Segmented-clad fiber design for tunable leakage loss

This paper proposes a novel segmented-clad fiber (SCF) design in which the spectral variation of leakage loss of the fundamental mode can be finely tuned by varying the fiber parameters. A fiber with such optimized spectral variation of leakage loss should find application in the realization of inherently gain-flattened optical fiber amplifiers, wavelength filters, wavelength-flattened attenuators, etc. In this paper, the authors present SCF designs optimized for realizing inherently gain-flattened S-band erbium-doped fiber amplifier (EDFA) and high-gain discrete Raman fiber amplifier (RFA). Amplifier characteristics have been modeled in both cases, and simulations show that a 20-dB gain with ±0.9 dB of gain ripple over a 30-nm bandwidth in S-band is achievable with the designed EDFA based on the optimized SCF. In case of discrete RFA based on SCF, a 20-dB net gain with ±0.5-dB ripple is shown to be achievable over a 28-nm wavelength range in S-band.