Template-mediated liquid quenching to expand the dimensions of bright green upconverters

Multiphoton upconverters generate visible or UV wavelengths from near-infrared excitation. Liquid-quenched upconverters provide excellent upconversion efficiency and pure upconversion emission spectra. However, the morphology of liquid-quenched upconverters has been limited to spherical shapes due to surface tension during melting. Here, we demonstrate that the morphology of liquid-quenched upconverters can be mediated by silicon templates. Microcube and microrod templates with various sizes were successfully filled with upconversion nanoparticles. Under a highly focused laser beam, liquid quenching was realized in the microcube and microrod templates only with width 2.0 μm because a sufficient volume of upconversion nanoparticles is required to overcome heat dissipation into the silicon walls. The high aspect ratio (1:10) of the microrod templates enables template-mediated liquid quenching as far as 20 μm along the length direction. Our study expands the dimensions of bright green upconverters for potential applications that include all-photonic integrated circuits.