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Active and passive optical waveguides are fundamental elements in modern telecommunications systems. A great number of optical crystals and glasses were identified and are used as good optoelectronic materials. However, fabrication of waveguides in some of those materials remains still a challenging task due to their susceptibility to mechanical or chemical damages during processing. Ion beam has been used for such purposes, along with other emerging techniques, like direct pulsed laser writing. Passive and active planar and channel optical waveguides, and optical Bragg gratings were fabricated in various glasses (like Er: TeO 2 -WO 3 glass) and undoped and doped crystals, Bi 4 Ge 3 O 12 , Bi 12 GeO 20 ) using masked or unmasked macrobeams or microbeams of light and medium-sized ions (C, N, O) in the 1.5 – 11 MeV energy range. Functionality of the optical elements was tested by m-line spectroscopy and end fire coupling technique. Structural changes in the implanted samples were studied by various optical microscopic techniques, spectroscopic ellipsometry, Rutherford backscattering and microscopic Raman spectroscopy. The results show that it is possible to produce integrated optical elements of unique properties using ion beam techniques.

Background and Objectives: Pancreatic cystic tumors are detected with increasing frequency globally. One large cross-sectional imaging study showed a prevalence of 25.5% for multifocal cystic tumors. A surgical series showed that single cysts within multifocal disease exhibit independent behavior in molecular and histological analyses. Our study describes the endoscopic ultrasound (EUS) appearance and prevalence of cystic tumors in multifocal disease, which has not previously been studied. Methods: We report a retrospective analysis of 545 consecutive patients with pancreatic cystic lesions who underwent EUS from January 2010 to July 2015. The patient demographics were 63% females and 37% males, mean age of 67 years, range 21–94. Results: On initial EUS, 315 (58%) of 545 patients had single lesions. 100 (32%) of 315 patients with single lesions had EUS follow-up, and the 11 patients who later developed multifocal disease were not included in our analyses. 230 (42%) of 545 had multiple cystic lesions on initial EUS and comprised our primary analysis. These patients (mean age 71.3) were significantly older (P < 0.05) than patients with single lesions (mean age 64.3). Of the 230 patients with multiple cystic tumors on initial EUS, 145 (63%) were women and 85 (37%) were men. Before EUS, computed tomography (CT) imaging only detected multiple cystic lesions in 16 (7%) of these patients in whom multiple lesions were later diagnosed on EUS. 83 (36%) of patients with multifocal disease had both simple and multilobulated cysts. 154 (67%) of patients with multifocal disease had cysts scattered throughout both the proximal region (uncinate, head, and neck) as well as in the distal region (body/tail) of the pancreas. 34 (15%) of patients with multifocal disease had solid internal nodules. Conclusion: Multifocal disease was seen in 42% of patients with cystic tumors evaluated by EUS, due to the increased sensitivity of EUS compared to CT. As cystic tumors are more common in females, multiple cystic tumors are also more common in female patients. The cystic lesions were both complex and simple in appearance on EUS in these patients, with 15% having a solid internal nodule, which has a predisposition for malignancy. As the majority of these patients had cystic lesions scattered throughout the pancreas, we recommend a complete pancreatic examination when performing EUS for pancreatic cysts detected on CT.

The H behaviour in a-Si, a-Ge, a-SiGe is stili debated, also thanks to their employment in photovoltaic solar cells whose performance depends on dangling bonds passivatìon by H. a-SiGe can be obtained by depositing altemating nano-layers of a-Si and a-Ge and intermixing the 2 atoms by annealing. Here results on H behaviour upon annealing of nano-structures made of 50 couples of very thin (3 nm each) altemating layers of a-Si and a-Ge are given. The superlattice nano-structures were deposited by sputtering. Hydrogen was added at flow rates of 0.4 to 6 mi/min. ERDA of a-Si and a-Ge single layers shovved that for flows ?1.5ml/min the incorporated H saturates at 16 at% and 7 at% in Si and Gè, respectively. IR optical absorbance showed that H is mostly incorporated as Si and Gè monohydrides. Annealing was done at 673 K for times between 1 and 10 h. The H behaviour in nano-structures as a function of annealing and H content was followed by IR optical absorbance, AFM and ERDA. With increasing annealing temperature/time the surface morphology degrades with formation of bumps and craters whose size and density increase with increasing H content. Upon annealing the signals of Ge-H and Si-H complexes disappear in the IR spectra indicating that H is released to the lattice. This supporta thè conclusion that it is thè released H that produces bumps and craters when the bumps blow up because of thè high internai pressure of H. ERDA of a-Si and a-Ge single layers, showing a faster H release in a-Ge than in a-Si, suggests that in thè superlattice nano-structures H is first released from thè a-Ge layers upon annealing. This agrees with literature reporting on thè lower binding energy of Ge-H with respect to Si-H. It also shows that H is unstable against annealing.

The influence of crystallographic orientation and ion fluence on the shape of damage distributions induced by 500 keV N+ implantation at room temperature into 6H SiC is investigated. The irradiation was performed at different tilt angles between 0 and 4 with respect to the 0001 crystallographic axis in order to consider the whole range of beam alignment from channeling to random conditions. The applied implantation fluence range was 2.5 1014 3 1015 cm 2. A special analytical method, 3.55 MeV 4He+ ion backscattering analysis in combination with channeling technique (BS C), was employed to measure the disorder accumulation simultaneously in the Si and C sublattices of SiC with good depth resolution. For correct energy to depth conversion in the BS C spectra, the average electronic energy loss per analyzing He ion for the 0001 axial channeling direction was determined. It was found that the tilt angle of nitrogen implantation has strong influence on the shape of the induc! ed disorder profiles. Significantly lower disorder was found for channeling than for random irradiation. Computer simulation of the measured BS C spectra showed the presence of a simple defect structure in weakly damaged samples and suggested the formation of a complex disorder state for higher disorder levels. Full-cascade atomistic computer simulation of the ion implantation process was performed to explain the differences in disorder accumulation on the Si and C sublattices. The damage buildup mechanism was interpreted with the direct-impact, defect-stimulated amorphization model in order to understand damage formation and to describe the composition of structural disorder versus the ion fluence and the implantation tilt angle.