The laser penetrates the filament heating it internally instead of only heating the outer surface. It's near-infrared (808 nm) so it heats the small cylinder o

The laser penetrates the filament heating it internally instead of only heating the outer surface. It's near-infrared (808 nm) so it heats the small cylinder of filament essentially uniformly throughout its volume. It's also nice because they can vary laser power much more effectively than you can vary the temperature of a conduction surface. https://arxiv.org/pdf/1709.05918.pdf https://arxiv.org/pdf/1709.05918.pdf