Polarization properties of single-mode fiber-optic waveguides with weak birefringence

Single-mode fiber-optic waveguides were constructed. They had an SiO₂ + GeO₂ core and an SiO₂ cladding, with weak internal birefringence. These waveguides were capable of distortion-free transmission monochromatic linearly polarized laser radiation over fiber lengths of from several centimeters to several hundreds of meters. A study was made of changes in the birefringence which occurred when external mechanical forces were applied to a waveguide (bending, tension, compression, torsion). It was found that on winding a waveguide into a coil of particular radius, without applying tension, the birefringence remained weak, while if tension was applied during the winding process the birefringence increased sharply. The possibility of controlling the birefringence is of practical interest in constructing various types of optical devices.