Determination of group and phase birefringence dispersion of Hi-Bi optical fiber using a broadband light source

The paper deals with the determination of group and phase birefringence of an experimental highly birefringent (Hi-Bi) optical fiber across a wide wavelength span ranging from 1200 nm to 1700 nm. Several approaches for birefringence determination are used and the results are discussed. For the investigation, a set of two plane polarizers, a broadband light source, and an optical spectrum analyzer are used. The front face of the Hi-Bi fiber is illuminated by a linearly polarized light from a broadband light source and the end face of the fiber is connected to a fiber plane polarizer. At the output of the fiber plane polarizer, a typical spectrum – an interference pattern consisting of a quasi-periodic distribution of maxima and minima is measured by an optical spectrum analyzer. From the positions of subsequent minima of the interference pattern measured by the optical spectrum analyzer, the group birefringence dispersion is determined. The mean value obtained is in good agreement with that calculated from a differential group delay. The phase birefringence dispersion is determined by finding the appropriate dispersion functions representing the phase birefringence by fitting the measured spectrum to a calculated one, as the character of the spectrum depends on the phase birefringence.