Using the semi-analytic transmission and propagation matrices for guided optical waves, the modal noise in optical waveguide is investigated for a simple three-slab waveguide and a step-index singlemode fiber. It is shown that modal noise can arise from the unbound radation modes which have been excited in the first junction and haven’t been sufficiently attenuated before reaching the second ju...

We study the detailed propagative characteristics of optical pulses in photonic band-gap PBG waveguides, coupled near resonantly to inhomogeneously broadened distributions of quantum dots. The line centers of the quantum-dot QD distributions are placed near a sharp discontinuity in the local electromagnetic density of states. Using finite-difference time-domain FDTD simulations of optical pulse...

In this paper, the propagation and scattering of acoustic waves in a flexible wave-guide involving step discontinuity at an interface is considered. The emerging boundary value problem is non-Sturm-Liouville and is solved by employing a hybrid mode-matching technique. The physical scattering process and attenuation of duct modes versus frequency regime and change of height is studied. Moreover,...

A Hybrid technique for the analysis of pyramidal horn antennas is proposed in this paper. The transition from a relatively small feeding waveguide to a larger radiating aperture is analyzed using the mode matching technique, while the discontinuity between the horn and free space is analyzed using the method of auxiliary sources. The resulting procedure is very stable and accurate while the com...

We have performed experiments on the laboratory scale to image seismic wavefronts of compressional waves that are guided between parallel fractures. The wavefronts are detected using water-coupled 1MHz piezoelectric transducers. The stiffness of the fractures is controlled by applying radial stress in a hydraulic stress apparatus that leaves the observation face of the fractured sample open to ...

In previous modeling works, the waveguide radiation in the free space is modeled using an infinite flange in aperture plan. In this paper, we propose a new formulation to analyze the radiation of twin rectangular waveguides in free space. Our formulation consists firstly in simulating the free space as rectangular waveguide and seeking the appropriate dimensions that do not affect scattering pa...

The incidence of thin-film-guided, in-plane unguided waves at oblique angles on straight discontinuities of dielectric slab waveguides, an early problem of integrated optics, is being reconsidered. The 3-D frequency domain Maxwell equations reduce to a parametrized inhomogeneous vectorial problem on a 2-D computational domain, with transparent-influx boundary conditions. We propose a rigorous v...

We develop and experimentally verify a theoretical model for the total efficiency η0 of evanescent excitation and subsequent collection of spontaneous Raman signals by the fundamental quasi-TE and quasi-TM modes of a generic photonic channel waveguide. Single-mode silicon nitride (Si3N4) slot and strip waveguides of different dimensions are used in the experimental study. Our theoretical model ...

One-dimensional digital waveguides are widely used to model traveling pressure waves along wind instrument bores comprised of concatenated cylindrical or conical sections. Waveguide filter elements model frequencydependent losses and delay (dispersion) occurring during propagation and at any boundary or discontinuity producing reflected and transmitted waves. In this work, a technique is descri...