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For the last few years, we have been carrying out tip-clearance (TC) measurements in turbine rigs using optical sensors in collaboration with the Aeronautical Technologies Center. Several turbines with different blade profiles have been tested with satisfying results. The reflective intensity-modulated sensor used in these tests is based on a trifurcated bundle of optical fibers. This sensor is the ideal candidate for TC measurements because of its low cost, simplicity, robustness and the capability of performing tip-timing measurements (TT) employing the same probe. In the case of TC measurements, the main requirement is a precision of at least 30 μm. In order to get this precision, the latest improvements of the sensor have been focused on reducing the modal noise at the endface of the transmitting fiber of the bundle. For this purpose, different approaches were developed using mode-scramblers, plastic optical fibers and a single-mode illuminating fiber. The results obtained in the tests demonstrate that it is possible to achieve the demanded precision. [ABSTRACT FROM AUTHOR]

Optical fiber sensors based on Brillouin scattering have been vigorously studied for structural health monitoring due to their capability of distributed strain and temperature measurement. However, real-time distributed strain measurement has been achieved only for two-end-access systems, which reduce the degree of freedom in embedding the sensors into structures and make the measurement no longer feasible when extremely high loss or breakage occurs at a point of the sensing fiber. Here we demonstrate real-time distributed measurement by intrinsically one-end-access "reflectometry" configuration by use of a correlation-domain technique. This system shows high performances, such as ultrahigh-speed operation (strain sampling rate of up to 100 kHz), high spatial resolution, wide strain dynamic range (up to > 2.0%), high signal-to-noise ratio, and system simplicity (cost efficiency). Breakage detection, tracking of a propagating mechanical wave, and distributed measurement using a plastic optical fiber are also demonstrated. [ABSTRACT FROM AUTHOR]

In this paper, we evaluate the biochemical protocol that has been used in our studies, for the immobilization of antibodies in cladding and uncladding Plastic Optical Fibers. Immobilization of antibodies anti-E.coli is the primary step in developing a biological immunosensor. This immunosensor is based on the immunocapture methodology, where the target cells (bacteria), are captured through the strong link with the recognition element (antibodies), identifying, in minutes, the presence of E.coli in contaminated water. [ABSTRACT FROM AUTHOR]

Optical sensors offer important advantages for sensing applications, compared to their electronic counterparts. These include electrical passiveness and insensitivity to electromagnetic interference. Of considerable interest are large two-dimensional arrays of optical sensors, fabricated in polymers using printing techniques. We describe here the design of waveguide-Bragg-gratingbased temperature sensors, fabricated by replication technologies. In contrast to silica fibers, thermal sensitivity of polymeric waveguide Bragg gratings is strongly dependent on the chemical and physical material properties. We introduce simulation results for waveguide and grating design and describe major differences between silica-based and polymeric waveguides with respect to their thermal expansion and thermo-optic coefficients. [ABSTRACT FROM AUTHOR]

A temperature-dependence coefficient of Brillouin frequency shift (BFS) in plastic optical fibers (POFs) is known to start decreasing drastically at a certain "Brillouin critical temperature". Here, we study the relationship between the critical temperature and the core glass transition temperature (Tg) using five poly(2,2,2-trifluoroethyl methacrylate) samples with different Tg values. In all the samples, the BFS is found to start decreasing abruptly at a temperature lower than Tg by approximately 10 °C, which agrees well with the phase transition starting temperature measured by using a differential scanning calorimeter. Thus, the critical temperature in POFs is shown to be adjustable by controlling Tg, leading to the possible development of distributed temperature sensors with ultra-high sensitivity. [ABSTRACT FROM AUTHOR]

In this work, we tested different POF biosensor formats in different concentrations of bacterial supensions. These biosensors are based on the immunocapture technique, and are prepared from a protocol for fixation of antibodies. The lock-in amplifier used in optoelectronic system which takes readings of the biosensor was replaced by a Microcontroller Arduino, simpler order. It was concluded that the variation of radius on the biosensor architecture provides a more sensitive reading of bacteria concentrations 106 and 104, allowing the further reading of other concentrations. [ABSTRACT FROM AUTHOR]

As a complement to classical sensors, Distributed Optical Fiber Sensors now play a prominent role in several engineering fields and act as an antenna array. Depending of the devices used (Raman, Rayleigh, or Brillouin scattering), measurement record depend on temperature, strain, or pressure profile. As the wanted signal is often hidden by noise and other undesired sources, we can express the problem as a source separation problem. In this paper, we show that with the help of recent techniques based on data decomposition and source separation (PCA, ICA NMF techniques) from the virtual antenna, we can accurately identify water leakages from a noisy Raman spectra or a strain profile from Brillouin spectra with a spatial resolution of 1cm instead of 1 meter for classical devices. [ABSTRACT FROM PUBLISHER]

In the safety analysis for the core of the 4th Generation Reactors, the Total Instantaneous Blockage (TIB) is a hypothetic accident scenario involving the melting of the blocked subassembly with a risk of propagation to the neighbouring subassemblies. To avoid this latter consequence a detection system has to scram the reactor. For Superphénix or EFR project a Delayed Neutron Detection Integrated (DND I) was considered as efficient to limit the melting to the first neighbouring subassemblies. Nonetheless for the CFV core the objective of improving the safety leads to limit the melting to the blocked subassembly. For this purpose, the CEA has launched a program development to find a new detection method. This paper provides a brief review of the feedback of R&D, progress and program on the various early non-nuclear detection methods investigated by the CEA: • Temperature measurement at the subassemblies outlet by thermocouples. The advantage of this method is that it will require no additional instrumentation to that already present for continuous monitoring. • Temperature measurement at the subassemblies outlet by Optical Fibers Bragg Grating (OFBG). This technology has the electromagnetic immunity, compactness and short response time. • Temperature measurement at the subassemblies outlet by ultrasound. The measuring point is located closer to the head subassembly and the response time could be shorter. • Acoustic detection of sodium boiling. Boiling occurs early in the accident progress and the area to be monitored may be covered by few sensors. • Subassemblies loss of flow detection by eddy-current flowmeters. This method seems logically the easiest and the most immediate method to detect a blockage. To date, none of these methods has been fully demonstrated to be feasible. It should be noted that temperature measurement methods will probably consist of the detection of a low increase rate using specific signal processing. These methods have been compared according to their performance that may be expected and their maturity level. The shorter time to qualifying is for eddy-current flowmeters and thermocouples. [ABSTRACT FROM PUBLISHER]

Considerable attention has been paid to aligned polymer nanofibers because of their appealing mechanical and piezoelectric properties. With modified electrospinning, the aligned poly (vinylidene fluoride) (PVDF) nanofibers can be produced. However, the roles of mechanical stretching and electrical poling during this process require further investigation. Here, we utilize a rotary drum to collect the fibers by both electrospinning and mechanical drawing approaches. The fiber mats were characterized by Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectrometer (FTIR) and X-Ray Diffraction (XRD), and were directly made into sensing films without post electric poling treatment. Their piezoelectricity was measured in our home-made dynamic air pressure sensor. Results show that the β-phase predominates in both electrospun and mechanically-spun nanofibers. However, sensor based on electrospun β-PVDF fiber mat presented a sensitivity of 178 mV/kPa, while only a very weak output signal was observed in the mechanically spun β-PVDF fiber mat. Therefore, mechanical stretching and electrical poling may play key roles in inducing the β-phase and orienting the dipoles in a preferential direction during electrospinning process, respectively. [ABSTRACT FROM PUBLISHER]

We described a calibration method for 3-dimensional tip position tracking sensor. This sensor consists of three optical fibers containing multiple fiber Bragg gratings. Each fiber Bragg grating measures a strain at their position as the sensor bends, then curvature and bending direction at the position is calculated. Finally, the position of the sensor tip was calculated from the information. Because the location of each fiber Bragg grating is very important to calculate tip position exactly, compensation to minimize the error caused by fabrication process is inevitable. The sensor was deflected in eight directions, and the position of the sensor tip was measured exactly by the camera with telecentric lens. Next, the deflected distance and tilted angle of the tip position from the original position were calculated by shape sensor. The two data were compared and compensated using simple linear regression analysis. The final error of calibrated single bending system was less than 1%. [ABSTRACT FROM PUBLISHER]

In this work, we present the results of a sensor exploiting a coating consisting of lutetium bisphthalocyanine (LuPc2) dispersed in a porous silica matrix deposited by a sol-gel process. LuPc2 shows a gasochromic effect in the telecommunication wavelengths range. The absorption spectrum in this range strongly decreases in contact with NO2. The sensor consists then in a coating deposited on a single-mode silica fiber tip in order to form a Fabry-Pérot cavity. An amplitude change in the reflected spectrum is observed after contact with 1 ppm NO2 thus showing its sensitivity to that gas. [ABSTRACT FROM PUBLISHER]

While interferometric fiber optic gyroscopes (IFOGs) are used in the inertial guidance area as replacements for traditional spinning rotor gyroscopes, the presence of optical noise as well as cost of such systems demonstrate that IFOGs still have not been optimized for this purpose. This paper proposes a solution to these problems, describing the design details and features of an optimized prototype attitude control system that uses depolarized IFOGs in the gyros and mounts depolarizers simultaneously on the entrance and exit of the fiber loop. Preliminary tests of an attitude control system built using these IFOGs demonstrate that this relatively low-cost system achieved the objective of compensating for the earth's spin and thus could be deployed as a system for the stabilization of telescopes. [ABSTRACT FROM PUBLISHER]

This paper describes a feasibility evaluation of multi-point sensing for hetero-core spliced (HC) optical fiber sensor network by using the internet-based protocol. This sensor is able to serve as a medium for data communications and as a sensor in the same fiber line simultaneously. In our previous study, we have successfully developed an optical fiber sensor network integrating data communications and sensing function using the (HC) optical fiber sensor. In order to extend the application of sensor network and remotely manage it, a network management method is required. We proposed and constructed an internet-based remote data acquisition sensor network by using one of the standard operation and maintenance protocols for the internet — Simple Network Management Protocol. This study aims to distinguish the status of fiber optics sensors for the management of the sensor network. The sensor network has been verified and the results demonstrated that the data communications is successfully performed in the systems while distinguishing status of HC optical fiber sensors. [ABSTRACT FROM PUBLISHER]

This paper presents the preparation and characteristics of an intensity-based tapered plastic optical fiber (POF) coated with a mixture of poly-vinyl alcohol (PVA) and SiO2 for sensing ethanol concentration in H2O. The 1.0 mm-diameter POF was tapered to a diameter of about 730 μm using tensile tester with thermostatic chamber and the total tapered length was 5.0 cm. The tapered section was coated with a sensing element comprising of a mixture of PVA polymer and SiO2 with a ratio of 9.0v%:1.0v%. A thin layer of protective coating was applied on this sensing element after it was thermally cured at 80°C. More light was guided into the core of the POF at sensing area with increasing concentration of ethanol. This effect is depicted from linear increase of light intensity within 630 nm to 644 nm wavelength region. The POF ethanol sensor has shown to exhibit repeatable results for measurement of 2.0% to 10.0% and 0.2% to 1.0% concentration of ethanol in water with the sensor sensitivity measured up to 35.67 per wt% of ethanol concentration. [ABSTRACT FROM PUBLISHER]

High precision refractive index (RI) measurement was achieved by utilizing the phase term of a Fourier-transformed interference signal. With a fiber-optic Fabry-Perot RI sensor, it was verified that the proposed method had high resolving performance in RI determination compared with the conventional wavelength tracing method. Even with a tiny variation in liquid RI, the Fourier-transformed phase shift showed high accuracy as much as 0.99995 of R square value. [ABSTRACT FROM PUBLISHER]

In this study, design and fabrication of a novel bent-tapered optical fiber sensor for enhanced Evanescent Wave Absorption (EWA) based sensing application is demonstrated. A combination of bending and tapering acts as a mode converter, which results in high penetration depth of evanescent field. In addition, tapered region of the probe increases the coupling efficiency at the detector end by V-number matching and thus helps in improving the signal to noise ratio significantly. Effect of taper ratios (ranging from 0.17 to 1) was investigated using fluorescein isothiocyanate (FITC) dye as a model analyte, binding directly to the functionalize fiber. Taper ratio of 0.37 showed the highest sensitivity towards FITC, and was found to be 2.4-fold better compared to untapered bent probe of similar length. The larger penetration depth coupled with higher sensitivity will be beneficial for sensing application involving larger analytes e.g. bacteria and virus. [ABSTRACT FROM PUBLISHER]

3D shape sensing of flexible snakelike instruments using fiber Bragg gratings is a current research topic in robot assisted single port surgery (SPS). Though some results are achieved, a practical implementation that can be applied for instruments in SPS has not yet been particularly described. The specific instruments have special technical properties as e.g. they allow very small bending radii. In this work, approaches for the building process of a shape sensor that meets the special technical requirements of these instruments are pursued and evaluated. The theoretical foundations and calculation methods are adapted to the built shape sensor. The overall goal is to develop a building process for a miniaturized shape sensor that can be integrated into medical instruments. A first macro sized shape sensor has been successfully produced, but the miniaturization causes serious difficulties. In this work experiences with the fiber handling and occurring problems in production are described in detail. In summary, the realization of a shape sensor has already proven to be technically feasible but for miniaturization, further research concerning the used materials and the practical fiber handling is necessary. [ABSTRACT FROM PUBLISHER]

The measurement of refractive index of liquids is of great importance as it is its prime optical property. There are several methods of refractive index measurement for liquids. But the accuracy of measurement is influenced by temperature fluctuations. In this paper, a method is proposed for the implementation of an accurate, portable and temperature resilient, fiber based refractometer for liquids. The analog front end of the refracto meter alone is a cost effective adulteration detector. It can be calibrated to measure the amount of adulteration or absolute refractive index of liquids. The temperature resilience in measurement is achieved using an instrumentation amplifier with high Common Mode Rejection Ratio (CMRR). This refractometer is implemented both using glass and plastic fibers. [ABSTRACT FROM PUBLISHER]

We propose a coupled add-drop ring resonator configuration for highly sensitive sensing. We theoretically examine the asymmetric Fano lineshapes of the two output ports of the proposed structure. The sharpness and the asymmetricity of the Fano resonance are linked to the high sensitivity. We theoretically calculate the sensitivity of the proposed coupled add-drop ring resonator as a sensor. The sensitivities of the two ports of our configuration can achieve 799.4 / rad (drop port) and 503.7 / rad (through port) respectively. The performance of the proposed structure is enhanced by almost 20 times than that of the single ring resonator based add-drop interferometer by introducing the upper ring resonator. This proposed configuration enables highly sensitive, compact and stable sensors. [ABSTRACT FROM PUBLISHER]

Photonic sensor networks possess the unique potential to provide the instrumentation infrastructure required in future smart grids by simultaneously addressing the issues of metrology and communications. In contrast to established optical CT/VT technology, recent developments at the University of Strathclyde in distributed point sensors for electrical and mechanical parameters demonstrate an enormous potential for realizing novel and effective monitoring and protection strategies for intelligent electrical networks and systems. In this paper, we review this technology and its capabilities, and describe recent work in power system monitoring and protection using hybrid electro-optical sensors. We show that wide-area visibility of multiple electrical and mechanical parameters from a single central location may be achieved using this technology, and discuss the implications for smart grid instrumentation. [ABSTRACT FROM PUBLISHER]

A non-contacting, non-destructive method for the characterization of small signal properties on piezoelectric single fibers is presented. The technique comprises ultrasound generation, propagation and detection within the fiber. Two electromechanically active segments are prepared by applying two pairs of ring electrodes and subsequent poling of the interspace material. Measurements are carried out in pulse-echo-mode by transmitting and receiving ultrasound with one of the two poled segments. The other segment operates under either closed or open circuit conditions causing a small time difference during runtime measurement. Applying the piezoelectric equations, the electromechanical data k33 and d33 and the elastic compliance s33 can be calculated. The practicability of the method was tested and verified for PZT fibers derived from the polysulphone process. The validity of the ultrasound runtime measurements is proved by simulation using an electromechanical model. [ABSTRACT FROM PUBLISHER]

Online monitoring of power devices' state is a very important part of the Smart Grid (SM) building plan. Icing on the overhead transmission lines cause great accidents and vast economic loss. In China, icing monitoring technology and relative research is a hot point. The current operating icing monitoring systems based on electrical measurement do not work efficiently because it cannot solve the problem of electromagnetic interference with power supply. The fiber optic sensors, with light as the measurement media, solve those problems perfectly. In this paper, an icing monitoring system based on Fiber Bragg Grating (FBG) sensors is proposed. The system architecture design, the sensors fixing methods, and the development of the monitoring software, are introduced in detail. [ABSTRACT FROM PUBLISHER]

Fibre optic sensing technology is one of the versatile and effective sensing technologies in the modern sensor era. Optical fibre sensing successfully manage to catch the positive attention of premium sensor-fabrication industries as well as the top researchers, scientists and automation engineers are preferring to apply FOS technology in various field applications in recent times. Furthermore, fiber optic sensors have a diversity of particular advantages such as faster response compare to other available sensing methods, economical fabrication procedure, very user-friendly, exceedingly receptive plus non-responsive to electromagnetic interference. This paper comprehensively discusses about various important large-scale practical applications of FOS technology both in government sectors as well as in private sectors. This paper also emphasizes on environmental application of FOS technology and also explains in details why FOS is preferable option for water quality management system. This paper also specifically highlights about latest available FOS materials which has been applied in the field of water quality management extensively to ensure a sustainable environment and to check effectively the quality of water for local residents. A dedicated part of this paper also discusses the significant advantages of FOS technology in annual rainfall trend analysis. [ABSTRACT FROM PUBLISHER]

Fiber optic sensors are one of the most competent, functional and accessible types of sensors that can be applied for diverse purposes and it delivers sustainable and effective results for most of the cases. It is frequently used to sense, measure and evaluate the physical and chemical properties such as microbending, strains, vibrations, accelerations, linear and rotary position, temperatures, pressures, determination of pH, fluid material's refractive index, checking of long pipeline's status etc. Polydimethylsiloxane (PDMS) is a special form of silicone elastomer or silicone rubber and it has very realistic and particular advantages as a diaphragm or coating material for fiber optic sensing technology for improved, more precise and steady output. This paper presents a comprehensive analysis of prior FOS technology with various coating materials for enhanced environmental application. A dedicated part of this paper also explains the exclusive characteristics of PDMS material and suitability for FOS coating. Potential future scope of PDMS material in FOS technology is discussed in the final section of this paper. [ABSTRACT FROM PUBLISHER]

We propose to use focused femtosecond laser pulses to inscribe scattering damage in the core of polymer optical fibers for interrogation as quasi-distributed sensor points by optical time domain reflectometry. Fiber bend measurement is demonstrated on off-center inscribed sensor points and absolute temperature measurement is presented by evaluation of the constant backscatter intensities from the inscribed structures relative to temperature-dependent Rayleigh scattering. Application possibilities and limitations of this new approach are discussed. [ABSTRACT FROM AUTHOR]

In this work, four U-shaped Plastic Optical Fiber (POF) sensors manufactured with a specially developed machine are characterized and implemented for refractometry. The measurement set-up consists of an LED and a photodiode connected to the ends of the fiber, and the signal is detected by a Lock-in Amplifier implemented in Matlab®. The calibration process led to the evaluation of the sensitivity, accuracy and repeatability by using solutions of sucrose for obtaining refractive indexes (RI) in the range 1.33 - 1.39. [ABSTRACT FROM AUTHOR]

A method is reported for improving the performance of a Fabry-Pérot optical accelerometer, based on the use of a V-beam mechanism to amplify the proof mass displacement. Amplification allows the sensitivity to be increased without compromising bandwidth or requiring an increase in cavity finesse. An analytical expression relating the amplification factor to the V-beam length, width and angle was derived and used to produce a series of differently angled devices. A 1.9° device was capable of detecting accelerations from 0.01 to 10 g rms. The 1.33° accelerometer produced an amplification of 18.6 ± 6.4. [ABSTRACT FROM PUBLISHER]

This paper reports a compact optical wavelength tracker, which consists of an electrically controlled tunable micro-ring resonator and a flip-chip bonded photodiode. The input optical wavelength is measured and the wavelength change is tracked by analyzing the photocurrent variation of the photodiode. This wavelength tracker has compact size (0.5 mm × 1.5 mm), high resolution (3 pm), cost-effective and can be easily integrated with other devices on a single chip. It offers a simple chip-level optical wavelength tracking and detection approach for low-cost batch production, which has potential applications in optical sensors and fiber communications. [ABSTRACT FROM PUBLISHER]

This paper adopts the design strategies involved in the biological flow sensors present on the body of the blind cave fish in order to engineer MEMS artificial flow sensors by employing micro/nano fabrication technologies. The MEMS sensor developed consists of Si60 polymer haircells fabricated by stereolithography. Biomimetic cupular fibrils are developed by electrospinning a solution of polyL-lactide/e-caprolactone (PLC) to form nanofibers. A bio-inspired hydrogel cupula is fabricated using precision drop-casting methods which enhances the performance of the flow sensor over the naked haircell sensor. The pyramid shaped nanofibers formed act as a scaffold supporting the swollen hydrogel. [ABSTRACT FROM PUBLISHER]

An optical ac-current sensor with large range and high accuracy is designed, which is based on magnetostriction effect and fiber-loop cavity ring-down technique. The model of the sensor is proposed which discribed the relationship of current, magnetic field, strain and ring-down time of the fiber loop. Simulation results show that both the measurement range and accuracy of the sensor are depended on prestress. The sensor is capable of measuring ac currents in the 2–50kA and the best resolution upto 0.1 A. The analysis of materials characterization and modeling can support the actual design process. [ABSTRACT FROM PUBLISHER]

An extrinsic-type fiber Fabry-Perot interferometer is proposed and demonstrated for vibrometric applications. The sensor operates on the principle of a “virtual” pseudo-dual cavity generated within the sensing arm due to the introduction of an adapted polarization-controlling optics into the optical path of the sensing cavity. This configuration enables two sets of “quadrature phase-shifted” interference signals with a circular polarization state along the fiber to be obtained. Experimental results show the competency of this technique for solving directional ambiguity of the target movement, improving resolution in the displacement measurements and, more significantly, compensating the problem of polarization-induced signal fading (PIF) of the fundamental interference fringe. The fiber interferometer has been found capable of displacement measurements from approximately 0.2 μm to 87 μm with a λ/64 resolution. A reference sensor was used for comparison with output data from the interferometer where an average percentage displacement error of approximately 0.64% was subsequently obtained. [ABSTRACT FROM PUBLISHER]

This paper describes the development process of a multimedia handbook of sensors [1] implemented as a website (on-line or off-line), from selecting the appropriate technologies to the realization [2]. The focus is on the development of interactive models of sensors and on how to use modern methods for distributing and sharing information on websites. Each webpage in the multimedia handbook contains text description of specific sensor principle, basic physical equations, information about practical usage, an interactive animated Microsoft Silverlight model and links to other information sources for the specific type of sensor. [ABSTRACT FROM PUBLISHER]

In the recent years much research effort has been devoted to practical navigation problems in getting larger ships safely, especially liner mega size container ships, into existing harbours. The important point of any navigational analysis lies in the accurate determination of the ship's hull additional sinkage and possible trim changes (squat) generated by hydrodynamic forces when the ship is sailing in restricted waters. This paper aims at presenting the possibility of using optical fiber technology for precise static draft reading which will be used as a datum for further proceedings to determine current draft as one of the important elements on calculating ship's squat in a seaway, and their possible application in pilotage services. The loaded ships passage plan on pilot portable computer can be upgraded by the data of under keel clearance and ship's squat using appropriate software for predicting dangerous situation of grounding at seaway. The main goal is to point out that pilot on board ship can determine the ship's hull squat of the ship underway, and predict imminent danger of grounding due to reduce under keel clearance. [ABSTRACT FROM PUBLISHER]

Temperature and strain sensors based on Fiber Bragg Gratings (FBG) are the most common optical sensors today. The properties of these sensors are well known, however interrogation techniques are still not standardized. The interrogator units typically have a high price, limiting the usage of such optical sensors. By carefully studying the properties of several interrogation techniques and developing an optimized version we will demonstrate that it is possible to significantly reduce the price of interrogation units. For this reason, presented are measurements of both temperature and strain sensitivity performed in various conditions that will be used in development of cost-optimized interrogator. [ABSTRACT FROM PUBLISHER]

A homogeneous, intensity modulated salinity sensor using Photonic Crystal Ring Resonator (PCRR) is proposed and designed for monitoring the salinity of seawater from 0 to 40%(0 to 40g/L) over the temperature between 0 to 25°C. The capability of the proposed sensor for sensing the salinity between 0 – 40% is theoretically examined. The sensor is composed of periodic Si rods embedded in an air host and a circular PCRR that is placed between the inline quasi waveguides. The concentration of salinity in seawater, changes the refractive index of the seawater. The change in refractive index of the seawater changes the output signal intensity of the sensor as seawater flowing insider the sensor. By detecting the output power and mapping to the salinity level, the salinity can be evaluated. Approximately, 2.69% of output power reduction is observed for every increasing 5% (5g/L) of salinity as the seawater has a unique refractive index for each salt level. With this underlying principle, the performance of the sensor is analyzed for different temperature. [ABSTRACT FROM PUBLISHER]

In this paper, we present the implemented a 28-Gb/s a receiver optical sub-assembly (ROSA) module by employing the proposed TO-CAN package and flexible printed circuit board (FPCB). We have proposed that signal path between the TO-CAN package and the FPCB have straight-line path and the FPCB incorporate signal line with open stub in order to alleviate signal distortion due to impedance mismatch. The 3-dB optical-to-electrical (O-E) bandwidth and receiver sensitivity of the ROSA module were measured as over 17 GHz and below −14 dBm at extinction ratio of 12 dB and bit error rate of 10−12. [ABSTRACT FROM PUBLISHER]

Two different locations of Erbium Doped Fiber (EDF) in dual ring configuration to generate double frequency shifted of multiwavelength Brillouin Erbium fiber laser (BEFL) have been investigated. The experimental results show that the location of EDF has important roles to determine the number of output Stoke signals and tuning range. Beside the Erbium gain, the Brillouin gain also contributes to the performance of BEFL. By putting the EDFA next to the BP, more Stokes lines with wider tuning range were obtained compare by putting the EDF next to the gain medium was observed. [ABSTRACT FROM PUBLISHER]

Interferometer is a device, which splits light waves into two components. The two beams travel in different paths and recombine after some relative propagation phase delay. Among the most commercial interferometers in the optical industries are Michelson, Fabry-Perot and Mach-Zehnder. In this paper, the basic operating principles and application fields of each type of interferometer are reviewed. The optical designs were conducted by running a simulation on a commercial optical software package, ASAP. [ABSTRACT FROM PUBLISHER]

Distributed optical fiber sensors by using Brillouin optical time-domain analysis (BOTDA) have been developed extensively by many researchers. Coding pulsed pump light of the BOTDA is an effective way to improve the signal-to-noise ratio (SNR). This article reports a new way to configure electrical signals that are amplified by an AC-coupled highspeed amplifier and then fed into an electro-optic modulator to generate coded pump light. The new configuration caused little distortion of the amplified electrical signals and consequently produced coded pump light with a good waveform with the modulator. The optical SNR of the coded BOTDA signals achieved by the new configuration was about 1dB better than that by a conventional way for 32 bit-length code. [ABSTRACT FROM PUBLISHER]

A fiber Bragg grating (FBG) based surface plasmon resonance (SPR) sensor is investigated using 2-D finite difference time domain (FDTD) simulation. The sensitivity and accuracy of the sensor with and without gratings is observed as well as the effect of changing the grating distance on the resonant wavelength. The findings show that high sensitivity of above 500nm/RIU and a fourfold increase in signal to noise ratio (SNR) is obtained by introducing FBG to the basic fiber optic based SPR structure. Increasing the grating period results in a red shift in the resonant wavelength, thus enabling multiple sensor fabrication on a single fiber optic cable. Simulation of the FBG based SPR sensor to detect alcohol concentration from 0 to 100% in water is also demonstrated. [ABSTRACT FROM PUBLISHER]

Although commercial tunable optical filters with integrated electronic controls are available, it costs much more than a manually tunable filter. This paper aims to demonstrate a simple procedure on mounting a manually tunable bandpass filter (TBF), with a mathematical model to represent the relation between the sensor's output and the central wavelength of the filter. A position sensor is used to match the central wavelength of the filter and the sensor's output. This results in a simple mount to actuate the TBF and the position of the wavelength is simply translated in terms of the output voltage. Although the accuracy of the system is not commercial grade, a rudimentary setup with promising results can be observed. We present the mount using very simple components, utilizing motorized actuation, with an analog voltage output which can bear any desired resolution for digitization. Finally, a mathematical model is developed to represent the wavelength-voltage relation. This setup paves way for researchers to log the central wavelength from tunable filters without the need for any equipment, at a much lower cost compared to its commercial counterparts. [ABSTRACT FROM PUBLISHER]

Opportunities exist for energy efficiency improvement and greenhouse gas emission reduction in fossil energy based electrical power generation through deployment of embedded sensors operating at extreme temperatures and under harsh conditions. Despite inherent advantages of optical based sensors, published literature discussing optical sensing materials is limited for temperatures of operation greater than 500°C. A clear need exists for additional fundamental and applied research efforts. Published literature discussing sensor materials for high temperature optical chemical sensing applications are reviewed and research opportunities / needs are highlighted. [ABSTRACT FROM PUBLISHER]

Superconducting power lines, field windings, motors, and generators offer significant potential reductions in size, weight, and power loss for high current and high magnetic field applications. To avoid damaging these superconductors, adequate cable cooling is required during high current loads. Luna's fiber optic distributed temperature sensing technology (based on Rayleigh backscatter) has recently demonstrated cryogen monitoring capabilities down to 15 K over 20 m sensor lengths, providing real time characterization of cryogen flow transients and temperature distributions within flexible cryostats used to cool superconducting cables. [ABSTRACT FROM PUBLISHER]

Obtaining temperature information is of great significance to distinguish borehole conditions, monitor oil-field performance, and optimize working system after hydrocarbon exploration and production started. Distributed temperature sensor is developed successively at home and abroad on the issue of gaining continuous temperature profile, which enables the obtainment of wellbore temperature profile over a certain period of time thus ensuring good reliability and accuracy. Fundamental ideas and characteristics of distributed temperature sensor measurement system are introduced in this paper, especially its application status in the process of hydrocarbon exploration and production both at home and abroad. Solutions are presented based on the current deficiency analysis and application prospects are also predicted. [ABSTRACT FROM PUBLISHER]

The quarter-wave plate is a crucial element of fiber-optic current sensor. The Verdet constant fluctuation which is caused by temperature decreases the stability of fiber-optic current sensor. Yet the temperature dependence of Verdet constant can be inherently compensated by means of non-perfect quarter-wave plate. Based on this method, the scheme of inherent temperature compensation to the fiber-optic current sensor is analyzed and the previous algorithm which optimizes the parameter of non-perfect quarter-wave plate is improved. Compared to the previous optimization algorithm, the system is more stable after optimization according to the simulation result. The theoretical result identifies the result of experiment. It is significant to the manufacture of quarter-wave plate in practice. [ABSTRACT FROM PUBLISHER]

An integrated optical gyroscope based on a passive silica-on-silicon resonator with a footprint of about 20 cm2 is reported in this paper. The optical characterization of the cavity has been carried out and the main experimental results are discussed. We derive the sensor performance in terms of minimum detectable angular velocity (or resolution) δΩ, underlining also the impact of the insertion loss in the silica-on-silicon device. Finally, we describe some technical approaches for improving the resolution. [ABSTRACT FROM PUBLISHER]

In this communication we report the study of novel optical fibers doped by semiconductor quantum dots (QDs). Different approaches have been investigated to realize liquid-core fibers filled with PbSe QDs and hollow-core fibers with deposition of layers of these nanoparticles. The optical characterization demonstrates good levels of QD emission which can be tunable over a wide range of IR wavelengths. Finally, for the first time, we propose also the fabrication of PbS QDs solid-core fibers by melt and draw technique. These promising results could give birth to a new family of amplifiers and laser photonic devices. [ABSTRACT FROM PUBLISHER]

Results on the measurement of flexural and longitudinal acoustic waves propagating in an optical fibre are presented. Using the extrinsic Fabry-Perot interferometric technique, parameters such as the acoustical wavelength and the acoustical phase velocity can be assessed. [ABSTRACT FROM PUBLISHER]

Photonic crystal fibres (PCFs), silica nanowires and silica aerogel are all structures which deploy the high index contrast between silica glass and air to enhance photonic functionality. We shall discuss the latest results in nonlinear wavelength conversion and sensing using PCFs and aerogels. [ABSTRACT FROM PUBLISHER]

In recent years there has been an increasing research interest aimed at the development of innovative integrated optic gyroscopes. Some authors have investigated coupled-resonator waveguiding structures formed by microrings mainly for their capability of manipulating light velocity, proposing also their application in phasesensitive optic gyroscopes. In this work we analyze the main performance parameters of an integrated optic gyroscope consisting of a three coupled ring resonator structure having different radii and coupling coefficients. The main result is the enhancement of the scale factor of the multi-ring-based gyroscope, without increasing the overall footprint, with respect to a conventional single ring resonator gyro. The final sensitivity of the gyroscope is also evaluated and compared with the conventional integrated optic gyroscope configuration. [ABSTRACT FROM PUBLISHER]