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Optics and photonics are key enabling technologies of the 21st century offering great potential for new applications in fields as diverse as medicine, environmental and prognostic structural health monitoring or aeronautics, among others. Many of these applications require the implementation of highly-functional optical sensor networks ideally realized by using cost-efficient materials with tailored...
Direct laser writing (DLW) is a powerful tool toward the development of ultimate three-dimensional (3D) photonic devices. Because of the increasing demand for realising nano-geometries, the diffraction-limited resolution associated with DLW should be overcome to access the nanoscale. To meet this challenge, the concept of 3D nano printing, which is called super-resolution photoinduction-inhibition...
When light propagates in a turbid medium, multiple scattering prevents it from reaching depths much greater than the mean free path. This limited propagation presents a problem for many fields where optical energy delivery through scattering media is critical, such as energy conversion in dye-sensitized solar cells, light-based medical techniques, or white LEDs. In this work we show that wavefront...
Photoacoustic microscopy (PAM) is a promising imaging modality that combines optical and ultrasound imaging. It combines the advantages of high ultrasonic spatial resolution and high optical contrast. When a short laser pulse illuminates the tissue, absorbed light leads to an acoustic emission via thermoelastic expansion [1]. The laser system needs to generate short enough pulses, i.e., several nanoseconds,...
Most non-conductive materials and non-polar liquids are transparent to terahertz frequencies (0.2–2THz), and due to their non-ionizing photon energies there is great interest and potential in imaging in the THz regime [1], However, the long wavelengths (1.5–0.15mm) mean that even diffraction limited imaging will fail to resolve structures of micron size many of which have interesting THz interactions...
Near-field imaging techniques have great potential in many applications, ranging from the investigation of the optical properties of solid state and 2D materials to the excitation and direct retrieval of plasmonic resonant modes, to the mapping of carrier concentrations in semiconductor devices. Further to this, the capability of performing imaging with non-ionizing terahertz (THz) radiation on a...
Fluorescence microscopy is a widely used tool in cell biology to resolve subcellular structures and reveal dynamic processes, such as molecular transport in or between cells. In the last decade, several techniques were developed that have enabled us to overcome the optical diffraction limit and to resolve even finer spatial structures.
The need for microoptical elements in various emerging fields such as astrophotonics, nonlinear optics and biomedicine create a demand for a new generation optics that would be lightweight/compact, resilient to harsh environment and easily integrable in other devices. Ultrafast pulses based direct laser writing 3D nanolithography produced microlenses seem as one of the candidates for such applications...
Integration of multiple functions on an optical micro-chip is going to revolutionize the exploitation of optics for various applications such as communication, optical sensing, and biomedicine. One of the enabling functions is amplification at 1.5 μm [1]. Rare-earth-doped amplifiers typically deliver a net gain per unit length of only a few dB/cm [2]. In spiral-shaped channel waveguides a total internal...
Melanoma skin cancer is one of the most lethal types of cancer due to comparably early development of metastasis. As preventative medical check-up, optical inspection using polarized light (dermoscopy) is the gold standard in medical practise. If a lesion is diagnosed to be suspicious, it is subsequently excised by a surgeon and analysed by means of histopathology. However, optical inspection so far...
There is always a special interest in trying to predict transitions, crisis, social revolutions, catastrophic events like the end of the world and, nowadays judging by the number of spam messages coming from clairvoyants, we strongly believe that the interest in predicting events of every type is growing fast. Almost always catastrophic events are produced when a bifurcation occurs in a dynamical...
Due to a strong light absorption by metals, it is believed that plasmonic nanostructures cannot be used for generating intensive radiation harmonics in the UV spectral range. We present results of investigation of the nonlinear optical interaction of laser radiation with a single gold nanostructure in the geometry of the Split-Hole Resonator (SHR) [1, 2] under the-state-of-the-art experimental realized...
It is well known that a thick scattering medium (e.g. a slab of paint) is opaque since incident waves are thoroughly scrambled [1, 2]. In the diffusive transport regime, the scattered light has an (ensemble-averaged) energy density that linearly increases with depth from the front surface to about one mean free path 1, and then decreases linearly with depth to the back surface. Two main questions...
Authentication of people or objects using physical keys is insecure against secret duplication. Physical unclonable functions (PUF) are special physical keys that are assumed to be unclonable due to the large number of degrees of freedom in their manufacturing [1]. Opaque scattering media, such as white paint and teeth, comprise of millions of nanoparticles in a random arrangement. Under coherent...
Multilevel modulations are becoming attractive, not only for metro-core optical communications, but also for the access sector. Designing cost-effective, easy-to-integrate multilevel modulators is mandatory to support high-bandwidth access interconnections, which may also require colorless operation. In this work, we propose a novel colorless multilevel transmitter architecture, based on reflective...
Thin films have a large impact on our day to day lives and they find a variety of uses including optical, electrical, or chemical coatings, biomimetics, and various sensors such as pH sensors. Great interest exists in nanoparticles and organic based thin films, due to ease of fabrication, low cost manufacturing, and easy tunability of various properties compared to the inorganic and semiconducting...
Inspired by the idea of an artificial skin-like sensor structure, we develop fully integrated sensor networks in large-sized thin polymer foils. The project is part of collaborative research center “PlanOS-planar optronic systems”. One key aspect of such systems is to avoid electronic components as far as possible so that the quantities to be measured are directly converted into properties of light.
Fiber lasers have come to a great prominence when it comes to stable high power and excellent beam quahty. They are used in industry for material processing, space apphcations as well as in medicine for precise surgery. Despite their widespread application they are not understood completely when it comes to longitudinal mode (LM) with stochastic phase relations and resulting nonlinear effects like...
Mid-infrared (mid-IR) wavelength range is utilized in applications such as gas sensing, medicine, defence, and material processing. When using picosecond pulses high peak power is reached at moderate pulse energy and the heat affected zone is low. A wavelength tunable mid-IR source would enable optimization of the laser-matter interaction in dependence on wavelength. Increase in processing speed requires...
Free-electron lasers are a new class of x-ray sources that deliver extremely intense, coherent x-ray flashes with femtosecond pulse length. The unprecedented brightness of these x-ray lasers opens the door for single shot imaging and non-linear spectroscopy approaches involving core-level states [1].
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