Deformation of single-mode optical fibers under static longitudinal stress

The deformation of single-mode fibers resulting from a longitudinally applied static force has been measured experimentally by means of high resolution heterodyne interferometry and analyzed theoretically using the second-order theory of elasticity and the photoelastic effect. Both the elongation of the fiber and the phase change of light propagating through the fiber have been measured as a function of tensile force. The values of the elastic constants measured for fibers with pure silica core and B2O3doped cladding are N/m²for the Young\´s modulus, for the nonlinearity constant of the longitudinal strain, and for the nonlinearity constant of the transverse strain. For unit elongations up to 0.3 percent, no creep, hysterisis, or relaxation effects have been observed within a resolution of one part in 10⁴.