The present invention is directed to the creation of optical waveguiding devices from standard optical fibers by the creation of zones of permanently altered refractive index characteristics therein. A high intensity femtosecond laser beam is focused at a predetermined target region in the fiber so as to soften the glass material at the target region. After aligning the focal region with the target region in the fiber there will be relative movement between the focal region and the fiber, which has the effect of sweeping the focal region across the fiber in a predetermined path, so as to create a secondary waveguide path. A portion of the light traveling along the core is removed from the core along the secondary waveguide path such that the device can be utilized as an attenuator, an optical tap, or a polarimeter.