Tailoring the spatial degree of freedom of light is an essential step towards the realization of advanced optical manipulation tools. A topical challenge consists of device miniaturization for ...improved performance and enhanced functionality at the micron scale. We demonstrate a novel approach that combines the additive three-dimensional (3D) structuring capability of laser polymerization and the subtractive subwavelength resolution patterning of focused ion beam lithography. As a case in point hybrid (dielectric/metallic) micro-optical elements that deliver a well-defined topological shaping of light are produced. Here we report on hybrid 3D binary spiral zone plates with unit and double topological charge. Their optical performances are compared to corresponding 2D counterparts both numerically and experimentally. Cooperative refractive capabilities without compromising topological beam shaping are shown. Realization of advanced designs where the dielectric architecture itself is endowed with singular properties is also discussed.
Orbital angular momentum carrying light beams are usedfor optical trapping and manipulation. This emerging trend provides new challenges involving device miniaturization for improved performance and ...enhanced functionality at the microscale. Here we discus a new fabrication method based on combining the additive 3D structuring capability laser photopolymerization and the substractive sub-wavelength resolution patterning of focused ion beam lithography to produce micro-optical elements capable of compound functionality. As a case in point of this approach binary spiral zone pattern based high numerical aperture micro-lenses capable of generating topological charge carrying tightly focused vortex beams in a single wavefront transformation step are presented. The devices were modelled using finite-difference time-domain simulations, and the theoretical predictions were verified by optically characterizing the propagation properties of light transmitted through the fabricated structures. The resulting devices had focal lengths close to the predicted values of f = 18 µm and f = 13 µm as well as topological charge ℓ dependent vortex focal spot sizes of ~ 1:3 µm and ~ 2:0 µm for ℓ = 1 and ℓ = 2 respectively.
Background:
Autologous fat grafting is widely used in plastic and reconstructive surgery. Liposuction methods play a key role in surgeons’ work efficiency, adipocyte viability, graft survival, and ...outcomes. We investigated the effect of four liposuction methods on adipocyte viability, debris, and surgeons’ work efficiency by measuring the active energy expenditure and changes in heart rate.
Methods:
Human lipoaspirate was harvested from patients’ removed abdominal flaps using four different liposuction methods, and we counted calories per aspirated volume and surgeons’ heart rate. Adipocytes were separated from the lipoaspirate immediately by digestion with 0.1% type I collagenase. After digestion, parts of the cells and debris were measured. Adipocytes were plated in an adipocyte maintenance medium containing Alamar blue reagent. The adipocyte metabolic activity was measured using a spectrophotometer.
Results:
After evaluating the active energy expenditure and changes in surgeons’ heart rate, the ultrasonic-assisted liposuction (UAL) method was determined to be the most ergonomic liposuction device for surgeons. In addition, adipocyte viability was higher in the UAL group than in the other groups, and debris was the lowest in the power-assisted liposuction 1 group (PAL1).
Conclusions:
Adipocyte viability is crucial for improving fat grafting outcomes. This study revealed that the viability of adipocytes is best preserved using the UAL and PAL1 liposuction methods. The UAL and PAL1 methods caused the least damage to the cells. The UAL method yielded the best results for surgeons’ work efficiency.
Microcavities filled with conjugated polymer active in strong light-matter interaction regime enable exciton-polariton condensates at room temperature. By imprinting lattices through nanostructuring ...and using a tunable platform, we can explore solid-state physics toy models.
We create exciton-polariton (strongly coupled light-matter quasi particles) Bose-Einstein condensates at room temperature 1 by optically exciting a ladder-type conjugated polymer 2 placed inside a ...tuneable Fabry-Perot microcavity 3. By Focussed Ion Beam (FIB) milling we fabricate different structure for inplane confinement, ranging from 0D (single Gaussian-shaped defect) to 2D ones (arrays of coupled Gaussian defects). In the first part of this work we focus on the basic building blocks of our system, the strong light-matter coupling and the exciton-polariton condensation localized in a 0D Gaussian-shaped defect structure. The strong coupling between the excitonic resonance of the conjugated polymer and the individual cavity modes is obtained by exciting the system while detuning the cavity length till the anti-crossing behaviour of the modes appears. By increasing the excitation power above threshold, we reach room temperature condensation in a single Gaussian defect. The condensation features are demonstrated by showing non-linear emission intensity, spectral line-narrowing and a characteristic blue shift as function of excitation power. To better characterize the condensation in such a system, we studied the angular emission (Fig. 1 (a) and (b)) and the first order coherence (Fig. 1 (c) and (d)) of the exciton-polaritons below and above threshold.
We unambiguously demonstrate the Pockels effect in integrated BaTiO 3 /Si devices and report the largest Pockels coefficient (r_{42}=923\ pm/V) of any thin-film material. We show a strong ...electro-optic response beyond 25 GHz and monolithic integration compatible with silicon photonic platforms.
In this paper we present numerical simulations of various plasmonic and silicon-on-insulator (SOI) nanostructures for optical label free biosensors. The results are presented for study of SOI micro ...wheel resonators and plasmonic gold nano ring, cup and disc arrays. We show that implementation of the sub-wavelength structures into the devices increases the light-matter interaction and the sensitivity of the biosensors. The simulations are performed using finite element method (FEM) and finite-difference-time-domain (FDTD) method.
Azo-compounds in polymers will likely play an increasingly important role in engineering of silicon photonics and plasmonic nano-devices for E-O modulation, parametric generation, switching and ...sensing. In this paper, we present a phenomenological theory of all-optical poling and photo-assisted electric field poling of azo-dye doped polymers and compare theoretical simulation results with experimental all-optical poling transients at varying temperatures obtained for azophenylcarbazole type azo-dyes in polycarbonate polymer matrix.
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