KMnF3:Yb3+,Er3+@KMnF3:Yb3+ active-core–active-shell nanoparticles with enhanced red up-conversion fluorescence for polymer-based waveguide amplifiers operating at 650 nm
We demonstrated optical amplification at 650 nm in KMnF3:Yb3+,Er3+@KMnF3:Yb3+ active-core–active-shell nanoparticle (NP) doped polymer waveguides pumped by a 976 nm laser diode for the first time. KMnF3:Yb3+,Er3+ NPs were synthesized via a solvothermal method. With the excitation of a 976 nm laser diode, bright red upconversion (UC) fluorescence was observed from KMnF3:Yb3+,Er3+ NPs owing to the existence of efficient energy transfer between Er3+ and Mn2+:2H11/2,4S3/2 + 6A1 → 4I15/2 + 4T1,2H9/2 + 6A1 → 4I13/2 + 4T1 and 4I15/2 + 4T1 → 4F9/2 + 6A1. The red UC emissions originated from the 4F9/2 → 4I15/2 transition of Er3+. Furthermore, the red UC emissions of KMnF3:18 mol% Yb3+,1 mol% Er3+@KMnF3:2 mol% Yb3+ NPs were enhanced by 7.5 times compared to that of KMnF3:18 mol% Yb3+,1 mol% Er3+ core-only NPs after coating an active shell containing Yb3+ ions on the core-only NPs. The above results showed that the active-shell could be used to not only suppress surface quenching but also transfer the pump light to the core region efficiently through Yb3+ ions inside the active-shell. By using KMnF3:18 mol% Yb3+,1 mol% Er3+@KMnF3:2 mol% Yb3+ NPs as the gain medium and doping NPs into a polymer waveguide, we constructed polymer-based waveguide amplifiers. For an input signal power of 7.4 mW and a pump power of 45.2 mW, a relative optical gain of ∼3.5 dB was obtained at 650 nm in a 17 mm-long waveguide.
- This article is part of the themed collection: 2015 Journal of Materials Chemistry C Hot Papers