Hans Georg Limberger

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Water absorption and thermal response of adhesive composite joints were investigated by measurements and numerical simulations. Water diffusivity, saturation, swelling, and thermal expansion of the constituent materials and the joint were obtained from gra ...

We present a digital holographic microscope that permits one to image polarization state. This technique results from the coupling of digital holographic microscopy and polarization digital holography. The interference between two orthogonally polarized re ...

All-fiber optical phase modulators were fabricated by coating standard telecommunication optical fibers with thin films of piezoelectric ZnO. Piezoelectric optical fiber coatings of PbZrxTi1-xO3(PZT) were also produced, and the actuation capability necessary for making optical fiber modulators is demonstrated. Both the ZnO and the PZT fiber coatings were deposited by reactive direct current magnetron sputtering of metal targets. The geometry of the sputtering system, fiber rotation, and reactive sputtering

Fibers doped with bismuth show broad luminescence bands around 750, 1100, and 1400 nm with spectral bandwidths of 100 to 200 nm at room temperature. The luminescence bands can be observed by pumping broad absorption bands in the visible or near infrared spectrum (around 500, 700, 800, 1000, and 1360 nm). Bismuth fiber laser action has been demonstrated using FBG in standard germanosilicate fibers as intra-core laser mirrors. In this work we report about the investigation of refractive index and luminescence

Fiber optic modulators were fabricated by coating optical fibers with electrode and piezoelectric ZnO layers. The techniques of piezoelectric fiber optic modulator (PFOM) fabrication are presented, and the microstructure and crystallographic texture of the coatings are analyzed, Ln order to produce thick (approximately 5 mu m) ZnO coatings, it was necessary to study the reactive de magnetron sputtering process in O-2/Ar gas mixtures under conditions close to the transition between an oxidized and nonoxidize

The demand for capacity is growing exponentially with about 40-60% per year passing the installed network capacity. For the last two decades the transmission capacity per fiber has increased by more than three orders of magnitude: Single channel (wavelength and polarization) electronically time-division multiplexed (ETDM) transmission showed a growth of one order of magnitude over the last two decades reaching 100 Gb/s; and multi-channel wavelength division multiplexing (WDM) increased the transmission capa

This paper investigates the use of embedded optical fiber Bragg gratings to measure strain near a stress concentration within a solid structure. Due to the nature of a stress concentration (i.e. the strong non-uniformity of the strain field) the assumption that the grating spectrum in reflection remains a single peak with a constant bandwidth may not be valid. Compact tension specimens including a controlled notch shape are fabricated with embedded optical fiber Bragg gratings at identical locations but wit

The adhesive bonding of composite materials can be applied to assemble light-weight structures for aeronautical applications. However, the application of adhesive bonds in primary load-bearing structures is limited by the lack of adequate techniques to mon ...

Investigates the use of embedded optical fiber Bragg gratings to measure strain near a stress concentration within a solid structure. Due to the nature of a stress concentration (i.e., the strong nonuniformity of the strain field), the assumption that the grating spectrum in reflection remains a single peak with a constant bandwidth is not valid. Compact tension specimens including a controlled notch shape are fabricated, and optical fiber Bragg gratings with different gage lengths are embedded near the not

A new class of active fiber devices based on piezoelectric coated optical fibers is currently being developed. The piezoelectric coating is used to produce acoustic waves within the optical fiber and these acoustic waves interfere with optical signals passing through the fiber waveguide. Optical phase modulation devices based on piezoelectric coated fibers have been demonstrated and the behavior of these devices will be reviewed. A second type of active optical fiber device has been fabricated by integratin

The mechanical resistance of UV irradiated optical fibers has been investigated by dynamic fatigue tests. The intrinsic Weibull distribution of the pristine and chemically stripped fiber were almost identical. The high germanium doped fiber was homogeneously irradiated using a KrF Excimer with different pulse energy densities and different total doses, both corresponding to typical Bragg grating fabrication conditions. The Weibull distribution of the irradiated fibers depends on the pulse energy density and

Reflection, transmission and loss filters based on fiber Bragg gratings are key components in future wavelength division multiplexing telecommunication networks. A shift of the Bragg wavelength, λg, can be achieved by applying a strain or heating the fiber section containing the grating. We report on Bragg grating devices that use a thin metallic coating to directly heat the fiber or a piezoelectric coating to strain it. Such integrated tunable filter devices show DC tuning and modulation capabilitie

An all-fiber tunable filter device that uses a resistive fiber coating to directly heat an intra-core Bragg grating is presented. Bragg gratings were fabricated in a hydrogen-loaded standard telecommunication fiber by a KrF excimer laser with a fluence of 50 mJ/cm2 per pulse. Electrical connections were realized with gold wires at the ends of the coated section and a total resistance of 38 Ω was measured. A large wavelength tuning range of 2.15 nm was obtained by application of a low electrical power

Characteristics of one-cascade (1.06 double right arrow 1.24 mum) and two-cascade (1.06 double right arrow 1.24 double right arrow 1.48 mum) phosphorus-doped fiber Raman lasers are studied. The cavities of both lasers are formed by Bragg gratings written directly in the active fiber. Double-cladding Yb3+ and Nd3+ ion fiber lasers with lambda similar to 1.06 mum were employed for pumping. These lasers were pumped, in their turn, by diode laser arrays with lambda similar to 0.98 mum (Yb) and lambda similar to

Permanent Bragg gratings in monomode optical fibers are obtained by irradiation through an interference pattern of an ultraviolet laser. The main parameters of such gratings, in particular the index modulation amplitude and their length, are precisely determined by a fine adjustment between the measured reflectivity and a theoretical curve. Gratings have been formed in a standard monomode telecommunication fiber, with reflectivities above 90% and with bandwidths on the order of 1 to 3 nm. Their reflectivity

Fiber gratings irradiated by CW-laser show a breaking strength and a lifetime performance similar to that of pristine fiber, on pulsed KrF-laser irradiation. In this paper we report on the mechanical reliability of fibers irradiated by UV light using the side exposure technique. Homogeneous excimer laser irradiation reduces the mechanical resistance considerably depending on the fluence per pulse and the laser wavelength. With increasing pulse energy density the mechanical resistance is lowered. In contrary

Optical low coherence reflectometry and fiber Bragg gratings written in small diameter (50 micrometer) optical fibers were used for measurements of non-homogenous internal strain fields inside an epoxy specimen with sub-grating length resolution. The resul ...

The Colladon symposium is a public event that will honor the physicist Jean-Daniel Colladon (1802-1890). He was a scientist born in Geneva and well known for his measurements of the speed of sound in the lake of Geneva, his development of tunnel drilling machines, as well as gas light installations in his home town. However, only few people associate his work also with light guiding and fiber optics. In fact, Colladon demonstrated for the first time in 1841 the guiding of light in a liquid jet of water at t

The cluster beam technique offers promise of becoming a useful tool for chemists in their search for new compounds. Using this technique elemental vapors can be made to react under controlled conditions to form units of condensed matter (clusters) small enough to be analyzed in a mass spectrometer, but still large enough to contain several structural building blocks. Periodic patterns in cluster mass spectra often allow these building blocks to be uniquely indentified. Of particular interest is the identifi

Two all-fiber wavelength tunable devices, one utilizing thermal tuning and a second based on strain tuning, have been produced by combining resistive Ti/Pt and piezoelectric ZnO fiber coatings with fiber Bragg gratings (FBGs). The Ti and Pt coatings with thicknesses of 40 and 300 nm, respectively, were deposited by sequential magnetron sputter deposition. ZnO fiber coatings with a thickness of 18 mu m were deposited by dual magnetron reactive sputtering. Joule heating of the Ti/Pt fiber coating was employed

Hans Georg Limberger

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An experimental-numerical investigation of hydrothermal response in adhesively bonded composite structures

Polarization microscopy by use of digital holography: application to optical- fiber birefringence measurements

Sputter deposited piezoelectric fiber coatings for acousto-optic modulators

ArF laser induced refractive index and luminescence changes in Bi-doped aluminosilicate fibers - INVITED

Fabrication and structural analysis of ZnO coated fiber optic phase modulators

Workshop: Towards high capacity fibers for space and mode division multiplexed transmission

Measurement of Stress Concentrations Using Embedded Bragg Optical Fiber Bragg Grating Sensors

Monitoring strain gradients in adhesive composite joints by embedded fiber Bragg grating sensors

Embedded optical fiber Bragg grating sensor in a nonuniform strain field: measurements and simulations

Piezoelectric coatings for active optical fiber devices

Mechanical degradation of optical fibers induced by UV light

Efficient active Bragg grating tunable filters

High performance wavelength-tunable filter based on in-fiber Bragg grating and electrically resistive coating

Highly efficient one- and two-cascade Raman lasers based on phosphosilicate fibers

Formation and spectral characterisation of Bragg gratings in standard single-mode optical fibers

Mechanical reliability of UV irradiated fibers: application to Bragg grating fabrication - invited

Distributed strain measurements using fiber Bragg gratings in small-diameter optical fiber and low-coherence reflectometry

Jean-Daniel Colladon symposium "milestones in light guiding"

Compound clusters

Wavelength tunable fiber Bragg grating devices based on sputter deposited resistive and piezoelectric coatings