Tm3+:CaF2 planar waveguides grown by liquid phase epitaxy on CaF2 substrates showing signal enhancement at 1.92μm

We report on relative gain measurements at 1.92 μm in Tm:CaF 2 films grown on pure CaF 2 substrates by using Liquid Phase Epitaxy with CaCl 2 as a solvent. Electron microscopy and X-ray diffraction measurements show that the Tm 3+ :CaF 2 films are about 5 μm thick and have a small lattice mismatch with the CaF 2 substrate. Room temperature emission spectra of the Tm 3+ ions around 1.9 μm exhibit the same structure as in the bulk crystals and the lifetime of the 3 F 4 metastable level is found equal to about 12.8 ms. The Tm:CaF 2 films are guiding optical waves and exhibit a relative gain of 7% at 1.92 μm when pumped at 0.765 μm.