Multi-functional, tunable microfluidic optical fiber devices

Thermal effects in passive optical silica fibers with copper winding were investigated. A numerical model of the fibers heating under laser radiation propagation conditions is proposed. A method for optical power measurements of the fiber lasers is proposed.

Synthetically analyze the power distribution communication network technology in the smart power grid link. It mainly includes the summary of the smart distribution network, electric power communication backbone network and then layer communication requirements, the network mode and the application mode of WLAN technology in the distribution network, EPON network technology, micropower wireless technology, PTN technology and power broadband wireless systems. State the demand of the smart power distribution business and put forward technical guidance for the smart power distribution communication network scheme. In view of the complex distribution network architecture, more nodes and scattered, complex business types data business needs, put forward the integrated solutions of optical fiber communication as the backbone access, wireless bandwidth, passive optical communication as the coverage, the short distance wireless communication as the main terminal access. It provides a reference for the communication plan of distribution side.

We present an integrated tunable liquid-core/liquid-cladding (L2) optical fiber, based on a novel three-dimensional hydrodynamic focusing scheme that enables the production of a tunable circular liquid core located in the center of the channel, regardless of the flow-rate ratio of the cladding and core liquids.

Electrically tunable optical fiber device based on hollow-core fiber infiltrated with liquid crystal

A method for obtaining the mode characteristics of a tunable filter by a polymer-dispersed liquid crystal (TSFP) is presented, where the optical characteristics are analyzed using the coupled-mode theory. The TSFP is modeled as a fiber-to-planar waveguide (PWG) coupler with 4 layers, including a fiber cladding layer, a polymer-dispersed liquid crystal (PDLC) as a buer layer, a PWG layer, and overlay layer. When applied to a 3-layer waveguide without a buer layer, the proposed model gave more exact solutions for the TSFP. The coupling is easily tuned by using the heat of the electrode, and more occurred for the buer layer with a higher index of refraction.

Being the new frontier of science and technology, as the near earth space begins to attract attention, low cost and rapidly deployable earth observation satellites are becoming more important. Among other things these satellites are expected to carry out missions in the general areas of science and technology, remote sensing, national defense and telecommunications. Except for critical missions, constraints of time and money practically mandate the use of commercial-off-the-shelf (COTS) components as the only viable option. The near earth space environment (~50-50000 miles) is relatively hostile and among other things components/devices/systems are exposed to ionizing radiation. Photonic devices/systems are and will continue to be an integral part of satellites and their payloads. The ability of such devices/systems to withstand ionizing radiation is of extreme importance. Qualification of such devices/systems is time consuming and very expensive. As a result, manufacturers of satellites and their payloads have started to ask for radiation performance data on components from the individual vendors. As an independent manufacturer of both passive and active specialty silica optical fibers, Nufern is beginning to address this issue. Over the years, Nufern has developed fiber designs, compositions and processes to make radiation hard fibers. Radiation performance data (both gamma and proton) of a variety of singlemode (SM), multimode (MM), polarization maintaining (PM) and rare-earth doped (RED) fibers that find applications in space environment are presented.

Novel chalcogenide glass-based fiber opens up the mid-infrared (MIR) range for real-time monitoring and control in medical diagnostics and chemical processing. Fibers with long wavelength cut-off are of interest here. Sulfide, selenide and telluride based chalcogenide glass are candidates, but there are differences in their glass forming region, thermal stability and in the short and long wavelength cut-off positions. In general sulfide and selenide glasses have greater glass stability, but shorter long-wavelength cut-off edge, compared to telluride glasses; selenide-telluride glasses are a good compromise. Low optical loss selenide-telluride based long wavelength fibers could play a substantial role in improving medical diagnostic systems, chemical sensing, and processing, and in security and agriculture. For biological tissue, the molecular finger print lies between ~3-15 μm wavelengths in the MIR region. Using MIR spectral mapping, information about diseased tissue may be obtained with improved accuracy and in vivo using bright broadband MIR super-continuum generation (SCG) fiber sources and low optical loss fiber for routing. The Ge-As-Se-Te chalcogenide glass system is a potential candidate for both MIR SCG and passive-routing fiber, with good thermal stability, wide intrinsic transparency from ~1.5 to 20 μm and low phonon energy. This paper investigates Ge-As-Se-Te glass system pairs for developing high numerical aperture (NA) small-core, step-index optical fiber for MIR SCG and low NA passive step-index optical fiber for an in vivo fiber probe. Control of fiber geometry of small-core optical fiber and methods of producing the glass material are also included in this paper.

Tunability of optical signal filters such as fiber Bragg gratings is important for high volume data communications. A magnetically tunable and latchable optical fiber Bragg grating structure has been devised, and a fine wavelength control as well as a broad-range wavelength tunability has been demonstrated. A spinodally decomposed, anisotropically elongated microstructure was induced in Fe–Cr–Co alloys to fabricate square-loop, programmable magnets. The adjustable attractive force between the magnetic poles was used to controllably strain the grating and induce a very large shift in the Bragg reflection wavelength by as much as 15 nm (which is equivalent to more than 36-channel span in a high density optical communication system). This novel approach can be useful not only for a variety of optical communication networking applications, but also for imparting latchable reconfiguration of structural periodicity and functional properties in a wide class of materials and devices.

The chemistry of sol-gel derived silica and refractive metal oxide has been systematically studied. Sol-gel processes have been developed for preparing porous silica and semiconductor metal oxide materials. Micelle/reversed micelle techniques have been developed for preparing nanometer sized semiconductor metal oxides and noble metal particles. Techniques for doping metal ions, metal oxides and nanosized metal particles into porous sol-gel material have also been developed. Optical properties of sol-gel derived materials in ambient and high temperature gases have been studied by using fiber optic spectroscopic techniques, such as fiber optic ultraviolet/visible absorption spectrometry, fiber optic near infrared absorption spectrometry and fiber optic fluorescence spectrometry. Fiber optic spectrometric techniques have been developed for investigating the optical properties of these sol-gel derived materials prepared as porous optical fibers or as coatings on the surface of silica optical fibers. Optical and electron microscopic techniques have been used to observe the microstructure, such as pore size, pore shape, sensing agent distribution, of sol-gel derived material, as well as the size and morphology of nanometer metal particle doped in sol-gel derived porous silica, the nature of coating of sol-gel derived materials on silica optical fiber surface. In addition, the chemical reactions of metal ion, nanostructured semiconductor metal oxides and nanometer sized metal particles with gas components at room temperature and high temperatures have also been investigated with fiber optic spectrometric methods. Three classes of fiber optic sensors have been developed based on the thorough investigation of sol-gel chemistry and sol-gel derived materials. The first group of fiber optic sensors uses porous silica optical fibers doped with metal ions or metal oxide as transducers for sensing trace NH{sub 3} and H{sub 2}S in high temperature gas samples. The second group of fiber optic sensors uses sol-gel derived porous silica materials doped with nanometer particles of noble metals in the form of fiber or coating for sensing trace H{sub 2}, NH{sub 3} and HCl in gas samples at for applications ambient temperature. The third classes of fiber optic sensors use sol-gel derived semiconductor metal oxide coating on the surface of silica optical fiber as transducers for selectively sensing H{sub 2}, CH{sub 4} and CO at high temperature. In addition, optical fiber temperature sensors use the fluorescence signal of rare-earth metal ions doped porous silica optical fiber or the optical absorption signal of thermochromic metal oxide materials coated on the surface of silica optical fibers have also been developed for monitoring gas temperature of corrosive gas. Based on the results obtained from this project, the principle of fiber optic sensor techniques for monitoring matrix gas components as well as trace components of coal gasification derived syngas has been established. Prototype sensors for sensing trace ammonia and hydrogen sulfide in gasification derived syngas have been built up in our laboratory and have been tested using gas samples with matrix gas composition similar to that of gasification derived fuel gas. Test results illustrated the feasibility of these sensors for applications in IGCC processes.

The Fibre Optic Well Monitoring (FOWM) system performs permanent downhole measurements of pressure and temperature. The system has no electronic components downhole and is based on a resonating silicon micro-machined structure, which is excited and interrogated optically through an optical fibre. By using passive optical sensors downhole and optical fibre communication, much of the system complexity can be removed from the harsh downhole environment and brought to the more benign seabed or production platform environment. This results in a reliable system even for high temperature operation.

This paper presents a real-time remote water level monitoring system based on dense wavelength division multiplexing (DWDM)-passive optical fiber sensor (OFS) network for the application of the Internet of Things (IoT). This network employs a broadband light source based on amplified spontaneous emission (ASE) as a seed light. This ASE light is spectrum-sliced by an athermal type arrayed waveguide grating (200 GHz × 16 channel), then distributed towards multiple sensing units (SU). Here, 16 SUs are installed vertically at the specified height in the water pool according to the design specification (i.e., spatial resolution). Then, each SU reflects an optical spectrum having a different reflection coefficient depending on the surrounding medium (e.g., air or water). By measuring these reflected optical spectra with an optical spectrum analyzer, the water level can be easily recognized in real time. However, as the sensing distance increases, system performance is severely degraded due to the Rayleigh Back-Scattering of the ASE light. As a result, the remote sensing capability is limited at a short distance (i.e., <10 km). To overcome this limitation, we propose a simple signal processing technique based on feature extraction of received optical spectra, which includes embedding a peak detection algorithm with a signal validation check. For the specific, the proposed signal processing performs the peak power detection, signal quality monitoring, and determination/display of the actual water level through three function modules, i.e., data save/load module, signal processing module, and Human–Machine Interface display module. In particular, the signal quality of the remote sensing network can be easily monitored through several factors, such as the number of spectral peaks, the wavelength spacing between neighboring peaks and the pattern of detected peak power. Moreover, by using this validation check algorithm, it is also possible to diagnose various error types (such as peak detection error, loss of data and so on) according to the pattern of measured optical spectra. As a result, the IoT sensor network can recognize 17 different level statuses for the water level measurement from a distance of about 25 km away without active devices such as optical amplifiers (i.e., passive remote sensing).

The optical fiber has been extensively used as a sensor in some special fields. Because the optical fiber exists crackles itself and also produce the micro-crack as well as local damage, the fatigue behavior of the optical fiber become the main problem we care about. This paper presents the experimental study on the fatigue performance of bare fiber under static, dynamic and cyclic load. The corresponding fatigue life index (Stress corrosion index) n can be obtained, which are 17.14, 11.83 and 5.88, respectively. The experiment data reveal that fatigue life index is related to loading mode and is treated as the indicator of crack propagation resistance of materials. Because dynamic and cyclic loads can induce additional damage, the fatigue life declines dramatically under the same stress levels.

Optical fibers have been the basis of the modern information technology since Kao and Hockham proposed glass waveguides as a practical medium for communication in 1965. A lot of different optical fiber active/passive devices including couplers, interferometers, gratings, resonators and amplifiers have been widely employed for applications on telecommunications and sensing networks (Agrawal, 2002). For a number of applications, it is important to reduce the device’s size. Small size is often attractive for particular sensing applications because of some benefits such as fast response to detecting small objection with little perturbation on the object being measured. There are two steps to obtain fiber devices as small as possible. First, it is to taper or etch the fiber and reduce its diameter. A subwavelength-scale microfiber is the basic element of miniature fiber devices and subsystems (Tong et al., 2003; Brambilla et al., 2004, 2005, 2010). The second is to engineer the microfiber to realize miniature version of conventional fiber devices. There are various fabrication methods to engineer the microfiber, such as CO2 laser, femtosecond (fs) laser, HF acid etching, arc splicing and focused ion beam (FIB). Most of these techniques have the difficulties in carving the microfiber freely because of the resolution. The latest progress in FIB technique has opened a new widow for ultra-small size fiber devices. So far, FIB is the most flexible and powerful tool for patterning, cross-sectioning or functionalizing a subwavelength circular microfiber due to its small and controllable spot size and high beam current density. FIB systems have been produced commercially for approximately thirty years, primarily for large semiconductor manufacturers. FIB systems operate in a similar fashion to a scanning electron microscope (SEM) except, rather than a beam of electrons and as the name implies, FIB systems use a finely focused beam of ions that can be operated at low beam currents for imaging or high beam currents for site specific sputtering or milling (http://en.wikipedia.org/wiki/Focused_ion_beam). The fine and controllable ion spot size and high beam current density are perfect for microand nano-fabrications with high spatial resolution (~ 10 nm). As a result, FIB has recently become a popular candidate for fabricating high-quality micro-devices or high-precision microstructures. Originally, FIB processing was used for mask repair (Liang et al., 2000), integrated circuit chip repair/modification (Liu et al., 2006), cross-sectional imaging of critical parts of

The modal characteristics of tapered single mode optical fibers and its strain sensing characteristics by using mechanically induced long period fiber gratings are presented in this work. Both Long Period Fiber Gratings (LPFG) and fiber tapers are fiber devices that couple light from the core fiber into the fiber cladding modes. The mechanical LPFG is made up of two plates, one flat and the other grooved. For this experiment the grooved plate was done on an acrylic slab with the help of a computer numerical control machine. The manufacturing of the tapered fiber is accomplished by applying heat using an oxygen-propane flame burner and stretching the fiber, which protective coating has been removed. Then, a polymer-tube-package is added in order to make the sensor sufficiently stiff for the tests. The mechanical induced LPFG is accomplished by putting the tapered fiber in between the two plates, so the taper acquires the form of the grooved plate slots. Using a laser beam the transmission spectrum showed a large peak transmission attenuation of around -20 dB. The resultant attenuation peak wavelength in the transmission spectrum shifts with changes in tension showing a strain sensitivity of 2pm/μɛ. This reveals an improvement on the sensitivity for structure monitoring applications compared with the use of a standard optical fiber. In addition to the experimental work, the supporting theory and numerical simulation analysis are also included.

Practical optical fiber devices, particularly erbium-doped fiber amplifiers (EDFAs), are poised to tap the tremendous bandwidth of optical fibers in next-generation lightwave transmission systems, while enhancing network flexibility and reliability. Optical fiber amplifiers have come a long way since the first demonstration of a neodymium-doped type by Snitzer and Koester in 1964. It was not until the mid-1980s, however, that researchers began to revitalize and extend the field of rare-earth doped fiber devices by combining the technologies of low-loss silica optical fibers, rare-earth doped lasers, and semiconductor pump sources. Later this year, they will be practically applied in a big way.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>