Comments about birefringence dispersion, with group and phase birefringence measurements in polarization-maintaining fibers

Abstract

A recent JEOS-RP publication proposed Comments about Dispersion of Light Waves, and we present here complementary comments for birefringence dispersion in polarization-maintaining (PM) fibers, and for its measurement technique based on channeled spectrum analysis. We start by a study of early seminal papers, and we propose additional explanations to get a simpler understanding of the subject. A geometrical construction is described to relate phase birefringence to group birefringence, and it is applied to the measurement of several kinds of PM fibers using stress-induced photo-elasticity, or shape birefringence. These measurements confirm clearly that the difference between group birefringence and phase birefringence is limited to 15-20% in stress-induced PM fibers (bow-tie, panda, or tiger-eye), but that it can get up to a 3-fold factor with an elliptical-core (E-core) fiber. There is also a surprising result with a solid-core micro-structured PM fiber, that is also based on shape birefringence.

Simultaneous measurement of thickness and group refractive index in birefringent crystals

“…At present, most of the studies on refractive index measurement focus on the measurement of single-index materials, while the measurement of birefringent materials is less and more focused on the maximal birefringent index between the ordinary light and the extraordinary light [20][21][22][23]. Shindo and Hanabusa [24] measured the optical properties of birefringent materials using a photo-elastic modulator.…”