Now showing items 1-20 of 39

    • A 500 MHz carbon nanotube transistor oscillator 

      Pesetski, A. A.; Baumgardner, J. E.; Krishnaswamy, S. V.; Zhang, H.; Adam, J. D.; Kocabaş, Coşkun; Banks, T.; Rogers, J. A. (American Institute of Physics, 2008-09)
      Operation of a carbon nanotube field effect transistor (FET) oscillator at a record frequency of 500 MHz is described. The FET was fabricated using a large parallel array of single-walled nanotubes grown by chemical vapor ...
    • Alignment controlled growth of single-walled carbon nanotubes on quartz substrates 

      Xiao, J.; Dunham, S.; Liu, P.; Zhang, Y.; Kocabaş, Coşkun; Moh, L.; Huang, Y.; Hwang, K. -C.; Lu, C.; Huang, W.; Rogers, J. A. (American Chemical Society, 2009-09-11)
      Single-walled carbon nanotubes (SWNTs) possess extraordinary electrical properties, with many possible applications in electronics. Dense, horizonally aligned arrays of linearly configured SWNTs represent perhaps the most ...
    • Atomic layer deposited Al 2O 3 passivation of type II InAs/GaSb superlattice photodetectors 

      Salihoğlu, Ömer; Muti, Abdullah; Kutluer, Kutlu; Tansel, T.; Turan, R.; Kocabaş, Coşkun; Aydınlı, Atilla (AIP, 2012)
      Taking advantage of the favorable Gibbs free energies, atomic layer deposited (ALD) aluminum oxide (Al 2O 3) was used as a novel approach for passivation of type II InAs/GaSb superlattice (SL) midwave infrared (MWIR) single ...
    • Broadband THz modulators based on multilayer graphene on PVC 

      Kaya, E.; Kakenov, Nurbek; Kocabaş, Coşkun; Altan, H.; Esentürk, O. (IEEE, 2016)
      In this study we present the direct terahertz time-domain spectroscopic measurement of CVD-grown multilayer graphene (MLG) on PVC substrate with an electrically tunable Fermi level. In a configuration consisting MLG and ...
    • Chemically addressed switching measurements in graphene electrode memristive devices using in situ XPS 

      Kocabaş, Coşkun; Köymen, Itır; Aydoğan Göktürk, Pınar; Süzer, Şefik (Royal Society of Chemistry, 2019-08)
      The memristor has been the topic of heated research activity since the Pt/TiO2/TiOx/Pt structure was reported by Hewlett-Packard Labs. The characteristics of memristors such as the pinched hysteresis loops and time and ...
    • Compressive sensing imaging with a graphene modulator at THz frequency in transmission mode 

      Özkan, V. A.; Takan, T.; Kakenov, Nurbek; Kocabaş, Coşkun; Altan, H. (IEEE, 2016)
      In this study we demonstrate compressive sensing imaging with a unique graphene based optoelectronic device which allows us to modulate the THz field through an array of columns or rows distributed throughout its face.
    • Controlling phase of microwaves with active graphene surfaces 

      Balcı, Osman; Kakenov, Nurbek; Kocabaş, Coşkun (American Institute of Physics Inc., 2017)
      In this letter, we report a method to control the reflection phase of microwaves using electrically tunable graphene devices. The device consists of mutually gated large-area graphene layers placed at a quarter-wave distance ...
    • Coupled plasmonic cavities on moire surfaces 

      Balcı, Sinan; Karabıyık, Mustafa; Kocabaş, Aşkın; Kocabaş, Coşkun; Aydınlı, Atilla (Springer, 2010-08)
      Surface plasmon polariton (SPP) waveguides formed by coupled plasmonic cavities on metallic Moire surfaces have been investigated both experimentally and numerically. The Moire surface, fabricated by interference lithography, ...
    • Direct imaging of localized surface plasmon polaritons 

      Balcı, Sinan; Karademir, Ertuğrul; Kocabaş, Coşkun; Aydınlı, Atilla (Optical Society of America, 2011-08)
      In this Letter, we report on dark field imaging of localized surface plasmon polaritons (SPPs) in plasmonic waveguiding bands formed by plasmonic coupled cavities. We image the light scattered from SPPs in the plasmonic ...
    • Electrically controlled terahertz spatial light modulators with graphene arrays 

      Kakenov, Nurbek; Takan, T.; Özkan, V. A.; Balcı, Osman; Polat, Emre Ozan; Altan, H.; Kocabaş, Coşkun (IEEE, 2016)
      Gate-tunable high-mobility electrons on atomically thin graphene layers provide a unique opportunity to control electromagnetic waves in a very broad spectrum. In this paper, we describe an electrically-controlled multipixel ...
    • Electrically switchable metadevices via graphene 

      Balcı, Osman; Kakenov, Nurbek; Karademir, E.; Balcı, S.; Çakmakyapan, S.; Polat, E. O.; Cağlayan, H.; Özbay, Ekmel; Kocabaş, Coşkun (American Association for the Advancement of Science, 2018)
      Metamaterials bring subwavelength resonating structures together to overcome the limitations of conventional materials. The realization of active metadevices has been an outstanding challenge that requires electrically ...
    • Electrically unbiased driven airborne capacitive micromachined ultrasonic transducer design 

      Ünlügedik, Aslı; Atalar, Abdullah; Kocabaş, Coşkun; Oğuz, H. Kağan; Köymen, Hayrettin (IEEE, 2012)
      We present a design method for airborne capacitive micromachined ultrasonic transducers (CMUT). We use an equivalent lumped element circuit to model both electrical and mechanical properties of CMUT and analyze it in ...
    • Femtosecond pulse generation from a Ti3+: Sapphire laser near 800 nm with voltage reconfigurable graphene saturable absorbers 

      Baylam, Işınsu; Özharar, Sarper; Kakenov, Nurbek; Kocabaş, Coşkun; Sennaroglu, Alphan (OSA - The Optical Society, 2017)
      We experimentally show that a voltage-controlled graphene-gold supercapacitor saturable absorber (VCG-gold-SA) can be operated as a fast saturable absorber with adjustable linear absorption at wavelengths as low as 795 nm. ...
    • Femtosecond pulse generation from an extended cavity Cr4+: Forsterite laser using graphene on YAG 

      Baylam I.; Ozharar, S.; Natali Cizmeciyan, M.; Balcı, Osman; Pince, Erçağ; Kocabaş, Coşkun; Sennaroglu, A. (Optical Society of America, 2013)
      A room temperature, multipass-cavity, femtosecond Cr4+:forsterite laser was modelocked with a single-layer graphene saturable absorber on a YAG substrate. The resonator produced nearly transform-limited 92 fs pulses near ...
    • Graphene mode-locked diode-pumped Cr:LiSAF laser at 857 nm 

      Canbaz, F.; Kakenov, Nurbek; Kocabaş, Coşkun; Demirbaş, U.; Sennaroglu, A. (IEEE, 2015)
      The Cr:LiSAF gain medium, belonging to the class of Cr:colquiirite lasers, possesses a broad gain bandwidth suitable for the generation of femtosecond pulses near 850 nm [1]. Because the nonlinear refractive index of these ...
    • Graphene nanoreactors : photoreduction of prussian blue in aqueous solution 

      Nappini, Silvia; Matruglio, Alessia; Naumenko, Denys; Dal Zilio, Simone; Lazzarino, Marco; De Groot, Frank M.F.; Kocabaş, Coşkun; Balcı, Osman; Magnano, Elena (American Chemical Society, 2017)
      Prussian dyes are characterized by interesting photomagnetic properties due to the photoinduced electron transfer involved in the Fe oxidation and spin state changes. Ferromagnetic Prussian blue (PB) in contact with titanium ...
    • Graphene supercapacitor as a voltage controlled saturable absorber for femtosecond pulse generation 

      Baylam, I.; Çizmeciyan, M. N.; Özharar, S.; Polat, Emre Ozan; Kocabaş, Coşkun; Sennaroğlu, A. (OSA, 2014)
      For the first time to our knowledge, we employed a graphene supercapacitor as a voltage controlled saturable absorber at bias voltages of 0.5-1V to generate 84-fs pulses from a solid-state laser near 1255 nm.
    • Graphene-based plasmonics 

      Balci S.; Polat E.O.; Kocabaş, Coşkun (Pan Stanford Publishing, 2015)
      The unique electrical, optical, and chemical properties of the two-dimensional crystal of carbon, graphene, stimulated great interest for plasmonics in reduced dimensions. Notably, controlled electrostatic doping on graphene ...
    • Graphene-gold supercapacitor as a voltage-controlled saturable absorber for femtosecond pulse generation 

      Baylam, I.; Balcı, Osman; Kakenov, Nurbek; Kocabaş, Coşkun; Sennaroğlu, A. (OSA, 2015)
      We report, for the first time to our knowledge, a voltage-controlled graphene-gold supercapacitor saturable absorber, as a modulator with adjustable insertion loss for low-gain mode-locked lasers. Nearly transform-limited, ...
    • High frequency performance of individual and arrays of single-walled carbon nanotubes 

      Balcı, Osman; Kocabaş, Coşkun (Institute of Physics Publishing, 2012-05-28)
      We have studied the high frequency performance limits of single-walled carbon nanotube (SWNT) transistors in the diffusive transport regime limited by the acoustic phonon scattering. The relativistic band structure of ...