Mechanical Properties Of Phosphate Glass Optical Fibres

In this work, step-index 40/135um diameter optical fibres produced from two slightly different lithium phosphate glasses were subjected to mechanical characterisation. Tensile tests were carried out on fibres with gage length from 10 to 150mm, allowing for the determination of the failure stress (ranging from ~200-400 MPa) and the elastic modulus (60 GPa). Some tests were also performed with the fibre "immersed" in water; an important sub-critical crack growth effect was pointed out, and a fatigue susceptibility parameter (n) equal to 11.4 was determined. The analysis of fracture mirror allows an estimated fracture toughness equal to 0.5 MPa m0.5.