High-Gain Optical Amplification of Europium–Aluminum (Eu³⁺–Al)-Nanocluster-Doped Planar Polymer Waveguides

Abstract

We have fabricated a planar poly(methyl methacrylate) (PMMA) optical waveguide doped with 10 wt % Eu–Al nanoclusters, and have successfully demonstrated optical amplification at 610 nm excited by a N2 laser (λ=337 nm). The gain of the optical amplification was found to be as high as 5.57 dB/mm, which, to the best of our knowledge, is the highest observed for various rare-earth (RE)-doped planar optical waveguides. An Er–Al-nanocluster-doped PMMA optical waveguide has also been successfully fabricated, and guided emission at around 1.55 µm has been observed in spite of the large absorption loss induced by PMMA. The RE-metal nanoclusters can therefore be regarded as promising candidates as the active materials for polymer-based waveguide-type optical amplification devices.