| 1. |
- Camara, A. R., et al.
(författare)
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LSPR-based fiber optic sensing with chemically deposited Au nanoparticles
- 2010
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Ingår i: Latin America Optics and Photonics Conference (LAOP) 2010. - Washington, D.C. : OSA. - 9781557529039
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Konferensbidrag (refereegranskat)abstract
- A refractive index fiber optic sensor based on Localized Surface Plasmon Resonance (LSPR) and specular reflection from chemically deposited gold nanoparticles has been characterized, presenting a sensitivity of 38 nm/RIU.
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| 2. |
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| 3. |
- Canalias, Carlota, et al.
(författare)
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Backward quasi phase matched second harmonic generation in sub-micron periodically poled KTiOPO4
- 2005
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Ingår i: 2005 Conference on Lasers & Electro-Optics (CLEO), Vols 1-3. - WASHINGTON : OPTICAL SOC AMERICA. ; , s. 2264-2266
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Konferensbidrag (refereegranskat)abstract
- 1mm thick KTiOPO4 was poled with 720nm domain period by employing UV-lithography, chemical patterning and electric field poling. The structure was used to demonstrate 6 and 7 order quasi-phase matched backward second harmonic generation.
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| 4. |
- Canalias, Carlota, et al.
(författare)
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Backward quasi-phase-matched second-harmonic generation in submicrometer periodically poled flux-grown KTiOPO4
- 2005
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:18, s. 181105-1-181105-3
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Tidskriftsartikel (refereegranskat)abstract
- A 1 turn thick flux-grown KTiOPO4 sample was poled with a 720 nm domain period by employing deep-UV laser lithography, chemical patterning, and electric field poling. An atomic force microscope was used to characterize the periodic domain structure. The sample was used to demonstrate sixth and seventh order quasi-phase-matched backward second-harmonic generation.
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| 5. |
- Canalias, Carlota, et al.
(författare)
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Progress in Sub-Micrometer Periodicity of Quasi-Phase Matching Structures
- 2009
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Ingår i: 2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum Electronics and Laser Science Conference, CLEO/QELS 2009. - Washington, D.C. : IEEE. - 9781424451845 ; , s. 906-907
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Konferensbidrag (refereegranskat)abstract
- We report on the progress in fabrication of sub-micrometer ferroelectric domain gratings in KTiOPO4. Periods as short as 565 nm have been created in the bulk of the crystal by electric-filed poling.
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| 6. |
- Chesini, Giancarlo, et al.
(författare)
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All-fiber devices based on photonic crystal fibers with integrated electrodes
- 2009
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Ingår i: Optics Express. - 1094-4087. ; 17:3, s. 1660-1665
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Tidskriftsartikel (refereegranskat)abstract
- A special kind of microstructured optical fiber is proposed and fabricated in which, in addition to the holey region (solid core and silica-air cladding), two large holes exist for electrode insertion. Either Bi-Sn or Au-Sn alloys were selectively inserted into the large holes forming two parallel, continuous and homogeneous internal electrodes. We demonstrate the production of a monolithic device and its use to externally control some of the guidance properties (e. g. polarization) of the fiber.
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| 7. |
- Claesson, Åsa, et al.
(författare)
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UV-transparent coatings for optical fiber
- 1997
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Konferensbidrag (refereegranskat)abstract
- Bragg gratings have been produced in germanosilicate optical fibers by exposing the fiber, through a polymer coating, to an interference pattern in the ultraviolet wavelength region. Two different coatings, Teflon AF@ 1600 and Kynar@ 7201, were applied on the fiber by dip coating and their optical properties in the 200-300 nm range were investigated. During the grating fabrication process, Teflon AF showed no sign of degradation at the fluencies required for efficient grating manufacturing. When Kynar 7201 was used, the coating darkened and decomposed
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| 8. |
- Coucheron, David A., et al.
(författare)
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Laser recrystallization and inscription of compositional microstructures in crystalline SiGe-core fibres
- 2016
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Glass fibres with silicon cores have emerged as a versatile platform for all-optical processing, sensing and microscale optoelectronic devices. Using SiGe in the core extends the accessible wavelength range and potential optical functionality because the bandgap and optical properties can be tuned by changing the composition. However, silicon and germanium segregate unevenly during non-equilibrium solidification, presenting new fabrication challenges, and requiring detailed studies of the alloy crystallization dynamics in the fibre geometry. We report the fabrication of SiGe-core optical fibres, and the use of CO2 laser irradiation to heat the glass cladding and recrystallize the core, improving optical transmission. We observe the ramifications of the classic models of solidification at the microscale, and demonstrate suppression of constitutional undercooling at high solidification velocities. Tailoring the recrystallization conditions allows formation of long single crystals with uniform composition, as well as fabrication of compositional microstructures, such as gratings, within the fibre core.
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| 9. |
- de Oliveira, R., et al.
(författare)
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Fabrication and Optical Characterization of Silica Optical Fibers Containing Gold Nanoparticles
- 2015
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 7:1, s. 370-375
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Tidskriftsartikel (refereegranskat)abstract
- Gold nanoparticles have been used since antiquity for the production of red-colored glasses. More recently, it was determined that this color is caused by plasmon resonance, which additionally increases the material's nonlinear optical response, allowing for the improvement of numerous optical devices. Interest in silica fibers containing gold nanoparticles has increased recently, aiming at the integration of nonlinear devices with conventional optical fibers. However, fabrication is challenging due to the high temperatures required for silica processing and fibers with gold nanoparticles were solely demonstrated using sol-gel techniques. We show a new fabrication technique based on standard preform/fiber fabrication methods, where nanoparticles are nucleated by heat in a furnace or by laser exposure with unprecedented control over particle size, concentration, and distribution. Plasmon absorption peaks exceeding 800 dB m(-1) at 514-536 nm wavelengths were observed, indicating higher achievable nanoparticle concentrations than previously reported. The measured resonant nonlinear refractive index, (6.75 ± 0.55) × 10(-15) m(2) W(-1), represents an improvement of >50×.
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| 10. |
- dos Santos, F. Eroni P., et al.
(författare)
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Evaluation of the third-order nonlinear optical properties of tellurite glasses by thermally managed eclipse Z-scan
- 2009
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 105:2
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Tidskriftsartikel (refereegranskat)abstract
- The third-order nonlinearity is measured for TeO2-ZnO-Na2O (TZN) glasses codoped with BaO, Nb2O5, and La2O3. The results for the sign and magnitude of the nonlinearity were obtained using a combination of the eclipse Z-scan with thermal nonlinearity managed Z-scan, whereas the Kerr shutter technique was employed to obtain the electronic time response of the nonlinearity, all performed with 76 MHz repetition rate 150 fs pulses at 800 nm. The results show a fast response (< 200 fs) and a nonlinear refractive index varying from 1.5 to 3.5x10(-15) cm(2)/W, depending upon glass composition. At the peak power level employed, nonlinear absorption was negligible. The results obtained are in good agreement with other tellurite compositions reported, confirming the electronic origin of the nonlinearity.
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| 11. |
- Fernandez, A. F., et al.
(författare)
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Chemical composition fiber gratings in a high mixed gamma neutron radiation field
- 2006
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Ingår i: IEEE Transactions on Nuclear Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 53:3, s. 1607-1613
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Tidskriftsartikel (refereegranskat)abstract
- Fiber Bragg gratings are all-fiber wavelength-selective refractive index structures manufactured through UV exposure of optical fibers. Their applications range from WDM all-fiber filters, dispersion compensators and fiber laser resonators for optical telecommunication applications to different types of point or distributed optical fiber sensors for a large variety of applications. The nuclear industry is considering the use of photonic technology for data communication in the next generation of nuclear power plants. In addition, fiber Bragg grating sensors are being evaluated by the nuclear industry for structural integrity and temperature monitoring. This work aims to study, in harsh radiation environments, a new type of FBG referred to as chemical composition grating. These gratings differ from other types of FBG in that their refractive index structure is attributed to a change in the chemical composition. Chemical composition gratings have shown to be extremely temperature stable surviving temperatures in excess of 1000 degrees C. We have experimentally studied the effect of very harsh gammaneutron radiation on the properties of chemical composition gratings fabricated in a Ge-F doped silica optical fiber.
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| 12. |
- Ferraris, Sara, et al.
(författare)
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Chemical, mechanical and antibacterial properties of silver nanocluster/silica composite coated textiles for safety systems and aerospace applications
- 2014
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 317, s. 131-139
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Tidskriftsartikel (refereegranskat)abstract
- This work describes the chemical, mechanical and antibacterial properties of a novel silver nanocluster/silica composite coating, obtained by sputtering, on textiles for use in nuclear bacteriological and chemical (NBC) protection suites and for aerospace applications.The properties of the coated textiles were analyzed in terms of surface morphology, silver concentration and silver release in artificial sweat and synthetic tap water, respectively. No release of silver nanoparticles was observed at given conditions.The water repellency, permeability, flammability and mechanical resistance of the textiles before and after sputtering demonstrated that the textile properties were not negatively affected by the coating.The antibacterial effect was evaluated at different experimental conditions using a standard bacterial strain of Staphylococcus aureus and compared with the behavior of uncoated textiles.The coating process conferred all textiles a good antibacterial activity. Optimal deposition conditions were elaborated to obtain sufficient antibacterial action without altering the aesthetical appearance of the textiles.The antibacterial coating retained its antibacterial activity after one cycle in a washing machine only for the Nylon based textile.
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| 13. |
- Fokine, Michael, et al.
(författare)
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CO2 laser structuring of semiconductor-core glass fibers
- 2014
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Ingår i: Optics InfoBase Conference Papers. - : OSA - The Optical Society. - 9781943580194
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Konferensbidrag (refereegranskat)abstract
- A scanning CO2 laser system is used to process semiconductor core glass fibers. The conditions can be tuned to melt the core and soften the glass, producing resonators, tapers and bends.
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| 14. |
- Fokine, Michael
(författare)
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Formation of thermally stable chemical composition gratings in optical fibers
- 2002
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Ingår i: Journal of the Optical Society of America. B, Optical physics. - 0740-3224 .- 1520-8540. ; 19:8, s. 1759-1765
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Tidskriftsartikel (refereegranskat)abstract
- Experimental results and a discussion of possible chemical pathways in the formation of thermally stable chemical composition gratings in optical fibers are presented. Gratings are formed through high-temperature treatment of UV-exposed hydrogen-loaded fibers. The final refractive-index modulation is ascribed to variations in fluorine concentration attained by periodically increased diffusion of fluorine. The mechanism behind this increase is the formation of mobile hydrogen fluoride from chemical reactions of fluorine and UV-induced hydroxyl, which occur with the spatial periodicity of the UV pattern. A hydroxyl-assisted increase in fluorine diffusion has been verified by time-of-flight secondary-ion mass spectroscopy. Formation of ultrastable grating by periodic variation of oxygen concentration through diffusion of molecular water is also discussed.
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| 15. |
- Fokine, Michael
(författare)
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Growth dynamics of chemical composition gratings in flourine-doped silica optical fibers
- 2002
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 27, s. 1974-1976
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Tidskriftsartikel (refereegranskat)abstract
- The refractive-index modulation of chemical composition gratings in fluorine-germanium-doped silica fibers as a function of thermal treatment during manufacturing has been studied. The final grating strength was found to depend strongly on an intermediate annealing step, with an optimum temperature near 600-700 degrees C, before development at a fixed temperature of 1000 degrees C. Low-temperature treatment, aimed at removing any remaining hydrogen from the fiber, performed at 100 degrees C for 20 h before the annealing step, also significantly increased the final refractive-index modulation.
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| 16. |
- Fokine, Michael
(författare)
-
Growth dynamics of chemical composition gratings in fluorine-doped silica optical fibers
- 2002
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 27:22, s. 1974-1976
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Tidskriftsartikel (refereegranskat)abstract
- The refractive-index modulation of chemical composition gratings in fluorine-germanium-doped silica fibers as a function of thermal treatment during manufacturing has been studied, The final grating strength was found to depend strongly on an intermediate annealing step, with an optimum temperature near 600-700degreesC before development at a fixed temperature of 1000degreesC. Low-temperature treatment, aimed at removing any remaining hydrogen from the fiber, performed at 100degreesC for 20 h before the annealing step, also sigificantly increased the final refractive-index modulation.
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| 17. |
- Fokine, Michael
(författare)
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High temperature miniature oven with low thermal gradient for processing fiber Bragg gratings
- 2001
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 72:8, s. 3458-3461
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Tidskriftsartikel (refereegranskat)abstract
- A miniature oven for processing fiber Bragg gratings in excess of 1000 degreesC has been projected and evaluated. The dimensions and the design of the oven allow rapid insertion and removal of the fiber during heating and minimizes mechanical degradation of the fiber. The 22 mm long oven has a flat zone at 1000 degreesC of 16 mm with a temperature variation of less than 2% and 20 mm with a temperature variation of 10%. The long term stability (hours) is +/- 20 degreesC measured at the center of the oven at 1000 degreesC. Rapid heating is possible, and heating optical fibers to 1000 degreesC shows a delay of approximately 400 ms before the core reaches thermal equilibrium.
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| 18. |
- Fokine, Michael, et al.
(författare)
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High-temperature treatment of hydrogen loaded GeO2 : SiO2 glasses for photonic device fabrication
- 2006
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier BV. - 0022-3093 .- 1873-4812. ; 352:07-jun, s. 494-499
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature treatment of hydrogen loaded silica- and germanium doped silica glass, also referred to as OH flooding, has been studied. The removal mechanism of hydroxyl groups in silica glass, during OH flooding, occurs by formation and diffusion of molecular hydrogen, while in germanium doped silica the main diffusion mechanism is attributed to diffusion of molecular water. UV exposure of OH flooded and non-treated germanium doped silica samples, from a ArF laser at 193 nm, show large changes in the asymmetric stretching vibration of Si-O-Si bridges, indicating compaction of the glass network. In addition, the thermal relaxation kinetics of the UV induced compaction are found to be similar for non-treated samples and OH flooded samples.
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| 19. |
- Fokine, Michael, et al.
(författare)
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Large increase in photosensitivity through massive hydroxyl formation
- 2000
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Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 25:5, s. 302-304
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Tidskriftsartikel (refereegranskat)abstract
- We report a large increase in photosensitivity of germanium-doped silicate fibers by rapid heat treatment of hydrogen-loaded fibers at 1000 degrees C before exposure of the fibers to 242-nm radiation. The increase in photosensitivity is compared with thermally induced absorption caused by introduction of massive amounts of hydroxyl species. The absorption loss was measured to be 0.02 dB/cm mol.% OH at 1.55 mu m. Strong gratings (Delta n > 1 x 10(-4)) in germanium-free phosphorous-doped fibers in the presence of 242-nm radiation have also been manufactured by this technique.
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| 20. |
- Fokine, Michael, 1970-, et al.
(författare)
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Laser based 3D printing of fused silica glass
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- Custom made glass fabrication often requires highly skilled scientific glass blowers, or advanced processing techniques and access to clean-room technologies. Additive manufacturing, or 3D printing, of optical quality glass structures would be a valuable complementary approach and is highly sought after. However, 3D printing glass has proven to be a significant challenge with the main issues related to the high temperatures associated with glass processing, stress and crack formation due to thermal expansion and brittleness. Early attempts using laser sintering of glass powder, either dry or using binding agents [1], resulted in opaque glass following debinding and sintering. Today optically clear glass has been reported using different techniques, including filament based [2], extrusion [3], and light curable resins mixed with nano-powders [4], among others [5].
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| 21. |
- Fokine, Michael, 1970-, et al.
(författare)
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Laser structuring, stress modification and Bragg grating inscription in silicon-core glass fibers
- 2017
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Ingår i: Optical Materials Express. - : Optical Society of America. - 2159-3930 .- 2159-3930. ; 7:5, s. 1589-1597
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Tidskriftsartikel (refereegranskat)abstract
- Semiconductor core fibers have numerous potential applications in optoelectronics and photonics, and the key to realizing these opportunities is controlled processing of the material. We present results on laser treatments for manipulating the core structure as well as the glass cladding. More specifically, using quasi-CW 10.6 mu m radiation, the clad glass can be softened and the core can be controllably melted. This is shown to permit tapering, localized formation of optical resonators, and stress modification of the as-drawn fiber and structures within it. Shown for the first time to the authors' knowledge are Bragg gratings written by modification of the silicon/glass interface using fs laser illumination at 517 nm. The cores of these fibers show stress alterations, with indications of quasi-periodic stress relief in the glass.
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| 22. |
- Fokine, Michael
(författare)
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Manipulating glass for photonics
- 2009
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Ingår i: PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE. - : Wiley. - 1862-6300. ; 206:5, s. 880-884
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Tidskriftsartikel (refereegranskat)abstract
- A generalized concept for local manipulation of three-dimensional glass materials is described. The basic principle is to use means to deposit energy into the material to enable localized and selective changes in the bond structure of the glass matrix, causing a localized modification of the thermal equilibrium properties of the material. The different regions of the glass will then behave differently when the sample is subsequently heated homogeneously. If the difference in the thermal dynamics between modified and un-modified regions is significant, thermal treatment of the material can result in a self-organizing structure. The aim here is to provide a generalized concept of differential systems and self-organizing structures, using chemical composition Bragg gratings as an example. In this case, differential diffusion results in self-organizing structures consisting of a variation of the chemical composition, with compositional features smaller than 250 nm.
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| 23. |
- Fokine, Michael, 1970-, et al.
(författare)
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Optical Characterization of Plasmonic Metamaterial Absorber
- 2010
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Konferensbidrag (refereegranskat)abstract
- A reflectance/transmittance experiment setup to characterize a sub-wavelength, wide-angle, ultrathin metamaterial absorber at optical frequency regime is shown, and the measured results are presented.
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| 24. |
- Fokine, Michael, 1970-
(författare)
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Photosensitivity, chemical composition gratings and optical fiber based components
- 2002
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The different topics of this thesis include high-temperaturestable fiber Bragg gratings, photosensitivity and fiber basedcomponents. Fiber Bragg gratings (FBG) are wavelength dispersiverefractive index structures manufactured through UV exposure ofoptical fibers. Their applications range from WDM filters,dispersion compensators and fiber laser resonators fortelecommunication applications to different types of point ordistributed sensors for a variety of applications. One aim of this thesis has been to study a new type of FBGreferred to as chemical composition grating. These gratingsdiffer from other types of FBG in that their refractive indexstructure is attributed to a change in the chemicalcomposition. Chemical composition gratings have shown to beextremely temperature stable surviving temperatures in excessof 1000 oC. Photosensitivity of pure silica and germanium-dopedcore fibers in the presence of hydroxyl groups has also beenstudied and different types of fiber based components have beendeveloped. The main result of the thesis is a better understanding ofthe underlying mechanism of the formation of chemicalcomposition gratings and their decay behavior at elevatedtemperatures. The refractive index modulation is caused by aperiodic change in the fluorine concentration, which has beenverified through time-of-flight secondary-ion-mass spectrometryand through studies of the decay behavior of chemicalcomposition gratings. A model based on diffusion of dopants hasbeen developed, which successfully predicts the thermal decayat elevated temperatures. Studies of the dynamics of chemicalcomposition grating formation have resulted in a manufacturingtechnique that allows for reproducible gratingfabrication. The main results regarding photosensitivity is a method tosignificantly increase the effect of UV radiation on standardtelecommunications fiber. The method, referred to asOH-flooding, has also been applied to pure-silica core fibersresulting in the first report of strong grating formation insuch fibers. Finally, research into different schemes for developingfiber-based components has resulted in two types of singlefiber integrated Mach-Zehnder interferometers; one passiveinterferometer that can be used as an optical filter and oneactive interferometer controlled with internal metalelectrodes. Keywords:optical fibers, fiber Bragg gratings,photosensitivity, thermal stability, fiber sensors, chemicalcomposition gratings, fiber components, Mach-Zehnderinterferometer, optical switch, optical modulator.
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| 25. |
- Fokine, Michael, et al.
(författare)
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Poled glasses for optical devices
- 2008
-
Ingår i: Photonics North 2008. - : SPIE. - 9780819473288 ; , s. 709918-
-
Konferensbidrag (refereegranskat)abstract
- Thermal poling is an efficient way to induce optical second-order nonlinearity in different types of glasses, which typically have macroscopic inversion symmetry. In this paper we present a study on the current dynamics during thermal poling of glasses and relate these results to the formation dynamics of the depletion region, which is closely linked to the induced optical second order nonlinearity. Based on a simple theoretical viewpoint, supported by experimental results, we propose that thermal poling of glasses, and space-charge formation in dielectrics in general, can be viewed as an ionic RC circuit. This, to some extent modified view oil thermal poling in glasses, opens up new opportunities to study and control the depletion layer dynamics subsequently leading to better control of the thermal poling induced optical second order nonlinearity in glasses.
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