Abstract

Calcium gadolinium aluminate (CaGdAlO₄, shortly CALGO) is an attractive laser host material for doping with rare-earth ions. It belongs to the tetragonal class (sp. gr. I4/mmm) and exhibits a structure disorder (a random distribution of Ca²⁺ and Gd³⁺ cations over the same lattice sites). Still, CALGO features high thermal conductivity and appealing thermo-optical properties. The disordered nature of the host matrix determines a significant inhomogeneous spectral broadening for the dopant ions. Thulium (Tm³⁺) doped CALGO was applied for femtosecond pulse generation at 2 µm [1]. Recently, there is a great interest to another emission of Tm³⁺ ions at 2.3 - 2.5 µm according to the ³H₄ ³H₅ transition, Fig. 1(a). The main constraint for ultrashort pulse generation from Tm-lasers at these wavelengths consists of the lack of broadband-emitting materials. In the present work, we explore the potential of Tm:CALGO for laser operation at 2.3 µm, for the first time, to the best of our knowledge.

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