Algae have gained increasing attention as promising food from both an environmental and nutritional perspective. However, current understanding is still limited. This report summarizes the status of knowledge for this emerging sector, focusing on micro- and macroalgae species most relevant for Europe (particularly Sweden). Environmental impacts, with focus on climate, are evaluated through literature reviews and analysis of existing life cycle assessments (LCAs), and nutritional potential in the form of data compilation and calculation of nutrient density scores. Overall, findings reveal that current data is incomplete and of poor representativeness. Most LCAs are not performed on commercial production, but at pilot or experimental scale, why often only indicative drivers for greenhouse gas emissions may be identified. For microalgae, there is a wide diversity of production systems in different conditions across the globe. Based on the data at hand, energy use is a key hotspot across most studies for this production, driven by the requirements of different types of systems and species, and to location. For macroalgae production, despite poor representativeness of especially green and red macroalgae, key aspects for minimizing greenhouse gas emissions are associated with energy consumption and use of materials for farming such as ropes. No LCA exists on wild harvested macroalgae, representing the largest production volume in Europe (>95%); large-scale wild harvest may also be associated with risks to ecosystems unless suitable management is enforced. Significant data gaps also exist in food composition databases regarding nutrient and heavy metal content in algae (e.g., vitamins and omega-3 fatty acids). When available, nutrient content was found to be highly variable within and across species, but overall, the evaluation of nutritional quality indicated that algae may be a considerable source of minerals and vitamin B12. The contribution of fiber and protein is generally minimal in a 5 g dry weight portion of macroalgae; microalgae may have higher protein content, and also fat. However, excessive amounts of iodine and several heavy metals may be represented even in very small amounts of unprocessed macroalgae. In summary, the suggested potential of farmed algae as a sustainable food resource is overall strengthened by its generally low carbon footprint during production compared to other food raw materials. However, more input data are needed to fill data gaps regarding both environmental impacts and nutrient quality, and effects from different processing, as well as improved understanding of nutrient and contaminant bioavailability. Pending further research, careful considerations of risks and benefits associated with algae production and consumption should be applied.

An all-fiber integrated device capable of separating and counting particles is presented. A sequence of silica fiber capillaries with various diameters and longitudinal cavities are used to fabricate the component for size-based elasto-inertial passive separation of particles followed by detection in an uninterrupted continuous flow. Experimentally, fluorescent particles of 1 μm and 10 μm sizes are mixed in a visco-elastic fluid and fed into the all-fiber separation component. The particles are sheathed by an elasticity enhancer (PEO - polyethylene oxide) to the side walls. Larger 10 μm particles migrate to the center of the silica capillary due to the combined inertial lift force and elastic force, while the smaller 1 μm particles are unaffected, and exit from a side capillary. A separation efficiency of 100% for the 10 μm and 97% for the 1 μm particles is achieved at a total flow rate of 50 μL min−1. To the best of our knowledge, this is the first time effective inertial-based separation has been demonstrated in circular cross-section microchannels. In the following step, the separated 10 μm particles are routed through another all-fiber component for counting and a counting throughput of ∼1400 particles per min is demonstrated. We anticipate the ability to combine high throughput separation and precise 3D control of particle position for ease of counting will aid in the development of advanced microflow cytometers capable of particle separation and quantification for various biomedical applications. 

Fibre-optic based sensing technologies are becoming popular in the field of geophysics since enable long range and high spatial resolution acoustic measurements. In this work, we present preliminary results obtained using quasi-distributed Fibre-Bragg grating sensing and Distributed Acoustic Sensing (DAS) to monitor seismic activities in an operational underground mine. 12 FBGs and 800 metres of fiber optic cable was installed in the tunnel lining an operational mine and recorded mine seismicity such as production blasts and a small seismic activity of magnitude 1.41 in September 2022. 

Nutrient and toxicant levels as well as their bioavailability in S. latissima and Ulva species (fenestrata, intestinalis, rigida) were reviewed. Nutritional quality was assessed by nutrient contribution to daily reference intake (DRI) per portion (5 g dry weight), nutrient density score NRF21.3, and comparisons to reference foods. Toxicological assessments comprised tolerable daily intake (TDI)-levels. Based on mean %DRI per portion, S. latissima and Ulva species were good sources (%DRI >15) of calcium, magnesium, iron, selenium, and vitamin B12. Mean %DRI was <10% for fiber, sodium, and protein. Toxicological concerns were mainly due to iodine (mean %TDI per portion: 3160% for S. latissima and 41–91% for Ulva species). Mean %TDIs for inorganic arsenic, cadmium, and lead were <20% for S. latissima and 9–97%, 6–15%, and 21–46%, for the selected Ulva species, respectively. Bioavailability data were scarce and is, together with nutritional impact of processing, an important aspect to address in future studies.

A fiber optic health-monitoring system for refractory lining in steel-making processes is presented. Its applicability as an early-warning system for lining damage is demonstrated by the results obtained in a field trial, in which 240 m of fiber was embedded in the lining of an electric arc furnace. The system is based on Raman distributed sensing and polyimide coated fibers in metal tube. The results presented from temperature cycling and calibration at temperatures up to 600 °C show that adequate accuracy and stability for the application can be attained.

Microfluidics has emerged rapidly over the past 20 years and has been investigated for a variety of applications from life sciences to environmental monitoring. Although continuous-flow microfluidics is ubiquitous, segmented-flow or droplet microfluidics offers several attractive features. Droplets can be independently manipulated and analyzed with very high throughput. Typically, microfluidics is carried out within planar networks of microchannels, namely, microfluidic chips. We propose that fibers offer an interesting alternative format with key advantages for enhanced optical coupling. Herein, we demonstrate the generation of monodisperse droplets within a uniaxial optofluidic Lab-in-a-Fiber scheme. We combine droplet microfluidics with laser-induced fluorescence (LIF) detection achieved through the development of an optical side-coupling fiber, which we term a periscope fiber. This arrangement provides stable and compact alignment. Laser-induced fluorescence offers high sensitivity and low detection limits with a rapid response time making it an attractive detection method for in situ real-time measurements. We use the well-established fluorophore, fluorescein, to characterize the Lab-in-a-Fiber device and determine the generation of ∼ 0.9 nL droplets. We present characterization data of a range of fluorescein concentrations, establishing a limit of detection (LOD) of 10 nM fluorescein. Finally, we show that the device operates within a realistic and relevant fluorescence regime by detecting reverse-transcription loop-mediated isothermal amplification (RT-LAMP) products in the context of COVID-19 diagnostics. The device represents a step towards the development of a point-of-care droplet digital RT-LAMP platform. © 2022, The Author(s).

We demonstrate the use of the electrooptic effect to control the propagation constant of the guided modes in silicate few mode fibers with internal electrodes. The electrooptic effect induces a perturbation of the fiber's refractive index profile that controls intermodal interference. To increase the electrooptic effect the silicate fibers are poled. The response time is in the nanosecond range. 

The electrooptic effect is used in a few-mode fiber to control intermodal interference. The fiber has internal electrodes and is poled to increase its electrooptic coefficient. The response time is in the nanosecond range. © Optica Publishing Group 2022, © 2022 The Author(s)

Ultrathin 25μm optical fibers with FBG sensors are manufactured and used as vibration sensors in glass-fiber reinforced composites. The use of ultrathin fibers is discussed, and their manufacture is described. © 2022 The Authors.

We present early design and simulation work on a novel X-ray imaging detector. The intent of the FleX-RAY project is to create a digital X-ray detector that is capable of producing high-resolution images, is flexible enough to produce an image on a curved surface, and is capable of self-reporting its final shape. The X-rays will be detected on a sheet of scintillating optical fibers, which will guide the scintillation light to single-photon avalanche photodiodes. This setup allows the electronics and hardware to be moved out of the path of the X-ray beam, limiting the need for additional shielding. Self-shape-reporting will be achieved using a flexible ultra-thin glass substrate with optical waveguides and Bragg gratings, processed by femtosecond laser point-by-point writing. The functionalized glass substrate allows precise measurement of strains, which can be used to calculate the shape. © 2022 The Author(s).

fs-point-by-point through the coating written FBGs as a basis for novel sensor concepts using 25μm optical fiber. fs-point-by-point FBGs in novel single mode fiber with a cladding diameter of 25μm have been produced in fiber that is 5 times smaller than conventional telecommunication optical fiber. The development opens the path to new sensor types including miniature pressure sensors with a diameter of only 330μm (1Fr.). © 2022 The Author(s).

Electrical corona discharge is employed in this work to deposit ions on the surface of an optical fiber, creating a strong electric field that is used for poling. Green laser light propagating in the core frees photocarriers that are displaced by the poling field. The technique presented can induce a higher optical nonlinearity than previously obtained in traditional optical poling with internal metal electrodes. To date, a maximum second order nonlinearity 0.13 pm/V has been achieved for a 15 kV corona discharge bias. 

In this work, we report on a twin-core fiber sensor system that provides improved spectral efficiency, allows for multiplexing and gives low level of crosstalk. Pieces of the referred strongly coupled multicore fiber are used as sensors in a laser cavity incorporating a pulsed semiconductor optical amplifier (SOA). Each sensor has its unique cavity length and can be addressed individually by electrically matching the periodic gating of the SOA to the sensor’s cavity roundtrip time. The interrogator acts as a laser and provides a narrow spectrum with high signal-to-noise ratio. Furthermore, it allows distinguishing the response of individual sensors even in the case of overlapping spectra. Potentially, the number of interrogated sensors can be increased significantly, which is an appealing feature for multipoint sensing. © 2022, The Author(s).

In this work, we present a quantitative (statistical) 3D morphological characterization of optical fibers used in electric-field sensing. The characterization technique employs propagation-based x-ray phase-contrast microcomputed tomography (micro-CT). In particular, we investigate specialty optical fibers that contain microstructured holes that are electro-optically modified by thermal poling to induce second-order nonlinear effects (SONE). The efficiency of the SONE is reflected in the characterization parameter, Vπ, which is highly dependent on the dimensions of the fiber. The fiber microstructures must be uniform to support the fabrication of reproducible devices. The results obtained using the micro-CT technique show that uncertainty of ±1.7% arises in the determination of the expected value of the voltage that causes a change in the phase of the electromagnetic wave equal to π rad (Vπ ), demonstrating a great advantage, compared with other techniques e.g. SEM, which would need at least 1000 images of the cross-section of an optical fiber, taken at different points, making the process more expensive and time-consuming.

The hybrid electronically addressable random (HEAR) laser is a novel type of random fiber laser that presents the remarkable property of selection of the fiber section with lasing emission. Here we present a joint analysis of the correlations between intensity fluctuations at distinct wavelengths and replica symmetry breaking (RSB) behavior of the HEAR laser. We introduce a modified Pearson coefficient that simultaneously comprises both the Parisi overlap parameter and standard Pearson correlation coefficient. Our results highlight the contrast between the correlations and presence or not of RSB phenomenon in the spontaneous emission behavior well below threshold, replica-symmetric ASE regime slightly below threshold, and RSB phase with random lasing emission above threshold. In particular, in the latter we find that the onset of RSB behavior is accompanied by a stochastic dynamics of the lasing modes, leading to competition for gain intertwined with correlation and anti-correlation between modes in this complex photonic phase. 

In this work, we explore the interrogation of an array of fiber Bragg gratings as part of a laser cavity. A semiconductor optical amplifier in a sigma-shaped fiber cavity provides gain and is gated periodically at a rate that matches the roundtrip time associated with each grating of the array. The interrogator exhibits clear laser properties such as a threshold and linewidth narrowing. Besides improving the signal-to-noise ratio and enabling the re-use of wavelengths, it is found that this interrogation scheme enables monitoring of weak gratings spaced by less than 1 cm. Intracavity grating interrogation studied here is found to be a simple and powerful way to increase the number of sensor points for industrial applications. 

The sensing properties of fiber Bragg gratings (FBG) inscribed in single mode fiber with a 5 μm diameter core and 25 μm diameter cladding are studied experimentally for temperature, strain, bending, and surrounding refractive index. Compared to normal single mode fiber, the diameter of this fiber is 5 times smaller and it stretches 14.5 times more at the same applied load. Therefore, it is much more flexible and stretchable, while maintaining excellent optical quality at wavelengths near 1550 nm. In addition to a core mode back reflection resonance, strong FBGs inscribed in this fiber show a relatively small number of narrow bandwidth (0.7 nm) cladding mode resonances separated in wavelength by 2.5–6 nm. This relatively coarse spectral comb can then be used to sense many different kinds of perturbations involving core and cladding modes. In particular, unlike cladding-mode based sensors made from tilted FBGs, all resonances are of the same azimuthal order as the core mode (i.e. HE1m). This feature makes these gratings particularly sensitive to bending which causes the appearance of new resonances and reduced amplitudes of the original ones, each by up to 10 dB/mm−1 of curvature. On the other hand, the temperature sensitivities of all modes are similar to that of standard fiber (around 11 pm/oC) while strain sensitivities are somewhat higher (1.6–1.7 pm/μstrain). The surrounding refractive index sensitivity is also increased (by a factor of 3) over normal fiber, mostly due to the increased modal dispersion of the modes of the thinner cladding. Furthermore, it is possible to serially multiplex different gratings at different wavelengths by interleaving their resonance combs and preserving each grating identity in the combined spectrum.

In this work, we present the design and fabrication of a fiber device that performs digital droplet microfluidics for molecular diagnostics. A variety of fibers and capillaries were used to build three connected modules dedicated to droplet generation, incubation, and fluorescence detection which enables a uniaxial arrangement. This is in contrast to the traditional 2-dimensional lab-on-a-chip architecture. We characterize our fiber device using a fluorescein dilution series. Our observed detection limit is on the order of 10 nM fluorescein. We demonstrate our all-fiber device for the fluorescence readout after loop-mediated isothermal amplification (LAMP) of synthetic SARS-CoV-2. Our results suggest that this fiber device can successfully distinguish between positive and negative samples in molecular diagnostics. We propose that our fiber device offers benefits over microfluidic chip techniques such as easier optical integration, much simpler sample loading, and faster diagnosis with high specificity and sensitivity. Keywords: All-fiber device, microfluidics, optofluidics, loop-mediated isothermal amplification (LAMP), molecular diagnostics, SARS-CoV2.

We present a novel C-cavity concept for tunable lasers. The laser is based on a semiconductor optical amplifier (SOA), serving both as a gain medium as well as a modulator, and a chirped fiber Bragg grating (C-FBG) which acts as the end mirrors on both cavity ends. Driving the SOA with a pulse pair with variable delay enables wavelength tuning by targeting different regions in the C-FBG with the circulating pulse. The cavity design allows for wide tuning while maintaining a constant repetition rate, we show a tuning range of 35 nm -limited by the C-FBG's reflection bandwidth. Time-multiplexed operation with four different wavelengths is also demonstrated. Furthermore, the laser performance and dynamics under different operating conditions are analyzed and discussed.

Rapporten behandlar digitalisering – att införa ny digital teknik – i förvaltningsverksamheten av broar. Omfattningen är en förstudie med syftet att identifiera behovet av framtida forskning för en långsiktig utveckling av broförvaltningen. En grundläggande ansats var att en digitalisering ska minska behovet av kostsamma underhållsåtgärder men bibehålla en hög säkerhet för våra broar. Projektets mål var att samla information om digitala informationsmodeller som skapas under investeringsskedet, utvärdera överlämningen av digitala modeller till förvaltningsskedet, och värdera den eventuella nyttan med digital informationsinsamling för tillståndsbedömning och underhållsplanering. En viktig del av detta var beskrivningen av dagens förvaltningssystem och hur det skulle kunna utvecklas. Studierna har bedrivits genom en enkätundersökning med respondenter från konsultfirmor aktiva inom broprojektering, intervjuer med tekniska experter och litteratursökningar. Resultatet visar att projekteringen av broar idag huvudsakligen görs genom byggnads-informationsmodellering (BIM). Inriktningen är mot byggskedet där samordning och kommunikation bedöms vara de största nyttorna. Överlämningen till förvaltningen består dock av relationsritningar i formen av enkla ritningsfiler. Trots att Trafikverkets strategi för BIM beskriver att en informationsmodell bör leva kvar under hela brons livslängd, finns det tveksamheter huruvida en modell från projekteringen är lämplig som förvaltningsmodell. Istället lyfts andra metoder fram för att skapa en modell av det byggda utförandet. Till exempel optiska metoder för skanning och fotogrammetri. Förvaltningssystemen bör utvecklas med funktioner för att lagra och tillgängliggöra stora mängder digital information från sensorer maskinella inspektioner. Syftet är att minska osäkerheterna i det byggda utförandet och graden av nedbrytning, för att slutligen skapa ett bättre underlag för beslut om åtgärder. Ett framtida scenario är en digital tvilling som speglar den verkliga konstruktionen och uppdateras kontinuerligt genom sensordata. Gällande hårdvara för mätningar behöver sensorer och system utvecklas med avseende på energiförbrukning, energiskördning och underhållsåtgärder, t.ex. genom kombinationer av utbytbara komponenter med kort livslängd och andra delar med lång livslängd. Fiberoptiska sensorer visar på lovande egenskaper men utveckling behövs för att göra dem mer kostnadseffektiva i relation till konventionella sensorer.

In this work, we report about the fabrication and characterization of long period gratings (LPG) in so-called side-hole fibers (SHF). They have a different number (one, two, and four) of micro-channels in the cladding region, developing along the longitudinal direction of the optical fiber. For the first time, LPG inscription was performed by electric discharge technique in these fibers, resulting in devices with good spectral features, i.e. deep and narrow attenuation bands. The gratings were characterized in terms of response to surrounding refractive index, temperature, and strain, demonstrating the effectiveness of the fabrication process. The final aim is to provide a flexible sensing platform for the development of micro-fluidic devices for different applications.

A compact fiber capillary based microflow cytometer capable of detecting side-scattered-light is demonstrated by using a 450 angle-cleaved metal coated optical fiber tip.

This work describes the use of FBGs inscribed in optical fiber with electrodes for voltage sensing. The results show a quadratic voltage dependence. The device can be explored for a multipoint, single-ended voltage sensing device.

We report here a novel architecture for a random fiber laser exploiting the combination of a semiconductor optical amplifier (SOA) and an erbium doped fiber (EDF). The EDF was optically biased by a continuous wave pump laser, whereas the SOA was arranged in a fiber loop-mirror and driven by nanosecond duration current pulses. Laser pulses were obtained by synchronizing the SOA driver to the returning amplified Rayleigh back-scattered light from a selected short section of the EDF. By tuning the SOA pulse rate, random lasing was achieved by addressing selected meter-long sections of the 81-m long EDF, which was open-ended. Laser oscillation can be potentially obtained with SOA modulation frequencies from several kHz to the MHz regime. We discuss the mechanism leading to the hybrid random laser emission, connecting with phase sensitive optical time domain reflectometry and envision potential applications of this electronically addressable random laser.

Using various fiber capillaries with different diameters and multiple holes we develop an optofluidic component capable of separating micron-sized beads emulating cells and bacteria, exploiting particle focusing in a viscoelastic fluid and analyzed optically.  © 2020 The Author(s).

Nowadays there is an increasing demand for the cost-effective monitoring of potential threats to the integrity of high-voltage networks and electric power infrastructures. Optical fiber sensors are a particularly interesting solution for applications in these environments, due to their low cost and positive intrinsic features, including small size and weight, dielectric properties, and invulnerability to electromagnetic interference (EMI). However, due precisely to their intrinsic EMI-immune nature, the development of a distributed optical fiber sensing solution for the detection of partial discharges and external electrical fields is in principle very challenging. Here, we propose a method to exploit the third-order and second-order nonlinear effects in silica fibers, as a means to achieve highly sensitive distributed measurements of external electrical fields in real time. By monitoring the electric-field-induced variations in the refractive index using a highly sensitive Rayleigh-based CP-φOTDR scheme, we demonstrate the distributed detection of Kerr and Pockels electro-optic effects, and how those can assign a new sensing dimension to optical fibers, transducing external electric fields into visible minute disturbances in the guided light. The proposed sensing configuration, electro-optical time domain reflectometry, is validated both theoretically and experimentally, showing experimental second-order and third-order nonlinear coefficients, respectively, of χ⁽²⁾ ~ 0.27 × 10^-12 m/V and χ⁽³⁾ ~ 2.5 × 10^-22 m²/V² for silica fibers.

Here, we present an overview of the ellipsometric characterization of hybrid thin films and metal nanoparticles by surface plasmon resonance (SPR) spectroscopy, together with the dynamic control of the optical properties of the latter for applications in optoelectronic devices. A description of traditional techniques used for the determination of the thickness and refractive index of organic thin films deposited over the SPR planar sensing platforms is presented, with a discussion of the most recent applications in the ellipsometric characterization of thin film of metal nanoparticles and graphene layers. We conclude by describing recent results developing a dynamically tunable plasmonic pixel, where the electric-field-controlled alignment of gold nanorods in a colloidal suspension can enable optical switching at frequencies greater than megahertz.

The cement industry is facing pressure to find technological solutions in reducing greenhouse gas emissions owing to the large amount of process emissions originating from the calcination of limestone. In this communication, an all-fibre gas monitoring system based on anti-resonant hollow-core fibres is proposed. An on-field test was performed in the harsh environment of a cement factory and it demonstrated the feasibility of using this system for low-concentration carbon dioxide and carbon monoxide monitoring in exhaust fumes

Monitoring the presence of external electric fields over large distances and detecting losses along power transmission networks, is of extreme importance nowadays due to concerns with environment, efficiency, cost and safety. In this work, we evaluate a method to achieve distributed measurements of the quadratic electro-optic Kerr effect in silica fibers in a distributed way. For this purpose, we integrate a twin-hole fiber filled with BiSn alloy electrodes and monitor its electric-field induced refractive index (RI) change Δn by using a chirped-pulse phase-sensitive OTDR (CP-ΦOTDR). By exploiting its high sensitivity (RI changes of the order of 10-9), we demonstrate that the proposed system is able to detect the intrinsic quadratic electrooptic nonlinearity (the electric Kerr effect) in the fiber, an effect that is usually considered to be too weak to be exploited for practical applications. Additionally, we show that the CP-ΦOTDR is sufficiently sensitive to measure the electric Kerr effect with untreated standard telecommunication fibers under realistic fields.

Optical fibers are inherently designed to allow no interaction between the guided light and the surrounding optical radiation. Thus, very few optical fiber-based technologies exist in the field of optical radiation sensing. Accomplishing fully-distributed optical radiation sensing appears then as even more challenging since, on top of the lack of sensitivity explained above, we should add the need of addressing thousands of measurement points in a single, continuous optical cable. Nevertheless, it is clear that there exist a number of applications which could benefit from such a distributed sensing scheme, particularly if the sensitivity was sufficiently high to be able to measure correctly variations in optical radiation levels compatible with the earth surface. Distributed optical radiation sensing over large distances could be employed in applications such as Dynamic Line Rating (DLR), where it is known that solar radiation can be an important limiting factor in energy transmission through overhead power cables, and also in other applications such as thermo-solar energy. In this work, we present the proof-of-concept of the first distributed bolometer based on optical fiber technology and capable of detecting absolute changes of irradiance. The core idea of the system is the use of a special fiber coating with high emissivity (e.g., carbon coating or black paint). The high absorption of these coatings translates into a temperature change that can be read with sufficiently high sensitivity using phase-sensitive reflectometry. To demonstrate the concept, we interrogate distinct black-coated optical fibers using a chirped-pulse ÖOTDR, and we readily demonstrate the detection of light with resolutions in the order of 1% of the reference solar irradiance, offering a high-potential technology for integration in the aforementioned applications.

Joule effect and thermal response of several carbon coated fibers are modelled and analysed. An electro thermally driven all-fiber phase modulator based on these principles is proposed and a proof of concept of it is characterized. This kind of fibers could be the basis for developing all fiber components aimed to operate in environments where the strength increase and impermeability to hydrogen diffusion guaranteed by the carbon coating is crucial.

Fiber Bragg gratings (FBGs) in a poled silicate fiber are used to detect external voltage applied to the fiber's internal electrodes. This work shows a basic proof-of-concept of a single-ended, fiber-based voltage sensor that can be used to measure periodic high-voltage signals. The setup can be extended to a multiplexed e-field interrogation system and used in the electric power industry for remote sensing of transmission lines and power plants..

A second-order nonlinearity was induced in silica fibers poled by exposure to ultraviolet (UV) radiation and simultaneous high voltage applied to internal electrodes. The UV light source was a tubular lamp with spectral peak at 254 nm. The highest second-order nonlinear coefficient measured through the linear electro-optic effect was 0.062 pm/V. The erasure of the recorded voltage with UV excitation was studied, and the stability of the poled fiber at a temperature exceeding ~400 K was investigated. By eliminating the use of a focused laser beam as excitation source, the technique enables poling many pieces of fiber in parallel.

This work combines fiber optic sensors with additive manufacturing to enable integration of temperature and strain sensors in metal components. In this paper, we present a fiber optic sensor network integrated in press hardening tools to monitor the contact between the tool and the metal sheet during forming operation. The tools are manufactured through metal powder bed fusion using laser melting processes (PBF-SLM), after which the tools are prepared for sensor integration. A demonstrator press hardening tool with integrated fiber optic sensors was heated using an electric heat foil and the sensor measurements was compared to a thermal simulation model. The sensor technology is based on Fiber Bragg Gratings (FBGs), integrated at several positions along the optical fiber. FBGs are in-fiber sensors that are multiplexed. lt is possible to place hundreds of FBG sensors along one single fiber, thus allowing for quasidistributed sensing of temperature or strain. The optical fiber itself can be less than 100 micrometer in diameter, allowing for sensing at several points in a minimally invasive way, when integrated in a tool or component.

This work presents an on-field validation of an in-house built real-Time phase-OTDR for monitoring the status of roller bearings. The acoustic sensor prototype was designed and assembled at RISE and evaluated on a 1 m diameter bearing at SKF AB facilities in Göteborg, Sweden. A 0.24 numerical aperture single-mode optical fiber was installed in the bearing lubrication groove, which is 50 mm large and 5 mm deep. Tests were performed to verify the response of the phaseOTDR to acoustic emissions in the bearing such as hammer hits and running the rollers at different loads. The fiber optic sensor results agree with the measurements performed by a standard industrial high sensitivity electronic accelerometer used for comparison. Moreover, as opposed to the reference electronic sensor, the phase-OTDR proved to be insensitive to electrical disturbances present on the environment.

Silicate fibers with internal electrodes are optically poled without a laser by side-exposure to radiation from a UV tubular lamp. Electrooptic coefficients κ(2)∼ 0.04 pm/V and Vπ = 810 V are obtained

Silicate fibers with internal electrodes are optically poled without a laser by side-exposure to radiation from a UV tubular lamp. Electrooptic coefficients χ(2) ~ 0.04 pm/V and Vπ = 810 V are obtained.

We demonstrate a tunable narrow-linewidth laser based on a semiconductor optical amplifier and a linearly chirped FBG. High tuning resolution and small power variation over 40 nm tuning range were achieved by optimizing the drive current.

A distributed bolometer operating over transparent-coated and carbon-coated optical fibers is proposed. The detection of light with irradiance sensitivities of in the order of 1% of the reference solar irradiance is readily demonstrated. 

This report describes filters for washing machines designed to remove either microplastic fibres or lint from laundry water and investigates possibilities and challenges with such filters from a practical and environmental perspective. The report includes results from a literature study and a laboratory study. Other studies on microplastics from laundry water are summarized briefly. It can be concluded that filtering solutions for washing machines which claim to remove lint and microplastic fibres can be purchased and installed. Three of the filtering solutions were tested in laboratory washing trials and were found to retain some of the microplastic, hence decreasing the amount of microplastic released with the laundry water. The retention was most profound the first time the new fabric was washed. To judge exactly how well the filters remove microplastics during realistic domestic washing conditions would require more comprehensive laboratory work. It is also necessary to further investigate how efficient the filters should be to present an alternative that is technologically, economically feasible as well as environmentally beneficial. Although the filters may retain microplastic fibres it may be necessary to design filtering solutions that are sufficiently user-friendly so that the filters are not by-passed by the user, and that there are good options for emptying or replacing the filters.

Certain applications of fiber sensors (e.g. avionics, oil industry) imply extreme operating conditions spurring the development of hermetic all-fiber devices. We present a hermetic all-fiber phase modulator based on Joule heating in a carbon-coated fiber. 

There is little knowledge about the release of microplastics from industrial laundries. This study was carried out to provide information about microplastics released in waste water from laundries. Six Swedish industrial laundries participated in the study. Of these two mainly washed hospital laundry, two mainly work wear, one mainly hotel laundry and one mainly mats. Small particles between 5-15 μm were dominant in this study, regardless of types of textiles washed or whether the laundry had a waste water treatment facility. From the microscopic, FTIR and SEM analyses it could be concluded that microplastics were not dominant in this size range. Most of the particles (in the 5 to 15 μm range) were of other materials (for example minerals, metal fragments, silica, aluminium silicate, yeast, starch). From the results from the measurements, calculations were made to estimate the number of released microplastic particles. The release varied significantly between the different laundries. If the calculations were based on an assumed best-case scenario, between 5 000 and 4 550 000 of microplastic particles were released per kg of washed textile. If a worst-case scenario was assumed, between 15 000 and 5 375 000 microplastic particles were released per kg of washed textile. Three laundries with either chemical or biological waste water treatment adjacent to the production facilities were involved in the study. The water treatment had a significant impact on reducing the numbers of particles. The numbers of fibre-shaped particles released were reduced by 65, 96 and 97% for the different facilities. This shows that waste water treatment at the laundry can be an efficient way of reducing the levels of particles released to the WWTP.

Liquid crystal based devices can arbitrarily control the amplitude, phase and polarization of light, enabling disruptive technologies such as flat screen televisions and smart phones. Yet, the Achilles heel of these devices are their slow, millisecond switching speeds, constraining potential applications. Here we develop the concept of a dynamic plasmonic pixel as a novel paradigm for liquid crystal devices using the electric field controlled alignment of gold nanorods. Experiments were performed using an electro-optic fluid fiber device, which enabled convenient interaction of light, electric fields and the nanorod suspension. We studied the evolution of the electric-field induced alignment of gold nanorods and demonstrate microsecond switching times, 3 orders of magnitude faster than a traditional Freederickcz-based liquid crystal alignment mechanism. We find that the dynamics of the alignment agrees well with the Einstein-Smoluchowski relationship. Furthermore, by digitally switching the nanorods between orthogonally aligned states, we show switching frequencies greater than MHz can be achieved. The development of these dynamically tunable plasmonic pixels may lead to ultrafast optical switches, filters, displays and spatial light modulators.

A fiber probe traps single micrometer-particles by fluid suction into a hollow microstructure and enables optical identification by the fluorescence light collected in a fiber core. The probe finds applications in life-science and environmental monitoring.

Acousto-optic coupling in polyimide-coated single-mode optical fibers using flexural elastic waves is demonstrated. The effect of the polyimide coating on the acousto-optic interaction process is analyzed in detailed. Theoretical and experimental results are in good agreement. Although the elastic attenuation is significant, we show that acousto-optic coupling can be produced with a reasonably good efficiency. To our knowledge, it is the first experimental demonstration of acousto-optic coupling in optical fibers with robust protective coating.

We present the experimental demonstration of in-fiber acousto-optic coupling in a polyimide-coated optical fiber. Although the presence of the polyimide coating increases is significantly the attenuation of the acoustic wave, we show that acousto-optic interaction can still be produced with reasonable efficiency. The effect of the polyimide coating on the acousto-optic interaction process is analyzed in detailed. Theoretical and experimental results are in good agreement. To our knowledge, this is the first experimental demonstration of acousto-optic coupling in optical fibers with robust protective coating.

We demonstrate the digital electric field induced switching of plasmonic nanorods between "1" and "0" orthogonal aligned states using an electro-optic fluid fiber component. We show by digitally switching the nanorods that thermal rotational diffusion of the nanorods can be circumvented, demonstrating an approach to achieve submicrosecond switching times. We also show, from an initial unaligned state, that the nanorods can be aligned into the applied electric field direction in 110 ns. The high-speed digital switching of plasmonic nanorods integrated into an all-fiber optical component may provide opportunities for remote sensing and signaling applications. © 2017 Author(s).