Trapping Individual Upconverters Using Rectangle Nanoapertures

We report the optical trapping of single Er
³⁺
/Yb
³⁺
co-doped up-converting fluorescent nanoparticle with rectangle aperture on gold sample using a continuous wave 980 nm single-beam laser. The laser also excites visible luminescence from the nanoparticles. This feature enables us to analyze the number of individual nanoparticles loading into a trap stage. We record the number of trapped nanoparticles using a CCD camera which also can be confirmed by measuring the variation in the laser intensity transmitted through the rectangle aperture. The rectangle aperture enhances the local field that serve in enabling trapping and enhancing the emission of up-converting nanoparticles. In addition, we investigate the impact of rectangle dimensions on the ratio of emitted upconversion in the 544 nm to 655 nm range. Results show a change in ratio of upconversion peaks in the range of 544 nm to 655 nm while sweeping through different lengths of rectangular aperture. This study could help improve the understanding of lanthanide upconversion nanoparticle interaction with plasmonic gold nanoapertures at the nanoscale level.