| 1. |
- Coucheron, David A., et al.
(author)
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Laser recrystallization and inscription of compositional microstructures in crystalline SiGe-core fibres
- 2016
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In: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 7
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Journal article (peer-reviewed)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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| 2. |
- de Oliveira, R., et al.
(author)
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Fabrication and Optical Characterization of Silica Optical Fibers Containing Gold Nanoparticles
- 2015
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In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 7:1, s. 370-375
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Journal article (peer-reviewed)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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| 3. |
- Fokine, Michael, 1970-, et al.
(author)
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Laser structuring, stress modification and Bragg grating inscription in silicon-core glass fibers
- 2017
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In: Optical Materials Express. - : Optical Society of America. - 2159-3930 .- 2159-3930. ; 7:5, s. 1589-1597
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Journal article (peer-reviewed)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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| 4. |
- Gibson, Ursula J., et al.
(author)
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Future of semiconductor-core optical fibers
- 2018
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In: Optics InfoBase Conference Papers. - : OSA - The Optical Society. - 9781557528209
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Conference paper (peer-reviewed)abstract
- Semiconductor-core optical fibers hold promise for long wavelength transmission systems as well as for nonlinear and active optoelectronic devices. This talk includes a status report on fiber properties and a prospectus of some future directions.
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| 5. |
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| 6. |
- Gibson, U. J., et al.
(author)
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Semiconductor-core optical fibers
- 2017
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In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. ; , s. 22-23
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Conference paper (peer-reviewed)abstract
- Recent results on silicon and SiGe-core fibers for infrared applications, as well as newdata on III-V core materials, and device concepts for semiconductor-core fibers are presented.
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| 7. |
- Guo, Wenhua, et al.
(author)
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Fabrication of long-period fiber gratings through periodic ablation using a focused CO2-laser beam
- 2015
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In: Optical Materials Express. - : Optical Society of America. - 2159-3930 .- 2159-3930. ; 5:11, s. 2702-2714
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Journal article (peer-reviewed)abstract
- Fabrication of long period gratings in optical fibers through periodic ablation using a focused CO2 laser beam has been studied. During the thermal ablation process most of the energy is absorbed at the glass surface, due to the high extinction coefficient of silica at the laser wavelength, resulting in rapid increase in temperature. Subsequent heat dissipation occurs through vaporization and ejection of molten material, heat conduction axially along the fiber, radiation and through convection. The high surface temperatures involved during ablation can result in a significant increase in temperature of the fiber itself, causing unwanted off-resonance background losses during grating fabrication. In order to minimize losses the temperature needs to be sufficiently low to avoid micro-bending and core deformation, triggered by the decrease in viscosity, while at the same time enabling strong grating formation through laser induced modification of the glass. In this work we have used short-period fiber Bragg gratings in order to assess the temperature dynamics within the fiber during ablation. Using a single grating written into the core, positioned below the point of ablation, we measure the peak temperature within the core of the fiber. When ablation was performed between two gratings, forming a short Fabry-Perot cavity, a different and faster response was recorded, which we ascribe to thermally induced stress and strain caused by the thermal expansion of the surface during ablation. By identifying suitable processing parameters we successfully fabricate strong long-period gratings with background losses of 0.5 dB to 1 dB when periodically ablating the fiber with up to 50 pulses. Experimental results indicate that the maximum core temperatures during ablation under these conditions are limited to within 600 degrees C to 1000 degrees C.
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| 8. |
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| 9. |
- Holmberg, Patrik, 1971-, et al.
(author)
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Influence of pre-annealing on the thermal regeneration of fiber Bragg gratings in standard optical fibers
- 2015
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In: Optics Express. - : Optical Society of America. - 1094-4087. ; 23:21, s. 27520-27535
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Journal article (peer-reviewed)abstract
- A detailed study of the dynamics during thermal regeneration of fiber Bragg gratings, written in hydrogen-loaded standard single-mode fibers using a ns pulsed 213 nm UV laser, is reported. Isothermal pre-annealing performed in the range 85 degrees C to 1100 degrees C, with subsequent grating regeneration at 1100 degrees C, resulted in a maximum refractive index modulation, Delta n(m) similar to 1.4.10(-4), for gratings pre-annealed near 900 degrees C while a minimum value of Delta n(m) similar to 2.10(-5) was achieved irrespective of pre-annealing temperature. This optimum denote an inflection point between opposing thermally triggered processes, which we ascribe to the reaction-diffusion mechanism of molecular water and hydroxyl species in silica. The results shed new light on the mechanisms underlying thermal grating regeneration in optical fibers.
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| 10. |
- Liu, Chunxin, 1991-, et al.
(author)
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Fabrication of a widely tunable fiber Bragg grating filter using fused deposition modeling 3D printing
- 2019
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In: Optical Materials Express. - 2159-3930 .- 2159-3930. ; 9:11, s. 4409-
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Journal article (peer-reviewed)abstract
- The use of 3D-printing for designing a simple wavelength tunable device based on fiber Bragg gratings is demonstrated. Using fused deposition modeling (FDM), the fiber Bragg grating is embedded into a beam of polyethylene terephthalate glycol (PETG). Through bending, resulting in compression or tension of the optical fiber, the Bragg wavelength could be continuously tuned over a range of 60 nm, with maintained reflectivity and 3-dB linewidth.
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| 11. |
- Song, S., et al.
(author)
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Crystalline GaSb-core optical fibers with room-temperature photoluminescence
- 2018
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In: Optical Materials Express. - : OPTICAL SOC AMER. - 2159-3930 .- 2159-3930. ; 8:6, s. 1435-1440
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Journal article (peer-reviewed)abstract
- Glass-clad, GaSb-core fibers were drawn and subsequently laser annealed. The as-drawn fibers were found to be polycrystalline, possess Sb inclusions, and have oxide contamination concentrations of less than 3 at%. Melting and resolidifying regions in the cores using 10.6 mu m CO2 laser radiation yielded single crystalline zones with enhanced photoluminescence (PL), including the first observation of strong room temperature PL from a crystalline core fiber. Annealed fibers show low values of tensile strain and a bandgap close to that of bulk GaSb.
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| 12. |
- Song, S., et al.
(author)
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GaSb-core optical fibers
- 2017
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In: Optics InfoBase Conference Papers. - : OSA - The Optical Society. - 9781557528209
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Conference paper (peer-reviewed)abstract
- This paper reports recent results on the formation of GaSb-core fibers, formed by molten-core drawing. Purity, crystallographic results and preliminary photoluminescence data are provided for both the as-drawn and laser annealed fibers.
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| 13. |
- Song, S., et al.
(author)
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Laser restructuring and photoluminescence of glass-clad GaSb/Si-core optical fibres
- 2019
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In: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 10
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Journal article (peer-reviewed)abstract
- Semiconductor-core optical fibres have potential applications in photonics and optoelectronics due to large nonlinear optical coefficients and an extended transparency window. Laser processing can impose large temperature gradients, an ability that has been used to improve the uniformity of unary fibre cores, and to inscribe compositional variations in alloy systems. Interest in an integrated light-emitting element suggests a move from Group IV to III-V materials, or a core that contains both. This paper describes the fabrication of GaSb/Si core fibres, and a subsequent CO2 laser treatment that aggregates large regions of GaSb without suppressing room temperature photoluminescence. The ability to isolate a large III-V crystalline region within the Si core is an important step towards embedding semiconductor light sources within infrared light-transmitting silicon optical fibre.
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| 14. |
- Sørgård, T., et al.
(author)
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Reduced loss in SiGe-core optical fibers
- 2018
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In: Optics InfoBase Conference Papers. - : Optical Society of America. - 9781557528209
-
Conference paper (peer-reviewed)abstract
- We investigate CO2 laser processing of SiGe-core glass fibers, and show that homogeneous, low optical loss cores can be made. Coaxial Ge-rich centers within the semiconductor cores can also be fabricated.
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| 15. |
- Theodosiou, A., et al.
(author)
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Characterisation of silicon fibre Bragg grating in near-infrared band for strain and temperature sensing
- 2018
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In: Electronics Letters. - : Institution of Engineering and Technology. - 0013-5194 .- 1350-911X. ; 54:24, s. 1393-1395
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Journal article (peer-reviewed)abstract
- Fibre Bragg grating inscription in the crystalline silicon (Si)-core fibre is described using visible light femtosecond laser pulses. The femtosecond pulses at 517 nm propagate through the transparent silica glass cladding and are fully absorbed by the Si core generating locally high temperatures and stress fields in forming the grating periods. The Si FBGs were characterised in reflection, calibrated for a first time as strain and temperature sensors and compared with that of FBGs inscribed in standard silica fibres.
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| 16. |
- Theodosiou, A., et al.
(author)
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Fs laser inscription of FBGs in silicon core silica clad optical fibres
- 2017
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In: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. ; , s. 24-25
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Conference paper (peer-reviewed)abstract
- We present results on fs laser inscription of Bragg gratings in Si-core fibres throughmodification of the silicon-glass interface; this results in stress modulation with indications ofquasi-periodic stress relief in the glass.
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| 17. |
- Wu, Wei, et al.
(author)
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Ge-capped SiGe core optical fibers
- 2019
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In: Optical Materials Express. - : OPTICAL SOC AMER. - 2159-3930 .- 2159-3930. ; 9:11, s. 4301-4306
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Journal article (peer-reviewed)abstract
- CO2 laser processing offers the possibility to inscribe structures within glass-clad SiGe-core fibers by altering the spatial distribution of the Si and Ge. Spatial segregation of Ge to the end of a fiber is shown via optical transmission measurements used to alter the local bandgap, and the curved end of the fiber focuses the output of a multimode fiber. Scalable fabrication is demonstrated using a commercial CO2 laser engraver for processing of arrays.
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