Efficiency of ocular UV protection by clear lenses.

Ocular UV doses accumulate all-day, not only during periods of direct sun exposure. The UV protection efficiency of three clear lenses was evaluated experimentally, validated by simulation, and compared to non-UV protection: a first spectacle lens with a tailored UV absorber, a second spectacle lens, minimizing UV back reflections, as well as a third spectacle lens, combining both. A tailored UV-absorber efficiently reduced overall UV irradiance to 7 %, whereas reduction of back-reflections still left UV irradiance at 42 %.

Ultraviolet radiation oxidative stress affects eye health.

In the eye, ultraviolet radiation (UVR) is not known to contribute to visual perception but to mainly damage multiple structures. UVR carries higher energy than visible light and high dose exposure to UVR causes direct cellular damage, which has an important role in the development of cancer. This review provides an overview on the most recent knowledge on the role of UVR in oxidative stress (OS) in relation to noncancer ocular pathologies: various corneal pathologies, cataract, glaucoma and age-related macular degeneration.

Optical imaging of post-embryonic zebrafish using multi orientation raster scan optoacoustic mesoscopy.

Whole-body optical imaging of post-embryonic stage model organisms is a challenging and long sought-after goal. It requires a combination of high-resolution performance and high-penetration depth. Optoacoustic (photoacoustic) mesoscopy holds great promise, as it penetrates deeper than optical and optoacoustic microscopy while providing high-spatial resolution.

Scattering correction through a space-variant blind deconvolution algorithm.

Scattering within biological samples limits the imaging depth and the resolution in microscopy. We present a prior and regularization approach for blind deconvolution algorithms to correct the influence of scattering to increase the imaging depth and resolution. The effect of the prior is demonstrated on a three-dimensional image stack of a zebrafish embryo captured with a selective plane illumination microscope.

Densely Packed Microgoblet Laser Pairs for Cross-Referenced Biomolecular Detection.

Parallel readout of the micro-lasers facilitates effective mutual filtering of highly localized refractive index and temperature fluctuations in the analyte. Cross-referenced detection of two different types of proteins and complete chemical transducer reconfiguration is demonstrated. Selective surface functionalization of the individual lasers with high spatial accuracy is achieved by aligned microcontact stamping.

Efficient free-space read-out of WGM lasers using circular micromirrors.

Lasing from whispering-gallery mode (WGM) resonators occurs omnidirectional in azimuthal plane. Most applications of WGM resonators require spectral analysis with off-chip detectors, where in-plane emission and beam divergence hinder efficient detection. We demonstrate redirecting WGM laser emission from all azimuthal angles using a circular micromirror placed around the cavity.

Organic semiconductor distributed feedback laser pixels for lab-on-a-chip applications fabricated by laser-assisted replication.

The integration of organic semiconductor distributed feedback (DFB) laser sources into all-polymer chips is promising for biomedical or chemical analysis. However, the fabrication of DFB corrugations is often expensive and time-consuming. Here, we apply the method of laser-assisted replication using a near-infrared diode laser beam to efficiently fabricate inexpensive poly(methyl methacrylate) (PMMA) chips with spatially localized organic DFB laser pixels.

Large-scale parallel surface functionalization of goblet-type whispering gallery mode microcavity arrays for biosensing applications.

A novel surface functionalization technique is presented for large-scale selective molecule deposition onto whispering gallery mode microgoblet cavities. The parallel technique allows damage-free individual functionalization of the cavities, arranged on-chip in densely packaged arrays. As the stamp pad a glass slide is utilized, bearing phospholipids with different functional head groups.

Organic semiconductor distributed feedback (DFB) laser as excitation source in Raman spectroscopy.

As an application of organic semiconductor distributed feedback (DFB) lasers we demonstrate their use as excitation sources in Raman spectroscopy. We employed an efficient small molecule blend, a high quality resonator and a novel encapsulation method resulting in an improved laser output power, a reduced laser line width and an enhanced power stability. Based on theses advances, Raman spectroscopy on selected substances was enabled.

Pump spot size dependent lasing threshold in organic semiconductor DFB lasers fabricated via nanograting transfer.

Optically excited organic semiconductor distributed feedback (DFB) lasers enable efficient lasing in the visible spectrum. Here, we report on the rapid and parallel fabrication of DFB lasers via transferring a nanograting structure from a flexible mold onto an unstructured film of the organic gain material. This geometrically well-defined structure allows for a systematic investigation of the laser threshold behavior.

On-chip microlasers for biomolecular detection via highly localized deposition of a multifunctional phospholipid ink.

We report on a novel approach to realize on-chip microlasers, by applying highly localized and material-saving surface functionalization of passive photonic whispering gallery mode microresonators. We apply dip-pen nanolithography on a true three-dimensional structure. We coat solely the light-guiding circumference of pre-fabricated poly(methyl methacrylate) resonators with a multifunctional molecular ink.

The invention of immersion ultramicroscopy in 1912-the birth of nanotechnology?

Dawn of nanotechnology: the immersion ultramicroscope was patented a century ago. When an analyte was examined with an antique instrument and with state-of-the-art technology, the historic assumptions were confirmed: the size and shape of the nanoparticles are in the same range as that described 100 years ago. The spectra of the Tyndall cones caused by the shape of the nanoparticles were also described correctly-long before electron microscopy was able to image single nanoparticles.

Direct laser writing for nanoporous liquid core laser sensors.

We report the fabrication of nanoporous liquid core lasers via direct laser writing based on two-photon absorption in combination with thiolene-chemistry. As gain medium Rhodamine 6G was embedded in the nanoporous polybutadiene matrix. The lasing devices with thresholds of 19 µJ/mm(2) were measured to have bulk refractive index sensitivities of 169 nm/RIU at a laser wavelength of 600 nm, demonstrating strongly increased overlap of the modes with the analyte in comparison to solid state evanescent wave sensors.

Flexible coupling of high-Q goblet resonators for formation of tunable photonic molecules.

We report on a method for a highly flexible arrangement of polymeric high-Q whispering gallery mode resonators. Parallel on-chip fabricated goblet resonators are detached from the substrate by bonding a gold wire to the field-free center of their polymeric cavity. This enables the precise control of the resonator's spatial position.

Diffusion driven optofluidic dye lasers encapsulated into polymer chips.

Lab-on-a-chip systems made of polymers are promising for the integration of active optical elements, enabling e.g. on-chip excitation of fluorescent markers or spectroscopy.

Design of plasmonic grating structures towards optimum signal discrimination for biosensing applications.

Sensors based on surface plasmon resonances (SPRs) have proven themselves as promising devices for molecular investigations - still there is potential to determine the geometrical parameter set for optimal sensing performance. Here we propose a comprehensive design rule for one-dimensional plasmonic grating structures. We present an analytical approach, which allows for estimation of the grating parameters for best SPR coupling efficiency for any geometry and design wavelength.

Continuously tunable solution-processed organic semiconductor DFB lasers pumped by laser diode.

The fabrication and characterization of continuously tunable, solution-processed distributed feedback (DFB) lasers in the visible regime is reported. Continuous thin film thickness gradients were achieved by means of horizontal dipping of several conjugated polymer and blended small molecule solutions on cm-scale surface gratings of different periods. We report optically pumped continuously tunable laser emission of 13 nm in the blue, 16 nm in the green and 19 nm in the red spectral region on a single chip respectively.

Direct laser writing for active and passive high-Q polymer microdisks on silicon.

We report the fabrication of high-Q polymeric microdisks on silicon via direct laser writing utilizing two-photon absorption induced polymerization. The quality factors of the passive cavities are above 10(6) in the 1300 nm wavelength region. The flexible three-dimensional (3D) lithography method allows for the fabrication of different cavity thicknesses on the same substrate, useful for rapid prototyping of active and passive optical microcavities.

Strongly confined, low-threshold laser modes in organic semiconductor microgoblets.

We investigate lasing from high-Q, polymeric goblet-type microcavities covered by an organic semiconductor gain layer. We analyze the optical modes in the high-Q cavities using finite element simulations and present a numerical method to determine the cutoff thickness of the gain layer above which the whispering gallery modes are strongly confined in this layer. Fabricated devices show reduced lasing thresholds for increasing gain layer thicknesses, which can be explained by a higher filling factor of the optical modes in the gain layer.

Plastic lab-on-a-chip for fluorescence excitation with integrated organic semiconductor lasers.

Laser light excitation of fluorescent markers offers highly sensitive and specific analysis for bio-medical or chemical analysis. To profit from these advantages for applications in the field or at the point-of-care, a plastic lab-on-a-chip with integrated organic semiconductor lasers is presented here. First order distributed feedback lasers based on the organic semiconductor tris(8-hydroxyquinoline) aluminum (Alq3) doped with the laser dye 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyril)-4H-pyrane (DCM), deep ultraviolet induced waveguides, and a nanostructured microfluidic channel are integrated into a poly(methyl methacrylate) (PMMA) substrate.

All-polymer organic semiconductor laser chips: parallel fabrication and encapsulation.

Organic semiconductor lasers are of particular interest as tunable visible laser light sources. For bringing those to market encapsulation is needed to ensure practicable lifetimes. Additionally, fabrication technologies suitable for mass production must be used.

Low-cost label-free biosensors using photonic crystals embedded between crossed polarizers.

There is a strong need for low-cost biosensors to enable rapid, on-site analysis of biological, biomedical, or chemical substances. We propose a platform for label-free optical biosensors based on applying the analyte onto a surface-functionalized photonic crystal slab and performing a transmission measurement with two crossed polarization filters. This dark-field approach allows for efficient background suppression as only the photonic crystal guided-mode resonances interacting with the functionalized surface experience significant polarization rotation.

Fluorescence excitation on monolithically integrated all-polymer chips.

All-polymer chips with integrated optical waveguides and microfluidic channels were built as a platform for fluorescence excitation of biological samples. Their functionality has been shown for four cases: (i) fluorescence of labeled phospholipids inside a microfluidic channel, (ii) fluorescence of stained cells inside a microfluidic channel, (iii) fluorescence of labeled phospholipids on top of a polymer waveguide, and (iv) fluorescence of stained cells on top of a polymer waveguide.