Visible spectrum absorption cross section of Cr³⁺in the²E state of pink ruby

Absorption cross sections of Cr3+in the metastable2E states of pink ruby (0.05 percent Cr2O3) have been measured forE ⊥ Cbetween 4000 Å and 7000 Å at 297°K and 115°K. Both 0 degree and 90 degree ruby rods were measured in a flash absorption apparatus having a spectral resolution of 50 Å. The broad excited state absorption bands centered at 5600 Å appear to correlate with the positions of2T1(3T1) level, while the narrow band centered at 4540 Å correlates well with the predicted2A2(1E) level. The effect of excited state absorption on laser operation is discussed in this paper.