Multi-siting and mode locking in a Yb3+:CS-FAP laser

A Yb3+:CS-FAP (Yb3+:Ca4Sr(PO4)(3)F) laser has been actively mode locked to generate pulses as short as 35 ps, which were far from transform limited. Intra cavity pulse compression failed to realise the femtosecond pulse generation potential of this relatively broad bandwidth (similar to 10 nm) and efficient laser material. Site-selective excitation techniques were employed to demonstrate an excitation wavelength-dependent laser emission. This spectral inhomogeneity arises from the disorder on the metal host site which is due to random Ca and Sr occupation. Such a characteristic most likely prohibited ultrashort pulse generation with this sample. (C) 1997 Elsevier Science B.V.