A single-stage 1112 nm fiber amplifier with large gain for laser cooling of ytterbium

We present a single-stage Yb fiber amplifier pumped at 1064 nm which amplifies a low-power (5 mW) signal from a commercial distributed feedback (DFB) fiber laser at 1112 nm to several hundred mW. Compared to conventional fiber amplifiers, which are typically pumped at shorter wavelength, the single-stage gain of the amplifier is increased to more than 20 dB and the ASE level is reduced by an order of magnitude. Frequency doubling in a PPLN waveguide produces light at 556 nm, which is used to capture Yb atoms in a magneto-optical trap on the 1S0\(\rightarrow\) 3P1 intercombination line.