Optical Fiber Devices Research Articles

Theoretical Approach of Soil Slope Slip Monitoring Based on Composite Optical Fiber Devices

Theoretical Approach of Soil Slope Slip Monitoring Based on Composite Optical Fiber Devices

Multifunctional Metamirror: Polarization Splitting and Focusing

Metasurfaces are paving the way to improve traditional optical components by integrating multiple functionalities into one optically flat metasurface design. We demonstrate the implementation of a multifunctional gap surface plasmon-based metasurface which, in reflection mode, splits orthogonal linear light polarizations and focuses into different focal spots. The fabricated configuration consists of 50 nm thick gold nanobricks with different lateral dimensions, organized in an array of 240 nm x 240 nm unit cells on the top of a 50 nm thick silicon dioxide layer, which is deposited on an optically thick reflecting gold substrate. Our device features high efficiency (up to ~65%) and polarization extinction ratio (up to ~30 dB), exhibiting broadband response in the near-infrared band (750-950 nm wavelength) with the focal length dependent on the wavelength of incident light. The proposed optical component can be forthrightly integrated into photonic circuits or fiber optic devices.

Tailoring the Optical Parameters of Optical Fiber Interferometer With Dedicated Boron‐Doped Nanocrystalline Diamond Thin Film

An optical fiber interferometer using nanocrystalline boron‐doped diamond film is investigated. The diamond films are deposited on glass plates using a Microwave Plasma‐Enhanced Chemical Vapor Deposition (µPE CVD) system. The growth time is 3 h, with boron doping level of 10 000 ppm producing films (B‐NCD‐10) of thickness ≈200 nm. The presence of boron atoms in the diamond film is evident in Raman spectrum as peaks at 1212 and 1306 cm−1. The scanning electron microscopy (SEM) images show homogenous and continuous surface morphology, thus enabling the use of the diamond film as a reflective layer in fiber optic devices. The optical fiber interferometric sensor in Fabry‐Pérot configuration with a diamond reflective layer as a mirror was designed and built. Measurements are performed using two superluminescent diodes with central wavelengths of 1290 and 1550 nm. The detection of the measured signal is achieved using an optical spectrum analyzer. All devices are connected with commercially available, single‐mode telecommunications fibers and coupler. Using B‐NCD‐10 films in fiber optic interferometer a very high value of the measured signal contrast is obtained, equal to 0.99. The use of B‐NCD‐10 film as a reflective surface allows the Fabry‐Pérot cavity length to be reduced while achieving very good signal visibility. Consequently, the volume of the sample in the cavity can be reduced, compared with that of the traditional mirrors.

Fiber optic shape sensor system for a morphing wing trailing edge

The objective of this work is to present a conceptual design and the modelling of a distributed sensor system based on fiber optic devices (Fiber Bragg Grating, FBG), aimed at measuring span-wise and chord-wise variations of an adaptive (morphing) trailing edge. The network is made of two different integrated solutions for revealing deformations of the reference morphing structure. Strains are confined to typical values along the span (length) but they are expected to overcome standard ranges along the chord (width), up to almost 10%. In this case, suitable architectures may introduce proper modulations to keep the measured deformation low while preserving the information content. In the current paper, the designed monitoring system combines the use of a span-wise fiber reinforced patch with a chord-wise sliding beam. The two elements make up a closed grid, allowing the reconstruction of the complete deformed shape under the acceptable assumption that the transformation refers to regular geometry variations. Herein, the design logic and some integration issues are reported. Preliminary experimental test results are finally presented.

Repetitive Immunosensor with a Fiber-Optic Device and Antibody-Coated Magnetic Beads for Semi-Continuous Monitoring of Escherichia coli O157:H7.

A rapid and reproducible fiber-optic immunosensor for Escherichia coli O157:H7 (E. coli O157:H7) was described. The biosensor consisted of a flow cell, an optical fiber with a thin Ni layer, and a PC linked fluorometer. First, the samples with E. coli O157:H7 were incubated with magnetic beads coated with anti-E. coli O157:H7 antibodies and anti-E. coli O157:H7 antibodies labeled cyanine 5 (Cy5) to make sandwich complexes. Then the Cy5-(E. coli O157:H7)-beads were injected into a flow cell and pulled to the magnetized Ni layer on the optical fiber set in the flow cell. An excitation light (λ = 635 nm) was used to illuminate the optical fiber, and the Cy5 florescent molecules facing the optical fiber were exposed to an evanescent wave from the optical fiber. The 670 nm fluorescent light was measured using a photodiode. Finally, the magnetic intensity of the Ni layer was removed and the Cy5-E. coli O157:H7-beads were washed out for the next immunoassay. E. coli O157:H7, diluted with phosphate buffer (PB), was measured from 1 × 105 to 1 × 107 cells/mL. The total time required for an assay was less than 15 min (except for the pretreatment process) and repeating immunoassay on one optical fiber was made possible.

Theoretical investigation of intensity-dependent optical nonlinearity in graphene-aided D-microfiber

We theoretically investigate the intensity-dependent optical nonlinearity in graphene-aided D-microfiber, by tuning the chemical potential of graphene and varying radial distance and radii of the D-microfiber. Utilizing an interplay between graphene and the enhanced evanescent field of a guided mode in the waveguide of interest, the net utility of nonlinear coefficient is harnessed up to a very high value of 106 W−1m−1. Importantly, which is ∼ two orders of magnitude larger than in PMMA–graphene–PMMA waveguide. The highly dispersive nature of the waveguide, D ∼ 103 ps/nm-km, and large nonlinear figure-of-merit, FOMNL∼ 1.29, have raised the possibilities of utilizing slow light structures to operate devices at few watts power level with microscale length. These studies have opened one window towards the next-generation all fiber-optic graphene nonlinear optical devices.

Ballistic and snake photon imaging for locating optical endomicroscopy fibres.

We demonstrate determination of the location of the distal-end of a fibre-optic device deep in tissue through the imaging of ballistic and snake photons using a time resolved single-photon detector array. The fibre was imaged with centimetre resolution, within clinically relevant settings and models. This technique can overcome the limitations imposed by tissue scattering in optically determining the in vivo location of fibre-optic medical instruments.

Slope Slip Characteristics of Composite Optical Fiber Devices Based on Model Test

Slope Slip Characteristics of Composite Optical Fiber Devices Based on Model Test

No evidence for toxicity after long-term photobiomodulation in normal non-human primates.

In this study, we explored the effects of a longer term application, up to 12weeks, of photobiomodulation in normal, naïve macaque monkeys. Monkeys (n=5) were implanted intracranially with an optical fibre device delivering photobiomodulation (red light, 670nm) to a midline midbrain region. Animals were then aldehyde-fixed and their brains were processed for immunohistochemistry. In general, our results showed that longer term intracranial application of photobiomodulation had no adverse effects on the surrounding brain parenchyma or on the nearby dopaminergic cell system. We found no evidence for photobiomodulation generating an inflammatory glial response or neuronal degeneration near the implant site; further, photobiomodulation did not induce an abnormal activation or mitochondrial stress in nearby cells, nor did it cause an abnormal arrangement of the surrounding vasculature (endothelial basement membrane). Finally, because of our interest in Parkinson's disease, we noted that photobiomodulation had no impact on the number of midbrain dopaminergic cells and the density of their terminations in the striatum. In summary, we found no histological basis for any major biosafety concerns associated with photobiomodulation delivered by our intracranial approach and our findings set a key template for progress onto clinical trial on patients with Parkinson's disease.

Design of vibration sensor based on fiber Bragg grating

Fiber grating is a kind of new type of fiber optic light source device which has been rapidly changing in the refractive index of the core in recent years. Especially, it can realize the high precision of the external parameters by means of the special structure design and the encapsulation technology [1, 2]. In this paper, a fiber grating vibration sensor which is suitable for vibration monitoring in key areas is designed based on the technical background of vibration monitoring system. The sensor uses a single beam structure and pastes the fiber Bragg grating (FBG) to measure the vibration wavelength on the surface. When the vibration is simply harmonic vibration, the Bragg reflection wavelength will change periodically, and the periodic variation of the wavelength curve can be measured by the fiber grating demodulator, then the correctness of the experimental results is verified. In this paper, through the analysis of the data measured by the demodulator, the MATLAB software is used to verify the data, and the different frequency domains, the modes, and the phase frequency curves are obtained. The measurement range is 0 Hz–100 Hz, and the natural frequency is 90.6 Hz.

Theoretical and experimental study of macrobending losses in coated single-mode fibers

A macrobending loss formula for single-mode fibers, which is shown to accurately predict the bend loss of a single-mode fiber with complex or real refractive index coating, is presented. Theoretical simulations and experimental measurements of bend loss in a fiber with nickel coating obtained by chemical plating and acrylate buffer coating are also presented. Agreements between simulations and measurements support the validity of the theoretical formula. Results show that the large imaginary part of the refractive index of the coating can intensify the bend loss oscillation behaviors, which implies that the bent fiber with metal coating can be utilized in fiber-optic devices.

Thermo-optic characteristic of DNA thin solid film and its application as a biocompatible optical fiber temperature sensor.

We report unique thermo-optical characteristics of DNA-Cetyl tri-methyl ammonium (DNA-CTMA) thin solid film with a large negative thermo-optical coefficient of -3.4×10-4/°C in the temperature range from 20°C to 70°C without any observable thermal hysteresis. By combining this thermo-optic DNA film and fiber optic multimode interference (MMI) device, we experimentally demonstrated a highly sensitive compact temperature sensor with a large spectral shift of 0.15 nm/°C. The fiber optic MMI device was a concatenated structure with single-mode fiber (SMF)-coreless silica fiber (CSF)-single mode fiber (SMF) and the DNA-CTMA film was deposited on the CSF. The spectral shifts of the device in experiments were compared with the beam propagation method, which showed a good agreement.

FRI-07 A RACE TO IMAGING REVOLUTION: PIONEERS IN FIBER OPTICS

You have accessJournal of UrologyHistory of Urology: History Forum1 Apr 2017FRI-07 A RACE TO IMAGING REVOLUTION: PIONEERS IN FIBER OPTICS Kimberly A Maciolek and Sara L Best Kimberly A MaciolekKimberly A Maciolek More articles by this author and Sara L BestSara L Best More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.2472AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Until the 20th century, visualization beyond tortuous anatomic and mechanical contours posed a perennial hurdle for physicians and military engineers alike. The end of World War II coincided with profound discoveries in imaging through flexible glass fibers. However, discoveries in fiber optics were not widely distributed and gained little traction for practical use. Both Abraham van Heel and Harold Hopkins separately overcame this by publishing their work in Nature, enigmatically, in the same issue. We sought to discover the timeline of events preceding the publications and explain the coincidental timing. METHODS PubMed, Google Scholar, HathiTrust and ProQuest were searched for sources describing van Heel and Hopkins′ work on fiber optic imaging devices. Also, since both men are deceased we interviewed Jeff Hecht (City of Light: History of Fiber Optics, 1999) and reviewed his research documents, including articles translated from Dutch and correspondence with Hopkins and William Brouwer, van Heel′s assistant. RESULTS Van Heel, professor of optics at the Technical University of Delft in the Netherlands, focused on coating individual glass fibers to maximize the light delivery and potential length of the fibers. Hopkins, a professor of optics at the Imperial College in London, used bundles of many tiny fibers to increase image resolution. Both innovations proved crucial to fiber optics′ success. When Frits Zernike, another Dutch optics expert, learned of Hopkins′ work while receiving his Nobel prize in physics, he shared this information with van Heel and sparked a race to publish. Van Heel was the first of the two to publish his findings. The article appeared in De Ingenieur in June 1953, but had geographically limited readership. To address this, van Heel also sent a letter to the editor of Nature. This was received on May 21, 1953, but delayed in publishing until January 2, 1954. 82‰ of letters in the 5 issues centered around January 2, 1954 were published within 2 months of receipt. Van Heel′s letter appears above a longer letter documenting Hopkins′ own work. Although Hopkins denied prior knowledge of van Heel′s work, Brouwer references Hopkins as the editor of van Heel′s letter and suggests his role in the delay in publication. CONCLUSIONS Harold Hopkins′ pioneering work to improve the image quality of the first flexible fiberscopes is well documented. However, van Heel′s simultaneous and independent contribution of fiber coatings to increase light delivery should also be credited. When considered together, both Hopkins and van Heel′s discoveries launched modern fiber optics and changed the field of urology forever. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e1062-e1063 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Kimberly A Maciolek More articles by this author Sara L Best More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Formation and Applications of the Secondary Fiber Bragg Grating.

Being one of the most proven fiber optic devices, the fiber Bragg grating has developed continually to extend its applications, particularly in extreme environments. Accompanying the growth of Type-IIa Bragg gratings in some active fibers, a new resonance appears at the shorter wavelength. This new type of grating was named “secondary Bragg grating” (SBG). This paper describes the formation and applications of the SBGs. The formation of the SBG is attributed to the intracore Talbot-type-fringes as a result of multi-order diffractions of the inscribing beams. The SBG presents a variety of interesting characteristics, including dip merge, high-temperature resistance, distinct temperature response, and the strong higher-order harmonic reflection. These features enable its promising applications in fiber lasers and fiber sensing technology.

Mitigating nonlinear propagation impairments of ultrashort pulses by fractional temporal self-imaging.

We present a new approach to mitigate nonlinear impairments-mainly induced by self-phase modulation (SPM)-of high-repetition-rate optical pulses propagating through fiber-optic devices (amplifiers, propagation lines, etc.). The proposed approach is based on pulse division before nonlinear propagation, followed by pulse recombination using fractional temporal self-imaging (also known as the Talbot effect) in a dispersive medium. This approach directly addresses practical limitations of previous mitigation methods when applied to a train of pulses with a high repetition rate, in the gigahertz range and above. Effective reduction of SPM by a factor of ≃5 is experimentally demonstrated on picosecond optical pulses at a repetition rate of 6GHz. The proposed method can be scaled to achieve higher SPM-reduction factors using a compact and robust fiber-optics scheme.

Integrated Fiber-Optic Device Based on a Combination of a Piezoelectric Transducer and a Bulk-Structured Bi2Te3 Topological Insulator for Q-Switched Mode-Locking of a Fiber Laser

We propose a single, integrated fiber-optic device that possesses both passive Q-switching and active mode-locking functions. The structure of the integrated fiber-optic device consists of a bulk-structured Bi2Te3 topological insulator (TI) layer sandwiched between the surface of a piezoelectric transducer and the flat side of a side-polished fiber. The Bi2Te3 TI is used as a saturable absorption material to induce Q-switching while the piezoelectric transducer is used to produce an acousto-optical modulation function for mode-locking. The integrated fiber-optic device is used within an erbium fiber ring cavity to readily produce stable Q-switched mode-locked pulses at 1559 nm. Control of the modulation index of the acousto-optic modulation part together with the pump power was also shown to be able to change the laser operating regimes among CW, Q-switching, Q-switched mode-locking, and mode locking.

Analysing Human Nails Composition by Using Laser Induced Breakdown Spectroscopy

This study investigated the elemental composition of pathological and normal nails, according to different age groups and genders. The nail elemental composition was analyzed by using Laser Induced Breakdown Spectroscopy (LIBS) technique. A Q-switched Nd:YAG laser at 1064 nm with output energy of 100 mJ, pulse duration of 6 ns and repetition rate of 1 Hz was fired to the human nails sample. The laser pulse ablated the target sample surface and produced plasma plume with characteristic spectral line comprising sample's elemental composition. The plasma emission spectrum of nail samples were captured by fibre optic detection device and spectrometer equipped with ASEQ Spectra Software for elemental analysis. The elements detected in nails were Mg, Al, Ca, P, Ti, K and Na. Classification of nails into different age groups and genders demonstrate efficient results if compared with Dietary Reference Intakes (DRI). The results indicate that Ca, Al, Ti, P and K composition were higher among female. However, Mg and Na were higher among male. The results also show that Ca and K element decline as the age increase in both genders. The pathological nails' elemental compositions were also noticeably related to the nail disorder condition itself. It is proven that LIBS could be a possible method for analyzing the nails and identification of various nail disorders.

Effect of heat treatment on absorption and fluorescence properties of PbS-doped silica optical fibre

The effect of heat treatment on the optical properties of a PbS-doped silica optical fibre was investigated. The experimental results showed that the absorption peak of the fibre red shifted from 1032 to 1133 nm when the heat treatment temperatures were carried out at 900, 950, 1000, and 1100 °C for 1 h, respectively. At the same time, when the heat treatment at 900 °C was carried out for 2, 5, 10, 20, and 40 h, the absorption spectra of the fibre showed a red shift from 1074 to 1143 nm. In addition, the intensity of the absorption peak increased from 0.258 to 1.384 dB/m and the full width at half maximum (FWHM) became narrower (from 130 to 50 nm) as the heat treatment proceeded. Moreover, the photoluminescence (PL) intensity in the wavelength range of 1100–1500 nm decreased with an increase in the heat treatment temperature. The theoretical analysis, using an effective mass method, showed that the effective band gap energy and average size of the lead sulphide (PbS) quantum dots (QDs) in the silica fibre core varied from 1.199 to 1.083 eV and from 4.28 to 4.81 nm, respectively. The results indicate that the size of the PbS QDs present in the silica fibre core could be controlled by a proper heat treatment, which is of great interest in optical fibre amplifiers and other fibre optic devices.

Recent Developments in Micro-Structured Fiber Optic Sensors

Recent developments in fiber-optic sensing have involved booming research in the design and manufacturing of novel micro-structured optical fiber devices. From the conventional tapered fiber architectures to the novel micro-machined devices by advanced laser systems, thousands of micro-structured fiber-optic sensors have been proposed and fabricated for applications in measuring temperature, strain, refractive index (RI), electric current, displacement, bending, acceleration, force, rotation, acoustic, and magnetic field. The renowned and unparalleled merits of sensors-based micro-machined optical fibers including small footprint, light weight, immunity to electromagnetic interferences, durability to harsh environment, capability of remote control, and flexibility of directly embedding into the structured system have placed them in highly demand for practical use in diverse industries. With the rapid advancement in micro-technology, micro-structured fiber sensors have benefitted from the trends of possessing high performance, versatilities and spatial miniaturization. Here, we comprehensively review the recent progress in the micro-structured fiber-optic sensors with a variety of architectures regarding their fabrications, waveguide properties and sensing applications.

Grating-coupling-based excitation of Bloch surface waves for lab-on-fiber optrodes.

In this paper, we investigate the possibility to excite Bloch surface waves (BSWs) on the tip of single-mode optical fibers. Within this framework, after exploring an idealized, proof-of-principle grating-coupling-based scheme for on-tip excitation of BSWs, we focus on an alternative configuration that is more robust with respect to fabrication-related non-idealities. Subsequently, with a view towards label-free chemical and biological sensing, we present a specific design aimed at enhancing the sensitivity (in terms of wavelength shift) of the arising resonance with respect to changes in the refractive properties of the surrounding environment. Numerical results indicate that the attained sensitivities are in line with those exhibited by state-of-the-art plasmonic bioprobes, with the key advantage of exhibiting much narrower spectral resonances. This prototype study paves the way for a new class of miniaturized high-performance surface-wave fiber-optic devices for high-resolution label-free optical biosensing, and represents an important step forward in the "lab-on-fiber" technology roadmap.