The increasing capability for manufacturing a wide variety of optoelectronic devices from polymer and polymer–silicon hybrids, including transmission fibre, modulators, detectors and light sources, suggests that organic photonics has a promising future in communications and other applications.

Organic photonics for communications

Changing environmental conditions, especially temperature, have been observed to be a complicated factor affecting vibration properties, such as frequencies, mode shapes, and damping, of civil structures. This paper reviews technical literature concerning variations in vibration properties of civil structures under changing temperature conditions. Most of these studies focus on variations in frequencies of bridge structures, with some studies on variations in mode shapes and damping and other types of structures. Statistical approaches to correlation between temperature and frequencies are also reviewed. A quantitative analysis shows that variations in material modulus under different temperatures are the major cause of the variations in vibration properties. A comparative study on different structures made of different materials is carried out in laboratory. Two real structures, the 1,377-m main span Tsing Ma Suspension Bridge and the 600-m-tall Guangzhou New Television Tower, are examined. Both laboratory experiments and field testing, regardless of different construction materials used and structural types, verify the quantitative analysis. Variations in frequencies of reinforced concrete structures are much more significant than those of steel structures.

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Temperature effect on vibration properties of civil structures: a literature review and case studies

The field of visible light communications (VLC) has gained significant interest over the last decade, in both fibre and free-space embodiments. In fibre systems, the availability of low cost plastic optical fibre (POF) that is compatible with visible data communications has been a key enabler. In free-space applications, the availability of hundreds of THz of the unregulated spectrum makes VLC attractive for wireless communications. This paper provides an overview of the recent developments in VLC systems based on gallium nitride (GaN) light-emitting diodes (LEDs), covering aspects from sources to systems. The state-of-the-art technology enabling bandwidth of GaN LEDs in the range of >400 MHz is explored. Furthermore, advances in key technologies, including advanced modulation, equalisation, and multiplexing that have enabled free-space VLC data rates beyond 10 Gb/s are also outlined.

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A review of gallium nitride LEDs for multi-gigabit-per-second visible light data communications

The number of services providing large-volume information content, such as high-definition movies, continues to increase rapidly. Single-mode glass optical fiber (SM GOF), which has been widely deployed in data trunk lines and pipelines connecting large cities and nations, has already become indispensable as an information transmission medium. However, SM GOF is mechanically weak and lacks sufficient bending ability. Moreover, as the core diameter is very small, just 10 μm, extremely precise techniques and expensive devices are required to connect fibers to signal receiving devices. It is therefore difficult to lay SM GOF for very short reach networks, such as local area networks in buildings. These difficulties are recognized as the problem of the ‘last hundred meters’ for optical fiber infrastructure. Plastic optical fiber (POF) has a relatively large-diameter core and is flexible enough to be laid down for network infrastructure in the last hundred meters. However, POF has two important weaknesses: it has significantly lower bandwidth than GOF, and its attenuation is far higher. Recent developments conquering both of these issues now mean that POF is regarded as the strongest candidate at present for optical data transmission over the last hundred meters. Here we review the status of POF development and research, particularly with respect to the application of ‘photonics polymer’.

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The future of plastic optical fiber

Researchers and administrative authorities have long recognized the significance of implementing long-term structural health monitoring (SHM) systems for civil infrastructures, especially large-span space structures or other complex infrastructures, in order to secure structural safety and issue warnings regarding the structural damage prior to costly repair or even collapse. This paper starts with a critical review of SHM objectives and standardization for the SHM in civil infrastructures. At the same time as an example, the authors present their experiences through the case study of SHM applications for large and complex civil infrastructures through a custom-made polytypic and synchronous data acquisition device that was utilized in the SHM of the large-span gymnasium in Dalian. The paper concludes with a discussion of state-of-the-art in the SHM for civil infrastructures, highlighting areas where further work is needed.

State-of-the-art in structural health monitoring of large and complex civil infrastructures

Basics of Optical Data Communication.- Optical Fibers.- Passive Components for Optical Fibers.- Active Components for Optical Systems.- Planar Waveguides.- System Design.- Standards.- Application of Polymer Optical and Glass Fibers.- Optical Measuring Methods.- Simulation of Optical Waveguides.- POF Clubs.

POF handbook : optical short range transmission systems

From the Publisher:
"POF - Polymer Optical Fibers for Data Communication contains a comprehensible introduction to the theory of POF light propagation, as well as an updated summary of publications on POF systems with detailed descriptions and new applications." "The focus of the book is laid on: transmitters and receivers, connectors, cables and wires with POF, testing and measuring and finally on materials and reliability and durability. The book gives a summary of different POF types with a comparison of characteristics and explanations on possible applications and manufacturing methods. It contains a presentation of different measuring methods for POF with a list of current standards and an overview of active and passive components for POF systems with a comprehensive comparison of characteristics." Furthermore, there is a well-founded description of performance calculations for POF systems with many suggestions for new solutions. In the book are almost 500 multicolor illustrations, charts and tables and a list of over 300 references.

Pof-Polymer Optical Fibers for Data Communication

This chapter summarizes the state of the art and current developments of guidelines for structural health monitoring (SHM) and performance control. Technical guidelines and standards for condition monitoring and technical diagnostics of rotary machines and for non-destructive testing are not reviewed in this chapter.

Guidelines for Structural Health Monitoring

The optical transmission loss behavior was investigated for commercially available poly(methyl methacrylate) (PMMA) based polymer optical fibers (POFs). POFs were exposed to various climates of temperature and humidity. Optical transmission measurements using multiplexer (a prototype device) reveal that POFs exhibited an early drop-off followed by a slow decline of transmission at 100°C with low humidity and nearly 100% loss of transmission at the early stages of exposure at 92°C with 95% relative humidity (RH) and at 120°C with low humidity. Fourier transform infrared (FTIR) and gel permeation chromatography (GPC) analysis data show no significant molecular changes in the PMMA core after climatic exposures. However, the attenuated total reflection (ATR)–FTIR data shows a few molecular changes in claddings due to degradation. Scanning electron microscopy (SEM) data illustrate the shrinkage and folding structure in claddings. The loss of the optical transmission at the early (initial) stages of exposure is attributed to the physical changes (like thermal expansion), and the same at the later stages mainly to chemical changes (e.g., oxidative degradation). The experiments conducted here show that the POFs optical transmission stability is strongly dependent on the chemical composition of claddings. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 860–870, 2007

Aging behavior of polymer optical fibers: Degradation characterization by FTIR

Embedded conventional fibre Bragg grating (FBG) sensors with acrylate coating have been chosen for monitoring novel textile-reinforced composite materials with a complicated wavy structure as a result of reinforcing textures. Problems of monitoring this type of material occur due to the harsh fabrication technology of the composite and its complicated structure. Embedded fibre sensors are exposed to the influence of transverse and point-wise deformations. To what extent will these effects influence the measurement signal of a sensor? Temperature cycles, tension and vibration tests were carried out to answer this question. Transverse and point-wise deformation and micromechanical indentation tests on non-embedded FBG sensors were carried out to clarify the reliability of recorded signals.

https://iopscience.iop.org/article/10.1088/0957-0233/15/8/001/pdf

Werner Daum

Papers

POF handbook : optical short range transmission systems

Pof-Polymer Optical Fibers for Data Communication

Guidelines for Structural Health Monitoring

Aging behavior of polymer optical fibers: Degradation characterization by FTIR

How to reliably measure composite-embedded fibre Bragg grating sensors influenced by transverse and point-wise deformations?