PhoenixD Magazine - News from the German Cluster of Excellence on Optics and Photonics

News from the German Cluster of Excellence PhoenixD on Optics and Photonics at Leibniz University Hannover with reports, interviews, portraits and the PhoenixD chronicle. Scientific topics are integrated optics, optics production, optical materials and others.DFG - Deutsche Forschungsgemeinschaft/Exzellenzstrategie des Bundes und der Länder/EXC 2122, Projekt-ID 390833453/E

Methacrylate-Based Copolymers for Polymer Optical Fibers

Waveguides made of poly-methyl-methacrylate (PMMA) play a major role in the homogeneous distribution of display backlights as a matrix for solid-state dye lasers and polymer optical fibers (POFs). PMMA is favored because of its transparency in the visible spectrum, low price, and well-controlled processability. Nevertheless, technical drawbacks, such as its limited temperature stability, call for new materials. In this work, the copolymerization technique is used to modify the properties of the corresponding homopolymers. The analytical investigation of fourteen copolymers made of methyl-methacrylate (MMA) or ethyl-methacrylate (EMA) as the basis monomer is summarized. Their polymerization behaviors are examined by NMR spectroscopy with subsequent copolymerization parameter evaluation according to Fineman-Ross and Kelen-Tüdös. Therefore, some r-parameter sets are shown to be capable of copolymerizations with very high conversions. The first applications as high-temperature resistant (HT) materials for HT-POFs are presented. Copolymers containing isobornyl-methacrylate (IBMA) as the comonomer are well-suited for this demanding application

Investigation on harsh environmental effects on polymer fiber optic link for aircraft systems

To integrate polymer fiber based physical layer for avionic data network, it is necessary to understand the impact and cause of harsh environments on polymer fiber optic components and harnesses. Since temperature and vibration have a significant influence, we investigate the variation in optical transmittance and monitor the endurance of different types of connector and splices under extreme aircraft environments. Presently, there is no specific aerospace standard for the application of polymer fiber and components in the aircraft data network. Therefore, in the paper we examine and define the thermal cycling and vibration measurement set up and methods to evaluate the performance capability of the physical layer of the data network. Some of the interesting results observed during the measurements are also presented. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

POLYMER OPTICAL FIBER SPLICING TECHNIQUE FOR AVIONIC APPLICATIONS: FIRST STEP TOWARDS STANDARDIZATION

In summary, the investigation shows the temperature sensitivity of the POF splices restricted their use specifically to non-critical applications. However, avionic POF splice can be realized in the future with suggested modification

POWER BUDGET AND SYSTEM PERFORMANCE ANALYSIS OF THE POF LINK FOR FUTURE AVIONIC APPLICATIONS

This paper aims to provide reliable and basic measurement data on the influence of flat connectors with an airgap (SMA) and connectors with physical contact (ST, SC) on the power margin and system performance of polymer optical fiber link for avionic applications

Universal Fibre Laser Model Used for the Simulation of 2 mu m Thulium Fibre Lasers

A universal simulation model for rare earth doped cw fibre lasers is presented. The model is based on generic rate and gain equations and therefore is very compact. It can be used for any fibre doped with one or several rare earth ions. The model allows for spectral simulations as well as radial discretization of the fibre. An algorithm was developed which optimizes the longitudinal fibre segmentation of the model. Spectroscopic parameters for Thulium doped fibre lasers are taken from the literature or derived from calculations. Calculated multiphonon up-conversion rates take the thermalisation of closely spaced states into account. The simulation is compared with measurement results of a coupled wavelength shift observed in a tunable fibre ring laser. The simulation allows to investigate possible explanations and it indicates that the phenomenon is a measurement artefact

A Systematic Comparison of Near-Field Beamforming and Fourier-based Backward-Wave Holographic Imaging

In this paper we show the equivalence of near-field beamforming and backward-wave reconstruction algorithm. The proof is carried out analytically with two different approaches, using the principle of stationary phase from a signal processing point of view and the angular spectrum representation as an electromagnetic point of view. A comparison of the time complexity of the near-field beamforming and backward-wave reconstruction algorithm is given. A detailed discussion of the constraints required for a digital implementation is presented, leading to limitations for the chosen system parameters, especially for the backward-wave reconstruction approach. An exemplarily scenario is simulated and processed, confirming the found equivalence between the two very different approaches of image reconstruction. An additional measurement with a 120 GHz radar showcases the capabilities of both algorithms and validates our findings