Department of Physics

Burst-mode Yb-doped fiber amplifier system optimized for low-repetition-rate operation

Kalaycıoğlu, H.; Akçaalan, Ö.; Yavaş, S.; Eldeniz, Y. B.; Ilday, F. Ö. (Optical Society of America, 2015)

We report on the burst-mode operation of a polarization-maintaining Yb-doped multi-stage all-fiber amplifier capable of generating 10-pulse 100 ns long bursts of 400 μJ total energy. The corresponding average energy per ...

Cavity formation in split ring resonators

Caglayan, H.; Bulu, I.; Loncar, M.; Ozbay, E. (Elsevier BV, 2008-12)

We report that it is possible to obtain a cavity structure by the deformation of a unit cell of an split ring resonator (SRR) structure. We presented the Q-factor of the cavity resonance as 192 for an SRR-based single ...

Graphene-enabled electrically controlled terahertz spatial light modulators

Kakenov, N.; Takan, T.; Ozkan, V. A.; Balcı, O.; Polat, E. O.; Altan, H.; Kocabas, C. (Optical Society of America, 2015-05-01)

In this Letter, we demonstrate a broadband terahertz (THz) spatial light modulator using 5×5 arrays of large area graphene supercapacitors. Our approach relies on controlling spatial charge distribution on a passive matrix ...

Multifunctional integrated photonic switches

Demir, H. M.; Sabnis, V. A.; Fidaner, O.; Zheng, J.-F.; Harris, J. S.; Miller, D. A. B. (Institute of Electrical and Electronics Engineers, 2005)

Traditional optical-electronic-optical (o-e-o) conversion in today’s optical networks requires cascading separately packaged electronic and optoelectronic chips and propagating high-speed electrical signals through and ...

FRET-LEDs involving colloidal quantum dot nanophosphors

Nizamoğlu, S.; Sari, E.; Baek, J. H.; Lee, I. H.; Sun, X. W.; Demir, H. V. (Webcom Communications, 2010)

Semiconductor nanocrystal quantum dots (NQD) with their narrow and tuneable emission are promising candidates to serve as color convertors integrated on light-emitting diodes (LEDs). The use of nonradiative energy transfer, ...

Stable dispersion of iodide-capped PbSe quantum dots for high-performance low-temperature processed electronics and optoelectronics

Sayevich, V.; Gaponik, N.; Plötner, M.; Kruszynsk, M.; Gemming, T.; Dzhagan, V. M.; Akhavan, S.; Zahn, D. R. T.; Demir, H. V.; Eychmüller, A. (American Chemical Society, 2015)

Here, we present a ligand exchange of long insulating molecules with short, robust, and environmentally friendly iodide ions via a mild flocculation of PbSe nanocrystals (NCs). This ligand exchange leads to the formation ...

Blue liquid lasers from solution of CdZnS/ZnS ternary alloy quantum dots with quasi ‐ continuous pumping

Wang, Y.; Leck, K. S.; Ta, V. D.; Chen, R.; Nalla, V.; Gao, Y.; He, T.; Demir, H. V.; Sun, H. (Wiley - VCH Verlag GmbH & Co. KGaA, 2015)

A blue (ca. 440 nm) liquid laser with an ultra‐low threshold through which quasi‐continuous wave pumping is accessible is achieved by engineering unconventional ternary CdZnS/ZnS alloyed‐core/shell QDs. Such an achievement ...

Semiconductor nanocrystals as rare-earth alternatives

Erdem, T.; Demir, H. V. (Macmillan Publishers, 2011)

Ginga observations of XI820 — 303 in the globular cluster NGC 6624

Ercan, E. N.; Cruise, A. M.; Kellett, B. J.; Saygili, K. (Oxford University Press, 1993)

We present the first spectral observations obtained by Ginga of the low-mass X-ray binary source X1820-303 located in the globular cluster NGC6624. Two twocomponent spectral models are found to provide good fits to the ...

Coupling and phase analysis of cavity structures in two-dimensional photonic crystals

Guven, K.; Ozbay, E. (American Physical Society, 2005)

An experimental and numerical study of the coupling properties of cavity waveguides and the phase advancement through the coupled cavity waveguides in two-dimensional photonic crystals is presented. We find that the ...

High – repetition - rate ultrafast fiber lasers for material processing

Kalaycıoğlu, H.; Elahi, P.; Akçaalan, Ö.; Ilday, F. Ö. (Institute of Electrical and Electronics Engineers, 2017)

Ultrafast lasers operating at high repetition rates, in particular the GHz range, enable new possibilities in lasermaterial processing, particularly accessing the recently demonstrated ablation-cooled regime. We provide ...

Transmission, refraction, and focusing properties of labyrinth based left‐handed metamaterials

Özbay, E.; Bulu, I.; Caglayan, H. (Wiley- VCH Verlag GmbH & Co. KGaA, 2007-04)

In this present article, we studied the transmission, refraction and focusing properties of one, two and three dimensional labyrinth based left-handed metamaterials. We demonstrated that the proper periodic arrangement of ...

Radiation properties of a split ring resonator and monopole composite

Alici, K. B.; Özbay, E. (Wiley-VCH Verlag GmbH & Co. KGaA, 2007-02-20)

We studied the far field radiation properties of a new resonator antenna composed of split ring resonators (SRRs) and a monopole. It is shown that the antenna size at the operation frequency (3.52 GHz) is approximately one ...

Unusual fluorescent properties of stilbene units and cdzns/zns quantum dots nanocomposites : white-light emission in solution versus light-harvesting in films

He, T.; Gao, Y.; Gao, y.; Lin, X.; Chen, R.; Hu, W.; Zhao, X.; Wang, Y.; Demir, H. V.; Fan, Q.; Grimsdale, A. C.; Sun, H. (Wiley - V C H Verlag GmbH & Co. KGaA, 2016)

Nanocomposites with organic–inorganic properties represent a new fi eld of basic research and offer prospects for many novel applications in extremely diverse fi elds, due to their remarkable emerging new properties and ...