  Here, we demonstrate all-fiber direct amplification of 11 picosecond pulses
from a gain-switched laser diode at 1063nm. The diode was driven at a
repetition rate of 40MHz and delivered 13$\mu$W of fiber-coupled average output
power. For the low output pulse energy of 0.33pJ we have designed a multi-stage
core pumped preamplifier based on single clad Yb-doped fibers in order to keep
the contribution of undesired amplified spontaneous emission as low as possible
and to minimize temporal and spectral broadening. After the preamplifier we
reduced the 40MHz repetition rate to 1MHz using a fiber coupled pulse-picker.
The final amplification was done with a cladding pumped Yb-doped large mode
area fiber and a subsequent Yb-doped rod-type fiber. With our setup we achieved
amplification of 72dBs to an output pulse energy of 5.7$\mu$J, pulse duration
of 11ps and peak power of >0.6MW.
