Researcher:
Yorulmaz, İsmail

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PhD Student

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İsmail

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Yorulmaz

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Yorulmaz, İsmail

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Now showing 1 - 7 of 7
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    Publication
    2.3-μm Tm3+: YLF laser passively Q-switched with a Cr2+: ZnSe saturable absorber
    (Optical Soc Amer, 2017) N/A; N/A; Canbaz, Ferda; Yorulmaz, İsmail; Sennaroğlu, Alphan; PhD Student; PhD Student; Faculty Member; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 23851
    We report, what is to our knowledge, the first passively Q-switched operation of a 2.3-mu m Tm3+ : YLF laser by using a Cr2+ : ZnSe saturable absorber. In the experiments, a tunable Ti3+ : sapphire laser was used to end pump the Tm3+ : YLF gain medium inside an x cavity. A Cr2+ : ZnSe saturable absorber was also included in the cavity to initiate passive Q switching. At all pump power levels above lasing threshold, passively Q-switched operation of the Tm3+ : YLF laser could be obtained at 2309 nm with pulse durations and repetition frequencies in the ranges of 1.21.4 mu s and 0.3-2.1 kHz, respectively. Analysis of power dependent repetition rate data further gave an estimated value of 3.1% for the round-trip saturable loss of the Cr2+ : ZnSe saturable absorber.
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    Publication
    Efficient and low-threshold alexandrite lasers pumped by high-brightness diodes
    (Optical Society of America (OSA), 2013) Baali, Ilyes; Kurt, Adnan; Sumpf, Bernd; Erbert, Götz; Leitenstorfer, Alfred; Demirbas, Umit; N/A; N/A; Department of Physics; Department of Physics; Beyatlı, Ersen; Yorulmaz, İsmail; Sennaroğlu, Alphan; PhD Student; PhD Student; Faculty Member; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; 229317; N/A; 23851
    We present low-cost and highly efficient continuous-wave Alexandrite lasers pumped by recently developed high-brightness diodes. A 19-mW lasing threshold, 38% slope efficiency, 200 mW output power, and a broad tuning range (724-816 nm) were realized.
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    Publication
    Kerr-lens mode-locked 2.3-mu m tm3+:ylf laser as a source of femtosecond pulses in the mid-infrared
    (Optical Soc Amer, 2017) N/A; N/A; Department of Physics; Department of Physics; Canbaz, Ferda; Yorulmaz, İsmail; Sennaroğlu, Alphan; PhD Student; PhD Student; Faculty Member; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 23851
    We report what is to our knowledge a new source of femto-second pulses in the mid-infrared, based on a Kerr-lens mode-locked (KLM) Tm3+ : YLF laser at 2303 nm. An un-doped ZnSe substrate was included in the resonator to provide enhanced nonlinear phase modulation during KLM operation. The Tm3+ : YLF laser was end-pumped with a continuous-wave Ti3+ : sapphire laser at 780 nm. With 880 mW of pump power, we generated 514-fs pulses at a pulse repetition rate of 41.5 MHz with an average power of 14.4 mW. The spectral width (full width at half-maximum) was measured as 15.4 nm, giving a time-bandwidth product of 0.44. We foresee that the wide availability of this gain medium, as well as the straightforward pumping scheme near 800 nm, will make 2.3-mu m, mode-locked Tm3+ : YLF lasers versatile sources of ultrashort pulses in the mid-infrared. (C) 2017 Optical Society of America
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    Efficient and low-threshold Alexandrite laser pumped by a single-mode diode
    (Optica Publishing Group, 2014) Kurt, Adnan; Demirbaş, Ümit; Yorulmaz, İsmail; Beyatlı, Ersen; Sennaroğlu, Alphan; PhD Student; PhD Student; Faculty Member; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; School of Medicine; N/A; 229317; 205925
    We report a low-threshold and efficient Alexandrite laser that is pumped by only one state-of-the-art single-spatial-mode diode. The pump diode provided 170 mW of output power at 635 nm. In continuous wave (cw) laser experiments, we demonstrated lasing thresholds as low as 13 mW, slope efficiencies as high as 36%, output powers up to 48 mW, and a tuning range extending from 736 nm to 823 nm. Laser slope efficiency, laser output power, fluorescence lifetime, and emission intensity were further shown to decrease monotonically with increasing temperature. Pure cw operation could be obtained under most circumstances. However, selfQ- switching (SQS) was also observed in slightly misaligned laser cavities. During SQS, stable pulses with pulsewidths in the 5-15 mu s range and pulse repetition rates in the 10-35 kHz range have been obtained. We believe that this compact and efficient Alexandrite laser system may be an attractive source for several applications.
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    Publication
    Low-threshold diode-pumped 2.3-mu m Tm3+:YLF lasers
    (IEEE-Inst Electrical Electronics Engineers Inc, 2018) N/A; Department of Physics; Department of Physics; Yorulmaz, İsmail; Sennaroğlu, Alphan; PhD Student; Faculty Member; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; College of Sciences; N/A; 23851
    We demonstrate low-threshold diode-pumped operation of a continuous-wave Tm3+:YLF laser near 2.3 mu m and provide a detailed experimental investigation of its lasing characteristics. A narrow-line, tunable Ti3+:sapphire laser was first used to measure the excitation spectrum and investigate the absorption saturation behavior of the 1.5 at.% Tm3+:YLF gain medium. A single-mode, 120-mW laser diode operating at 792 nm was then used as a pump source to demonstrate low-threshold lasing at 2.3 mu m. With a 1% output coupler, diode-pumped operation could be obtained with as low as 25 mW of incident threshold pump power. With 119 mW of pump power, as high as 10.5 mW of out-put power could be obtained at 2305 nm with a slope efficiency of 11.4%. By using a second, 250-mW laser diode, a resonator with variable output coupling was constructed to measure the threshold pump power and power slope efficiency as a function of output coupling. The minimum threshold pump power at output coupling levels approaching 0% was measured to be 4 mW. Results further showed that the slope efficiency decreased with increasing output coupling beyond 0.7%. The stimulated emission cross section at 2305 nm was further determined to be 0.68 x 10(-20) cm(2) from lasing threshold data.
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    Publication
    Passive q-switching of a Tm3+:YLF laser at 2.3 μm with a Cr2+:ZnSe saturable absorber
    (Optica Publishing Group (formerly OSA), 2017) N/A; N/A; Department of Physics; Department of Physics; Canbaz, Ferda; Yorulmaz, İsmail; Sennaroğlu, Alphan; PhD Student; PhD Student; Faculty Member; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 23851
    We describe, for the first time to our knowledge, passive Q-switching of a 2.3-μm Tm3+:YLF laser. By using a Cr2+:ZnSe saturable absorber, pulses with 1.2-1.4 μs duration and 0.3-2.1 kHz repetition frequency were generated.
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    Publication
    Kerr-lens mode-locked and graphene mode-locked operations of a 2.3-μm Tm3+:YLF laser
    (Optica Publishing Group (formerly OSA), 2018) Bae, J.E.; Choi, S.Y.; Rotermund, F.; N/A; N/A; Department of Physics; Department of Physics; Canbaz, Ferda; Yorulmaz, İsmail; Sennaroğlu, Alphan; PhD Student; PhD Student; Faculty Member; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 23851
    We report, what is to our knowledge, the first demonstration of Kerr-lens mode-locked and graphene mode-locked operations of a 2.3-μm Tm 3+ :YLF laser, yielding ultrashort pulses of 514 fs and 2 ps, respectively, at 2303 nm.