The relationship between the design parameters and small molecule detection sensitivity of porous silicon waveguides is theoretically and experimentally analyzed. Perturbation theory calculations suggest that the sensitivity asymptotically approaches infinity as the porosity of the waveguide approaches a critical porosity for a given mode and the resonant coupling angle of light into the wavegu...

A novel scheme is presented that can be used to efficiently pump optical waveguide amplifiers. It is based on the coupling between two adjacent waveguides, where pump light is gradually coupled from a nonabsorbing pump waveguide into the amplifier waveguide. The coupling between the waveguides in such a configuration is calculated using an improved coupled mode theory (CMT). The proposed distri...

Although brute-force simulations of Maxwell’s equations, such as FDTD methods, have enjoyed wide success in modeling photonic-crystal systems, they are not ideally suited for the study of weak perturbations, such as surface roughness or gradual waveguide transitions, where a high resolution and/or large computational cells are required. Instead, we suggest that these important problems are idea...

A low cross-polarization slot array antenna in the narrow wall of ridge waveguide is presented. A non-angled slot which is created in the narrow wall of the ridge waveguide is considered to be used as radiating resonant slot. The normalized resistance and normalized reactance curves are presented for design purposes. A six element slot array waveguide antenna with ridges on its narrow wall is t...

Development of techniques for characterization of extremely thin films is an important challenge in terahertz (THz) science and applications. Spectroscopic measurements of materials on the nanometer scale or of atomic layer thickness (2D materials) require a sufficient terahertz wave–matter interaction length, which is challenging to achieve in conventional transmission geometry. Waveguide-base...

Introduction: Travelling wave MR imaging exploits the waveguide action of the RF shield. The transmitting and receiving patch antenna is placed at the beginning of the bore of the scanner. Different sections of the bore will have different wave impedances due to different loading conditions. This can lead to abrupt changes in impedance causing large reflections and inefficient power transfer to...

We develop a novel perturbation theory formulation to evaluate polarization-mode dispersion (PMD) for a general class of scaling perturbations of a waveguide profile based on generalized Hermitian Hamiltonian formulation of Maxwell’s equations. Such perturbations include elipticity and uniform scaling of a fiber cross section, as well as changes in the horizontal or vertical sizes of a planar w...

Focusing on the use of planar waveguides as platforms for highly sensitive attenuated total reflection spectroscopy of organic thin films, we extend the ray optics model to provide absorbance expressions for the case of dichroic layers immobilized on the waveguide surface. Straightforward expressions are derived for the limiting case of weakly absorbing, anisotropically oriented molecules in th...

The sonar equation rests on the assumption that received sound pressure level after scattering can be written in decibels as a sum of four terms: source level, transmission loss from the source to the target, target strength, and transmission loss from the target to the receiver. This assumption is generally not valid for scattering in a shallow water waveguide and can lead to large errors and ...