Low loss single mode wavelength division multiplexing with etched fiber arrays.

A 9-channel grating single-mode wavelength-division multiplexing scheme is demonstrated at 1.5micron with the lowest insertion loss reported to date. The low loss is realized by using a linear array of single-mode fibers as a channel concentrator with core-to-core separation arbitrarily reduced by controlled etching of the fiber cladding. The close spacing maximizes the ratio, in wavelength, of channel width to channel spacing and the almost lossless nature of the fiber results in insertion losses limited only by Fresnel reflections and grating efficiency.