Cladding-Pumped Erbium-Ytterbium Co-Doped Fiber Amplifier With Dual-Wavelength Auxiliary Signal Injection of 1030 and 1040 nm

We propose and demonstrate a cladding-pumped, erbium-ytterbium co-doped fiber amplifier (EYDFA) scheme based on dual wavelength auxiliary signal injection technique to solve the issue of the backward Yb-ASE self-lasing under strong pumping for the high-power fiber amplification of 1.5-μm kHz-linewidth linearly-polarized laser signal. With the dual wavelength auxiliary signal of 1030 and 1040 nm injection, the allowable maximum pump power without triggering the backward Yb-ASE self-lasing can be greatly increased due to the relieving effect on the inhomogeneous gain broadening. For an EYDFA with 3.8-m erbium-ytterbium co-doped double-clad fiber, the net output power is improved to 13.8 W, while the linewidth of the amplified single-transverse-mode linearly-polarized 1560 nm laser signal is still only 3.5 kHz. The SBS effect is observed to be trivial during the fiber amplification.