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For both tunable lasers and laser biosensors which function due to refractive index changes on the devices, modelling of the laser's emission wavelength is essential for optimization. However, methods commonly used are time consuming or not precise. Here a simple yet precise emission wavelength modelling method is presented. It is used for analysis of hybrid first order distributed feedback (DFB) lasers with varying high index layer thickness and second order DFB laser sensors.

The integration of optical transducers is generally considered a key issue in the further development of lab-on-a-chip microsystems. We present a technology for the integration of miniaturized, polymer based lasers, with planar waveguides, microfluidic networks and substrates such as structured silicon. The flexibility of the polymer patterning process, enables fabrication of laser light sources and other optical components such as waveguides, lenses and prisms, in the same lithographic process step on a polymer. The optically functionalised polymer layer can be overlaid on any reasonably flat substrate, such as electrically functionalised Silicon containing photodiodes. This optical and microfluidic overlay, interfaces optically with the substrate through the polymer-substrate contact plane. Two types of integrable laser source devices are demonstrated: microfluidic- and solid polymer dye lasers. Both are based on laser resonators defined solely in the polymer layer. The polymer laser sources are optically pumped with an external laser, and emits light in the chip plane, suitable for coupling into chip waveguides. Integration of the light sources with polymer waveguides, micro-fluidic networks and photodiodes embedded in a Silicon substrate is shown in a device designed for measuring the time resolved absorption of two fluids mixed on-chip. The feasibility of three types of polymers is demonstrated: SU-8, PMMA and a cyclo-olefin co-polymer (COC) -- Topas. SU-8 is a negative tone photoresist, allowing patterning with conventional UV lithography. PMMA and Topas are thermoplasts, which are patterned by nanoimprint lithography (NIL).

We have successfully fabricated and characterized a micro-cavity fluidic dye laser with metallic mirrors, which can be integrated with other microfluidic systems without adding further process steps. A laser dye solution is pumped through a microfluidic channel containing the laser cavity. The microfluidic channel structure, which is formed in SU-8 photoresist, is sandwiched between Pyrex glass wafers, bonded together at low temperature by means of SU-8. The laser was characterized using Rhodamine 6G laser dye dissolved in ethanol as the active medium, and optically pumped by a frequency doubled Nd:YAG laser. The dye solution was optimized, and lasing was observed at a wavelength of 570 nm with a full width half maximum linewidth of 5.7 nm and the optical pumping power density threshold for lasing was 34 mW cm−2.

There is presented a method for geometrically modifying high-index dielectric structures on a support structure, said method comprising providing a support structure, a first plurality of high-index dielectric structures being supported by the support structure, said method further comprising changing a geometry specifically of high-index dielectric structures within a second plurality of high- index dielectric structures, wherein the second plurality of high-index dielectric structures is a sub-set of the first plurality of high-index dielectric structures, wherein said changing the geometry is carried out by photothermally melting at least a portion of each of the high-index dielectric structures within the second plurality of high-index dielectric structures by irradiating the second plurality of high-index dielectric structures with incident electromagnetic radiation having an incident intensity in a plane of the second plurality of high-index dielectric structures, and thereby exciting resonances associated with each of the high- index dielectric structures within the second plurality of high-index dielectric structures, wherein said support structure comprises a first plurality of topographical features, and wherein the first plurality of high-index dielectric structures are given by high-index dielectric structures on or in said topographical features, and/or holes in a high-index dielectric film, wherein said holes correspond to said topographical features.

Intravital Multiphoton Microscopy (MPM) is an extremely powerful imaging modality for the investigation of renal pathophysiology in mice[1]. It uniquely allows to assess renal function and morphology at the same time and in the living animal. Following the implementation of an Abdominal Imaging Window (AIW)[2], it is possible to assess the same kidney regions by MPM serially for up to several weeks and to obtain longitudinal information regarding cellular behavior and changes in tissue structure. The conduction of serial MPM studies in live animals is however technically challenging. Kidneys are located in the abdominal cavity immediately below the diaphragmatic muscle and are thus subjected to significant breathing movements, which can create image artefacts. To protect renal tissue from phototoxicity during repeated scanning of the same regions, low laser excitation power is advisable, which however results in low signal to noise (SNR). Lastly, in order to detect structural changes over time in an unbiased manner, individual time points need to be registered to create an overlay of renal structures imaged on individual time points.Here, we present a workflow for the acquisition and image processing of serial MPM volumetric data of transgenic mouse kidneys, expressing a multicolor fluorescent protein reporter system on endothelial cells (ECs).A custom 3D-printed animal holder was developed to mechanically decouple the kidney from breathing movements. Data acquisition was performed following the implantation of an abdominal imaging window on low-dose Tamoxifen-induced Cdh5-CreERT2-Confetti mice, which identify endothelial cells by demonstrating 1 out of possible 10 color combinations through the specific co-expression of 2 out of 4 fluorescent proteins (CFP, GFP, YFP, RFP)[3]. To serially image the same fields of view (FOVs) for up to 3 weeks, the surface of the kidney was glued to the AIW and mapped to create an atlas for long-term navigation. A femtosecond laser was used as a micromanipulator to induce a localized thermal ablation in renal ECs. The entire post-acquisition image processing protocol was performed in the FIJI ImageJ distribution[4]. Images were denoised with a 3D Noise2Void deep neural network[5], [6]. The Descriptor-based series registration plugin from Preibisch et al[7] was used to align the single focal planes in each volume. Finally, volumes were registered to the data from the first scanning day with a rigid Euler transform using the FIJI Elastix wrapper[8], to run the external intensity-based Elastix registration software[9].Our custom 3d-printed animal holder provided a good imaging stabilization while largely removing image artefacts due to breathing. Noise2Void image denoising, significantly increased the SNR of the data while not requiring ground truth “clean” training datasets. The first 2D registration step minimized the effect of residual breathing movements. Rigid 3D registration with Elastix provided a way to accurately align volumes acquired at different time points. The algorithm paired to the use of binary masks proved quite robust when challenged with substantial progressive changes in tissue morphology in response to laser injury.Thanks to its ability to provide biological information both at sub-cellular as well as to image tissue regions up to several square millimeters, serial intravital microscopy exists at the intersection between “traditional” fluorescence microscopy and medical imaging. MPM data analysis can benefit from the integration of solutions developed for both fields. Our workflow exploits multiple open-source tools running under a common FIJI framework to provide a freely available and fully reproducible approach to study the plasticity of ECs and renal tissue remodeling in response to injury.

The invention provides a microfluidic device for mixing liquid reagents, the device comprises, a chip forming at least one reaction chamber between a bottom and a top and extending between an inlet and an outlet. To enable manufacturing from less rigid materials, the device comprises pillars extending from the bottom to the top. The invention further provides a method of mixing reagents by use of the device

We investigate the capacitance tuning of nanoscale split-ring resonators. An LC-model predicts a simple dependence of resonance frequency on slit aspect ratio. Experimental and numerical data follow the predictions of the LC-model.

Embodiments of the present invention include a cuvette (100) for use in determining a refractive index of a sample matter in a spectrophotometer (600), the cuvette comprising a container (102) for holding the sample matter, the container (102) having an entry window (121) that allows input radiation to reach the sample matter, the container furthermore having an exit window (122) that allows a part of the input radiation to exit the container part, the entry window and the exit window defining a radiation path; and comprising a photonic crystal (101) rigidly attached to the container or integrally formed in the container and arranged in the radiation path, the photonic crystal having a grating part (111) causing a reflectance spectrum of the photonic crystal to exhibit a resonance. A spectrophotometer is also provided.

Two different effects of opto fluidic tuning of polymer photonic crystal band edge lasers are demonstrated. A device symmetry different from that of the photonic crystal is imposed by the global shape of the device. This causes the device to emit in fewer directions, and the relative intensities of these signals depend on cladding refractive index. The wavelength of the emission in any direction depends on cladding refractive index with a sensitivity of 1 nm per 10-2 refractive index units.

This invention relates to a method of and a system (100) for identification or estimation of a refractive index of a liquid (120) comprising a light receiving part (111) adapted to receive polarised or non-polarised light (125; 135), a light emitting part (112) adapted, during use, to transmit light (130), an optical structure (110) being adapted to receive, during use, polarised light (125) via or from the light receiving part (111), and being adapted to receive, during use, a liquid (120) having a predetermined refractive index to be identified or estimated, and a first polariser (115) adapted, during use, to receive transmitted light (132) from the optical structure (110) and the received liquid (120), wherein the light receiving part (111), the received liquid (120), the first polariser (115), and the light emitting part (112) defines an optical path and wherein the system (100); is adapted, during use, to pass the received light (135) through the optical path so that a narrow wavelength range of the transmitted light (130) is influenced by the predetermined refractive index of the received liquid (120) and that the influenced narrow wavelength range, when observed by a user and/or captured by an image capturing unit (501), enables identification or estimation of the predetermined refractive index of the liquid (120). In this way, a method and a system for identification or estimation of a refractive index of a liquid is readily provided.

We present the enhanced transduction of a photonic crystal dye laser for gas sensing via deposition of an additional swelling polymer film. Device operation involves swelling of the polymer film during exposure to specific gases, leading to a change in total effective refractive index. Experimental results show an enhancement of 16.09 dB in sensing ethanol vapor after deposition of a polystyrene film. We verify different responses of the polystyrene film when exposed to either ethanol vapor or increased humidity, indicating selectivity. The concept is generic and, in principle, straightforward in its application to other intracavity-based detection schemes to enable gas sensing.

We demonstrate liquid core waveguides defined by UV to enable selective water infiltration in nanoporous polymers, creating an effective refractive index shift Δn=0.13. The mode confinement and propagation loss in these waveguides are presented.

There is presented a method for geometrically modifying plasmonic structures on a support structure, such as for printing or recording, said method comprising changing a geometry specifically of plasmonic structures, wherein said changing the geometry is carried out by photothermally melting at least a portion of each of the plasmonic structures within the second plurality of plasmonic structures by irradiating, the plasmonic structures with incident electromagnetic radiation having an incident intensity in a plane of the second plurality of plasmonic structures, wherein said incident intensity is less than an incident intensity required to melt a film of a corresponding material and a corresponding thickness as the plasmonic structures within the second plurality of plasmonic structures.

We demonstrate spectral filtering with state-of-the-art Bragg gratings in plasmonic V-groove waveguides fabricated by wafer scale processing based on nanoimprint lithography. Transmission spectra of the devices having 16 grating periods exhibit spectral rejection of the channel plasmon polaritons with 8.2 dB extinction ratio and -3 dB bandwidth of Δλ = 39.9 nm near telecommunications wavelengths. Near-field scanning optical microscopy measurements verify spectral reflection from the grating structures, and the oscillations of propagating modes along grating-less V- grooves correspond well with effective refractive index values calculated by finite element simulations in COMSOL. The results represent advancement towards the implementation of plasmonic V-grooves with greater functional complexity and mass-production compatibility.

Color pixels composed of plasmonic nanostructures provide a highly promising approach for new display technologies, capable of vivid, robust coloration and incorporating the use of low-cost plasmonic materials.[1] Silicone elastomers, usually in the shape of polydimethylsiloxane (PDMS) elastomers, are commonly used to replicate structures mainly on the micro scale but recently also on the nano scale. PDMS dielectric elastomers are promising materials and have the potential to be used in novel applications, especially due to the ability to be formed into complex shapes and still provide actuation.[2] This project deals with the development of PDMS based silicone elastomers with the ability to easily replicate structures on the nano scale of the silicon stamps (Fig.1 a-e). After obtaining the PDMS reproduction, the surface with plasmonic colouring due to siliver depostion on a nanopillar array can change color if the pillars height is altered through the elastomer actuation (Fig.2). The color change response depends on the mechanical and dielectric properties of the PDMS dielectric elastomers. This design strategy has the potential to open the door for next-generation flexible photonic devices for a wide variety of visible-light applications.

Liquid core waveguides are fabricated by selective UV-assisted hydrophilization of a nanoporous polymer. An added benefit of the nanoporous core is the ability to exclude large objects, making them ideal for analysis of turbid fluids.

The objectives of the present study were: (1) to estimate technical and economic effects of using one vs. multiple TMR feeding groups under different dairy herd and management characteristics (feed level, daily milk yield thresholds for group change, production potential and reproduction and culling for replacement management strategy); and (2) to establish optimum energy content of mixed rations when feeding one TMR all cows in milk (TMR-1). TMR refer to total mixed rations and defines ad libitum feeding of a mixed ration of all feeding ingredients except water. Data were simulated using a mechanistic, dynamic, stochastic simulation model. Equal feed intake per cow per year was obtained with a significantly lower energy content of the initial ration when feeding TMR-1, and the effect of the daily milk yield thresholds used to decide group change were higher than the effect of feeding two vs. three groups. Production and economic effects of the feeding strategies were generally explained by feed intake per cow per year with TMR-1 being inferior at high feed intake due to higher concentrates intake and lower milk production per cow. Optimum energy content according to total net revenue when feeding TMR-1 was affected by milk and concentrate prices, production potential, and reproduction and culling management strategies. Optimum energy content was affected significantly when evaluated as net revenue per kg energy corrected milk (ECM) produced instead of total net revenue (ECM = kg milk (0.383 fat% + 0.242 protein% + 0.7832)/3.140).

The 0.7 2e^2/h conductance anomaly is studied in strongly confined, etched GaAs/GaAlAs quantum point contacts by measuring the differential conductance G as a function of source-drain bias V_sd and gate-source bias V_gs as well as a function of temperature. In the V_gs - V_sd plane we use a grayscale plot of the transconductance dG/dV_gs to map out the bias dependent transitions between the normal and anomalous conductance plateaus. Any given transition is interpreted as arising when the bias controlled chemical potential mu_d (mu_s) of the drain (source) reservoir crosses a subband edge e_a in the point contact. From the grayscale plot we extract the constant normal subband edges e_0, e_1, ... and most notably the bias dependent anomalous subband edge e'_0(mu_d) split off from e_0. We show by applying a finite-bias version of the recently proposed BCF model, how the bias dependence of the anomalous subband edge is the key to analyze various experimental observations related to the 0.7 anomaly., Comment: 7 pages, 9 figures, 19th Nordic Semiconductor Meeting, invited paper