Model Results of Er-Yb Double Clad Fiber Amplifier

摘要

We present model calculations of gain at 1550 nm for Er-Yb double clad amplifiers as a function of pump power, pump wavelength, signal input power, and fiber length. The absorption coefficient of Yb varies ( by a factor of ～ 5) with the pump wavelength in the range of 910 to 990 nm. However, semiconductor lasers may be available only at certain wavelengths. Thus it is important to calculate optical gain and amplified output power as a function of pump wavelength. The calculation shows that significant optical gain and amplified output power can be obtained even if the pump laser wavelength is not at the peak absorption wavelength. The gain decreases with increasing input signal. We show that a high power Er-Yb co-doped double-clad fiber amplifier also exhibits high gain for Yb transition near 1060 nm. This is not unexpected since the input pump causes population inversion in Yb. More than 100 W of amplified power can be obtained using 24m long fiber with 300 W of total pump power by using side-pumping method. Side pumping increases the efficiency over end pumping for high output power.