1 research outputs found
Transversely Divergent Second Harmonic Generation by Surface Plasmon Polaritons on Single Metallic Nanowires
Coherently adding
up signal wave from different locations are a
prerequisite for realizing efficient nonlinear optical processes in
traditional optical configurations. While nonlinear optical processes
in plasmonic waveguides with subwavelength light confinement are in
principle desirable for enhancing nonlinear effects, so far it has
been difficult to improve the efficiency due to the large momentum
mismatch. Here we demonstrate, using remotely excited surface plasmon
polaritons (SPPs), axial collimated but transversely divergent second
harmonic (SH) generation in a single silver nanowire–monolayer
molybdenum disulfide hybrid system. Fourier imaging of the generated
SH signal confirms the momentum conservation conditions between the
incident and reflected SPPs and reveals distinct features inherent
to the 1D plasmonic waveguides: (i) the SH photons are collimated
perpendicular to the nanowire axis but are divergent within the perpendicular
plane; (ii) the collimation (divergence) is inversely proportional
to the length of the active region (lateral confinement of the SPPs);
and (iii) the SH emission pattern resembles that of an aligned dipole
chain on top of the substrate with an emission peak at the critical
angle. Our results pave the way to generate and manipulate SH emission
around subwavelength waveguides and open up new possibilities for
realizing high efficiency on-chip nonlinear optics