Ti:sapphire: Material, Lasers and Amplifiers
Abstract:
The Ti:Al2O3 (Ti:sapphire) laser has several ancestors, including the first laser [1], based on the crystal ruby, formally Cr3+ ions doped into sapphire (Al2O3). Ti:sapphire employs the same robust host crystal as in ruby, which is crucial for the ruby laser to operate under the intense optical pumping from flashlamps, required by the three-level nature of the ruby laser transition. Another class of ancestors were the first broadly tunable solid-state lasers, based on divalent transition-metal ions, such as Ni2+ and Co2+, doped into mainly fluoride host crystals, such as MgF2 [25]. While these types of lasers could be tuned over an impressive range of wavelengths (16002500 nm in the case of Co:MgF2 [6]),the low gain and the general need to operate under cryogenic cooling were drawbacks that limited their utility