Self-consistent finite/infinite element scheme for unbounded guidedwave problems

An efficient finite-element approach for the eigenmode analysis of unbounded guided-wave problems is described using decay-type infinite elements. To determine an optimum set of decay parameters, two algorithms based on successive approximation are presented and their validity is checked by application to an optical fiber problem     

An efficient scalar finite element formulation for nonlinearoptical channel waveguides

A self-consistent numerical approach based on the scalar finite element method is described for the analysis of both TE-like and TM-like nonlinear guided waves in optical channel waveguides. In order to improve the convergence and accuracy of solutions, isoparametric elements and numerical integration formulae derived by Hammer et al. are introduced. Numerical results are presented for nonlinear elliptical core optical fibers, and it is confirmed that in this approach, highly accurate solutions can be obtained with small scale computation. Furthermore, graded-index nonlinear optical channel waveguides are also analyzed, and the influence of refractive-index profiles on propagation characteristics of the nonlinear guided waves is investigated     

A 1.2 GFLOPS neural network chip for high-speed neural networkservers

This paper describes a digital neural network chip for high-speed neural network servers. The chip employs single-instruction multiple-data stream (SIMD) architecture consisting of 12 floating-point processing units, a control unit, and a nonlinear function unit. At a 50 MHz clock frequency, the chip achieves a peak speed performance of 1.2 GFLOPS using 24-bit floating-point representation. Two schemes of expanding the network size enable neural tasks requiring over 1 million synapses to be executed. The average speed performances of typical neural network models are also discussed     

A complete set of normal modes in three-layered electron waveguides

Mathematical expressions are given for guided and radiation modes including nonpropagating parts in three-layered electron waveguides, in addition to gaining a clear understanding of the difference between electron and optical waveguides in terms of normal modes. According to the dispersion diagrams, it is shown that a complete set of normal modes for electron waveguides depends on the electron's total energy and that in the quantum-well-type waveguide the discrete modes and the continuous modes radiating to one side of the film are reduced to nonpropagating modes in a certain energy range, whereas a complete set of normal modes for optical waveguides always consists of three types of modes: guided modes, substrate radiation modes, and substrate-cover radiation modes. In addition, the discrete modes and the continuous modes radiating to one side of the film are not reduced to nonpropagating modes in the entire range of frequencies. Also, it is shown that the guided modes always exist in electron waveguides composed of arbitrarily different Al-concentration ratios in the film, substrate, and cover regions, and a new waveguiding quantum-step-type structure, which utilizes the total reflection at both the potential rise and drop is proposed, whereas in optical waveguides, the guided modes exist only in the structure in which the refractive index of the film is higher than those of the substrate and of the cover     

A novel positive resist for deep UV lithography

A novel positive resist was prepared by sensitizing poly(p-trimethylsilyloxystyrene) with p-nitro-benzyl-9, 10-diethoxyanthracene-2-sulfonate (NBAS) which was found to be a deep UV bleachable acid precursor. The silylated polymer is converted to alkaline soluble poly(p-hydroxy-styrene) in the presence of acid and a small amount of water. The photoresist gives high resolution positive patterns on imagewise exposure with deep UV light with a sensitivity of 15 mJ/cm².