Preservation of good beam quality over several hundred meters in highly multimode fibers

We analyze the requirements and demonstrate good beam quality transportation over several hundred meters in highly multimode step-index fibers. The beam quality factor is preserved over 100m (M2 ≈ 1.3) and degrades linearly to M2 ≈ 2.0 at 300m

Polarization maintaining behavior of hollow-core fibers

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Analysis of polarization maintaining behavior in inhibited coupling hollow-core photonic crystal fibers (IC-HC-PCF)

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Desmopressin Acetate in Intracranial Haemorrhage

Introduction. The secondary increase in the size of intracranial haematomas as a result of spontaneous haemorrhage or trauma is of particular relevance in the event of prior intake of platelet aggregation inhibitors. We describe the effect of desmopressin acetate as a means of temporarily stabilising the platelet function. Patients and Methods. The platelet function was analysed in 10 patients who had received single ( = 4) or multiple ( = 6) doses of acetylsalicylic acid and 3 patients (control group) who had not taken acetylsalicylic acid. All subjects had suffered intracranial haemorrhage. Analysis was performed before, half an hour and three hours after administration of desmopressin acetate. Statistical analysis was performed by applying a level of significance of ≤ 0.05. Results. (1) Platelet function returned to normal 30 minutes after administration of desmopressin acetate. (2) The platelet function worsened again after three hours. (3) There were no complications related to electrolytes or fluid balance. Conclusion. Desmopressin acetate can stabilise the platelet function in neurosurgical patients who have received acetylsalicylic acid prior to surgery without causing transfusion-related side effects or a loss of time. The effect is, however, limited and influenced by the frequency of drug intake. Further controls are needed in neurosurgical patients

Phase shift induced degradation of polarization caused by bends in inhibited-coupling guiding hollow-core fibers

International audienceWe report on a comprehensive analysis of the polarization-maintaining behavior of two different kinds of inhibited-coupling guiding hollow-core fibers and the influence of fiber bends. A phase shift induced degradation of the incident linear polarization state was observed due to a mismatch of the propagation constants of the orthogonally polarized LP01-modes of the fiber. This effect was predicted theoretically and is corroborated with numerical simulations and experimental results. It is shown that the phase shift is enhanced by a reduction of the bending radius of the fiber, but can be circumvented by orienting the polarization of the injected beam either parallel or perpendicular to the plane of bending