Optical fiber tapers at 1.3micron for self-aligned beam expansion and single-mode hardware.

We have experimentally demonstrated the applicability of optical fiber tapers at 1.3micron as a simple and practical means of achieving beam expansion in a self-aligned unitary structure. These devices have a standard 8.1micron core at one end which gradually increases in cross section to the order of 100micron at the other end. Tapers are envisioned as basic building blocks in a multitude of single-mode optical components. Experiments performed on a batch of eight tapers, drawn from a preform without a central index depression, verified, to experimental accuracy, that no significant amount of mode conversion or beam distortion takes place in the taper. The insertion loss of the taper was found to be under 0.1 dB.