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Plasmonic color metasurfaces enable high resolution, ink-free color decoration and sensing devices. This work presents a full solution from design of plasmonic color elements suitable for master origination by 248 nm Deep Ultraviolet (DUV) lithography to production grade manufacture of plasmonic color metasurfaces on plastic substrates. Design of hybrid aluminum disk-hole structures with hybridized multiple resonances, which are controlled by the disk-hole distance, enables plasmonic color generation across the visible spectrum with larger sized nanostructures, above 160 nm. Such larger structures can be defined by 248 nm DUV lithography as a cost-efficient and high throughput alternative to, e.g., electron beam lithography.

The advent of resonant dielectric nanomaterials has provided a new path for concentrating and manipulating light on the nanoscale. Such high-refractive-index materials support a diverse set of low-loss optical resonances, including Mie resonances, anapole states, and bound states in the continuum. Through these resonances, high-refractive-index materials can be used to engineer the optical near field, both inside and outside the nanostructures, which opens up new opportunities for Raman spectroscopy. In this review, we discuss the impact of high-refractive-index nano-optics on Raman spectroscopy. In particular, we consider the intrinsic Raman enhancement produced by different dielectric resonances and their theoretical description. Using the optical reciprocity theorem, we derive an expression which links the Raman enhancement to the enhancement of the stored electric energy. We also address recent results on surface-enhanced Raman spectroscopy based on high-refractive-index dielectric materials along with applications in stimulated Raman scattering and nanothermometry. Finally, we discuss the potential of Raman spectroscopy as a tool for detecting the optical near-fields produced by dielectric resonances, complementing reflection and transmission measurements.

Plasmonic color generation from metal nanostructures has attracted intensive attention because of their excellence in achieving high spatial resolution, strong color contrast, and long‐term durability. The limited area of plasmonic patterns anchored on substrates and produced by current top‐down methods, however, severely restricts the advanced developments and potential applications in structural color display. Herein a robust method for realizing the laser printing of plasmonic colors inside transparent gold nanodisk‐embedded poly(dimethylsiloxane) matrices is presented. It is found that various colors can not only be easily generated by embedding gold nanodisks of different sizes, but also finely varied by adjusting the laser pulse intensity during printing. It is further demonstrated that multiple color layers can be laser‐printed at different depths. Stereoscopic images in the 3D matrices are laser‐printed with sizes as large as 12 × 15 mm2 and a resolution of 4600 dots per inch.

Pyrolytic carbon microelectrodes (PCMEs) are a promising alternative to their conventional metallic counterparts for various applications. Thus, methods for the simple and inexpensive patterning of PCMEs are highly sought after. Here, we demonstrate the fabrication of PCMEs through the selective pyrolysis of SU-8 photoresist by irradiation with a low-power, 806 nm, continuous wave, semiconductor-diode laser. The SU-8 was modified by adding Pro-Jet 800NP (FujiFilm) in order to ensure absorbance in the 800 nm range. The SU-8 precursor with absorber was successfully converted into pyrolytic carbon upon laser irradiation, which was not possible without an absorber. We demonstrated that the local laser pyrolysis (LLP) process in an inert nitrogen atmosphere with higher laser power and lower scan speed resulted in higher electrical conductance. The maximum conductivity achieved for a laser-pyrolyzed line was 14.2 ± 3.3 S/cm, with a line width and thickness of 28.3 ± 2.9 µm and 6.0 ± 1.0 µm, respectively, while the narrowest conductive line was just 13.5 ± 0.4 µm wide and 4.9 ± 0.5 µm thick. The LLP process seemed to be self-limiting, as multiple repetitive laser scans did not alter the properties of the carbonized lines. The direct laser writing of adjacent lines with an insulating gap down to ≤5 µm was achieved. Finally, multiple lines were seamlessly joined and intersected, enabling the writing of more complex designs with branching electrodes and the porosity of the carbon lines could be controlled by the scan speed.

Aluminum plasmonics is emerging as a promising platform in particular for the ultraviolet-blue spectral band. We present the experimental results of propagating channel plasmon-polaritons (CPP) waves in aluminum coated V-shaped waveguides at the short visible wavelength regime. The V-grooves are fabricated by a process involving UV-photolithography, crystallographic silicon etching, and metal deposition. Polarization measurements of coupling demonstrate a preference to the TM-aligned mode, as predicted in simulations.

Laser printing with a spatial light modulator (SLM) has several advantages over conventional raster-writing and dot-matrix display (DMD) writing: multiple pixel exposure, high power endurance and existing software for computer generated holograms (CGH). We present a technique for the design and manufacturing of plasmonic metasurfaces based on ultrafast laser printing with an SLM. As a proof of principle, we have used this technique to laser print a plasmonic metalens as well as high resolution plasmonic color decorations. The high throughput holographic resonant laser printing (HRLP) approach enables on-demand mass-production of customized metasurfaces., Comment: Supplementary information is available upon request to authors

We demonstrate a microfluidic reaction chamber that mimics a microcentrifuge tube where reagents can be mixed sequentially at a known stoichiometry. The device has no moving parts or valves and is made by hot embossing in a polymer foil. Sample and reagents are filled in the reaction chamber by controlled guiding of the air/liquid interface in a rectangular array of pillars. The operation of the device is demonstrated by performing isothermal DNA amplification in nL volumes. In our device, 28 pg of DNA from λ-phage, a virus with a 48 kilo base genome, is amplified 500 times thus the amplification product is suitable for library preparation for second generation sequencing. We show that fabrication by hot embossing does not introduce significant contamination and that our device is performing comparably well to test tube amplification and current PDMS-based chip technology.

Colors of materials are precisely laser-controlled using new manufacturing technology with nanopatterned semiconductor surfaces., Man-made structural colors, which originate from resonant interactions between visible light and manufactured nanostructures, are emerging as a solution for ink-free color printing. We show that non-iridescent structural colors can be conveniently produced by nanostructures made from high-index dielectric materials. Compared to plasmonic analogs, color surfaces with high-index dielectrics, such as germanium (Ge), have a lower reflectance, yielding a superior color contrast. Taking advantage of band-to-band absorption in Ge, we laser-postprocess Ge color metasurfaces with morphology-dependent resonances. Strong on-resonance energy absorption under pulsed laser irradiation locally elevates the lattice temperature (exceeding 1200 K) in an ultrashort time scale (1 ns). This forms the basis for resonant laser printing, where rapid melting allows for surface energy–driven morphology changes with associated modification of color appearance. Laser-printable high-index dielectric color metasurfaces are scalable to a large area and open a new paradigm for printing and decoration with nonfading and vibrant colors.

Lasing emission from random cavities formed in networks of electrospun Rhodamine-doped polymer fibers is presented. Spatially resolved spectroscopy and spectral analysis prove that the observed laser emission stems from individual ring resonators randomly distributed throughout the network. These electrospun fiber lasers represent a facile and straightforward configuration for developing novel photonic devices that may advantageously utilize the network morphology.

Display Omitted We replace e-beam patterning with nanoimprint lithography patterning.The nanoimprinted devices have equal quality as commercially available devices.The devices have 40mW output and more than 50dB side mode suppression ratio.Nanoimprint of 40nm lines with an aspect ratio of 4:1. Dense wavelength division multiplexing lasers play a major role in today's long-haul broadband communication. Typical distributed feedback laser cavities consist of long half-pitch gratings in InGaAsP on InP substrates with grating periods of around 240nm. The lasers include a quarter wavelength shift in the grating, and are single mode with high side-mode suppression. Typically, such lasers are patterned using e-beam lithography (EBL). We present a fabrication method based on patterning by thermal nanoimprint lithography, which is potentially less costly and faster than EBL.Thermal nanoimprint lithography of laser gratings raises two types of challenges: (1) The imprint process itself is delicate due to the mechanical fragility of indium phosphide substrates and the thermal mismatch between the substrate and the silicon stamp. (2) The subsequent processing puts requirements on the imprint resist thickness after patterning, and the alignment between the crystallographic direction of the substrate and the grating pattern.Working laser arrays were produced, with >40mW optical power and side mode suppression ratios of more than 50dB in all 12 channels.

A monolithic polymer optofluidic chip for manipulation of microbeads in flow is demonstrated. On this chip, polymer waveguides induced by Deep UV lithography are integrated with microfluidic channels. The optical propagation losses of the waveguides are measured to be 0.66+/-0.13dB/mm at a wavelength of @l=808nm. An optimized bead tracking algorithm is implemented, allowing for determination of the optical forces acting on the particles. The algorithm features a spatio-temporal mapping of coordinates for uniting partial trajectories, without increased processing time. With an external laser power of 250mW, a maximum scattering force of 0.84 pN is achieved for 5@mm diameter polystyrene beads in water.

Design guidelines for optimizing the sensing performance of nanoimprinted second order distributed feedback dye lasers are presented. The guidelines are verified by experiments and simulations. The lasers, fabricated by UV-nanoimprint lithography into Pyrromethene doped Ormocomp thin films on glass, have their sensor sensitivity enhanced by a factor of up to five via the evaporation of a titanium dioxide (TiO2) waveguiding layer. The influence of the TiO2 layer thickness on the device sensitivity is analyzed with a simple model that accurately predicts experimentally measured wavelength shifts induced by varied superstrate refractive indices. The superstrate refractive index is additionally shown to determine which of the possible waveguiding modes dominates for lasing, indicating a method to flexibly select the polarization of the laser. The detection limit of the sensor system is further discussed, finding an optimum at 7.5· 10−6 RIU. Wavelength changes caused by dye bleaching must be taken into account for long-term measurements.

This paper describes color printing on nanoimprinted plasmonic metasurfaces by laser post-writing, for flexible decoration of high volume manufactured plastic products. Laser pulses induce transient local heat generation that leads to melting and reshaping of the imprinted nanostructures. Different surface morphologies that support different plasmonic resonances, and thereby different color appearances, are created by control of the laser pulse energy density. All primary colors can be printed, with a speed of 1 ns per pixel, resolution up to 127,000 dots per inch (DPI) and power consumption down to 0.3 nJ per pixel.

A highly sensitive distributed feedback (DFB) dye laser sensor for high frame rate imaging refractometry without moving parts is presented. The laser sensor surface comprises areas of different grating periods. Imaging in two dimensions of space is enabled by analyzing laser light from all areas in parallel with an imaging spectrometer. Refractive index imaging of a 2 mm by 2 mm surface is demonstrated with a spatial resolution of 10 μm, a detection limit of 8 10-6 RIU, and a framerate of 12 Hz, limited by the CCD camera. Label-free imaging of dissolution dynamics is demonstrated.

Recently, we show a method of color printing on nanoimprinted plasmonic metasurfaces using laser post-writing. Laser pulses induce transient local heat generation that leads to melting and reshaping of the imprinted nanostructures [1]. Depending on the laser pulse energy density, different surface morphologies that support different plasmonic resonances can be created. This technology creates a laser printer capable of producing color images with a resolution up to 127,000 DPI. With tailored trains of laser pulses, multiple optical states are flatiron onto the metasurface film with a nanoscale controlling. Thus, this diffraction-limited-resolution optical writing process can be further used to demonstrate a variety of applications in addition to large-area structural color printing. Multi-focus Fresnel zone plates with subwavelength focus, and more meta-surfaces different functions, such as spectroscope filters, Raman substrates and biosensors are also applicable.

Here we show a method of color printing on nanoimprinted plasmonic metasurfaces [1] using laser post-writing. Laser pulses induce transient local heat generation that leads to melting and reshaping of the imprinted nanostructures [2]. This leads to melting and reshaping of the imprinted 20nm Al structures embedded in plastics. Depending on the laser pulse energy density, different surface morphologies that support different plasmonic resonances leading to different color appearances can be created. Color printing by this technology has several advantages over dye technology: ink/toner-free, sub-wavelength resolution and the production of bright and non-fading colors. This technology creates a laser printer capable of producing images with a resolution of 127,000 DPI. It will be possible to save data invisible to the naked eye. This includes serial numbers or bar codes of products and other information. It can also be used on a larger scale to personify products such as mobile phones with unique decorations, names, etc‥ This laser technology may create environmentally sound color printing solutions and simplify the production for consumer products.

Nitrogen-vacancy (NV) centers in diamonds are interesting due to their remarkable characteristics that are well suited to applications in quantum-information processing and magnetic field sensing, as well as representing stable fluorescent sources. Multiple NV centers in nanodiamonds (NDs) are especially useful as biological fluorophores due to their chemical neutrality, brightness and room-temperature photostability. Furthermore, NDs containing multiple NV centers also have potential in high-precision magnetic field and temperature sensing. Coupling NV centers to propagating surface plasmon polariton (SPP) modes gives a base for lab-on-a-chip sensing devices, allows enhanced fluorescence emission and collection which can further enhance the precision of NV-based sensors. Here, we investigate coupling of multiple NV centers in individual NDs to the SPP modes supported by silver surfaces protected by thin dielectric layers and by gold V-grooves (VGs) produced via the self-terminated silicon etching. In the first case, we concentrate on monitoring differences in fluorescence spectra obtained from a source ND, which is illuminated by a pump laser, and from a scattering ND illuminated only by the fluorescence-excited SPP radiation. In the second case, we observe changes in the average NV lifetime when the same ND is characterized outside and inside a VG. Fluorescence emission from the VG terminations is also observed, which confirms the NV coupling to the VG-supported SPP modes., 22 pages, 13 figures

We experimentally demonstrate coupling of fluorescent light from a single bacterium into a plasmonic V-groove waveguide mode. This result is the first step in the construction of an efficient bioplasmonic chip for diverse sensing applications.

Electrohydrodynamic jetting is used to manufacture dye-doped polymer fiber resonators. We present comb-like laser emission from different polymer/dye combinations and report the use of these structures as sensitive detection of ethanol and methanol.

Colour generation by plasmonic nanostructures and metasurfaces has several advantages over dye technology: reduced pixel area, sub-wavelength resolution and the production of bright and non-fading colours. However, plasmonic colour patterns need to be pre-designed and printed either by e-beam lithography (EBL) or focused ion beam (FIB), both expensive and not scalable processes that are not suitable for post-processing customization. Here we show a method of colour printing on nanoimprinted plasmonic metasurfaces using laser post-writing. Laser pulses induce transient local heat generation that leads to melting and reshaping of the imprinted nanostructures. Depending on the laser pulse energy density, different surface morphologies that support different plasmonic resonances leading to different colour appearances can be created. Using this technique we can print all primary colours with a speed of 1 ns per pixel, resolution up to 127,000 dots per inch (DPI) and power consumption down to 0.3 nJ per pixel.

Metasurfaces are nanostructured surfaces with engineered optical properties - currently impacting many branches of optics, from miniaturization of optical components to realizing high-resolution structural colors. The optical properties of metasurfaces can be traced to the individual meta-atoms, which set the nature of the optical response, e.g., plasmonic for metallic meta-atoms or photonic for dielectric meta-atoms. Combining multiple types of responses opens up new horizons in design of optical materials, but has so far been avoided due to the fabrication difficulties associated with constructing a metasurface composed of several meta-atom materials. Here, we present a multi-material design approach by optically post-processing a metasurface constructed from self-assembled polystyrene spheres coated with silver. Using our concept of resonant laser printing, we locally alter the initial plasmonic response of the meta-atoms to a pure photonic response. Our work constitutes a conceptually different way of designing metasurfaces and can pave the way for realizing multi-material metasurfaces on large areas while being cost effective., Independent Research Funding Denmark (7026-00117B); VILLUM FONDEN (17400).

We present a novel design, fabrication, and characterization of reflecting gratings for long-range surface plasmon polaritons (LR-SPPs) at telecom wavelengths. LR-SPP waveguides consisting of a thin (12nm) gold film embedded in a thick ([email protected]) layer of dielectric polymer cladding are structured by nanoimprint lithography to form a reflecting Bragg grating. By performing spectrally resolved transmission measurements pronounced Bragg grating behaviour is observed, with the transmission dip increasing (up to ~12dB) with the increasing grating length.

A chip scale optofluidic tunable laser is realized by generating a periodic bubble array within a microfluidic channel. By controlling the periodicity via external pressure the lasing frequency is tuned over a broad range.

Although metals are commonly shiny and highly reflective, we here show that thin metal films appear black when deposited on a dielectric with antireflective moth-eye nanostructures. The nanostructures were tapered and close-packed, with heights in the range 300-600 nm and a lateral, spatial frequency in the range 5–7 μm−1. A reflectance in the visible spectrum as low as 6% and an absorbance of 90% was observed for an Al film of 100 nm thickness. Corresponding experiments on a planar film yielded 80% reflectance and 20% absorbance. The observed absorbance enhancement is attributed to a gradient effect causing the metal film to be antireflective, analogous to the mechanism in dielectrics and semiconductors. We find that the investigated nanostructures have too large spatial frequency to facilitate efficient coupling to the otherwise non-radiating surface plasmons. Applications for decoration and displays are discussed.

A chip scale tunable laser in the visible spectral band is realized by generating a periodic droplet array inside a microfluidic channel. Combined with a gain medium within the droplets, the periodic structure provides the optical feedback of the laser. By controlling the pressure applied to two separate inlets we can change the period of the droplet array. As a result, the lasing frequency is tuned over a broad spectral range. Using this configuration, we demonstrate wavelength tunability of about 70 nm and lasing threshold of about 15 μJ/mm2.

Dye-doped polymer fiber networks fabricated with electrospinning exhibit comb-like laser emission. We identify randomly distributed ring resonators being responsible for lasing emission by making use of spatially resolved spectroscopy. Numerical simulations confirm this result quantitatively.

Tapered metallic grooves have been shown to support plasmons -- electromagnetically coupled oscillations of free electrons at metal-dielectric interfaces -- across a variety of configurations and V-like profiles. Such plasmons may be divided into two categories: gap-surface plasmons (GSPs) that are confined laterally between the tapered groove sidewalls and propagate either along the groove axis or normal to the planar surface, and channelled plasmon polaritons (CPPs) that occupy the tapered groove profile and propagate exclusively along the groove axis. Both GSPs and CPPs exhibit an assortment of unique properties that are highly suited to a broad range of cutting-edge nanoplasmonic technologies, including ultracompact photonic circuits, quantum-optics components, enhanced lab-on-a-chip devices, efficient light-absorbing surfaces and advanced optical filters, while additionally affording a niche platform to explore the fundamental science of plasmon excitations and their interactions. In this Review, we provide a research status update of plasmons in tapered grooves, starting with a presentation of the theory and important features of GSPs and CPPs, and follow with an overview of the broad range of applications they enable or improve. We cover the techniques that can fabricate tapered groove structures, in particular highlighting wafer-scale production methods, and outline the various photon- and electron-based approaches that can be used to launch and study GSPs and CPPs. We conclude with a discussion of the challenges that remain for further developing plasmonic tapered-groove devices, and consider the future directions offered by this select yet potentially far-reaching topic area., Comment: 32 pages, 34 figures

High frame rate refractometric dissolution and fluid flow monitoring in one and two dimensions of space with distributed feedback dye laser sensors is presented. The sensors provide both low detection limits and high spatial resolution.

Taking the next step from individual functional components to higher integrated devices, we present a feasibility study of a lab-on-a-chip system with five different components monolithically integrated on one substrate. These five components represent three main domains of microchip technology: optics, fluidics and electronics. In particular, this device includes an on-chip optically pumped liquid dye laser, waveguides and fluidic channels with passive diffusive mixers, all defined in one layer of SU-8 polymer, as well as embedded photodiodes in the silicon substrate. The dye laser emits light at 576 nm, which is directly coupled into five waveguides that bring the light to five different locations along a fluidic channel for absorbance measurements. The transmitted portion of the light is collected at the other side of this cuvette, again by waveguides, and finally detected by the photodiodes. Electrical read-out is accomplished by integrated metal connectors. To our knowledge, this is the first time that integration of all these components has been demonstrated.

We present a solid state polymer microcavity dye laser, fabricated by thermal nanoimprint lithography (NIL) in a dye-doped thermoplast. The thermoplast poly-methylmethacrylate (PMMA) is used due to its high transparency in the visible range and its robustness to laser radiation. The laser dye is Rhodamine 6G ClO4. This dye is shown to withstand temperatures up to 240 °C without bleaching, which makes it compatible with the thermal nanoimprint lithography process. The 1.55 µm thick dye-doped PMMA devices are fabricated on a SiO2 substrate, yielding planar waveguiding in the dye-doped PMMA with two propagating TE–TM modes. The laser cavity has the lateral shape of a trapezoid, supporting lasing modes by reflection on the vertical cavity walls. The solid polymer dye lasers emit laterally through one of the vertical cavity walls, when pumped optically through the top surface by means of a frequency doubled, pulsed Nd:YAG laser. Lasing in the wavelength region from 560 to 570 nm is observed from a laser with a side-length of 50 µm. In this proof of concept, the lasers are multimode with a mode wavelength separation of approximately 1.6 nm, as determined by the waveguide propagation constant(s) and cavity dimensions. The stamps used in this work were fabricated by UV-lithography, limiting the lateral dimensional control of the devices. The resolution of NIL is ultimately limited by the quality of the stamps. Using electron beam lithography for stamp fabrication, the NIL process presented here offers the possibility for adding mode-selecting elements, e.g., diffractive- or sub-wavelength optical elements. ©2004 American Institute of Physics

We investigate a micro-fluidic dye laser, which can be integrated with polymer-based lab-on-a-chip microsystems without further processing steps. A simple rate-equation model is used to predict the lasing threshold. The laser device is characterised using the laser dye Rhodamine 6G dissolved in ethanol, and the influence of dye concentration on the lasing wavelength and threshold is investigated. The experiments confirm the predictions of the rate-equation model, that lasing can be achieved in the 10 μm long laser cavity with moderate concentrations of Rhodamine 6G in ethanol, starting from 5×10 −3 mol/l. We also find that the lasing wavelength can be tuned between 565 and 593 nm, controlled by the dye concentration.

A sensing approach based on laser emissionfrom polymer fiber networks is presented. Poly(methyl methacrylate) (PMMA) fibers doped with a laser dye are fabricated by electrospinning. They form random loop resonators, which show laser emission upon optical pumping. The shift of the spectral position of the narrow lasing modes upon uptake of alcohol vapors (model vapors are methanol and ethanol) serves as sensor signal. Thus, the high sensitivity related to the spectral line shifts of cavity-based transducers can be combined with the fiber's large surface to volume ratio. The resulting optical sensors feature excellent sensing performance due to the large overlap (more than 80%) of light field and transducer. The shift of the laser modes results from the swelling of the polymer when exposed to solvent vapors. Due to distinctly different diffusion coefficients in polymers, the uptake dynamics reflected in the transient shift of the lasing peaks can be used to discriminate ethanol and methanol vapor in mixtures of them. The sensing mechanism is expected to be applicable to other solvent vapors that cause polymer swelling.

We present reflective plasmonic colors based on the concept of localized surface plasmon resonances (LSPR) for plastic consumer products. In particular, we bridge the widely existing technological gap between clean-room fabricated plasmonic metasurfaces and the practical call for large-area structurally colored plastic surfaces robust to daily life handling. We utilize the hybridization between LSPR modes in aluminum nanodisks and nanoholes to design and fabricate bright angle-insensitive colors that may be tuned across the entire visible spectrum.

We demonstrate >50% conversion of light to V-groove channel plasmon-polaritons (CPPs) via compact waveguide-termination mirrors. Devices are fabricated using UV-lithography and crystallographic silicon etching. The V-shape is tailored by thermal oxidation to support confined CPPs.

Four types of quantum point contacts (QPC) have been fabricated and their conductance vs gate voltage investigated at various temperatures and biases. Conventional high electron mobility transistor (HEMT) structures and inverted HEMT (I-HEMT) structures were used as starting material. The QPC constriction was formed by a shallow wet-etch and devices with constriction widths between 50 and 400 nm were investigated. On both types of heterostructures, two types of devices were fabricated. In the first type of device, an Al gate electrode was deposited directly on top of the etched constriction. The second type of device was made with a buried constriction by MBE regrowth of AlGaAs on top of the shallow etched sample and finally gate metalisation. For all four types of devices, conductance quantization was observed up to temperatures between 20 and 30 K. Separations between the first and second 1D subbands were found to be up to 20 meV for Al gated devices and up to 10 meV for the regrown devices.

In this work, a simple approach to tailor the intensity distribution of CPP modes in metallic V-grooves is demonstrated by modifying the waveguide cross-section.The procedure involves a thermal oxidation of V-grooves formed in crystallographic planes of silicon that enables sidewall and vertex angle adjustment.

A transparent, fully integrated electrically modulated projection technique is presented based on light guiding through a thin liquid crystal layer covering sub-wavelength gratings. The reported device operates at 10 V with response times of 4.5 ms. Analysis of the liquid crystal alignment shows that director-reorientation occurs over timescales on the order of 90 µs close to the grating surface. The technology is suitable for next generation heads-up-displays and reconfigurable multilayer photonic integrated circuits.

Nanostructured polymer surfaces with optical functionality are fabricated by up-scalable methods, nanoimprinting and injection moulding. The fabrication and performance of nanostructured polymer surfaces with anti-reflective functionality are discussed.

International audience; Enhanced control of diffraction through transparent substrates is achieved via disordered gratings in a silica sol-gel film. Tailoring the degree of disorder allows tuning of the diffractive behavior from discrete orders into broad distributions over large angular range. Gratings of optical quality are formed by silica sol-gel nanoimprint lithography and an optical setup for the measurement of continuous diffraction patterns is presented. Sound agreement is found between measurements and simulation, validating both the approach for redirection of light and the fabrication process. The disordered gratings are presented in the context of improved interior daylighting and may furthermore be suited to a wide variety of applications where controlled angular redirection of light is desired.

Meeting the need of biomedical users, we develop disposable Lab-on-a-Chip systems based on commercially available polymers. We are combining passive microfluidics with active optical elements on-chip by integrating multiple solid-state and liquid-core lasers. While covering a wide range of laser emission wavelengths, the chips have the size of microscope cover slips and use optical and fluidic interconnects only. Here, we present our latest realizations of integrated optofluidic lasers using whispering gallery mode or distributed feedback laser cavities.

We develop optical Lab-on-a-Chips on different platforms for marker-based and label-free biophotonic sensor applications. Our chips are based on polymers and fabricated by mass production technologies to integrate microfluidic channels, optical waveguides and miniaturized lasers.

We report on lasing in conical microcavities, which are made out of the low-loss polymer poly (methyl methacrylate) (PMMA) doped with the dye rhodamine 6G, and directly fabricated on silicon. Including a thermal reflow step during fabrication enables a significantly reduced surface roughness, resulting in low scattering losses of the whispering gallery modes (WGMs). The high cavity quality factors (above 2·106 in passive cavities) in combination with the large oscillator strength gain material enable lasing threshold energies as low as 3 nJ, achieved by free-space excitation in the quasistationary pumping regime. Lasing wavelengths are detected in the visible wavelength region around 600 nm. Finite element simulations indicate that lasing occurs in fundamental TE/TM cavity modes, as these modes have - in comparison to higher order cavity modes - the smallest mode volume and the largest overlap with the gain material. In addition, we investigate the effect of dye concentration on lasing wavelength and threshold by comparing samples with four different concentrations of rhodamine 6G. Observations are explained by modifying the standard dye laser model.

We facilitate photonic crystal lasers to sense gases via an additional swelling polymer film. We describe the transduction transfer function and experimentally demonstrate an enhanced ethanol vapor sensitivity over 15 dB with low humidity crosstalk.

We introduce visible light optical gratings to surface plasmon V-groove waveguides. Gradient e-beam dosage onto silicon stamp enables structuring V-grooves of varying depth. Nanoimprint lithography maintains a Λ=265 nm corrugation for gold surface devices.

Nanoporous liquid core waveguides, where both core and cladding are made from the same material, are presented. The nanoporous polymer used is intrinsically hydrophobic, but selective UV exposure enables it to infiltrate with an aqueous solution, thus raising the refractive index from 1.26 to 1.42. The waveguides are promising for integrated optofluidic sensor systems, where a long optical interaction length can be achieved with a small fluid sample. The propagation loss of a 200×200 °m waveguide is measured to 0.62 dB/mm.

We employ a planar metamaterial structure composed of a split-ring-resonator (SRR) and paired nano-rods to experimentally realize a spectral response at near-infrared frequencies resembling that of electromagnetically induced transparency. A narrow transparency window associated with low loss is produced, and the magnetic field enhancement at the center of the SRR is dramatically changed, due to the interference between the resonances with significantly different linewidths. The variation of the spectral response in terms of relative position of the bright and dark elements is evaluated with numerical simulations.

A nanoimprinted polymer chip with a thin near-infrared absorber layer that enables light-induced local heating (LILH) of liquids inside micro- and nanochannels is presented. An infrared laser spot and corresponding hot-spot could be scanned across the device. Large temperature gradients yield thermophoretic forces, which are used to manipulate and stretch individual DNA molecules confined in nanochannels. The absorber layer consists of a commercially available phthalocyanine dye (Fujifilm), with a narrow absorption peak at approximately 775 nm, dissolved in SU-8 photoresist (Microchem Corp.). The 500 nm thick absorber layer is spin-coated on a transparent substrate and UV exposed. Microand nanofluidic channels are defined by nanoimprint lithography in a 1.5 μm thick layer of low molecular weight polymethyl methacrylate (PMMA, Microchem Corp.), which is spin coated on top of the absorber layer. We have used a previously developed two-level hybrid stamp for replicating two V-shaped microchannels (width=50 μm and height = 900 nm) bridged by an array of 200 nanochannels (width and height of 250 nm). The fluidic channels are finally sealed with a lid using PMMA to PMMA thermal bonding. Light from a 785 nm laser diode was focused from the backside of the chip to a spot diameter down to 5 ..m in the absorber layer, yielding a localized heating (Gaussian profile) and large temperature gradients in the liquid in the nanochannels. A laser power of 38 mW yielded a temperature of 40oC in the center of a 10 μm 1/e diameter. Flourescence microscopy was performed from the frontside.

Transmission of light through an optically ultrathin metal film with a thickness comparable to its skin depth is significant. We demonstrate experimentally nearly-zero transmission of light through a film periodically modulated by a one-dimensional array of subwavelength slits. The suppressed optical transmission is due to the excitation of surface plasmon polaritons and the zero-transmission phenomenon is strongly dependent on the polarization of the incident wave., accepted by APL