Broadband emission from Cr-doped fibers fabricated by drawing tower

We report on the first fabrication of a Cr-doped fiber using a drawing-tower method with Cr:YAG as the core of the preform. Both Cr3+ and Cr4+ ions coexist in the Cr-doped fiber, and the amplified spontaneous emission (ASE) spectrum shows a broadband emission of 1.2 to 1.55 mum which can not be realized by using currently available fiber amplifiers. This indicates that the new Cr-doped fibers have the potential for being used as a broadband fiber amplifier to cover the bandwidth of the entire 1.3-1.6 mum range which exhibit 300 nm usable spectral bands.