79 research outputs found
Minimalist Approach for the Design of Microstructured Optical Fiber Sensors
We report on recent investigations regarding ultra-simplified designs for microstructured optical fiber sensors. This minimalist approach relies on the utilization of capillary-like fibersânamely embedded-core fibers, surface-core fibers, and capillary fibersâas platforms for the realization of sensing measurements. In these fibers, guidance of light is accomplished in an embedded or surface germanium-doped core or in the hollow part of capillaries. External stimuli can alter fiber wall thickness and/or induce birefringence variations, allowing, for the embedded-core and capillary fibers, to operate as pressure or temperature sensors. For the surface-core fiber design, the interaction between the guided mode and external medium allows the realization of refractive index sensing either by using fiber Bragg gratings or surface plasmon resonance phenomenon. Also, we report the realization of directional curvature sensing with surface-core fibers making use of the off-center core position. The attained sensitivities are comparable to the ones obtained with much more sophisticated structures. The results demonstrate that these novel geometries enable a new route toward the simplification of optical fiber sensors
Broadband dispersion compensation using inner cladding modes in photonic crystal fibers
A photonic crystal fiber is optimized for chromatic dispersion compensation by using inner cladding modes. To this end, a photonic-oriented version of the downhill-simplex algorithm is employed. The numerical results show a dispersion profile that accurately compensates the targeted dispersion curve, as well as its dispersion slope. The presented fiber has a simple structure, while radiation losses can be reduced simply by adding a few more air-hole rings. Fabrication tolerances are also considered showing how fabrication inaccuracies effects can be overridden by just adjusting the compensation lengt
Agarose-based structured optical fibre
Biocompatible and resorbable optical fibres emerge as promising technologies for in vivo applications like imaging, light delivery for phototherapy and optogenetics, and localised drug-delivery, as well as for biochemical sensing, wherein the probe can be implanted and then completely absorbed by the organism. Biodegradable waveguides based on glasses, hydrogels, and silk have been reported, but most of these devices rely on complex fabrication procedures. In this sense, this paper proposes a novel structured optical fibre made of agarose, a transparent, edible material used in culture media and tissue engineering. The fibre is obtained by pouring food-grade agar into a mould with stacked rods, forming a solid core surrounded by air holes in which the refractive index and fibre geometry can be tailored by choosing the agarose solution composition and mould design, respectively. Besides exhibiting practical transmittance at 633ânm in relation to other hydrogel waveguides, the fibre is also validated for chemical sensing either by detecting volume changes due to agar swelling/dehydration or modulating the transmitted light by inserting fluids into the air holes. Therefore, the proposed agarose-based structured optical fibre is an easy-to-fabricate, versatile technology with possible applications for medical imaging and in vivo biochemical sensing101CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO - CNPQCOORDENAĂĂO DE APERFEIĂOAMENTO DE PESSOAL DE NĂVEL SUPERIOR - CAPESFUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO - FAPESPNĂŁo temNĂŁo tem2017/25666-
Polymer optical fiber specklegram strain sensor with extended dynamic range
FAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICOCAPES - COORDENAĂĂO DE APERFEIĂOAMENTO DE PESSOAL E NĂVEL SUPERIORA polymer optical fiber strain sensor with extended dynamic range is reported. The proposed algorithm resets the reference fiber status depending on the magnitude of the specklegram deviation so the correlation coefficient never saturates, yielding a continuous response over the full range for both positive and negative strains. The technique was evaluated on the measurement of axial strains using a ZEONEX core, poly(methyl methacrylate) cladding multimode fiber, presenting reproducible results with 3 x 10(-3) mu epsilon(-1) sensitivity (similar to 15 mu epsilon resolution) within a 22,600 mu epsilon interval. In contrast to the available approaches, the presented method can retrieve the strain direction and does not require intensive image processing, thus providing a simple and reliable technique for mechanical measurements using multimode optical fibers. (C) 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)571119FAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICOCAPES - COORDENAĂĂO DE APERFEIĂOAMENTO DE PESSOAL E NĂVEL SUPERIORFAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICOCAPES - COORDENAĂĂO DE APERFEIĂOAMENTO DE PESSOAL E NĂVEL SUPERIOR2014/50632-62017/25666-2sem informaçãosem informaçã
Successful fiber sensing technologies and hot topics for the near future
Inside the Photonics field Optical Fiber Sensors (OFS) are currently being used and will still be used in the future in a wide number of applications because its properties present technical advantages over traditional techniques or, sometimes, is practically the only feasible solution. In this paper, the more successful techniques will be reviewed. Then a prospective for the near future of the market and hot topics in which invest research resources will be suggested
Hollow-core fiber-based speckle displacement sensor
The research enterprise towards achieving high-performance hollow-core
photonic crystal fibers has led to impressive advancements in the latest years.
Indeed, using this family of fibers becomes nowadays an overarching strategy
for building a multitude of optical systems ranging from beam delivery devices
to optical sources and sensors. In most applications, an effective single-mode
operation is desired and, as such, the fiber microstructure or the light
launching setups are typically designed for achieving such a behavior.
Alternatively, one can identify the use of large-core multimode hollow-core
fibers as a promising avenue for the development of new photonic devices. Thus,
in this manuscript, we propose and demonstrate the utilization of a large-core
tubular-lattice fiber for accomplishing a speckle-based displacement sensor,
which has been built up by inserting and suitably dislocating a single-mode
fiber inside the void core of the hollow fiber. The work reported herein
encompasses both simulation and experimental studies on the evolution of the
multimode intensity distributions within the device as well as the
demonstration of a displacement sensor with an estimated resolution of 0.7
{\mu}m. We understand that this investigation identifies a new opportunity for
the employment of large-core hollow fibers within the sensing framework hence
widening the gamut of applications of this family of fibers
Mid-IR hollow-core microstructured fiber drawn from a 3D printed PETG preform
FAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULOMid-infrared (mid-IR) optical fibers have long attracted great interest due to their wide range of applications in security, biology and chemical sensing. Traditionally, research was directed towards materials with low absorption in the mid-IR region, such as chalcogenides, which are difficult to manipulate and often contain highly toxic elements. In this paper, we demonstrate a Polyethylene Terephthalate Glycol (PETG) hollow-core fiber (HCF) with guiding properties in the mid-IR. Guiding is provided by the fiber geometry, as PETG exhibits a material attenuation 2 orders of magnitude larger than the HCF propagation loss. The structured plastic fiber preforms were fabricated using commercial 3D printing technology and then drawn using a conventional fiber drawing tower. The final PETG fiber outer diameter was 466 mu m with a hollow-core diameter of 225 mu m. Thermal imaging at the fiber facet performed within the wavelength range 3.5-5 mu m clearly indicates air guidance in the fiber hollow-core.8118FAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULOFAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO2014/50632-6AgĂȘncias de fomento estrangeiras apoiaram essa pesquisa, mais informaçÔes acesse artig
All-fiber broadband spectral acousto-optic modulation of a tubular-lattice hollow-core optical fiber
We demonstrate a broadband acousto-optic notch filter based on a
tubular-lattice hollow-core fiber for the first time. The guided optical modes
are modulated by acoustically induced dynamic long-period gratings along the
fiber. The device is fabricated employing a short interaction length (7.7 cm)
and low drive voltages (10 V). Modulated spectral bands with 20 nm half-width
and maximum depths greater than 60 % are achieved. The resonant notch
wavelength is tuned from 743 to 1355 nm (612 nm span) by changing the frequency
of the electrical signal. The results indicate a broader tuning range compared
to previous studies using standard and hollow-core fibers. It further reveals
unique properties for reconfigurable spectral filters and fiber lasers,
pointing to the fast switching and highly efficient modulation of all-fiber
photonic devices
Progress in the fabrication of the next-generation soft glass microstructured optical fibers
This paper was presented at the 1st Workshop on Specialty Optical Fibers and Their Applications, Sao Pedro, Sp, Brazil, 20-22 August, 2008.We report the fabrication of new soft glass microstructured optical fibers for sensing, high-nonlinearity and mid-infrared applications. The fibers were produced using the extrusion technique and a wide range of glass compositions. They demonstrate a wide variety of structural features and low propagation loss. © American Institute of Physics.Heike Ebendorff-Heidepriem, Roger C. Moore, and Tanya M. Monr
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
- âŠ