Residual infrared absorption in as-grown and annealed crystals of Ti:Al/sub 2/O/sub 3/

Spectroscopy of titanium-doped gallium lanthanum sulfide glass

“…The main peak occurs at 490 nm with the shoulder at 550 nm; these are attributed to transitions from the 2 T 2g ground state to the Jahn-Teller split 2 E g ͑E 3/2 ͒ and 2 E g ͑E 1/2 ͒ excited states [9]. A weak residual IR absorption has been identified in Ti:sapphire from around 650 to 1600 nm, peaking at 800 nm [9] and has been shown to be due to Ti 3+ -Ti 4+ pairs [10]. We therefore propose that the absorption at ϳ600 nm in Ti:GLS and Ti:GLSO is due to the 2 T 2g → 2 E g transition of octahedral Ti 3+ and the absorption at 980 nm in Ti:GLS is due to Ti 3+ -Ti 4+ pairs.…”

“…We therefore propose that the absorption at ϳ600 nm in Ti:GLS and Ti:GLSO is due to the 2 T 2g → 2 E g transition of octahedral Ti 3+ and the absorption at 980 nm in Ti:GLS is due to Ti 3+ -Ti 4+ pairs. The residual IR absorption coefficient of Ti 3+ :Al 2 O 3 has been shown to be proportional to the square of its blue-green absorption coefficient [9,10]. Because absorption due to Ti 3+ -Ti 4+ pairs is detrimental to the performance of the Ti:sapphire laser, much effort has been made to minimize it.…”

Progress in the growth of large scale Ti:sapphire crystals by the heat exchanger method (HEM) for petawatt class lasers

“…A parasitic absorption underneath the emission region is associated with Ti 3 + :Ti 4 + defect pairs in the host material [12][13][14][15]. This loss can seriously impair the ability to make Ti:sapphire lase, and can limit the bandwidth, as well.…”

“…One measure of the efficiency of the process used to grow or anneal the crystals, therefore, is a 532n FOM. Because of the reducing conditions in the furnace, HEM-grown Ti:sapphire contains minimal Ti 4+ content and as-grown FOM's of 100 have been observed with a 532 41 [13]. Crystal growth techniques such as Cz intrinsically produce a high content of Ti 4 + and low FOM's.…”

Application of predominance diagrams in melt growth of oxides

“…Performance of Ti:Sapphire is impaired by an absorption in the near infrared, i.e. the range of laser emission [10,11]. The ratio of the absorption coefficients α at pumping wavelength λ = 490 nm (sometimes 514 nm) and at the peak of the residual infrared absorption around 800 nm is commonly regarded a key figure of merit (FoM) of the crystals:…”