| 1. |
- 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).
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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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| 2. |
- Fokine, Michael, 1970-, et al.
(författare)
-
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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| 3. |
- Fokine, Michael, 1970-, et al.
(författare)
-
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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| 4. |
- Fokine, Michael, 1970-
(författare)
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Photosensitivity, chemical composition gratings and optical fiber based components
- 2002
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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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| 5. |
- Fokine, Michael, 1970-, et al.
(författare)
-
Specialty fiber fabrication using carbon monoxide laser heating
- 2023
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Ingår i: Specialty Optical Fibres. - : SPIE.
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Konferensbidrag (refereegranskat)abstract
- In this work we explore using a carbon monoxide (CO) laser towards specialty optical fiber fabrication specifically targeting the use of unconventional core materials, such as semiconductors as well as other crystalline materials, surrounded by a silica glass cladding. With laser heating there is a near instantaneous temperature response with a change in laser power. Highly localized heating minimizes overall thermal exposure reducing the duration that the core and cladding material interact at elevated temperatures. Localized heating also results in large temperature gradient across the liquid-solid interface, which is beneficial for crystallization kinetics. Compared to using CO2-lasers, the radiation from the CO-laser, which operates at 5.5 μm, has a much larger penetration depth in silica resulting in energy being deposited further into the material. This enables a more homogeneous transverse temperature distribution as well as a higher average temperature while minimizing surface vaporization. This talk covers the results from recent work using a CO laser for the fabrication of hybrid material optical fibers.
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| 6. |
- Fokine, Michael, 1970-, et al.
(författare)
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Spectral features of specular reflection from nanoparticle films
- 2010
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Ingår i: Physica Status Solidi. C, Current topics in solid state physics. - : Wiley. - 1610-1634 .- 1610-1642. ; 8:9, s. 2673-2675
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Tidskriftsartikel (refereegranskat)abstract
- In this work we analyze the internal reflection (Fresnel reflection) from Au nanoparticles on the end face of optical fibers. We demonstrate that changes in the refractive index of the surrounding medium can be detected by shifts in the reflection spectra associated with changes in the Localized Surface Plasmon Resonance of the Au-Nanoparticles. The spectral response is simulated using a model based on the interference in multilayer structures and can be described by transfer-matrix method.
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| 7. |
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| 8. |
- Gibson, Ursula J., et al.
(författare)
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Future of semiconductor-core optical fibers
- 2018
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Ingår i: Optics InfoBase Conference Papers. - : OSA - The Optical Society. - 9781557528209
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Konferensbidrag (refereegranskat)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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| 9. |
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| 10. |
- Gibson, U. J., et al.
(författare)
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Semiconductor-core optical fibers
- 2017
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. ; , s. 22-23
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Konferensbidrag (refereegranskat)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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