We demonstrate RF sputtered, non-epitaxially-grown semiconductor nanocrystallite-doped silica films for mode locking a Cr:forsterite laser. We controlled the size and the optical properties of the nanocrystallites by varying the ratio of InAs to SiO<sub>2</sub> during fabrication. Femtosecond pump–probe measurements were performed to characterize the nonlinear optical properties of these films, revealing their lower saturation fluences. Using the InAs-doped silica films as saturable absorbers permitted self-starting Kerr-lens mode locking (KLM), generating pulses of 25-fs duration with 91-nm spectral bandwidth at 1.3 µm . We also describe saturable-absorber mode-locked operation without KLM and investigate its dependence on intracavity dispersion.
© 2002 Optical Society of America
(140.4050) Lasers and laser optics : Mode-locked lasers
(140.7090) Lasers and laser optics : Ultrafast lasers
(230.4320) Optical devices : Nonlinear optical devices
(320.7080) Ultrafast optics : Ultrafast devices
R. P. Prasankumar, C. Chudoba, J. G. Fujimoto, P. Mak, and M. F. Ruane, "Self-starting mode locking in a Cr:forsterite laser by use of non-epitaxially-grown semiconductor-doped silica films," Opt. Lett. 27, 1564-1566 (2002)