Researcher:
Çankaya, Hüseyin

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Hüseyin

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Çankaya

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Çankaya, Hüseyin

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2007 - 2009152010 - 201820

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    Spectroscopic characterization of Tm3+:TeO2-K2O-Nb2O5 glasses for 2- μm lasing applications
    (Elsevier Science Bv, 2012) Kurt, Adnan; Speghini, Adolfo; Bettinelli, Marco; Department of Physics; Department of Physics; Department of Physics; Görgülü, Adil Tolga; Çankaya, Hüseyin; Sennaroğlu, Alphan; Master Student; Researcher; Faculty Member; Department of Physics; College of Sciences; College of Sciences; College of Sciences; N/A; N/A; 23851
    We have performed detailed experiments to investigate the spectroscopic properties of a new type of tellurite based host doped with thulium: Tm2O3:(0.70)TeO2-(0.15)K2O-(0.15)Nb2O5 having Tm2O3 concentrations of 0.125, 0.25, 0.5, and 1.0 mol%. By performing a Judd-Ofelt analysis of the absorption bands, we obtained average radiative lifetimes of 2.57 +/- 0.20 and 0.35 +/- 0.01 ms for the H-3(4) and F-3(4) levels, respectively. Furthermore, we also observed that an increase in the Tm2O3 concentration from 0.125 to 1.0 mol% results in a decrease of the measured fluorescence lifetime from 814 to 439 mu s and from 258 to 47 mu s for the H-3(4) and F-3(4) levels, respectively, due to efficient non-radiative decay. The highest quantum efficiency of 32% was obtained for the sample doped with 0.125 mol% Tm2O3 for the H-3(4) level. Results show that cross relaxation becomes important as the ion concentration is increased, leading to the quenching of the 1460-nm band and enhancement of the 1860-nm emission. The highest emission cross section of 6.85 x 10(-21) Cm-2 measured for the 1860-nm band reveals the potential of this host for the development of 2-mu m lasers in bulk glass as well as fiber media. (C) 2011 Published by Elsevier B.V.
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    Direct generation of 81 nJ pulses and external compression to a subpicosecond regime with a 4.9 MHz chirped-pulse multipass-cavity Cr⁴⁺:forsterite oscillator
    (Optical Soc Amer, 2011) Akturk, Selcuk; N/A; Department of Physics; Çankaya, Hüseyin; Sennaroğlu, Alphan; Researcher; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; N/A; 23851
    We report direct generation of 81 nJ chirped pulses from a room-temperature, Kerr lens mode-locked Cr4+:forsterite oscillator operating at 1258nm. To increase the pulse energy, the pulse repetition rate of the short x-type resonator was lowered from 143 to 4.9 MHz by the addition of a q-preserving multipass cavity, which provided an additional effective optical path length of 59.4m. The duration of the chirped pulses was around 5.5 ps with a spectral width of 21nm. The pulses were externally compressed to 607 fs by using a diffraction grating pair. To our knowledge, this is the highest reported pulse energy directly generated from a room-temperature mode-locked Cr4+:forsterite laser. (C) 2011 Optical Society of America
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    Spectroscopic investigation of Tm3+: TeO2-WO3 glass
    (Elsevier Science Bv, 2008) Özen, Gönül; N/A; N/A; N/A; Department of Physics; Kalaycıoğlu, Hamit; Çankaya, Hüseyin; Çizmeciyan, Melisa Natali; Sennaroğlu, Alphan; PhD Student; Researcher; PhD Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; N/A; 23851
    We studied the spectroscopic characteristics of telluride glass with the host composition (0.85)TeO2–(0.15)WO3, containing 0.25 and 1.0 mol% thulium oxide (Tm2O3). By analyzing the absorption spectra with the Judd–Ofelt theory, the average radiative lifetimes of 305±7.5 μs and 1.95±0.02 ms were determined for the 3F4 and 3H4 levels, respectively. Measured fluorescence lifetime of the 3F4 level decreased from 218 to 51 μs for the 0.25 and 1.0 mol% Tm2O3 doped samples, respectively, indicating the effect of boosted non-radiative decay at higher doping concentrations. A similar trend was observed for the 3H4 level, where the fluorescence lifetime decreased from 1.86 ms to 350 μs at these concentrations. The quenching of the 1460 nm (3F4→3H4) emission in favor of the 1800 nm (3H4→3H6) emission due to cross relaxation was further evident in the fluorescence spectra of the samples. The calculated stimulated emission cross sections (3.73±0.1×10−21 cm2 at 1460 nm and 6.57±0.07×10−21 cm2 at 1808 nm) reveal the potential importance of the Tm3+:(0.85)TeO2–(0.15)WO3 glass for applications in fiber-optic amplifiers and fiber lasers.
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    Preparation and spectroscopy of novel er(iii) doped polyurethaneureas for broadband uv-to-visible conversion
    (American Chemical Society (ACS), 2008) Department of Chemistry; Department of Chemistry; Department of Physics; Department of Physics; Department of Physics; Yılgör, Emel; Yılgör, İskender; Çankaya, Hüseyin; Kılcı, Reyhane; Sennaroğlu, Alphan; Reseacher; Faculty Member; PhD Student; Master Student; Faculty Member; Department of Chemistry; Department of Physics; College of Sciences; College of Sciences; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; 40527; 24181; N/A; N/A; 23851
    [No abstract available]
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    Subpicosecond pulse generation from a chirped-pulse multipass-cavity Cr4+: forsterite oscillator
    (Optical Society of America, 2011) Akturk, Selcuk; Department of Physics; Sennaroğlu, Alphan; Çankaya, Hüseyin; Faculty Member; Researcher; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; 23851; N/A
    We produced the highest pulse energy directly generated from a room-temperature, mode-locked Cr4+:forsterite oscillator. The chirped-pulse, multipass-cavity, 1261-nm oscillator operated at 4.9 MHz and produced 81-nJ pulses which could be externally compressed to 620 fs.
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    Efficient low-threshold multipass-cavity femtosecond Cr4+: forsterite laser
    (Optical Society of America, 2009) Fujimoto, James G.; Department of Physics; Sennaroğlu, Alphan; Çankaya, Hüseyin; Faculty Member; Researcher; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; 23851; N/A
    By using absorbed pump powers less than 2 W, we obtained pulses as short as 41 fs and pulse energies up to 5.1 nJ from a multipass-cavity Cr4+:forsterite laser operated at 11.7 MHz repetition rate.
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    Bulk Nd³+ -doped tellurite glass laser at 1.37 μm
    (Springer, 2010) N/A; Department of Physics; Çankaya, Hüseyin; Sennaroğlu, Alphan; Researcher; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; N/A; 23851
    We have demonstrated, for the first time to our knowledge, lasing at 1.37 mu m in a tellurite-based glass host doped with 0.5 mol.% neodymium: Nd3+:(0.8)TeO2-(0.2)WO3. The gain-switched laser could be operated with 59 mu J threshold pulse energy as well as 5.5% slope efficiency. As high as 6 mu J-pulses with a duration of 1.74 mu s were obtained. The pulse repetition rate was 1 kHz. The emission cross section from the threshold analysis turned out to be 1.57x10(-20) cm(2) at 1370 nm by taking into account excited-state absorption from F-4(3/2) to (4)G(7/2) energy level. Furthermore, the ratio of excited-state absorption to the emission cross section was found out to be 0.78 by using the slope efficiency value.
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    Subpicosecond pulse generation from a chirped-pulse multipass-cavity Cr4+:forsterite oscillator
    (IEEE, 2011) Aktürk, Selçuk; N/A; Department of Physics; Çankaya, Hüseyin; Sennaroğlu, Alphan; Researcher; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; N/A; 23851
    We produced the highest pulse energy directly generated from a room-temperature, mode-locked Cr4+:forsterite oscillator. The chirped-pulse, multipass-cavity, 1261-nm oscillator operated at 4.9 MHz and produced 81-nJ pulses which could be externally compressed to 620 fs.
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    Laser action in bulk Nd3+-doped telluride glass
    (IEEE, 2008) Özen, Gonul; Ovecoglu, Lutfu; N/A; N/A; N/A; Department of Physics; Kalaycıoğlu, Hamit; Çankaya, Hüseyin; Sennaroğlu, Alphan; PhD Student; Researcher; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 23851
    We report on the first observation of lasing in bulk Nd 3+ -doped (0.8)TeO 2 -(0.2)WO 3 glass at 1065 nm. Gain-switched operation was obtained with a slope efficiency of 12% at a pulse repetition rate of 1 kHz.
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    Poly 697-preparation and spectroscopy of novel Er(III) doped polyurethaneureas for broadband ultraviolet-to-visible conversion
    (American Chemical Society (ACS), 2008) N/A; N/A; Department of Physics; Department of Chemistry; Department of Chemistry; Çankaya, Hüseyin; Kılcı, Reyhane; Sennaroğlu, Alphan; Yılgör, Emel; Yılgör, İskender; PhD Student; Master Student; Faculty Member; Resercher; Faculty Member; Department of Physics; Department of Chemistry; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; College of Sciences; N/A; N/A; 23851; 40527; 24181
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