Polarization optics of twisted single-mode fibers

Abstract

In twisted single-mode optical fibers the polarization of light is affected by an elastooptically induced optical activity and by a modification of any linear birefringence present. These effects are discussed theoretically and demonstrated experimentally. The activity/twist ratio is alpha/tau approximately 0.13 ... 0.16 universally in weakly guiding silica fibers. Twisted fibers may be used as polarization rotators. A fiber with a +/-68 degrees double twist operates as a fast/slow mode interchanger, suitable for delay equalization.

A generalized geometrical representation of coupled mode theory

“…Light initially launched along the x axis, for instance, will follow circular trajectories about this @ in the rotating frame, and cycloidal trajectories in the lab frame. This result agrees with [17] and gives a clear picture of how the 27 term arises by appealing to (16) rather than solving a pair of simultaneous vector differential equations for w and _r.…”

“…We choose the g L representing the birefringence to be along the x axis. By the linearity of Section 111, these vectors may be added to obtain a resultant vector g. The Poincare sphere representation of spatially uniform linear and circular birefringence has been developed [17], and it is unnecessary to repeat it here: its representation looks like Fig. 5(c) with g L and 9 / 2 representing the linear and circular birefringence, respectively.…”

“…As a final example, we consider the case of twisted optical fiber with linear birefringence which has been treated by Ulrich and Simon [17]. We use the same coordinate system as before, referring the linear axes to the initial space axes.…”

Strain-induced spectral tuning of the whispering gallery modes in a cylindrical micro-resonator formed by a polymer optical fiber

“…where α −n 2 p 44 [34]. Here, p 44 is the elasto-optic coefficient of the fiber, and n is the refractive index of the core.…”

Detection of plasma equilibrium shifts with fiber-optic sensing of image currents

“…Bending of the filwr and prmrurc (m the fiber will inclure an unwanted The linear birefringence introduced by bending has been calculated [5] as (2) where p,1 and plz are the components of the strain-optical tensor of the fiber material, UP is the Poisson's ratio, p is the radius of the fiber and R M the radius of the bend. The induced circular birefriugence producecl by twisting the fiber is given by the following formula [6] …”