Photoinduced birefringence rotation in germanosilicate glass optical fiber

Experimental results are reported for the permanent photoinduced rotation of the principal axes of the birefringence in a circular-core single-mode optical fiber on exposure of the fiber to powerful argon-laser radiation at 488 nm. The linearly polarized laser beam was launched into the fiber along one of the principal axes of the initial birefringence in the fiber. After several exposures totaling 4 h, a rotation of as much as 57 degrees was observed in the orientations of the principal axes in addition to the photoinduced birefringence.