INFRARED EXCITED-STATE ABSORPTION OF NI2+ DOPED CRYSTALS

The excited state absorption spectra of Ni2+:MgO and Ni2+:Gd3Ga5O12 we re measured in the complete region of the infrared emission. The emiss ion band overlaps both with the excited state absorption band and the 3A2(3F) --> 3T2(3F) ground state absorption band. At low temperatures all bands are narrower and exhibit sharp structures, reducing the loss es to the laser emission. The structure of the excited state absorptio n spectrum of Ni2+:MgO at 10 K is assigned to zero phonon lines and vi brational sidebands of the T1, T2(3T1(3F)) spin-orbit components and t o vibrational sidebands of the E component.