Refractive Index Changes in Optical Fibers Subject to Diametral Stress.

The changes in refractive index induced by the photoelastic effect when an optical fiber is subjected to a uniformly applied diametral stress are described. For easily achievable values of the force per unit length applied to the fiber, it was found that regions of equal or higher refractive index than the core may be induced in the outer region of the fiber. Thus the stressed region is capable of acting as a mode converter that affects the transmission characteristics of the fiber. Author