Abstract

In the paper the spectroscopic properties of antimony-silicate-germanate glass and optical fiber co-doped with Yb³⁺/Ho³⁺ has been investigated. Upconversion luminescence at the wavelengths of 547 nm (⁵S₂(⁵F₄) → ⁵I₈) and 659 nm (⁵F₅ → ⁵I₈) in holmium ion was obtained as a result of phonon assisted energy transfer between Yb³⁺ and Ho³⁺ ions [1, 2]. Elaborated glass characterized by highest intensity of upconversion luminescence (1mol% Yb₂O₃/0.5mol% Ho₂O₃) was used as core of double-clad, off-set core optical fiber. In conventional double-clad optical fibers, only the meridional rays can be absorbed in inner cladding [3]. Offset the core from the center of the inner cladding enables to improve efficiency of optical pumping of the double-clad optical fiber. Basic parameters of the manufactured optical fiber (Fig. 1) were as follows: outer cladding diameter=400 µm, core diameter=15µm, NA_cladding=0.58, NA_core=0.4.

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