Segmented-clad fiber design for inherently gain-flattened L/sup +/-band TDFA

We present here an efficient design for high gain, inherently gain-flattened L/sup +/-band thulium-doped fluoride fiber amplifier (TDFA), based on a novel segmented clad fiber refractive index profile. Detailed simulations show that the designed amplifier is able to achieve 20-dB gain, with /spl plusmn/0.7-dB gain ripple over 40-nm bandwidth (1600-1640) nm. Performance comparisons of the proposed module with an L/sup +/-TDFA based on conventional W-fiber designs and on a conventional step-index fiber have also been carried out.