Step-index

Figure C2.15.15. The stmctural profile of a step index fibre.

Fig. 3. Types of optical fiber (a) multimode stepped index, (b) multimode graded index, and (c) single-mode stepped index.

Step-index Graded-index Multimode Multimode... 

Step-Index Multimode. The step-index multimode fiber has a sharp difference between the index of refraction of the core and that of the cladding (Fig. 16.8a). Light propagation in such a fiber is... 

Figure 16.9. Light propagation in a mnltimode step-index fiber.

Single Mode. The single-mode fiber has a step-index profile (Fig. 16.6c) and a small core diameter (typically 10 im) such that only one mode can travel through it. This is now the preferred system, particularly for long-distance transmission. The normal light source for multimode fibers is the light-emitting diode (LED). But... 

The simplest case of fibre structure is the step-index one, characterized by a constant circular refractive index profile in the core and polymer cladding of lower refractive index (Figure 3). The refractive indexes of the core and cladding depend on the materials used. The cores of these structures can be prepared from melts as well as from preforms without radial and azimutal variations of the refractive index. To obtain suitable mechanical... 

For, SHG it is desirable to fabricate fibres which allow single mode operation at the fundamental wavelength so that all the launched power is available for conversion. The frequencies for which single mode operation is possible in a step-index uniaxial crystal cored fibre with crystal axis along the fibre axis are given by (30.)... 

The theory of a straight and uniform MNF with a circular cross-section of radius a and a step-index profile is well developed59-61. A section of an MNF is shown in Fig. 13.3 in Cartesian coordinates (pc,y,z). The distribution of refractive index along the radius r = Jx2 + y2 of such MNF is... 

Multimode optical fibers, 11 131, 132 intermodal dispersion in, 11 134 Multimode stepped index optical fiber, 11 131, 132... 

In order to reflect these lead times, the concept of a timestamp is introduced. Timestamp is used in computer science documenting the system time when a certain event or transaction occurs e.g. for logging events (N.N. 2007). In the context of future inventory value planning, the time-stamp marks the period, when the first raw material has reached a certain stage in the value chain network included into a specific product. In the example illustrated in fig. 57, the raw material is processed in the same period to be converted into product 1. Therefore, all four value chain steps indexed from one to four occur in the same period and have the same time-stamp one. Conversion into product 2, however, requires additional time caused by production lead times, safety inventory and/or transportation time, that the steps indexed with five and six have a time stamp of two. The timestamp reflects that the inventory value of product 2 is not based on the raw material costs from the same period but based on the raw material costs from the previous period in order to reflect the lead time. Consequently, value chain indices and timestamps are defined for all steps and can cover multiple periods reflecting that raw materials in a global complex multi-stage value chain network can take several months, until they are sold as part of a finished product to the market. 

Abstract Investigation of spatiotemporal dynamics of optical pulse in step-index planar... 

The main purpose of this paper is to consider a two-dimensional non-stationary (2D-I-T) problem of a nonlinear waveguide excitation by a non-stationary light beam and to study spatiotemporal phenomena arising upon propagation of the beam in a step-index waveguide, first, in the quasi-static approximation and, second, with account of MD and SS effects. 

In papers , unsteady-state regime arising upon propagation of the stationary fundamental mode from linear to nonlinear section of a single-mode step-index waveguide was studied via numerical modeling. It was shown that the stationary solution to the paraxial nonlinear wave equation (2.9) at some distance from the end of a nonlinear waveguide has the form of a transversely stable distribution ( nonlinear mode ) dependent on the field intensity, with a width smaller than that of the initial linear distribution. 

We find below a set of stationary nonlinear modes for the step-index nonlinear waveguide, investigate their stability and global dynamics. The latter is simulated numerically by the FD-BPM as a solution to the Cauchy problem for waveguide junctions under consideration. 

Consider a step-index dielectric waveguide with a linear refractive index profile, ni x) = ( a < a), n i ( x > a). 

In this section, a problem of nonlinear waveguide excitation by stationary light beam has been investigated. In the analysis, an approach traditional for nonlinear optics and based on solution to nonlinear paraxial wave equation has been used. The range of light beam powers that induce nonlinear variation of refractive index comparable with linear contrast of the step-index waveguide has been considered. 

In this section, propagation of an optical pulse in a step-index nonlinear waveguide is simulated by the numerical technique described in Section 2. As a comparative parameter, the power evaluated by (3.2) p) at... 

In general, as the variation of the temporal profile of the non-stationary light beam due to the SS effect or the second-order GVD effect is continuous, emission of radiation field from the guiding region is also continuous upon propagation of the pulse. This emission prevents formation of a spatiotemporal soliton in the step-index guiding structures. 

In this paper, spatiotemporal dynamics of non-stationary light beam propagating through the junctions of step-index nonlinear waveguides have been investigated. 

Y.P. Chiou, Y.C. Chiang, H.C. Chang, Improved three-point formulas considering the interface conditions in the finite-difference analysis of step-index optical devices , J. Lightwave Technol. 18, 243-251 (2000). 

Figure 6.102 Schematic illustration of (a) step-index, (b) graded-index, and (c) single-mode optical fibers. Reprinted, by permission, from J. F. Shackelford, Introduction to Materials Science for Engineers, 5th ed., p. 611. Copyright 2000 by Prentice-Hall, Inc.

---