The objective of this article is to investigate whether or not a network containing one capacitor, one inductor, and three resistors is able to realize a given biquadratic function. This information should be sought before any synthesis procedure is attempted. It is hoped that the technique may be extended to higher order networks.

A theoretical prediction of the spectral width for 1.55µm wavelength surface emitting lasers with GaInAsP/InP multilayer distributed Bragg reflectors is presented. Our calculation shows that a considerable reduction of the linewidth to less that 1 MHz can be achieved by an appropriate design of the laser.

Scattering problem of an electromagnetic beam wave by a rectangular pit on a perfectly conducting substrate is rigorously analyzed. The pit is the canonical model of an optical disk pit. The numerical results of the far field patterns are presented for the various pit depths.

A simple adaptive scheme is proposed for controlling the length of time-steps for numerical simulation of Hopfield's networks.

An end-coupled stripline filter is analyzed by the current normal mode expansion method. It is shown that the frequency characteristics are well described with finite number of current normal modes which are existed in the frequency range of interest. This fact intimates the possibility of synthesizing the circuit by Foster-type equivalent circuit.

B(P)SCCO films were prepared on MgO substrate by a double cathode dc sputtering with a mosaic BiχSrCaCuyOz and (Bi0.7Pb0.3)χ SrCaCuyOz target. The films were deposited at 200 and 550, and then annealed. We have obtained the B(P)SCCO films with Tc of 90-100 K under the condition of the deposition at 550 and the in-situ annealing in 200 Torr O2 and the post-deposition annealing at 860.

This paper discusses a new simultaneous design method of both magnitude and phase of IIR digital filters. It is inherently a nonlinear problem to approximate the magnitude and phase of an IIR digital filter simultaneously. In this paper, however, such a nonlinear problem is converted into a linear one by vector rotation method and solved by the linear programming (LP) technique. As a result our method requires no initial guesses for any type of filter specifications. A stable digital filter is designed which approximately satisfies the linearity of the phase in the pass band and the given attenuation in the stop band. The design examples given in this paper shows the usefulness of the proposing method.

In this letter, we investigated in detail the basic characteristics of W type slab waveguide in the vicinity of the cutoff frequency. Concerning with the leaky mode, we obtained some interesting results.

For stable solution of a linear equation, the modified relaxation-based algorithms have been proposed in both fields of circuit simulation and digital signal processing. This letter describes the analogy between these modified iterative methods proposed independently in two fields.

Simple feed-forward type neural networks have been investigated to obtain those learning abilities and to obtain effects of initial values of network weights by back-propagation (BP) algorithm. Only restricted types of solutions are obtained by the BP algorithm out of many of them.

Using an interferometric detection technique with AC modulation for searching the interference fringe signal, highly accurate polarization mode dispersion (PMD) measurement with about 0.0028 ps/m resolution has been developed, and the PMD measurement in a 60 km-long installed optical submarine cabled fiber is presented.