68-fs passively mode-locked diode-pumped Yb3+:CaGdAIO4 laser with an average power of 520 mW

Yb
³⁺
:CaGdAIO
₄
is directly pumped with a 15 W 100 mum core fiber-coupled laser diode (LIMO) emitting around 980 nm. Two Gires-Tournois interferometers, each providing a negative group-velocity dispersion of -550 fs
²
, are inserted in the cavity to compensate the dispersion introduced by the crystal. A semiconductor saturable absorber (SESAM) is used to initiate and stabilize the passive mode-locked regime. To avoid a post compression, all the mirrors in the cavity mirrors were replaced by low GVD mirrors. The highest average power has been obtained with a 5% output coupler.