Abstract

Femtosecond Direct Laser Writing (fs-DLW) is a powerful technique of fabricating 3D photonic microstructures in transparent dielectric materials doped with rare-earth ions for waveguide (WG) laser applications [1]. It benefits from high precision of inscriptions, short fabrication times, and a variety of available WG geometries. Laser waveguides based on thulium ions (Tm³⁺) with emission around 2 µm (the ³F₄ → ³H₆ transition) are appealing as seed sources for WG and fiber amplifiers for medical and sensing applications. Calcium fluoride (CaF2) is an attractive host matrix for rare-earth doping because of its high thermal conductivity and strong ion clustering leading to broadband (“glassylike”) emission properties. In the present work, we report on the first Tm³⁺:CaF₂ waveguide laser.

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