Browsing by Subject "Optics and Photonics"
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Item Open Access Feature issue of digital holography and 3D imaging (DH) introduction(Optical Society of America (OSA), 2014-07) Hayasaki, Y.; Zhou, C.; Popescu, G.; Onural, LeventThe OSA Topical Meeting "Digital Holography and 3D Imaging (DH)," was held in Seattle, Washington, July 13-17, 2014. Feature issues based on the DH meeting series have been released by Applied Optics (AO) since 2007. This year Optics Express (OE) and AO jointly decided to have one such feature issue in each journal. The DH meeting will continue in the future, as expected, and the next meeting is scheduled to be held on 24-28 May 2015, in Shanghai Institute of Optics and Fine Mechanics, Shanghai, China. © 2014 Optical Society of AmericaItem Open Access Texturing of titanium (Ti6Al4V) medical implant surfaces with MHz-repetition-rate femtosecond and picosecond Yb-doped fiber lasers(Optical Society of American (OSA), 2011) Erdoǧan, M.; Öktem, B.; Kalaycioǧlu H.; Yavaş, S.; Mukhopadhyay P.K.; Eken, K.; Özgören, K.; Aykaç, Y.; Tazebay, U.H.; Ilday F.O.We propose and demonstrate the use of short pulsed fiber lasers in surface texturing using MHz-repetition-rate, microjoule- and sub-microjoule-energy pulses. Texturing of titanium-based (Ti6Al4V) dental implant surfaces is achieved using femtosecond, picosecond and (for comparison) nanosecond pulses with the aim of controlling attachment of human cells onto the surface. Femtosecond and picosecond pulses yield similar results in the creation of micron-scale textures with greatly reduced or no thermal heat effects, whereas nanosecond pulses result in strong thermal effects. Various surface textures are created with excellent uniformity and repeatability on a desired portion of the surface. The effects of the surface texturing on the attachment and proliferation of cells are characterized under cell culture conditions. Our data indicate that picosecond-pulsed laser modification can be utilized effectively in low-cost laser surface engineering of medical implants, where different areas on the surface can be made cell-attachment friendly or hostile through the use of different patterns. © 2011 Optical Society of America.Item Open Access Unidirectional transmission in photonic-crystal gratings at beam-type illumination(Optical Society of American (OSA), 2010) Cakmak, A.O.; Colak, E.; Serebryannikov, A.E.; Özbay, EkmelUnidirectional transmission is studied theoretically and experimentally for the gratings with one-side corrugations (non-symmetric gratings), which are based on two-dimensional photonic crystals composed of alumina rods. The unidirectional transmission appears at a fixed angle of incidence as a combined effect of the peculiar dispersion features of the photonic crystal and the properly designed corrugations. It is shown that the basic unidirectional transmission characteristics, which are observed at a plane-wave illumination, are preserved at Gaussian-beam and horn antenna illuminations. The main attention is paid to the single-beam unidirectional regime, which is associated with the strong directional selectivity arising due to the first negative diffraction order. An additional degree of freedom for controlling the transmission of the electromagnetic waves is obtained by making use of the asymmetric corrugations at the photonic crystal interface. © 2010 Optical Society of America.