New laser crystals for the generation of ultrashort pulses

Since the beginning of the 1990s, titanium sapphire has become the crystal of choice for the development of ultrashort laser systems producing very short and powerful pulses using the Chirped Pulse Amplification technique. In parallel to these developments leading to commercial products, new laser crystals have been studied in order to reach directly other wavelength ranges and to overcome the need to develop cw or pulsed green laser to pump the titanium sapphire crystal. In order to be able to directly pump the crystals with a very efficient and high-power semiconductor laser, new crystals doped with chromium or ytterbium ions have been developed. This article will review the latest development in this research field with the best performances obtained in terms of pulse duration.