Wavelength band-rejection filters based on optical fiber fattening by fusion splicing

A novel method to fabricate optical fiber band-rejection filters based on optical fiber fattening is presented. In this method, the fiber fattening is realized by applying a standard fusion splicing procedure on bare dispersion-shifted fibers. The method does not require additional special fixtures and can be implemented in any commercial fusion splicer machine. Using this method, we have fabricated short dispersion-shifted fiber filters with less than 3 mm length, >20 dB notch depths, and >100 nm bandwidth.