  We report on an in-band pumped SESAM mode-locked Ho:CALGO bulk laser with a
record-high average power of 8.7 W and an optical-to-optical efficiency of
38.2% at a central wavelength of 2.1 um. At this power level, the bulk laser
generates pulses with a duration of 369 fs at 84.4-MHz repetition rate,
corresponding to a pulse energy of 103 nJ and a peak power of 246 kW. To the
best of our knowledge, this is the highest average power and pulse energy
directly generated from a mode-locked bulk laser in the 2-3 um wavelength
region. Our current results indicate that Ho:CALGO is a competitive candidate
for average power scaling of 2 um femtosecond lasers.
