Fabrication of three-dimensional plasmonic cavity by femtosecond laser-induced forward transfer

Coherent selection of invisible high-order electromagnetic excitations

Far-field spectroscopy and mapping of electromagnetic near-field distribution are the two dominant tools for analysis and characterization of the electromagnetic response in nanophotonics. Despite the widespread use, these methods can fail at identifying weak electromagnetic excitations masked by stronger neighboring excitations. This is particularly problematic in ultrafast nanophotonics, including optical sensing, nonlinear optics and nanolasers, where the broad resonant modes can overlap to a significant degree. Here, using plasmonic metamaterials, we demonstrate that coherent spectroscopy can conveniently isolate and detect such hidden high-order photonic excitations. Our results establish that the coherent spectroscopy is a powerful new tool. It complements the conventional methods for analysis of the electromagnetic response, and provides a new route to designing and characterizing novel photonic devices and materials.

Modeling and experimental study of plasmonic lens imaging with resolution enhanced methods

Plasmonic lens imaging with some resolution enhancement methods are investigated in this paper, mainly by physical modeling and numerical simulations. The imaging model is based on the refined optical transfer function with extra reflection in imaging space and measured in variant magnetic and electric field components. The influences of structured light illumination and mask patterns^' modifications are considered as well. As experimental demonstrations, L-shaped slits pattern with a half-pitch of 60 nm is successfully imaged with 50 nm air distance, by using plasmonic cavity lens lithography and off-axis illumination with 365 nm wavelength light. This study is believed to provide the model and methods for the design of high resolution plasmonic lens employed in nano lithography and optical storage etc.

Investigation of splashing phenomena during the impact of molten sub-micron gold droplets on solid surfaces

The dynamics of splashing accompanying the impact of molten 800 nm diameter gold droplets on silicon, gold coated silicon, gold coated glass and polished solid gold surfaces has been studied. A novel method based on laser induced forward transfer has been developed to generate single submicron molten gold droplets. Splashing morphology has been characterized using Scanning Electron Microscopy (SEM) and Focused Ion Beam (FIB) techniques. It is found that the splashing of submicron gold droplets upon impact is enhanced by high droplet impact energy achieved by reducing the droplet flight distance and that an air layer resulting in a bubble becomes trapped under the impacting droplets even when the size of the droplet is less than one micron. Our results show that, under these conditions, heat transfer between the submicron droplet and the solid substrate is more important than surface roughness and surface tension in the evolution of splashing. A theoretical model has been developed to simulate the splashing characteristics of submicron gold droplets during impact. Both the experimental data and the analytical model show that splashing is enhanced by high heat transfer rates to the surface.

Scattering and absorption from strongly anisotropic nanoparticles

Strongly anisotropic particles with hyperbolic dispersion that are small compared with the wavelength show strong resonance in the near infrared. The unique resonance modes are insensitive to the host refractive index and independent of particle size. In addition, the far-field direction of scattering does not depend on incident angle. Because the strength of resonance is comparable to a plasmonic nanoparticle in the visible region, a hyperbolic-dispersed particle is a promising scatterer as well as local heater in the near infrared.