Equilibrium mode distribution

About: Equilibrium mode distribution is a research topic. Over the lifetime, 928 publications have been published within this topic receiving 14939 citations.

Coupled-Mode Theory of Multipath Interference in Quasi-Single Mode Fibers

Abstract: We use the power coupled-mode theory to study the interplay between multipath interference (MPI) and differential mode attenuation (DMA) in quasi-single mode (QSM) fibers. The analytical expressions derived assuming two mode propagation in QSM fibers show that MPI scales differently as a function of the span length for low and high DMA. Furthermore, we derive analytical expressions for the performance improvement of long-haul coherent optical communication systems using QSM fibers, taking into account the impact of excess loss and MPI on system performance. From these expressions, we calculate the maximum allowable coupling coefficient for different values of the DMA. We show, for example, that a QSM fiber with an effective area of 250 μm2, a coupling coefficient κ ≤ 6 × 10-4 km-1, and DMA equal to 4 dB/km offers a 1-dB performance advantage over a reference pure silica core single-mode fiber for spans of 100 km.

Circular hybrid plasmonic waveguide with ultra-long propagation distance

Abstract: We propose a novel plasmonic waveguide structure, which is referred to as a circular hybrid plasmonic waveguide (HPW) and consists of a metal wire covered with low- and high-index dielectric layers. The circular HPW exhibits two distinctly different modes, namely, the strongly localized mode and the extremely low-loss mode. Our numerical calculation demonstrates that the strongly localized mode exhibits 10-4 order scale in normalized mode area and can be performed even in tens of nanometer sizes of waveguide geometry. In the extremely low-loss mode, the HPW exhibits ultra-long propagation distance of more than 103μm that can be achieved by forming the dipole-like hybrid mode and properly adjusting the radius of the metal wire. It is also shown that, even with this long-range propagation, the mode area of the dipole-like hybrid mode can be maintained at subwavelength scale. The simultaneous achievement of a small mode area and ultra-long propagation distance contributes to the ultra-high propagation distance to mode size ratio of the waveguide. The HPW results are very helpful for plasmonic device applications in the fields of low-threshold nanolasers, ultrafast modulators, and optical switches.

Dispersion characteristics of dielectric tube waveguide loaded with plasma for leaky wave antenna application

Abstract: The leaky mode dispersion characteristics ( ω - β ) of a Dielectric Tube Waveguide Loaded with Plasma (DTWLP) is analytically solved and numerically computed using Muller’s complex root search algorithm with an aim to define its complex propagation constant behaviour. Consequently, complex leaky mode characteristics and its classification as guided mode, reactive mode and antenna mode have been investigated. These modal characteristics reveal wide fundamental antenna mode (TM01) with the variation in plasma density, which can find prospective application in high resolution radar and communication system where “re-tuning” of the antenna to a new frequency or making it electrically invisible is required. A computational cum simulation study is also performed using CST Microwave Studio software, which confirms our analytical findings.

Multimode optical waveguides, waveguide components and sensors

Abstract: The invention describes two types of multimode optical waveguides having special dip in the refractive index profile of their core providing conditions for propagation of a higher order mode with sharp central peak which field carries considerable part of the mode energy, while the fields of all other modes in the waveguide are mostly concentrated outside of this central peak region. The waveguide of the first type guides the mode only with one central peak while the mode in the waveguide of the second type has also an additional peak at the interface between the waveguide core and cladding providing a possibility to detect any influence on the mode field in its outer region by measuring the signal in the central peak of the mode. The useful properties of these two kinds of modes can be employed for designing new wavelength selective waveguide components for optical communications and sensors applications: an optical waveguide modulator, amplitude and interferometric sensors for different applications, bistable nonlinear components for logic switching and optical memory, wavelength selective chemical sensors of both amplitude and interferometric type, etc. Employing a material exhibiting electro-optical properties provides a possibility of tuning of the components proposed as well as fabrication of the sensors of electric fields.

Stable coherent MIMO transport over few mode fiber enabled by an adiabatic mode splitter

Abstract: Simulations confirm stable MIMO transport of three channels over a two mode fiber — even in the presence of fiber bending induced mode coupling — enabled by a new adiabatic mode splitter output coupler.