Consistent refractive index profile measurements of a step-index monomode optical fiber attained by several techniques

The methods implemented in our laboratory-far field, near field, refracted near field, and interfetometry-allow one to characterize very accurately the parameters of a step-index single-mode fiber by comparing the results. The step-index profile is obtained with a silica core and a borosilicate cladding by the MCVD process. Experimental results from the above techniques show a good match, confirming the validity of the usual assumptions founding the theories employed. Among the techniques used, the refracted near field seems better to check any type of index profile, a delicate task to perform with other methods.