Active Optical Fibers Research Articles

Preparation of surface-enhanced Raman scattering(SERS)-active optical fiber sensor by laser-induced Ag deposition and its application in bioidentification of biotin/avidin

A surface-enhanced Raman scattering(SERS) optical fiber sensor was prepared by the laser-induced deposition of Ag nanoparticle membrane on a silica optical fiber tip, which was applied to the real time SERS spectral monitoring on the biorecognition of biotin/avidin. The bioidentification of biotin/avidin was carried out through a indirect method, in which the bioidentification is based on the SERS response signal of a labeled dye(Atto610) after its fluorescence has been quenched totally by the deposited Ag nanoparticle membrane. By SERS monitoring the bioidentification process of biotin/avidin, it has been found that this recognition process is finished in 40 min. The lowest detection concentration of biotin is 1.0×10−7 mg/mL. This research is promising in the application of immunoassays on line and in vivo.

Active Optical Fibers Doped with Ceramic Nanocrystals

Erbium-doped active optical fiber was successfully prepared by incorporation of ceramic nanocrystals inside a core of optical fiber. Modified chemical vapor deposition was combined with solution-doping approach to preparing preform. Instead of inorganic salts erbium-doped yttrium-aluminium garnet nanocrystals were used in the solution-doping process. Prepared preform was drawn into single-mode optical fiber with a numerical aperture 0.167. Optical and luminescence properties of the fiber were analyzed. Lasing ability of prepared fiber was proofed in a fiber-ring set-up. Optimal laser properties were achieved for a fiber length of 20~m. The slope efficiency of the fiber-laser was about 15%. Presented method can be simply extended to the deposition of other ceramic nanomaterials.

Quenching of erbium and ytterbium luminescence by the random walk of H2 and D2 molecules in the silica glass of active optical fibers

Photoluminescence of Er3+ (transition 4I13/2→4I15/2, emission wavelength λe~1550nm) and Yb3+ (2F5/2→2F7/2, λe~1040nm) ions incorporated in the silica of optical fibers immersed in a H2 and/or D2 environment at a pressure of up to 120bar at temperatures of 80–873K is investigated. The spectra and decay kinetics of the steady state luminescence excited by a 975-nm laser diode are recorded. It is shown that the thermal motion of interstitial H2 and/or D2 molecules quickens the decay kinetics and decreases the luminescence intensity. The effect becomes noticeable at temperatures greater than ~200K and significantly increases with a further temperature increase in H2 and/or D2 environments. The luminescence decay curves increasingly differ from single exponents with the increase of temperature and become best fitted by stretched exponential dependencies. This effect is reversible at temperatures of up to 800K. We explain the revealed quenching effect of excited f-electron in terms of the rare earth ions due to the appearance of an additional relaxation channel involved in the excitation of vibrational degrees of freedom of diatomic molecules experiencing random walks inside the glass network. This study found that the closer the electron excitation energy of a rare earth ion to an energy gap in the vibration spectrum of a molecule, the greater the deactivation effect. The quenching rate significantly decreases when the molecules' rotational degrees of freedom are frozen out.

A switchable dual-wavelength erbium-doped fiber laser based on saturable absorber and active optical fiber ring filter

A dual-wavelength erbium-doped fiber laser (EDFL) with outstanding stability is presented. In the fiber laser system, two nested active optical fiber ring filters are configured to improve the comb spectrum performance, a saturable absorber is employed to form a gain grating for both filtering and frequency stabilizing, two cascaded fiber Bragg gratings (FBGs) are utilized to achieve dual-wavelength output, and a variable attenuator is arranged to adjust output power. Experimental results illustrate that the peak wavelength drift is less than 3 pm, and a good linear relationship between output power and pump power is realized.

Correlative Compositional Analysis of Fiber-Optic Nanoparticles

Development of new active optical fiber devices requires materials with augmented intrinsic properties, using luminescent ion–doped silica as a host glass. Nanoparticles (NPs) in optical fibers can provide this augmentation as they can combine the sturdiness and low cost of silica with particular spectroscopic behavior that would not appear in a pure silica local environment. Ideally, NPs would fully encapsulate luminescent ions to produce engineered spectroscopic properties. This technology would be of great interest for a large domain of applications: high power fiber lasers, random lasers, light sources with new wavelengths and telecommunications. As silicate systems have a large phase immiscibility domain when they contain divalent metal oxides (such as Mg), one can take advantage of thermal treatments inherent to the MCVD process to obtain NPs through phase separation. NPs are grown in situ within the material. Although glass-ceramics were discovered in 1950's, there is a great demand on experimental data to understand the early stages of nucleation [1]. Modern glass ceramics are generally obtained through many trial-and-error processing steps, involving variations in composition as well as thermal treatments. Although classical nucleation theory was the first model proposed to explain those phenomena, growth rate mismatches could encompass several order of magnitude. According to this capillary assumption-based model, nuclei properties are the same as those of the bulk (same structure and composition). Recent articles disprove assumption of structure, pointing toward NPs structural changes [2] and transition from amorphous nuclei to crystalline NPs [3]. Compositional changes for small particle sizes (~1-10 nm) have been measured in alloys with Anomalous Small Angle X-Ray Scattering (ASAXS) [4] and in steels with Atom Probe Tomography (APT) [5]. Recent developments in APT allowed the extension of such studies to glass-ceramics, presenting additional challenges in specimen preparation and yield [6]. In the current work, we report experimental data disproving the second capillary assumption at the early stage of nucleation-growth process.

A surface-enhanced Raman scattering (SERS)-active optical fiber sensor based on a three-dimensional sensing layer

To fabricate a new surface-enhanced Raman scattering (SERS)-active optical fiber sensor, the design and preparation of SERS-active sensing layer is one of important topics. In this study, we fabricated a highly sensitive three-dimensional (3D) SERS-active sensing layer on the optical fiber terminal via in situ polymerizing a porous polymer material on a flat optical fiber terminal through thermal-induced process, following with the photochemical silver nanoparticles growth. The polymerized polymer formed a 3D porous structure with the pore size of 0.29–0.81μm, which were afterward decorated with abundant silver nanoparticles with the size of about 100nm, allowing for higher SERS enhancement. This SERS-active optical fiber sensor was applied for the determination of 4-mercaptopyridine, crystal violet and maleic acid The enhancement factor of this SERS sensing layer can be reached as about 108. The optical fiber sensor with high sensitive SERS-active porous polymer is expected for online analysis and environment detection.

A surface-enhanced Raman scattering optrode prepared by in situ photoinduced reactions and its application for highly sensitive on-chip detection.

A surface-enhanced Raman scattering (SERS)-active optical fiber sensor combining the optical fiber waveguide with various SERS substrates has been a powerful analytical tool for in situ and long-distance SERS detection with high sensitivity. The design and modification of a high-quality SERS-active sensing layer are important topics in the development of novel SERS-active optical fiber sensors. Here, we prepared a highly sensitive SERS-active optrode by in situ fabrication of a three-dimensional porous structure on the optical fiber end via a photoinduced polymerization reaction, followed by the growth of photochemical silver nanoparticles above the porous polymer material. The fabrication process is rapid (finished within 1 h) and can be on line under light control. The porous structure supports vast silver nanoparticles, which allows for strong electromagnetic enhancement of SERS. Interestingly, the preparation of this SERS optrode and its utilization for SERS detection can all be conducted in a microfluidic chip. The qualitative and quantitative on-chip SERS sensing of organic pollutants and pesticides has been achieved by this SERS optrode-integrated microfluidic chip, and its high detection sensitivity makes it a promising factor in the analysis of liquid systems.

Highly efficient luminescent materials: Influence of the matrix on the photophysical properties of Eu(III) complex/polymer hybrids

Highly efficient luminescent materials based on the europium complex Eu(tta)3(phen) (tta = 2-thenoyltrifluoracetonato, Phen = 1,10-phenantroline) incorporated into different polymer matrixes (polyvinyl butyral, polysulfone and polyurethane) have been prepared. The photoluminescent hybrid films were prepared by solution mixing/drop casting which has been revealed as a very convenient method to prepare these polymeric materials because of the good homogeneous distribution of the Eu(III) complex into the polymer matrix. A detail analysis of the Fourier transform infrared spectra, UV/Vis spectra and photoluminescent properties is presented. These results agree with the conclusion that the polymer interact with the complex, act as antenna and transfer energy to the central Eu(III) ions. As a result of this interaction, the efficiencies of the doped films are dramatically enhanced (photoluminescence quantum yields in the range 58–86%) in comparison with that of the precursor complex. The luminescent Eu(tta)3(phen) complex-polymer hybrid materials developed in this study could be successfully applied in optical devices as polymer light-emitting diodes or active polymer optical fiber applications.

Synthesis and near-infrared luminescence properties of ternary Nd(III) complexes-optical materials

Nd(bfa)3(TPPO)2, Nd(tta)3(TPPO)2 and Nd(β-nta)3(TPPO)2 (bfa: 4,4,4-Trifluoro-1-phenyl-1,3-butanedione, tta: 4,4,4-Trifluoro-1-(2-thienyl)-1,3-butanedione, β-nta: 4,4,4-Trifluoro-1-naphthyl-1,3-butanedione, TPPO: triphenylphosphine oxide), three kinds of Nd(III) ternary complexes, were synthesized using β-diketonates and triphenylphosphine oxide as ligands. Fluorescence properties (including excitation spectra, emission spectra, emission lifetime, quantum yield, etc.) and thermal stabilities of the complexes were studied. Nd(tta)3(TPPO)2 having the sharpest emission band, highest relative emission intensity and shortest fluorescence lifetime shows that it will be a kind of promising material for applications in near infrared immunoassay, laser active medium and optical fibers.

Active Fiber Gas Sensor for Methane Detecting Based on a Laser Heated Fiber Bragg Grating

An active optical fiber gas sensor was developed in a cobalt-doped single mode fiber. This fiber can be heated up to a few hundred degrees Celsius by a heating laser, and a fiber Bragg grating (FBG) was fabricated inside this fiber as a thermometer. The Bragg wavelength of the FBG is sensitive to the thermal conductivity of the gas surrounding the fiber and can be used to monitor the concentration of a special gas once we know in advance the kind of gas. The proposed sensor is ideal for detecting explosive or corrosive gases in some practical application scenarios, such as gas pipeline, coal mine, flow meters, and so on. We have measured the methane concentration ranging from 0% to 4.8% (5% is its explosion limit) as a demonstration.

Modulating the photoluminescence of europium-based emitting polymers: Influence of the matrix on the photophysical properties

A series of luminescent materials have been prepared by the ternary europium complex Eu(tta)3(phen) (tta = 2-thenoyltrifluoroacetonato, phen = 1,10-phenanotroline) embedded into different polymer matrixes (polystyrene, poly(vinyl difluoride), poly(acrylonitryle) and poly(methyl methacrylate)) in order to investigate the effect of the polymer on the luminescent properties of the hybrid materials. Fourier transform infrared spectra (FTIR), UV/vis spectra, scanning electron microstructure (SEM) and luminescent properties of the europium complex and the hybrid materials are described in detail. In all cases, interaction between the polymer and the europium complex was observed from the above techniques. This interaction was strong enough to lead to a variation in the photoluminescent properties of the hybrid films: while poly(vinyl difluoride) doped polymers showed a reduce quantum yield (φ = 24%), a dramatic/significant enhanced in this parameter (φ up to 73%) was observed for the other materials in comparison with the φ value of the precursor complex (30.5%). This result may support the conclusion that while some polymers could interact with the complex, act as antennae and transfer energy to the central Eu(III) ion, other quench the luminescence of the complex. Based on this high φ, these films could be applied in top optical applications such as light-emitting diodes and/or active polymer optical fibers. © 2013 Elsevier B.V.

Inner cladding microstructuration based on symmetry reduction for improvement of singlemode robustness in VLMA fiber

Very large mode area, active optical fibers with a low high order mode content in the actively doped core region were designed by removing the inner cladding symmetry. The relevance of the numerical approach is demonstrated here by the investigation of a standard air-silica Large Pitch Fiber, used as a reference. A detailed study of all-solid structures is also performed. Finally, we propose new kinds of geometry for 50 μm core, all-solid microstructured fibers enabling a robust singlemode laser emission from 400 nm to 2200 nm.

Optical Fiber Technology 2012

Abstract The Conference on Optical Fibers and Their Applications, Nałȩczów 2012, in its 14th edition, which has been organized since more than 35 years, has summarized the achievements of the local optical fiber technology community, for the last year and a half. The conference specializes in developments of optical fiber technology, glass and polymer, classical and microstructured, passive and active. The event gathered around 100 participants. There were shown 60 presentations of 20 research and application groups active in fiber photonics, originating from academia and industry. Topical tracks of the Conference were: photonic materials, planar waveguides, passive and active optical fibers, propagation theory in nonstandard optical fibers, and new constructions of optical fibers. A panel discussion concerned teaching in fiber photonics. The conference was accompanied by a school on Optical Fiber Technology. The paper summarizes the chosen main topical tracks of the conference on Optical Fibers and Their Applications, Nałȩczów 2012. The papers from the conference presentations will be published in Proc. SPIE, including a conference version of this paper. The next conference of this series is scheduled for January 2014 in Białowie˙za.

The study of thermal connecting of telecommunication optical fibers (SiO2: GeO2) and EDF (SiO2: Al2O3, Er) fibers

Abstract. This paper presents the research on optimization of the splicing process in the electric arc of telecommunication optical fibers and erbium doped EDF fibers. The results of the calculations of diffusion coefficients GeO2 in telecommunication optical fibers and diffusion coefficients Er and Al2O3 (together) in the fiber EDF are presented. Diffusion coefficients were determined for the fusion temperature in the electric arc ≈2000°C, on the basis of changes, along the splice, of spliced thermoluminescence intensity profiles of the fibers. On the basis of knowledge of diffusion coefficients simulation calculation of loss joints of MC SMF fiber (Matched Cladding Single Mode Fiber - SiO2: GeO2) and NZDS SMF (Non Zero Dispersion Shifted - Single Mode Fiber - SiO2: GeO2) with EDF (Erbium Doped Fiber - SiO2: Al2O3, Er) was performed and presented as a function of diffusion time. Experimental studies of optimization of thermal connected MC SMF and NZDS SMF with EDF were presented and compared with theoretical results. This paper presents the results of microscopic observations of defects and diffusion, and X-ray microanalysis in the spliced areas of single-mode telecommunication optical fibers: MC SMF, NZDS-SMF and erbium doped active single mode optical fibers. Studies were performed with the use of the scanning electron microscope JSM5800LV and JSM6610A microscope equipped with EDS X-ray spectrometer. Results showing the influence of heating time on the diffusion of core dopants and the formation of deformations in the splice areas were presented.

Amplification of chirped pulses in inhomogeneous three-level active optical fibers

The possibility of efficient amplification of self-similar frequency-modulated wave packets in amplifiers inhomogeneous along their length is investigated. Special features of the amplification dynamics in erbium fiber amplifiers that operate according to the three-level scheme are analyzed. It is shown that active optical fibers with a specially designed profile of the normal group-velocity dispersion allow amplifying subpicosecond pulses with high efficiency.

Active optical fibres for application in laser and broadband ASE sources

Abstract The article brings into focus the present state of technology employing active fibres doped with rare earth (RE) ions for applications requiring power supply of several dozen watts and broadband ASE sources. Current trends in development of glasses and in construction of active fibres used in fibre sources of radiation within VIS-NIR range are presented. Technological constraints in the doping of fibre core glasses are discussed, with particular consideration of optimal RE concentration for technical applications. Characteristics of glasses are offered, and the glasses are used for manufacturing optical fibres with luminescence within the visible as well as near- and mid-infrared ranges. Also, requirements and luminescence properties concerning glasses co-doped with e.g. Nd3+/Yb3+,Tm3+/Ho3+ and Yb3+/Tb3+ are discussed. Results of research on the impact of technological parameters of glass matrices on luminescence properties of core glasses and optical fibres are quoted. For the doped glasses of which luminescence in a wide spectral range is desired, conditions for their processing into optical fibre systems are mentioned. Additionally, the impact of phonon energy in the glass on producing emission in a specified spectral range is analyzed. Furthermore, the article presents directions of technological studies to solve problems persisting in the phase of glass matrix design, as well as in determining the influence of fibre drawing process on the luminescence properties of core glasses and optical fibres, confirming the differences in luminescence stemming from the drawing process. Finally, some original designs of core glasses and active multicore fibre systems devised for construction of fibre radiation sources are presented.

Study of Lanthanum Aluminum Silicate Glasses for Passive and Active Optical Fibers

We are reporting onSiO2‐Al2O3‐La2O3glasses—with and withoutYb2O3—suitable for nonlinear and fiber laser applications. We will also be presenting successful supercontinuum generation and fiber laser operation around 1060 nm in step‐index fibers. We optimized the glass compositions in terms of thermal and optical requirements for both a highLa2O3andYb2O3concentration and good compatibility with a silica cladding. We also produced bulk samples, unstructured fibers, and structured fibers with aSiO2‐Al2O3‐La2O3core and silica cladding for this purpose.

Progress in the fabrication of rare earth doped optical fiber by standard and Sol-Gel derived granulated oxides

We produced active optical fibers by the doped granulate silica-method. The granulates were derived from the sol-gel technology. We determined volume percentage and distribution of chemical elements in the fabricated glasses fiber by the analytical technique of Energy-Dispersive X-ray (EDX), Scanning Electron Microscopy (SEM), Electron Probe Microanalysis (EPMA) and the degree of crystallization by X-Ray Diffraction analysis (XRD). Furthermore we measured fluctuations of the Refractive Index Profile (RIP) and scattering losses of the fiber core. It was observed from the RIP measurement that the average index difference with respect to the undoped silica was 5.3*10-3, and thus the optical fiber has a numerical aperture of 0.12. XRD measurements and investigations with SEM showed that the manufactured optical fiber has an amorphous structure. The dopant and co-dopant elements in the core region were uniformly distributed. Although we found strong isolated scattering centers in the fabricated fiber, the loss of the fibers was determined to be 0.35- 3dB/m for selected fiber pieces. Here we present our progress of improving the optical quality of fibers produced from granulates.

Composition of nanoparticles in optical fibers by Secondary Ion Mass Spectrometry

The development of new active optical fibre devices requires materials with « augmented » intrinsic properties, though using luminescent ion (LI) –doped silica as host glass. Optical fibers containing dielectric nanoparticles (DNP) grown by phase separation are proposed. DNP would optimally fully encapsulate LI to produce « engineered » spectroscopic properties. To determine the composition of DNP, Secondary Ion Mass Spectrometry imaging at high spatial resolution is employed. Through the use of this technique, we demonstrate without ambiguity the partition of Mg, P and Er in DNP. By increasing Mg concentration, Si concentration in DNP decreases, which explains the spectroscopic behaviour of Er.

Test of spectral emission and absorption characteristics of active optical fibers by direct side pumping

Emission and absorption are two main properties of active optical fibers that are important for fiber amplifiers and lasers. We propose a direct side pumping scheme for non-deconstructive evaluation of active optical fibers. This scheme enables a simple in situ test of both emission and absorption characteristics without cutting fiber and produces good accuracy with very low pumping background. A commercial Er-doped fiber and a home-made Bi/Er co-doped optical fiber have been tested to demonstrate that the scheme is a useful alternative technique for characterizing active optical fiber or waveguides.