Showing papers on "Coupled mode theory published in 1980"

Matrix theory for n-line mxicrowave coupler design

Abstract: The matrix equations respresenting wave propagation along a multiconductor system of transmission lines are solved giving expressions for the scattering parameters in terms of the parameters of the lines themselves. We demonstrate the extensions and generalisations of co- and contradirectional coupling, coupled-mode theory and also the concept of the non-mode-converting termination to multiline systems. Concentrating on the simplifying assumption of weak reflections at the terminations we extend the weak coupling approximation of coupled-mode theory to allow for strong coupling between adjacent lines. A demonstration of this is given in the design of a three-line equal power splitting coupler with an arbitrary phase shift between output ports at the centre frequency.

Theory of curved diffraction gratings

Abstract: A coupled-mode theory is presented for the curved diffraction grating. In general, a numerical analysis is required but it is shown that, for the circularly curved grating, the coupled-mode equations are linearly tapered and can be solved analytically. It is shown that, by curving a grating, both the input acceptance angle and the fractional bandwidth can be increased very substantially. The analysis is essentially two dimensional and has direct application to thin-film integrated optics.

Pulse propagation in a randomly perturbed ocean: Single pulse statistics

Abstract: A statistical theory of broadband single pulse propagation in a random ocean is presented. The mutual coherence function of the received signal is derived using an analysis based upon coupled mode theory. As propagation range increases, the combined effects of modal dispersion and random fluctuations spread the pulse and decompose it into a series of multiple arrivals.

Fundamental concepts in acoustic transducer array design

Abstract: Ceramic strip resonators with rectangular cross-section have been made with aspect ratios (width to height ratios) from 0.1 to 30 . The short and open circuit resonant frequencies have been plotted as a function of aspect ratio and show good agreement between experiment and a simple coupled mode theory. The effect of loading these resonators acoustically with solids and liquids has also been examined. The resonators we have measured had a center frequency of n ear 3 Miz and widths down to 0.12 wavelengths in water at this frequency. We have demonstrated for the first time that when the resonators are less than a wavelength in width, a complex acoustic load impedance must be used to accurately predict the electrical impedance of the resonator which is measured.