BEGIN:VCALENDAR VERSION:2.0 PRODID:IEEE vTools.Events//EN CALSCALE:GREGORIAN BEGIN:VTIMEZONE TZID:Turkey BEGIN:DAYLIGHT DTSTART:20380119T061407 TZOFFSETFROM:+0300 TZOFFSETTO:+0300 RRULE:FREQ=YEARLY;BYDAY=3TU;BYMONTH=1 TZNAME:+03 END:DAYLIGHT BEGIN:STANDARD DTSTART:20160907T000000 TZOFFSETFROM:+0300 TZOFFSETTO:+0300 RRULE:FREQ=YEARLY;BYDAY=1WE;BYMONTH=9 TZNAME:+03 END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTAMP:20190524T200720Z UID:64F4367B-4EB9-46FB-9962-AA98CC5C60E3 DTSTART;TZID=Turkey:20190517T133000 DTEND;TZID=Turkey:20190517T153000 DESCRIPTION:Speaker: Prof. F. Ömer Ilday\, Bilkent University\n\nTopic: "U ltrafast laser-driven self-organized nano- and micro-structuring"\n\nLocat ion: Middle East Technical University\, Ankara\, Turkey\n\nAbstract: Ultra fast laser processing has diverse applications\, including creation of pre cision microstructures. However\, scaling down to the nanoscale is strongl y limited by the wavelength of the laser and by the cubic size of processi ng time with the spatial resolution\, which we refer to\, colloquially\, a s the “fat fingers problem\,” the “explosion of complexity problem ” and the increasingly strong thermal fluctuations.\n\nThe alternative a pproach that we are pursuing is to utilize laser-driven self-organization and self-assembly to put together the intended structures\, which can be a rbitrarily smaller than the wavelength of the laser beam. These structures are\, then\, dictated by the nonlinear dynamics of the system\, which can be of a multitude of forms to be chosen from a limited\, by rich library. We can choose them by adjusting only one or few parameters\, typically\, the laser power or polarization and different regions within a material ca n have different structures.\n\nOur approach follows the principles laid o ut by luminaries like I. Progogine and H. Haken\, already\, in 1960s and 1 970s\, but was not applied to laser-material processing largely because mu ch of the technologies we rely on did not yet exist. Our implementation is inspired by the physics of mode-locking of lasers\, whereby modes that lo ck up in phase experience preferential “gain” over having random phase s\, which leads to a coherent structure in time. Similarly\, we arrange fo r a certain coherent (typically periodic\, but potentially aperiodic\, as well) spatial structure to experience higher gain over the alternatives. I n case of materials\, this is achieved by driving the material locally far from thermodynamic equilibrium\, which is necessary to gain access to mul titude of spatial structures to choose from. Higher “gain” is achieved by invoking nonlinearities in the form of positive feedback between laser beam-induced changes in the material and material change-induced effects back on the laser beam.\n\nWe first showed that we could create laser-indu ced spatial nanostructures on various material surfaces with unprecedented uniformity (Ilday et al.\, Nature Photon.\, 2013). Afterwards\, we have s howed the benefits of nonlinear feedback in extremely efficient laser-mate rial ablation (Ilday et al.\, Nature\, 2016)\, creation of self-organized 3D structures inside silicon (Ilday et al.\, Nature Photon.\, 2017)\, and self-assembly of colloidal nanoparticles (Ilday et al.\, Nature Commun.\, 2017). We recently extended our results to self-assembly of colloids as sm all as a few nanometers\, which is orders of magnitude smaller than the la ser beam size that we use. We will also discuss how the symmetries of the feedback interactions determine the symmetries of self-organized patterns\ , and how we can use even “noise” to select desired patterns.\n\nIn th ese demonstrations\, we have worked with physical systems that were delibe rately chosen to be completely different from each case\, from a silicon c rystal to molybdenum surfaces or colloidal nanoparticles\, to show that th is approach is not material\, size\, or interaction specifics. Their commo nality is that they are all nonlinear systems\, which we deliberately driv e far from equilibrium with the laser pulses. Although our focus is on und erstanding the basic physics\, the talk will briefly showcase several appl ications.\n\nBio: Dr. F. Ömer Ilday received the BS degree in theoretical physics from Boğaziçi University\, Istanbul\, Turkey\, in 1998. He took his PhD in applied physics from Cornell University\, Ithaca\, NY\, USA\, in 2003. He worked at Massachusetts Institute of Technology (MIT) from 200 3 to 2006. In 2006\, he joined Bilkent University as faculty member. He wa s awarded the European Research Council’s prestigious Consolidator Grant in 2013\, the first consolidator grant and the first ERC grant on basic s cience in Turkey. Dr. Ilday graduated valedictorian of the top-ranked Phys ics Department at Bogazici University in 1998. In 2003\, he received the p restigious RLE Fellowship from MIT. His contributions to science have been generously recognized through various awards\, including Findlay Award fr om Cornell University (2004)\, Outstanding Young Scientist Award from the Turkish Academy of Sciences (TÜBA-GEBIP) (2006)\, Teşvik Award from the Scientific and Technological Research Council of Turkey (TÜBİTAK) (2011) \, Engin Arık Science Award from the Turkish Physical Society (2012) and the top award in science in Turkey\, the Science Award of TÜBİTAK (2017) . He is a full member of the Science Academy of Turkey and a senior member of the Optical Society (OSA).\n\nSpeaker(s): Prof. Omer Ilday\, \n\nAnkar a\, Ankara\, Türkiye LOCATION:Ankara\, Ankara\, Türkiye ORGANIZER:ozergul@metu.edu.tr SEQUENCE:0 SUMMARY:IEEE AP/MTT/EMC/ED TURKEY CHAPTER SEMINAR SERIES -- SEMINAR 52 URL;VALUE=URI:https://events.vtools.ieee.org/m/199497 X-ALT-DESC:Description: <br /><p>Speaker: Prof. F. &Ouml\;mer Ilday\, Bilke nt University</p>\n<p>Topic: "Ultrafast laser-driven self-organized nano- and micro-structuring"</p>\n<p>Location:&nbsp\;Middle East Technical Unive rsity\, Ankara\, Turkey</p>\n<p>Abstract:&nbsp\;Ultrafast laser processing has diverse applications\, including creation of precision microstructure s. However\, scaling down to the nanoscale is strongly limited by the wave length of the laser and by the cubic size of processing time with the spat ial resolution\, which we refer to\, colloquially\, as the &ldquo\;fat fin gers problem\,&rdquo\; the &ldquo\;explosion of complexity problem&rdquo\; and the increasingly strong thermal fluctuations.</p>\n<p>The alternative approach that we are pursuing is to utilize laser-driven self-organizatio n and self-assembly to put together the intended structures\, which can be arbitrarily smaller than the wavelength of the laser beam. These structur es are\, then\, dictated by the nonlinear dynamics of the system\, which c an be of a multitude of forms to be chosen from a limited\, by rich librar y. We can choose them by adjusting only one or few parameters\, typically\ , the laser power or polarization and different regions within a material can have different structures.</p>\n<p>Our approach follows the principles laid out by luminaries like I. Progogine and H. Haken\, already\, in 1960 s and 1970s\, but was not applied to laser-material processing largely bec ause much of the technologies we rely on did not yet exist. Our implementa tion is inspired by the physics of mode-locking of lasers\, whereby modes that lock up in phase experience preferential &ldquo\;gain&rdquo\; over ha ving random phases\, which leads to a coherent structure in time. Similarl y\, we arrange for a certain coherent (typically periodic\, but potentiall y aperiodic\, as well) spatial structure to experience higher gain over th e alternatives. In case of materials\, this is achieved by driving the mat erial locally far from thermodynamic equilibrium\, which is necessary to g ain access to multitude of spatial structures to choose from. Higher &ldqu o\;gain&rdquo\; is achieved by invoking nonlinearities in the form of posi tive feedback between laser beam-induced changes in the material and mater ial change-induced effects back on the laser beam.</p>\n<p>We first showed that we could create laser-induced spatial nanostructures on various mate rial surfaces with unprecedented uniformity (Ilday et al.\, Nature Photon. \, 2013). Afterwards\, we have showed the benefits of nonlinear feedback i n extremely efficient laser-material ablation (Ilday et al.\, Nature\, 201 6)\, creation of self-organized 3D structures inside silicon (Ilday et al. \, Nature Photon.\, 2017)\, and self-assembly of colloidal nanoparticles ( Ilday et al.\, Nature Commun.\, 2017). We recently extended our results to self-assembly of colloids as small as a few nanometers\, which is orders of magnitude smaller than the laser beam size that we use. We will also di scuss how the symmetries of the feedback interactions determine the symmet ries of self-organized patterns\, and how we can use even &ldquo\;noise&rd quo\; to select desired patterns.</p>\n<p>In these demonstrations\, we hav e worked with physical systems that were deliberately chosen to be complet ely different from each case\, from a silicon crystal to molybdenum surfac es or colloidal nanoparticles\, to show that this approach is not material \, size\, or interaction specifics. Their commonality is that they are all nonlinear systems\, which we deliberately drive far from equilibrium with the laser pulses. Although our focus is on understanding the basic physic s\, the talk will briefly showcase several applications.</p>\n<p>Bio: Dr. F. &Ouml\;mer Ilday received the BS degree in theoretical physics from Bo ğazi&ccedil\;i University\, Istanbul\, Turkey\, in 1998. He took his PhD in applied physics from Cornell University\, Ithaca\, NY\, USA\, in 2003. He worked at Massachusetts Institute of Technology (MIT) from 2003 to 2006 . In 2006\, he joined Bilkent University as faculty member. He was awarded the European Research Council&rsquo\;s prestigious Consolidator Grant in 2013\, the first consolidator grant and the first ERC grant on basic scien ce in Turkey. Dr. Ilday graduated valedictorian of the top-ranked Physics Department at Bogazici University in 1998. In 2003\, he received the prest igious RLE Fellowship from MIT. His contributions to science have been gen erously recognized through various awards\, including Findlay Award from C ornell University (2004)\, Outstanding Young Scientist Award from the Turk ish Academy of Sciences (T&Uuml\;BA-GEBIP) (2006)\, Teşvik Award from the Scientific and Technological Research Council of Turkey (T&Uuml\;BİTAK) (2011)\, Engin Arık Science Award from the Turkish Physical Society (2012 ) and the top award in science in Turkey\, the Science Award of T&Uuml\;B İTAK (2017). He is a full member of the Science Academy of Turkey and a s enior member of the Optical Society (OSA).</p> END:VEVENT END:VCALENDAR