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Single-transverse-mode large-mode-area erbium-doped fiber amplifier for high-energy pulse amplification

Efficiency of energy extraction is an important issue for high-energy pulse amplification in fiber systems. High gain in the single-mode fiber amplifier is always accompanied by a considerable amount of amplified spontaneous emission (ASE). ASE efficiently saturates the gain, thus reducing the population inversion and limiting the stored energy. An improvement in scaling these sources with single-transverse-mode output to higher power levels can be achieved through an increasing in mode-field area or in a ring-doped fiber. These fiber designs reduce the small signal gain and hence restrict the inverted population depletion through gain saturation by ASE, so larger energies can be stored in the amplifier. In this paper, the effect of mode-field area on the efficiency of energy extraction of an erbium-doped fiber amplifier was studied.