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We present a spectroscopic overview of Cr +-doped Y3A150» (YAG), a new laser material for the near-infrared region (NIR). It is found that only 2% of the Cr ions are tetrahedrally coordinated Cr +.However, the optical spectra are dominated by this ion. The missing inversion symmetry for the tetrahedral site causes higher cross sections than are common for octahedrally coordinated ions. The experimental data include a survey of the absorption and emission features. Lifetime measurements, as well as piezospectroscopic experiments yield additional spectroscopic information. Our data suggest an energy-level assignment that is different from the one previously used to describe the spectrum. Instead of ascribing the strong NIR absorption band, centered at around 1000 nm, to the '8&('A2) 'E('T2) transition, we assign it to the '8&('A&)~'A2('T&) transition. This assignment is able to describe the polarization-dependent spectra, the piezospectroscopic results, and the results from earlier polarizationdependent saturation experiments.An analysis of the luminescence decay rate yields quantum eSciencies of around 49% at 10 K and 15% at room temperature, resulting in a peak emission cross section of 3.5X10 19 cm2

Saturation absorption experiments are conducted on the title compound at 1.064 μm with laser light propagating along both the [001] and [111] crystallographic axes. Rotation of the crystals about these axes during the experiments reveals that the transmission of the polarized 1.064 μm radiation is highly anisotropic in the saturation regime. The details of the anisotropy and saturation curves are explained using a simple model of subsets of optical centers along with a relevant set of rate equations. The ground and excited-state absorption cross sections at 1.064 μm are calculated to be σgs=5.7(±2)×10−18 cm2 and σes=8(±2)×10−19 cm2, respectively, and the optimum crystallographic orientation for utilization in optical devices is discussed.

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