Plasmonic nanoparticles with spectral properties in the UV-to-near-IR range have a large potential for the development of innovative optical devices. Similarly, microstructured optical fibers (MOFs) represent a promising platform technology for fully integrated, next-generation plasmonic devices; therefore, the combination of MOFs and plasmonic nanoparticles would open the way for novel applications, especially in sensing applications. In this Full Paper, a cost-effective, innovative nanoparticle layer deposition (NLD) technique is demonstrated for the preparation of well-defined plasmonic layers of selected particles inside the channels of MOFs. This dynamic chemical deposition method utilizes a combination of microfluidics and self-assembled monolayer (SAM) techniques, leading to a longitudinal homogeneous particle density as long as several meters. By using particles with predefined plasmonic properties, such as the resonance wavelength, fibers with particle-adequate spectral characteristics can be prepared. The application of such fibers for refractive-index sensing yields a sensitivity of about 78 nm per refractive index unit (RIU). These novel, plasmonically tuned optical fibers with freely selected, application-tailored optical properties present extensive possibilities for applications in localized surface plasmon resonance (LSPR) sensing.

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ORMOCER coated Fiber-Bragg-Gratings (FBGs) were investigated at cryogenic temperatures. Below T = 40 K the Bragg wavelength of uncoated FBG is nearly independent on temperature. ORMOCER coated FBG are temperature dependent over the whole temperature range investigated from 10 to 300 K. For 50-300 K, the ORMOCER coating contributes to an additional linear temperature shift of the Bragg wavelength of 2.4 pm/K. Below 40 K the temperature dependence decreases to 1.0 pm/K. ORMOCER coated FBGs can be used as sensor at cryogenic temperatures. Index Terms-FiberBragg grating (FBG) sensor, functional coating, temperature sensor.

In a deregulated EU railway market, monitoring the vehicle and infrastructure interfaces is mandatory for the enhanced availability of operation and for reducing costs. Therefore, infrastructure managers need monitoring tools on overhead contact lines (OCLs). We know from earlier investigations that a measurement of contact forces alone is not sufficient (Schröder et al 2013 Opt. Lasers Eng. 51 172–9). In this study, we introduce a system which is fast enough to detect short disturbances and which can be used with regular trains. It is based on fibre optic sensors integrated with conventional current collectors (CCs). The system is designed to monitor hard and soft hits on the CC in horizontal (driving) and vertical (contact) direction. It was systematically tested in the laboratory as well as in test runs on commercial railways in several countries. With its help, a variety of minor as well as serious defects have been discovered and repaired at the CC–OCL interface.

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