Crystal growth and optical properties of Cr 3+, Er 3+, RE 3+: Gd 3Ga 5O 12 (RE=Tm, Ho, Eu) for mid-IR laser applications

Abstract

In this paper we report on the optical properties of triply Cr 3+, Er 3+, and RE 3+ (RE=Tm, Ho, Eu) doped Gd 3Ga 5O 12 crystals that were grown by the Czochralski method. Optical absorption, near-infrared (NIR), and mid-infrared (mid-IR) fluorescence spectra were characterized for the fabricated crystals and corresponding luminescence decay measurements under 654 nm excitation were also carried out. Based on the analysis of energy transfer process between Er and RE (RE=Tm, Ho, Eu) ions, the energy transfer efficiency (ETE) values were evaluated, correspondingly. From the spectral data of all the studied crystals, it is observed that the co-doped Cr 3+ ion highly increases the absorption pump power and the three kinds of co-doped RE 3+ ions depopulate the Er: 4I 13/2 energy level effectively. The spectral analysis shows that titled rare earth doped crystals are promising materials for ∼3.0 μm mid-IR laser applications and among them Cr,Er,Eu:GGG is relatively more suitable due to its excellent optical properties compared with others.