Abstract

In recent years, considerable interest has been devoted to the laser emitting in the 1.5–2 μm range. Ho³⁺ and Tm³⁺ operate around 2 μm while Er³⁺ covers the 1.5 μm range. The development of high power laser diodes lasing around 0.78 and 0.98 μm allows the pumping of these ions. Engaged in the search for new laser materials, we are interested by the gehlenite Ca₂Al₂SiO₇ (CAS) matrix. In this matrix, there is an inhomogeneous broadening of the optical lines because of a structural disorder arising from the statistical distribution of Si⁴⁺ and half of the Al³⁺ ions on the same kind of tetrahedral sites. This host presents also high phonon frequency leading to short lifetime values when the energy gap difference between the emitting level and the one just below is small. Therefore, for the ions studied only the ⁴F_3/2 level for Nd³⁺ (τ = 280 μs), ⁴I_13/2 for Er³⁺; (τ = 7.6 ms) and ⁵I₇ level for Ho³⁺ (τ = 7.4 ms) present lifetime values in the hundred of microseconds to millisecond range. Laser rods of the RE³⁺-doped CAS have been obtained by the Czochralski process.

© 1994 IEEE