CRYSTAL-GROWTH AND SPECTROSCOPY OF TM3+ DOPED CA2AL2SIO7

This paper presents the optical properties of Tm3+ in the Gehlenite Ca2Al2SiO7 (Tm:CAS) laser host. Single crystals of Ca2-xTmxAl2+xSi1-xO7 (0<x<0.20) of good optical quality were obtained by floating zone and Czochralski methods. Absorption measurements lead to the assignment of energy level positions and the determination of the Judd-Ofelt parameters: Omega(2) = 1.7x10(-20) cm(2), Omega(4) = 1.5x10(-20) cm(2) and Omega(6) = 0.9x10(-20) cm(2). Broad absorption linked to high Tm3+ concentration in the crystals leads to a potential good material for diode pumping. Cross-relaxation and diffusion parameters are estimated from the lifetimes measurements and the main cross-relaxation schemes are determined. Non radiative multiphonon deexcitation and cross-relaxation mechanisms enhance the broad F-3(4)-->H-3(6) emission in the near infrared range. Manifold of the ground state level presents a large splitting around 808 cm(-1) favourable to the population inversion in the excited state.