title: Enhancement of second harmonic signal in nanofabricated cones.
abstract: Geometrical effects in optical nanostructures on nanoscale can lead to interesting phenomena such as inhibition of spontaneous emission,1,2 high-reflecting omnidirectional mirrors, structures that exhibit low-loss-waveguiding,3 and light confinement.4,5 Here, we demonstrate a similar concept of exploiting the geometrical effects on nanoscale through precisely fabricating lithium niobate (LiNbO3) nanocones arrays devices. We show a strong second harmonic generation (SHG) enhancement, shape and arrangement dependent, up to 4 times bigger than the bulk one. These devices allow below diffraction limited observation, being perfect platforms for single molecule fluorescence microscopy6 or single cell endoscopy.7 Nanocones create a confined illumination volume, devoid from blinking and bleaching, which can excite molecules in nanocones proximity. Illumination volume can be increased by combining the SH enhancement effect with plasmon resonances, excited thanks to a gold plasmonic shell deposited around the nanostructures. This results in a local further enhancement of the SH signal up to 20 times. The global SH enhancement can be rationally designed and tuned through the means of simulations.
authors.affiliation: Laboratory of Nanoscale Biology, Institute of Bioengineering, ‡Laboratory of Semiconductor Materials, Institute of Materials , §Laboratory of Nanophotonics and Metrology, Institute of Micro Engineering, and ∥Laboratory of Nanoscale Electronics and Structures, Institute of Electrical Engineering, School of Engineering, EPFL , 1015 Lausanne, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Dutto
authors.forename: M
authors.initials: M
authors.lastname: Heiss
authors.forename: A
authors.initials: A
authors.lastname: Lovera
authors.forename: O
authors.initials: O
authors.lastname: López-Sánchez
authors.forename: A
authors.initials: A
authors.lastname: Fontcuberta I Morral
authors.forename: A
authors.initials: A
authors.lastname: Radenovic
mesh_terms: D006046:Gold / Q000737:chemistry; D008027:Light; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology; D009556:Niobium / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D020349:Surface Plasmon Resonance
chemical_list: D010087:Oxides; D009556:Niobium; C091692:lithium niobate; D006046:Gold