High-resolution refractive index anisotropy measurement in optical fibers through phase retardation modulation.
We present an improved, high-resolution method for the measurement of phase retardation induced by the material birefringence of optical fibers. Such a method can be used to retrieve information about the spatial distribution of refractive index anisotropy in the fiber by comparing the accumulated phase of a polarization component oriented along the fiber transmission axis and another located in the transverse plane. The method is based on the nonlinear regression of a phase modulated signal of known modulation amplitude altered by the sample. Experimental results obtained with our method for a standard telecommunications fiber (the Corning SMF-28) as well as photosensitive fibers (Fibercore PS1250 and PS1500) are presented with a noise-limited phase resolution below 10(-4) radians and a spatial resolution below 1 microm. An analysis of the limitation of such measurement methods is also presented including diffraction by the fibers.
Sévigny
Benoit
B
Centre d'optique, photonique et laser, Fiber Optics Laboratory, Engineering Physics Department, Ecole Polytechnique de Montréal, P.O. Box 6079, Station Centre-ville, Montréal, Québec, Canada. benoit.sevigny@polymtl.ca
Busque
François
F
Godbout
Nicolas
N
Lacroix
Suzanne
S
Faucher
Mathieu
M