Specialty Optical Fibers Handbook

contrast is useful not only to maximize the birefringence, but also to prevent

radiation when the fiber is bent around a small radius. Another requirement

particularly useful in interferometers is that extraneous light launched into the

cladding is rapidly attenuated, even in short fiber lengths, minimizing spurious

interference [7]. This is satisfied by a nonguiding cladding, a cladding with an

index lower than the surrounding medium, often referred to as a depressed index

cladding. The elliptical fiber’s azimuthally stable modes are exploited in a new

set of higher order mode sensors not available with the standard circular core

fiber [8].

16.1.2 D-Shape Elliptical Core Fiber and Variations

with Assessable Regions

The D-shape elliptical core fiber ...