Toolbar   The Engineering Toolbar
The Ultimate Resource for Engineering and Technical Research. (Learn More)

Chapter 8: Staircase Concatenation Method

By Katsunari Okamoto
From Fundamentals of Optical Waveguides, Second Edition

For axially varying waveguides, the beam propagation method described in the preceding chapter is the most powerful technique for investigating linear and nonlinear lightwave propagation phenomena. In comparison with BPM, the staircase concatenation method is a classical technique that has been utilized for the analysis of axially varying waveguides. As explained in Chapter 7, the step size of numerical analysis in BPM is something between a fraction of the wavelength and several times the wavelength. Therefore calculation time and rounding errors will increase in the analysis of optical devices of several centimeters length. The staircase concatenation method is suitable for the analysis of such long devices. In this chapter, the basic concepts and procedures of the staircase concatenation method are explained via the example of fused-taper fiber couplers.

8.1. STAIRCASE APPROXIMATION OF WAVEGUIDE BOUNDARY

We will investigate here the transmission characteristics of the fused-taper (fused and elongated) coupler [1, 2] shown in Fig. 8.1. The fused-taper coupler is fabricated by first fusing the two parallel fibers with a burner or heater and then elongating it. The total diameter of the minimum waist region reaches about 20 30 m from the original diameter of the two fibers. In this case, the core diameter of each fiber becomes about 1 m (one-tenth of the original core diameter). Therefore, most of the light is not confined in the core region, and it spreads to the entire cladding. Light confinement is then provided by the air cladding. Since the refractive-index difference between...

Copyright Elsevier Inc. 2006 under license agreement with Books24x7
Products & Services
Fiber optic light guides are bundles of optical fibers used for the controlled deliver of light. They tend to be more rigid, and transmit well in both the visible and near-infrared (near-IR) regions of the electromagnetic spectrum.  Fiber optic light guides are sometimes called fiber optic light pipes (fiber optic lightpipes).  Search by Specification | Learn more about Fiber Optic Light Guides
Fiber optic couplers are optical devices that connect three or more fiber ends, dividing one input between two or more outputs, or combining two or more inputs into one output. Search by Specification | Learn more about Fiber Optic Couplers
Light guides conduct the flow of light from a light source to a point of use in areas that are too small or too hazardous to permit the installation of a light bulb. There are two basic types of light guides: liquid and fiber optic.  Light guides are sometimes called light pipes (lightpipes). Search by Specification | Learn more about Light Guides
Stairs and stairway products include treads, balusters, stringers, handrails and other stair components as well as complete pre-fabricated stairways. Learn more about Stairs and Stairway Products
Specialty optical fiber is modified, usually by doping, for a specialized function. It consists of one or more transparent fibers enclosed in a protective covering. Search by Specification | Learn more about Specialty Optical Fiber
Product Announcements
Fiberguide Industries, Inc. - Optical Fiber Taper
Tapered optical fibers can be made either by fusing a short tapered section onto a longer fixed diameter fiber, or, by very carefully controlling the drawing process to produce a single continuous... (read more)
Fiberguide Industries, Inc. - Hard Clad Silica Fiber (Low OH)
Numerical Aperature (N.A.) of 0.39 and hard polymer cladding that allows a high core-to-clad ratio, the Anhydroguide™ APCH is the low cost fiber of choice. The pure fused silica (SiO2) used in... (read more)
Fiberguide Industries, Inc. - Hard Clad Silica Fiber (Standard OH)
Numerical Aperature (N.A.) of 0.39 and hard polymer cladding that allows a high core-to-clad ratio, the Superguide™ SPCH is the low cost fiber of choice. The pure fused silica (SiO2) used in the... (read more)
Fiberguide Industries, Inc. - Plastic Clad Optical Fibers (Low OH)
When looking for a low cost fiber with a high numerical aperture (N.A.) for more efficient light coupling, the Anhydroguide™ PCS is the fiber of choice. With an N.A. of 0.37 and a plastic... (read more)
Fiberguide Industries, Inc. - Plastic Coated Silica/Silica (Standard OH)
When looking for a high quality fiber with superior transmission and a numerical aperture (N.A.) of 0.22 for efficient light coupling, the Superguide™ SFS is the fiber of choice. The... (read more)
 
Topics of Interest
OVERVIEW Upgrading telecommunication networks to increase their capacity is becoming increasingly important due to the rapid increase in network traffic caused by multimedia communications. Although... (Read More)
Absorption: The portion of optical attenuation in an optical fiber resulting from the conversion of optical power to heat; caused by impurities such as hydroxyl ions in the fiber. A/B Switch: A... (Read More)
Planar optical waveguides are the key devices to construct integrated optical circuits and semiconductor lasers. Generally, rectangular waveguides consist of a square or rectangular core surrounded by... (Read More)
2.4 WORKING DEFINITIONS OF CUTOFF WAVELENGTH 2.4.1 Introduction The cutoff wavelength of a single-mode optical fiber is the wavelength above which only a single bound mode, the fundamental LP... (Read More)
12.1   INTRODUCTION In previous chapters, the index of refraction n(x, y, z) was assumed to be constant, independent of position. In many applications, such as wave propagation in optical... (Read More)
See more product announcements for Fiber Optic Light Guides
High Power Laser Delivery Assemblies

High Power Laser Delivery Assemblies
Fiberguide Industries, Inc.


Light Line Converters from Fiberoptic Systems

Light Line Converters from Fiberoptic Systems
Fiberoptic Systems, Inc.


Fiber Optic Assemblies

Fiber Optic Assemblies
Fiberguide Industries, Inc.


11 See more product announcements for Fiber Optic Light Guides