Optical waveguide amplifiers based on NaYF₄: Er³⁺, Yb³⁺ NPs-PMMA covalent-linking nanocomposites

NaYF₄: Er³⁺, Yb³⁺ nanoparticles (NPs) were synthesized by using a high temperature thermal decomposition approach. Under a 980 nm laser excitation, intense emission at 1.53 μm from NaYF₄: Er³⁺,Yb³⁺ NPs was obtained. NaYF₄: Er³⁺, Yb³⁺ NPs-PMMA covalent-linking nanocomposite was prepared by copolymerization of the oleic acidmodified NaYF₄: Er³⁺, Yb³⁺ NPs and methylmethacrylate(MMA). In this case, the doping mass concentration of NPs in the polymer matrix could be up to 1%, which is 10 times larger than previously published results. We constructed optical waveguide amplifiers with a structure of embedded waveguide using the NPs-PMMA nanocomposite as the core material. For an input signal power of 0.14 mW and a pump power of 400 mW, a relative optical gain of 7.6 dB was obtained at 1540 nm in a 15 mm-long waveguide.