  We demonstrate femtosecond performance of an ultra-broadband
high-index-contrast saturable Bragg reflector consisting of a
silicon/silicon-dioxide/germanium structure that is fully compatible with CMOS
processing. This device offers a reflectivity bandwidth of over 700 nm and
sub-picosecond recovery time of the saturable loss. It is used to achieve
mode-locking of an Er-Yb:glass laser centered at 1540 nm, generating 220 fs
pulses, with the broadest output spectrum to date.
