Optical trapping of large metallic particles in air

In this paper, we introduce a horizontally oriented photophoretic ``boat'' trap that is capable of capturing and self-loading the largest reported (radius $\ensuremath{\ge}1\phantom{\rule{0.2em}{0ex}}\text{\ensuremath{\mu}}\mathrm{m}$) photophoreticaly trapped solid gold particles in air for more than 1 h. Once trapped, particles are held stably, without hopping, even as the trap is modified to scan axially or expanded to a larger size to increase the capture cross section. We theoretically present and experimentally demonstrate each of these affordances.