Abstract

Ti:sapphire will largely supercede organic dyes in ultrafast laser applications. We report two tunable lasers continuing this trend that may also eventually supplant the (ultrafast) color-center laser. The n₂ of the Ti:sapphire medium has been used to provide both amplitude modulation, through self-focussing, and phase modulation that, together with GVD, produces further pulse compression. These mode-locking techniques are generally applicable to vibronic solid-state laser media. Cr³⁺:LiSrAIF₆ is an attractive alternative to Ti:sapphire—owing to its greater storage capacity, lower threshold, and ability to be diode-pumped. We report what is to our knowledge the first 488-nm-pumped cw Cr³⁺:LiSrAIF₆ laser. This laser has been passively mode locked and, after the GVD of the system is optimized, yields pulses as short as 33 fs for only 500 mW pump power. We anticipate that similar techniques will be applied to new solid-state lasers tuning from 1.1 to 1.6 μm—the domain of cryogenic color-center lasers. Cr⁴⁺:YAG is a stable room-temperature laser that may be pumped at 1.06 μm and can lase from 1.35 to 1.56 μm. Our initial experiments on the first cw mode-locked Cr⁴⁺:YAG laser incorporating an acousto-optic modulator produced detector-limited pulses of <50 ps duration at 1.44 μm at up to 500 MHz.

© 1992 Optical Society of America