Creation of output ports in plasmonic nanowire waveguides through laser nano-welding

This paper explores the creation of additional output ports on silver nanowire (Ag NW) subwavelength waveguides through in situ laser nano-welding of an X-shaped Ag NW crossing system and a silver nanowire-nanoparticle system. Unlike laser-welding studies that utilize large laser spots to irradiate entire structures, we employ a tightly focused laser (<1 μm) that targets only the joints, resulting in a distinct polarization dependency of heat generation during the welding process. The outlets of surface plasmon polaritons (SPPs) from a single Ag NW were initially examined to confirm that the output spots originate from the SPPs, also highlighting their dual wavelength multiplexing capabilities. The welded joints perturb the propagation of SPPs along the Ag NWs, leading to enhanced emission from the propagating SPPs and the creation of additional output ports at these joints. Since focused lasers enable single-point welding, device modifications can be highly localized and performed on demand. This work advances the application of laser welding in nanowire-based photonic devices.