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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]., Part of ISBN 9798350345995QC 20231116

This thesis describes the development of a new prototyping technique for specialty optical fibers and covers all the fabrication steps from preform to fiber. The technique allows to produce fibers of a custom core structure and material composition, mainly focusing on semiconductor core fibers. By combining the optoelectronic properties of semiconductors with the advantages of the glass optical fiber platform, such fibers become a promising candidate in applications that require a wider infrared transmission window or stronger non-linear response. In contrast to traditional optical fibers, semiconductor core fibers are not standard off-the-shelf components. They exist as research samples, typically short in length, limited in core size, and exhibit a high loss due to the challenging and expensive fabrication process. The proposed preform fabrication method utilizes a carbon monoxide laser as a heat source. Employing this laser ensures extremely effective heat transfer to the preform with low surface silica vaporization, a minimal thermal gradient across the preform cross-section, and short exposure time of the preform to high temperatures. This allows to reduce the manufacturing time of the preforms and improve their optical properties. The aim of this thesis work was to design and build a system to fabricate fiber preforms made of semiconductors or other crystalline core materials. The work was primarily focused on preforms with silicon cores, but germanium and sapphire cores were also demonstrated. The ability to achieve preform tapering was a vital part of the preform fabrication. The process was developed using silicon as a test core material due to its abundance and widespread applications. As a typical representative of hybrid core materials, the properties of silicon imposed some common challenges that had to be addressed during the preform fabrication process. This includes a drastic difference in thermal expansion and thermal conductivity of the core comp, QC 220502

We report the development of a specialty optical fiber preform fabrication system based on carbon monoxide (CO) laser heating. The laser heating is accomplished via a single-beam optical arrangement integrated into a rotating glass lathe. The CO laser output power and its beam quality are affected by absorption of the laser radiation by water vapor present in the surrounding air. This is addressed by construction of an enclosed and fully motorized system to enable preform processing in a dry air environment. The performance of the system is evaluated, and the ability to maintain a desired preform processing temperature is demonstrated. Relevant aspects of preform manufacturing, such as glass cutting, splicing, tapering, and overcladding, are described in detail. The process of using these aspects to fabricate optical fiber preforms made of highly dissimilar materials and of various core-to-cladding ratios is discussed. Specialty fibers drawn from these preforms exhibit low-loss and show good optical performance., QC 20230124

Additive manufacturing of glass is an emerging technology that is foreseen to have a big impact on glass fabrication for innovative solutions within research, as well as for industrial applications. One approach is 3D printing using glass filaments. This technique is similar to directed energy deposition (DED) of metal wires using laser melting, which is highly versatile in printing complex structures. For glass, however, the technique is still at an early stage of development. Printing complex multi-layer structures have been challenging, often resulting in poor control of print geometry, excessive evaporation, as well as low repeatability. In this work we present a systematic study of filament-based 3D printing of silica-glass using CO2-laser heating. The study focuses on the bonding width (wetting) during first-layer printing onto fused quartz substrates and during multi-layer printing, i.e., layer-to-layer bonding. The main printing parameters that have been investigated include printing speed, filament feed rate, and incident laser power. Bonding widths from 17 to 221 mu m are achieved with 196 mu m diameter fused silica filaments in single line printing. Using experimentally determined printing parameters for such filament, 3D printed objects consisting of more than 100 layers were subsequently demonstrated. The results presented here provide an approach in glass 3D printing, using the filament-based technique, enabling highly complex glass structures to be fabricated., QC 20220920

Optical fibre consisting of a pure silicon core in silica cladding combines the advantageous properties of silicon waveguides with the convenience of optical fibre. However, the optical quality of these fibres is highly dependent on the crystalline structure and the purity of the silicon. The fabrication of these fibres requires engineering of the thermal gradients during the drawing process to ensure optimal crystallisation of the silicon. Here, we investigated the effects of draw speed and analyse the induced stresses at multiple stages in the fabrication process. The thermal exposure of the silicon while in contact with a silica cladding was found to increase the optical losses. This was attributed to the diffusion of impurities from the silica cladding into the silicon core., Part of proceedings. ISBN 978-1-5106-5157-9; 978-1-5106-5156-2, QC 20220831

We demonstrate a method for rapid prototyping of optical fibers. Silica-based glass rods were 3D printed using laser powder deposition. Different doping of the 3D printed rods is evaluated, including alumina, titania, and erbium-doped glass. The rods were subsequently used as the core material in preforms with optical fibers drawn using a laser-based draw tower. A transmission loss of 3.2 dB/m was found for a fiber with 1 wt% titania doped core and pure silica cladding. Using this fabrication method, prototyping from powder to optical fiber could be achieved within a few hours., QC 20220811

Rapid manufacturing of high purity fused silica glass micro-optics using a filament-based glass 3D printer has been demonstrated. A multilayer 5 x 5 microlens array was printed and subsequently characterized, showing fully dense lenses with uniform focal lengths and good imaging performance. A surface roughness on the order of R-a = 0.12 nm was achieved. Printing time for each lens was <10 s. Creating arrays with multifocal imaging capabilities was possible by individually varying the number of printed layers and radius for each lens, effectively changing the lens height and curvature. Glass 3D printing is shown in this study to be a versatile approach for fabricating silica micro-optics suitable for rapid prototyping or manufacturing., QC 20230921

We utilized a powder-based, 3D printing technique for prototyping optical fibers. Co-doped silica rods were printed using sub-micron powders with various compositions. The rods were sleeved and drawn into fibers. Ti/Al/Er-co-doped fibers are demonstrated., Part of ISBN 9781557528209SyskonpostNot duplicate with DiVA 1763568QC 20230622

Here, we present an innovative preform manufacturing technique for specialty optical fibers based on a carbon monoxide laser heating a rotating preform. The setup performance is evaluated with the aid of finite element modeling. The fabrication process is described in detail using silicon core preforms as a benchmark. The hybrid material nature of such a preform is addressed, together with the relevant characteristics, such as the difference in thermal conductivity and thermal expansion. Silicon core preforms with a wide range of core sizes were manufactured, proving the viability of this system for the development of specialty optical fibers based on novel materials., QC 20211217

An experimental, laboratory-scale optical fiber drawing tower based on CO laser heating has been developed and used to fabricate speciality optical fiber. The CO laser was utilized in a symmetric four beam heating system. The localized and responsive heating time of the laser-based furnace was beneficial for manufacturing crystalline core fibers, specifically, silicon core optical fibers. Moreover, the specific absorption properties of the CO laser radiation in silica have been evaluated with the aid of finite element modeling. In comparison to the more traditional CO2 laser, CO lasers were found to improve temperature uniformity and heating times while minimizing surface evaporation., QC 20211217

Silicon core optical fibres have been fabricated using an experimental draw tower based on a CO laser furnace. Fabricated fibres have achieved a submicron core size and shown a record low loss of 0.1 dBcm. Frontiers in Optics / Laser Science, Part of proceedings: ISBN 978-1-55752-820-9 QC 20220927

Rapid manufacturing of silica glass microlens arrays is demonstrated using a novel glass 3D printing technology. A 5×5 array was printed and subsequent characterization showed dense microlenses with uniform focal lengths and good imaging performance. Frontiers in Optics / Laser Science, Part of proceedings: ISBN 978-1-55752-820-9QC 20220927

Submitted to Optical Materials Express, finally published in DOI 10.1364/OME.459400QC 20220530

We report the development of a specialty optical fiber preform fabrication system based on carbon monoxide laser heating. The laser heating is realized via a single-beam optical arrangement and integrated into a rotating glass lathe. Various technical solutions are integrated to counteract the absorption of the laser emission in humid air. The performance of the implemented solutions is studied and the ability to maintain a desired temperature during preform manufacturing is demonstrated. Relevant aspects of preform manufacturing, such as glass cutting, splicing, tapering, and overcladding are described in detail. The process of using these aspects to fabricate optical fiber preforms made of highly dissimilar materials and of various core-to-cladding ratios is discussed. Specialty fibers drawn from these preforms exhibit low-loss and showed high optical performance., QC 20220518