|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1996 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1995 : ¥1,800,000 (Direct Cost : ¥1,800,000)
Transition metal ions Cr^<3+>, Ti^<3+> and rare earth ions Ce^<3+> in crystals are used as laser active ions. Since electron-phonon couplings of their ground and excited state electrons are quite different, the optical transitions feature broad absorption and emission bands, giving rise to a wide tuning range of laser oscillation. Recently, the demonstrations of optically pumped solid-state tunable lasers obtained from Cr^<3+> : LiCaAlF_6, Ti^<3+> : Al_2O_3, and Ce^<3+> : LiYF_4 crystals at room temperature were reported. In order to obtain new tunable solid state laser materials, we have examined the electronic properties of Cr^<3+>, Ti^<3+>, Ce^<3+> : CaYAlO_4 (CYA) using electron spin resonance (ESR) and optical spectroscopy.
ESR studies of Cr^<3+> in CYA show Cr^<3+> ions in sites with ordered and disordered configurations of the second nearest-neighbor Ca^<2+>/Y^<3+> ions, respectively. The polarized intensities of the ^4A_2-^4T_2 absorption band and the R_1-line fluorescence suggest that the CrO_6^<9-> octahedra undergo an angular distortion such that the magnetic z-axis of the spectrum is rotated away from the crystal c-axis.
The g tensor of Ce^<3+> in CYA was obtained to be g_<11>=2.6, g_*=1.6. The ESR results indicate that the wavefunction of the ground state of Ce^<3+> in CYA has a dominant component of |J,J_Z>=|5/2,5/2>. The absorption of Ce^<3+> in CYA was observed in the UV region (200-370nm) and the luminescence band has a peak at 490nm.