Sensing platforms: nano-fabrication, characterization and integration

Gediminas has started his PhD studies in 2010 here at Swinburne in the Centre for Micro-photonics in the group of Applied plasmonics under the supervision of professor Juodkazis. At that time, brand new, state-of-the-art clean-room was being built and he was one of the lucky few students to perform his research at these facilities. Using latest technologies, Gediminas soon started pushing the boundaries of modern nanotechnology. Currently, co-author of more than 30 scientific papers, Gediminas continues his career as an engineer in one of the largest open access clean-rooms in Australia

Arrays of Arbitrarily Shaped Nanoparticles: Overlay-Errorless Direct Ion Write

A simple solution to lithographically write down to 20-30 nm features over micrometer-sized nanoparticle arrays with high fidelity of pattern transfer from the designed to fabricated architectures is shown. It is achieved via a two-step approach: (i) fabrication of basic shape nanoparticles by electron beam lithography, gold deposition via sputtering and lift-off, then (ii) nano-patterning by focused ion beam lithography. Application potential of 3D tailored nanoparticles for nanotweezers is discussed on the basis of numerical modeling and experimental measurements of extinction

Ion-beam and plasma etching of a conical-pores photonic crystal for thin-film solar cell

Conical holes bored in the active layer of a thin-film silicon solar cell by ion-beam lithography (IBL) show increase of effective optical absorption in the underlying silicon active layer. The optical properties are numerically simulated by the 3D finite-difference time-domain method (3D-FDTD), showing wideband increase of the UV, visible, and IR quantum efficiency. An experimental fabrication procedure is developed using IBL for high wide-area repeatability. A further optimization on the cone shapes is performed in order to make fabrication feasible with plasma etching techniques

Topological Shaping of Light by Closed-Path Nanoslits

We propose a discrete set of continuous deformation of a circular nanoslit to generate and control optical vortices at the microscopic scale. The process relies on the interplay between the spin and orbital angular momentum degrees of freedom of light mediated by appropriate closed-path nanoslits milled on a thin gold film. Topological shaping of light is experimentally demonstrated in the visible domain. Moreover, all experimental observations are quantitatively validated by a simple model that takes into account the transverse manipulation of the optical phase via the space-variant form birefringence of subwavelength slits

High-precision interferometric monitoring of polymer swelling in an one-dollar optofluidic sensor

Swelling of poly-methylmethacrylate (PMMA) in weak solvents: water, ethanol and methanol was investigated by interferometry using a simple microfluidic sensor. A change of channel width by ±20 nm, comparable with the surface roughness of the polymer surface, is reliably detected and its temporal evolution was monitored in situ. Dynamics of polymer swelling over time periods from a few seconds to a few days were obtained. An optimized in-expensive microfluidic sensor design using hot embossing with gold sputtering is presented. Such a sensor can be used for high-fidelity adsorption-desorption interferometric sensing and its cost can be optimized for a single use

High-irradiance effects in femosecond laser fabrication

Laser micro-fabrication and micro-structuring of materials is usually carried out at the conditions close to the dielectric breakdown. Interplay between multi-photon and avalanche generation of electrons and thermal relaxation become critically important at those conditions in photo-polymerization, waveguide writing in glasses and for creation of new materials at the focal region. Relevant mechanisms of structuring are reviewed and discussed

Ion-beam and plasma etching of a conical-pores photonic crystal for thin-film solar cell

Abstract not reproduced here by request of the publisher. The text is available from: http://dx.doi.org/10.1117/12.203376

Fabrication of nanoparticles for generation of force and torque at nanoscale

Abstract not reproduced here by request of the publisher. The text is available from: http://dx.doi.org/10.1117/12.202457

3D nano-structures for laser nano-manipulation

The resputtering of gold films from nano-holes defined in a sacrificial PMMA mask, which was made by electron beam lithography, was carried out with a dry plasma etching tool in order to form well-like structures with a high aspect ratio (height/width ≈ 3-4) at the rims of the nano-holes. The extraordinary transmission through the patterns of such nano-wells was investigated experimentally and numerically. By doing numerical simulations of 50-nm and 100-nm diameter polystyrene beads in water and air, we show the potential of such patterns for self-induced back-action (SIBA) trapping. The best trapping conditions were found to be a trapping force of 2 pN/W/μm2 (numerical result) exerted on a 50-nm diameter bead in water. The simulations were based on the analytical Lorentz force model.

Chiral plasmonic nano structures : experimental and numerical tools

A combination of electron and ion beam lithographies has been applied to fabricate patterns of plasmonic nanoparticles having tailored optical functions: they create hot-spots at predefined locations on the nanoparticle at specific wavelengths and polarizations of the incident light field. Direct inscribing of complex chiral patterns into uniform nano-disks of sub-wavelength dimensions, over extensive 20 by 20 mu m2 areas, is achieved with high fidelity and efficiency; typical groove widths are in 10-30 nm range. Such patterns can perform optical manipulation functions like nano-tweezing and chiral sorting. Fabrication procedures can be optimized to pattern thin 0.1-2.5 mu m-thick membranes with chiral nanoparticles having sub15 nm grooves. Peculiarities of optical force and torque calculations using finite difference time domain method are presented