Numerical study of usefulness of parabolic index profile for the design of erbium doped fiber lasers and amplifiers

Abstract

In this paper, the usefulness of parabolic index profile with single clad as well as double clad fiber structure has been investigated for the design of erbium doped fiber amplifier (EDFA) and laser (EDFL). The characteristics of parabolic profile fiber lasers in terms of couple pump power and cavity length have been simulated for 980 nm pump and 1550 nm signal. At pump wavelength, the power confinement of double clad (94.55%) is higher than single clad (93.30%). At signal wavelength, the power confinement of double clad (83.80%) is much higher than single clad (67.88%). We found that, EDFL exhibits very high gain. Output power of 68.68 mw (18.36dBm) for single clad and 68.92 mw (18.38 dBm) for double clad is obtained at 140 mW pump power and 50 cm fiber length. It is observed that EDFA provides very high small signal gain in expense of low pump power and small fiber length. We obtained 40 dB small signal gain with 120 mW pump and 1m fiber length. Therefore, parabolic index profile may be useful to design EDFA and EDFL. In the case of EDFL, both geometry offer almost same performance but double clad shows very well result for EDFA.