Observation of discrete gap solitons in one-dimensional waveguide arrays with alternating spacings and saturable defocusing nonlinearity.

We consider, both experimentally and theoretically, the existence and stability of localized, symmetric, and antisymmetric gap solitons (GSs) in binary lattices of identical waveguides but with alternating spacings. Furthermore, the properties of surface GSs at the boundary of the lattice are explored.

Resonant delocalization and Bloch oscillations in modulated lattices.

We study the propagation of light in Bloch waveguide arrays exhibiting periodic coupling interactions. Intriguing wave packet revival patterns as well as beating Bloch oscillations are demonstrated. A new resonant delocalization phase transition is also predicted.

Linear and nonlinear light propagation at the interface of two homogeneous waveguide arrays.

We investigate linear and nonlinear light propagation at the interface of two one-dimensional homogeneous waveguide arrays containing a single defect of different strength. For the linear case and in a limited region of the defect size, we find trapped staggered and unstaggered modes. In the nonlinear case, we study the dependence of power thresholds for discrete soliton formation in different channels as a function of defect strength. All experimental results are confirmed theoretically using an adequate discrete model.

Comparison of UV-induced skin changes in sun-exposed vs. sun-protected skin- preliminary evaluation by reflectance confocal microscopy.

BACKGROUND: UV radiation (UVR) represents the main risk factor for skin cancer. Sunscreens are commonly used to prevent acute and chronic effects of UVR. The efficacy of sunscreens is currently determined by measurement of minimal erythema dose. Reflectance confocal microscopy represents a non-invasive imaging technique that allows the in- vivo characterization of the skin at near histological resolution. OBJECTIVE: The aim of this study was to compare standardized clinical and histological features of UV-exposure with morphological changes detected by RCM. RESULTS: RCM allowed the detection of morphological changes induced by UV including spongiosis, sunburn cells, micro-vesicles and blood vessel dilatation. The appearance of sunburn cells and micro-vesicles was depending on the dose of UV-B and on the individual susceptibility of the study participants. CONCLUSION: RCM seems to be beneficial for the non-invasive evaluation of dynamic changes following acute UV exposure. Similar to histopathology RCM allows the characterization of sunburn cells and micro-vesicle formation as a sign for acute photo damage. RCM may therefore be used for classification of sunburn reaction and to test the efficacy of sunscreens on a cellular level.