Flexible Polymer Planar Optical Waveguides

We report about design, fabrication and properties of flexible polymer optical planar waveguides made of Epoxy Novolak Resin as planar waveguides deposited on various foil substrates. The design of the presented planar waveguides was realized on the bases of modified dispersion equation and was schemed for 633 nm, 850 nm, 1310 nm and 1550 nm wavelength. Propagation optical loss measurements were done by the fibre probe technique at wavelegnth 633 nm (He-Ne laser) and samples have optical losses lower than 2 dB/cm. Unlike the up-to-now presented structures our constructin is fully flexible what makes it possible to be used in innovative photonics structures

Properties of Multimode Optical Epoxy Polymer Waveguides Deposited on Silicon and TOPAS Substrate

The paper reports on the fabrication and characterization of multimode polymer optical waveguides. Epoxy polymer EpoCore was used as the waveguide core material and EpoClad was used as a cladding and cover protection layer. The design of the waveguides was schemed for geometric dimensions of core 50 μm and for 850 nm and 1310 nm wavelengths. Proposed shapes of the waveguides were fabricated by standard photolithography process. Optical losses of the planar waveguides were measured by the fibre probe technique at 632.8 nm and 964 nm. Propagation optical loss measurements for rectangular waveguides were done by using the cut-back method and the best samples had optical losses lower than 0.53 dB/cm at 650 nm, 850 nm and 1310 nm

Design, Fabrication and Properties of Rib Poly(methylmethacrylimide) Optical Waveguides

We report about design, fabrication and properties of the polymer optical waveguides deposited on silica-on-silicon substrate. The design of the waveguides is based on a concept that geometric dimensions of the single mode polymer waveguide are determined by geometrical parameters of the silica layer. The design of the waveguides was schemed for 650 nm, 850 nm, 1310 nm and 1550 nm wavelength. The design of the presented planar waveguides was realized on the bases of modified dispersion equation while the ridge waveguides design was proposed following the Fischbeck concept. Both designs were refined applying RSoft software using beam propagation method. Proposed shapes of the waveguides were etched by standard photolithography process into the silica layers and polymer waveguide layers were subsequently deposited into the treated substrate by spin coating. Poly(methylmethacrylimide) was used as the waveguide core material and polymethylmethacrylate was used as a cover protection layer. Propagation optical loss measurements were done by using the cut-back method and the best samples had optical losses lower than 0.6 dB/cm at 650 nm, 1310 nm and 1550 nm

THE RAMAN SPECTROSCOPY USE FOR MONITORING OF CHANGES IN THE GLASS STRUCTURE OF THE THIN LAYERS CAUSED BY ION IMPLANTATION

In this paper, we have demonstrated the utility of Raman spectroscopy as a technique for the characterisation of changes in the glass structure of the thin layers caused by ion implantation. Various types of silicate glasses were implanted by Au+ ions with energy of 1.7 MeV and a fluence of 1 x 1016 ions.cm-2 to create gold nanoparticles in thin sub-surface layer of the glass. It was proved that the structure of the glass has an indisputable impact on the extent of depolymerisation of the glass network after implantation. It was shown that the degree of glass matrix depolymerisation can be described using the evaluation of Qn factors in the implanted layers from different depths. After analysis of Raman spectra, the relation between nucleation and the resulting parameters of the gold nanoparticles was put into connection with the feasibility of the glass to recover its structure during post-implantation annealing. Also the creation of new bonds in the glass network was discussed

Properties of Siloxane Based Optical Waveguides Deposited on Transparent Paper and Foil

In this paper, we present the properties of flexible planar optical waveguides made of siloxane-based polymer deposited on Xerox transparent paper and PLEXIGLAS foil substrate. Measurement of optical properties such as the waveguiding properties and refractive index is carried out by the prism coupling technique for five wavelengths (473, 632.8, 964, 1311 and 1552 nm) and propagation optical loss were measured by the fibre probe technique at a wavelength of 632.8 nm (He-Ne laser). The measurement proved waveguiding properties for all measured wavelengths and the losses generally did not exceed 0.40 dB/cm; the best samples had optical losses around 0.24 dB/cm

Thermal stability and photoluminescence properties of RE-doped (RE = Ho, Er, Tm) alumina nanoparticles in bulk and fiber-optic silica glass

We present the thermal stability and the photoluminescence properties of RE-doped (RE = Ho, Er, Tm) alumina nanoparticles in the phase system Al2O3-SiO2 with respect to the chemical composition and the thermal processing conditions applied in the fiber-optic technology. The alumina and silica soot reacted together to form mullite when the Al2O3 concentration was higher than 5 mol. %. We have demonstrated that the solubility limits of RE ions in the mullite nanocrystals are strongly limited. The RE ions preferentially occupy highly disordered positions on the nanoparticle surface or in the amorphous Al3+-enriched shell around the nanoparticles, exhibiting maximal lifetime of approx. 1.2 ms, 10.0 ms and 0.6 ms in the Ho-, Er- and Tm-doped samples. Rapid cooling of the samples with stoichiometric composition 3Al2O3.2SiO2 managed to prepare highly defective mullite nanocrystals with embedded RE ions, exhibiting promising photoluminescence lifetimes of 5.6 ms and 2.4 ms in the case of Ho3+ and Tm3+ ions, respectively. In optical fibers with 5 mol. % Al2O3, the formation of amorphous Al3+-enriched nanoparticles was observed and the photoluminescence lifetime was in a good agreement with corresponding bulk samples. Exploitation of the RE-doped stoichiometric mullite in the fiberoptic technology may be a perspective way to improve the photoluminescence efficiency of active optical fibers for high-power applications

The impact of a csDMARD in combination with a TNF inhibitor on drug retention and clinical remission in axial spondyloarthritis

OBJECTIVES: Many axial spondylarthritis (axSpA) patients receive a conventional synthetic DMARD (csDMARD) in combination with a TNF inhibitor (TNFi). However, the value of this co-therapy remains unclear. The objectives were to describe the characteristics of axSpA patients initiating a first TNFi as monotherapy compared with co-therapy with csDMARD, to compare one-year TNFi retention and remission rates, and to explore the impact of peripheral arthritis. METHODS: Data was collected from 13 European registries. One-year outcomes included TNFi retention and hazard ratios (HR) for discontinuation with 95% CIs. Logistic regression was performed with adjusted odds ratios (OR) of achieving remission (Ankylosing Spondylitis Disease Activity Score (ASDAS)-CRP < 1.3 and/or BASDAI < 2) and stratified by treatment. Inter-registry heterogeneity was assessed using random-effect meta-analyses, combined results were presented when heterogeneity was not significant. Peripheral arthritis was defined as ≥1 swollen joint at baseline (=TNFi start). RESULTS: Amongst 24 171 axSpA patients, 32% received csDMARD co-therapy (range across countries: 13.5% to 71.2%). The co-therapy group had more baseline peripheral arthritis and higher CRP than the monotherapy group. One-year TNFi-retention rates (95% CI): 79% (78, 79%) for TNFi monotherapy vs 82% (81, 83%) with co-therapy (P < 0.001). Remission was obtained in 20% on monotherapy and 22% on co-therapy (P < 0.001); adjusted OR of 1.16 (1.07, 1.25). Remission rates at 12 months were similar in patients with/without peripheral arthritis. CONCLUSION: This large European study of axial SpA patients showed similar one-year treatment outcomes for TNFi monotherapy and csDMARD co-therapy, although considerable heterogeneity across countries limited the identification of certain subgroups (e.g. peripheral arthritis) that may benefit from co-therapy