Polarization-independent magnetic control of the light phase in a chiral optical fiber

Abstract

The proposition is made to fine-tune the phase of an unpolarized guided mode in a chiral optical waveguide, or fiber, by a static magnetic field applied in the direction of the light propagation. The core of the fiber should consist of randomly oriented chiral molecules, and the magnetic field-induced change of the refractive index would be due to the magnetochiral effect [1]. Although the magnetochiral birefringence is very small for magnetic field strengths obtainable under routine laboratory conditions, the induced phase shift for a given magnetic field should be maximized by increasing the pathlength of light inside the field. This would be technically achievable by winding the optical fiber axially many times around the electric solenoid that generates the magnetic field, in such a way that the path of the light inside the fiber follows closely and over a distance as long as possible the magnetic induction lines.