Rasmus Nielsen

Channel plasmon polariton propagation in nanoimprinted V-groove waveguides

We present the results of optical characterization of metal V-groove waveguides using scanning near-field microscopy, showing broadband transmission with subwavelength confinement and propagation lengths exceeding 100 microm. An updated fabrication method using a combination of UV and nanoimprint lithography is presented. The developed approach is mass-production compatible, adaptable to different designs, and offers wafer-scale parallel fabrication of plasmonic components based on profiled metal surfaces.

GREEN AND TECHNICAL EFFICIENT GROWTH IN DANISH FRESH WATER AQUACULTURE

Aquaculture is the fastest growing animal food processing sector in the world. Nevertheless, growth inside the Organization for Economic Co-operation and Development has been stagnating, with few exceptions. The main reason is strict environmental regulations. This study investigates if green growth can be achieved by introducing new environmentally friendly water purification systems in Danish fresh water aquaculture. Data Envelopment Analysis is used to investigate whether different water purification systems and farm size influence technical efficiency. The empirical results indicate that different water purification systems have no significant influence, although it increases with farm size. The policy implications are that green growth is possible by implementing the new water purification systems, but farmers have no incentive to adopt the new systems under the present regulation. If green growth should be achieved, the present regulation needs to be changed, providing the farmers with an incentive to adopt environmentally friendly production methods.

V-groove plasmonic waveguides fabricated by nanoimprint lithography

Propagation of channel plasmon-polariton modes in the bottom of a metal V groove has been recently demonstrated. It provides a unique way of manipulating light at nanometer length scale. In this work, we present a method based on nanoimprint lithography that allows parallel fabrication of integrated optical devices composed of metal V grooves. This method represents an improvement with respect to previous works, where the V grooves were fabricated by direct milling of the metal, in terms of robustness and throughput.

Investigations of scattering and field enhancement effects in retardation-based plasmonic nanoantennas

Modifications in scattering strength of and local field enhancement by retardation-based plasmonic nanoantennas when being transformed from straight nanorods to split-rings are investigated. The scattering properties are monitored by linear reflection and extinction spectroscopy whereas local field enhancement is estimated from measurements on individual nanoantennas by nonlinear scanning optical microscopy in which two-photon-excited photoluminescence (TPL) is detected. The linear and nonlinear optical characterizations reveal, that the optical response of nanoantennas is dominated by constructively interfering short-range surface plasmon polaritons (SR-SPP) and that the transformation of straight nanorods into split-rings by bending significantly influences the scattering strength. Importantly, strong suppression of scattering for the fundamental SR-SPP mode is observed when the bend radius is decreased, a feature that we attribute to the decrease in the nanoantenna electric-dipole response in tact with its bending. The experimental observations are corroborated with numerical simulations using the finite-element method.

Fabrication of channel and wedge plasmon polarition devices by combined UV and nanoimprint lithography

We present a large-scale compatible fabrication method for channel and wedge plasmon polariton waveguides. Optical characterization of fabricated devices using SNOM shows sub-wavelength confinement and propagation lengths in the hundreds of microns.