Browsing by Subject "Fused silica"

Now showing 1 - 5 of 5

Open Access
Characterization of thermally poled germanosilicate thin films
(Optical Society of American (OSA), 2004) Ozean, A.; Digonnet, M.J.F.; Kino G.S.; Ay F.; Aydınlı, Atilla
We report measurements of the nonlinearity profile of thermally poled low-loss germanosilicate films deposited on fused-silica substrates by PECVD, of interest as potential electro-optic devices. The profiles of films grown and poled under various conditions all exhibit a sharp peak ∼0.5 μm beneath the anode surface, followed by a weaker pedestal of approximately constant amplitude down to a depth of 13-16 μm, without the sign reversal typical of poled undoped fused silica. These features suggest that during poling, the films significantly slow down the injection of positive ions into the structure. After local optimization, we demonstrate a record peak nonlinear coefficient of ∼1.6 pm/V, approximately twice as strong as the highest reliable value reported in thermally poled fused silica glass, a significant improvement that was qualitatively expected from the presence of Ge. ©2004 Optical Society of America.
Open Access
CO2 laser polishing of microfluidic channels fabricated by femtosecond laser assisted carving
(Institute of Physics Publishing, 2016-10) Serhatlioglu, M.; Ortaç, B.; Elbuken, C.; Bıyıklı, Necmi; Solmaz, M. E.
In this study, we investigate the effects of CO2 laser polishing on microscopic structures fabricated by femtosecond laser assisted carving (FLAC). FLAC is the peripheral laser irradiation of 2.5D structures suitable for low repetition rate lasers and is first used to define the microwell structures in fused silica followed by chemical etching. Subsequently, the bottom surface of patterned microwells is irradiated with a pulsed CO2 laser. The surfaces were characterized using an atomic force microscope (AFM) and scanning electron microscope (SEM) in terms of roughness and high quality optical imaging before and after the CO2 laser treatment. The AFM measurements show that the surface roughness improves more than threefold after CO2 laser polishing, which promises good channel quality for applications that require optical imaging. In order to demonstrate the ability of this method to produce low surface roughness systems, we have fabricated a microfluidic channel. The channel is filled with polystyrene bead-laden fluid and imaged with transmission mode microscopy. The high quality optical images prove CO2 laser processing as a practical method to reduce the surface roughness of microfluidic channels fabricated by femtosecond laser irradiation. We further compared the traditional and laser-based glass micromachining approaches, which includes FLAC followed by the CO2 polishing technique.
Open Access
Femtosecond laser fabrication of fiber based optofluidic platform for flow cytometry applications
(SPIE, 2017) Serhatlioglu, Murat; Elbuken, Çağlar; Ortac, Bülend; Solmaz, Mehmet E.
Miniaturized optofluidic platforms play an important role in bio-analysis, detection and diagnostic applications. The advantages of such miniaturized devices are extremely low sample requirement, low cost development and rapid analysis capabilities. Fused silica is advantageous for optofluidic systems due to properties such as being chemically inert, mechanically stable, and optically transparent to a wide spectrum of light. As a three dimensional manufacturing method, femtosecond laser scanning followed by chemical etching shows great potential to fabricate glass based optofluidic chips. In this study, we demonstrate fabrication of all-fiber based, optofluidic flow cytometer in fused silica glass by femtosecond laser machining. 3D particle focusing was achieved through a straightforward planar chip design with two separately fabricated fused silica glass slides thermally bonded together. Bioparticles in a fluid stream encounter with optical interrogation region specifically designed to allocate 405nm single mode fiber laser source and two multi-mode collection fibers for forward scattering (FSC) and side scattering (SSC) signals detection. Detected signal data collected with oscilloscope and post processed with MATLAB script file. We were able to count number of events over 4000events/sec, and achieve size distribution for 5.95μm monodisperse polystyrene beads using FSC and SSC signals. Our platform shows promise for optical and fluidic miniaturization of flow cytometry systems. © 2017 SPIE.
Open Access
On-machine fabrication of PCD and WC micro end mills using micro electro discharge machining
(Inderscience Enterprises Ltd., 2014) Oliaei, S.N.B.; Özdemir, C.; Karpat, Y.
Micro electro discharge machining (μ -EDM) process can be used to fabricate micro-milling tools of different geometries from tungsten carbide (WC) and polycrystalline diamond (PCD). The non-contact nature of EDM process makes micro tool fabrication a challenging task while offering the advantage of eliminating tool run out and clamping errors since micro tools fabricated on-machine. The tools are fabricated and used on the same spindle. In this study, a combination of block-EDM and wire electro discharge grinding (WEDG) techniques are used to fabricate micro end mills of different geometries. The influences of EDM process parameters on material erosion rate and surface roughness are examined. The performance of the fabricated micro-tools in ductile mode machining of fused silica has been investigated. It is found that micro end mills can be used to fabricate prototypes of microfluidics chips with acceptable quality. © 2014 Inderscience Enterprises Ltd.
Open Access
Thermally poled germanosilicate films with high second-order nonlinearity
(IEEE, 2005) Özcan, A.; Digonnet, M. J. F.; Kino, G. S.; Ay, Feridun; Aydınlı, Atilla
Accurate measurements of the second-order nonlinearity profile of thermally poled low-loss germanosilicate films grown on fused-silica substrates are reported, of interest as potential electro-optic devices. After optimization, we demonstrate a record high nonlinear coefficient d 33 ≈ 1.6 pm/V, a two-fold improvement over highest reported d 33 value in fused silica that we attribute to the presence of germanium.