Surface-Enhanced Resonance Raman Scattering (SERRS) Using Au Nanohole Arrays on Optical Fiber Tips

Abstract Circular and bow tie-shaped Au nanoholes arrays were fabricated on gold films deposited on the tips of singlemode optical fibers. The nanostructures were milled using focused ion beam with a high quality control of their shapes and sizes. The optical fiber devices were used for surfaceenhanced resonance Raman scattering (SERRS) measurements in both back-and forward-scattering geometries, yielding promising performance in both detection arrangements. The effect of the hole shape on the SERRS performance was explored with the bow tie nanostructures presenting a better SERRS performance than the circular holes arrays. The results present here are another step towards the development of optical fiber tips modified with plasmonic nanostructures for SERRS applications

Towards subdiffraction imaging with wire array metamaterial hyperlenses at MIR frequencies

We describe the fabrication of metamaterial magnifying hyperlenses with subwavelength wire array structures for operation in the mid-infrared (around 3 µm). The metadevices are composed of approximately 500 tin wires embedded in soda-lime glass, where the metallic wires vary in diameter from 500 nm to 1.2 µm along the tapered structure. The modeling of the hyperlenses indicates that the expected overall losses for the high spatial frequency modes in such metadevices are between 20 dB to 45 dB, depending on the structural parameters selected, being promising candidates for far-field subdiffraction imaging in the mid-infrared. Initial far-field subdiffraction imaging attempts are described, and the problems encountered discussed

Optical fiber anemometer based on a multi-FBG curvature sensor

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOANEEL - AGÊNCIA NACIONAL DE ENERGIA ELÉTRICAAn optical fiber anemometer based on a flexible multi-FBG curvature sensor is reported. The probe is comprised of a structured polymer shell with embedded single-mode fibers with written fiber Bragg gratings. When the sensor is bent, the different spectral shift of the Bragg wavelengths allows the determination of the mechanical stimulus. Moreover, the probe was also used as a cantilever sensor for assessing the airflow speed in a wind tunnel. The sensor presented sensitivities of 0.8 nm/m(-1) and 1.05 pm/(m/s) for curvature and square speed measurements, respectively, and the sensing characteristics can be improved by simply changing the material and the geometry of the bulk polymer shell, providing a versatile and feasible probe for the mechanical and flow measurements.1919SI87278732FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOANEEL - AGÊNCIA NACIONAL DE ENERGIA ELÉTRICAFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOANEEL - AGÊNCIA NACIONAL DE ENERGIA ELÉTRICA2014/50632-62016/25196-32017/25666-2001Sem informaçãoPD-2615-0011/201

Extruded antiresonant hollow core fibers for Mid-IR laser delivery

We report an overview of our recent progress in the design and fabrication of soft-glass based antiresonant hollow core fibers (AR-HCFs) for laser delivery in the mid-IR (5-11 μm). The fibers are fabricated by extrusion and subsequent drawing, using two different glasses: tellurite (70TeO2-13ZnO-10BaO-7Na2O), and chalcogenide (IG3, Ge30As13Se32Te25). The fabricated tellurite AR-HCFs can operate from 5 to 7 μm wavelength, and the IG3 AR-HCFs can operate further up to 11 μm wavelength. The numerical and experimental losses of the fundamental mode for the fabricated fibers are on the few dB/m level. Numerical modeling study indicates that, by improving the uniformity and shape of the capillaries, losses down to 0.1 dB/m in the mid-IR (5 to 11 μm) should be possible, making this solution attractive for the mid-IR laser delivery, such CO, CO2 and quantum-cascade lasers

Multimaterial and flexible devices made by fiber drawing

The ability to co-process different materials at the same time in a thermal process opens up the possibility of scalable fabrication of volumetric multimaterial and multifunctional devices with operation spanning from the UV to the microwave. Combining optical, mechanical and electronic properties of dielectrics (such as glass and polymers) and metals enables a plethora of applications in radiation manipulation. In this presentation I will discuss the process and the challenges of fiber drawing novel materials and material combinations such as: elastic polymers, biocompatible polymers, arsenic free soft-glasses and combinations of metal-dielectric structures. After discussing the process behind the realization of the novel fibers, I will show some very diverse uses of these exotic materials. I will report on our latest results on flexible fibers in generation of orbital angular momentum, realization of tunable metamaterials and wearable sensors, and I will present some applications of fiber drawn metamaterials for THz radiation