1.8 μm emission and excited state absorption in LHPG grown Gd0.8La0.2VO4:Tm3+ single crystal fibers for miniature lasers

This work presents the characterization of high optical quality Gd0.8La0.2VO4:Tm3+ single crystal fibers grown by the low cost laser heated pedestal growth technique. The 400 μm diameter fibers were grown completely free from inclusions, without the need of O2 atmosphere. Their structural and spectroscopic characteristics are very similar to those of GdVO4:Tm3+, with the advantageous inhomogeneous broadening that eliminates the need of temperature control of the diode pumping laser for excitation at 0.8 μm. ESA transitions do not affect the population in level 3F4 significantly, and intense emission is observed at 1.8 μm. On the other hand, the 1.45 μm emission is deeply affected by ESA, while pumped at 0.8 μm excitation. The lower cost and easier growth of compact, excellent optical quality single crystal fibers, as compared to GdVO4:Tm3+ bulk crystals, indicates the fibers are interesting candidates for the construction of miniature lasers in the eye-safe spectral region (1.5–2.0 μm).