Researcher:
Gündoğan, Mustafa

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Master Student

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Mustafa

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Gündoğan

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Gündoğan, Mustafa

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2009 - 20106

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Researcher Of Publications: search.filters.isAuthorOfPublication.d754d249-5869-4b86-8b71-bc63548d5bf3

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    Prolonged Raman lasing in size-stabilized salt-water microdroplets on a superhydrophobic surface
    (Optical Soc Amer, 2010) N/A; N/A; N/A; N/A; N/A; Department of Physics; Department of Physics; Karadağ, Yasin; Gündoğan, Mustafa; Yüce, Mehdi Yavuz; Çankaya, Hüseyin; Sennaroğlu, Alphan; Kiraz, Alper; PhD Student; Master Student; PhD Student; Researcher; Faculty Member; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; N/A; N/A; N/A; 23851; 22542
    We demonstrate prolonged Raman lasing from individual salt-water microdroplets with 10-20 mu m diameters located on a superhydrophobic surface. The mechanism is based on the absorption heating of a 1064 nm cw IR laser and the resonant heating of a 532 nm pulsed, pump laser. A clear hysteresis is observed in the lasing intensity as the droplet size is photothermally tuned by the IR laser, indicating a self-stabilization mechanism due to the resonant absorption of the pump laser. Using this mechanism, Raman lasing near 650 nm is sustained for up to 25 min, similar to 1000 times longer than lasing durations reported in previous studies.
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    Prolonged raman lasing in the size-stabilized salt-water microdroplets on a superhydrophobic surface
    (Optical Society of America, 2010) Department of Physics; N/A; Department of Physics; N/A; N/A; N/A; Sennaroğlu, Alphan; Çankaya, Hüseyin; Kiraz, Alper; Karadağ, Yasin; Gündoğan, Mustafa; Yüce, Mehdi Yavuz; Faculty Member; Researcher; Faculty Member; PhD Student; Master Student; PhD Student; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 23851; N/A; 22542; N/A; N/A; N/A
    We show prolonged Raman lasing from individual salt-water microdroplets located on a superhydrophobic surface using a self-stabilization mechanism based on the absorption heating of an infrared laser and resonant heating of a green laser.
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    High precision size tuning and stabilization of single salt-water microdroplets on a superhydrophobic surface
    (Ieee, 2009) N/A; Department of Physics; Department of Physics; N/A; N/A; N/A; Kiraz, Alper; Mestre, Michael; Karadağ, Yasin; Yorulmaz, Saime Çiğdem; Gündoğan, Mustafa; Faculty Member; Researcher; PhD Student; Master Student; Master Student; Department of Physics; College of Sciences; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 22542; N/A; N/A; N/A; N/A
    While their spherical geometry is mostly preserved, salt-water microdroplets can be studied in stable experimental conditions when standing on a superhydrophobic surface. Here, we report how the photothermal effect can be used to continuously tune or lock the whispering gallery mode (WGM) spectrum (therefore the size) of salt-water microdroplets on a superhydrophobic surface. The microdroplets are kept in the controlled atmosphere of a humidity chamber. Local heating by an infrared laser focused at the center of the microdroplet causes it to depart from its equilibrium size, shifting the WGM spectrum. This photothermal tuning effect is fully reversible and can be used to tune the microdroplet radius with a precision reaching 1 A by finely controlling the heating laser power. We demonstrate a new spectroscopy method based on this effect, and use it to measure Q-factors of WGM resonances of up to similar to 10(5). Conversely, focusing the heating laser to the microdroplet rim causes it to experience absorption resonances, leading to a hysteretic behavior when increasing and decreasing the laser power. We show that this behavior can be used to lock the size of a microdroplet and make it function as an optically bistable element. WGM resonances of microdroplets locked in such a way are probed using a tunable laser, showing a locking precision reaching < 0.01 nm over tens of minutes. These results indicate that the challenges in terms of position and wavelength stability inherent to liquid microdroplets surrounded by air can be overcome, and that they provide an easily tunable and lockable alternative to solid optical microcavities.
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    Direct measurement of high Q-factors in individual salt-water microdroplets by photothermal tuning spectroscopy
    (Optical Society of America, 2009) N/A; Department of Physics; N/A; Department of Physics; Gündoğan, Mustafa; Kiraz, Alper; Yorulmaz, Saime Çiğdem; Mestre, Michael; Master Student; Faculty Member; Master Student; Researcher; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; N/A; 22542; N/A; N/A
    We present measurements of high quality (Q) factors in liquid microdroplets standing on a superhydrophobic surface using the new photothermal tuning spectroscopy technique. Q-factors up to ~105 are observed from degenerate whispering gallery modes. © 2009 Optical Society of America.
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    Photothermal tuning and size locking of salt-water microdroplets on a superhydrophobic surface
    (Taylor and Francis inc, 2009) N/A; Department of Physics; N/A; N/A; N/A; Department of Physics; Mestre, Michael; Karadağ, Yasin; Yorulmaz, Saime Çiğdem; Gündoğan, Mustafa; Kiraz, Alper; Researcher; PhD Student; Master Student; Master Student; Faculty Member; Department of Physics; College of Sciences; 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; N/A; 22542
    Liquid microdroplets are attractive as optical microcavities with tunable resonances for applications in quantum optics and biological sensing, owing to their flexible nature and spherical shape. Salt-water microdroplets can be used in such experiments while standing on a superhydrophobic surface that preserves their spherical geometry. Here, we report how the photothermal effect enables continuous tuning or locking of the whispering gallery mode (WGM) spectrum and size of salt-water microdroplets on a superhydrophobic surface. Local heating by an infrared laser focused at the center of a microdroplet causes it to depart from its equilibrium size, shifting the WGM spectrum. This photothermal tuning effect is fully reversible and can be used to tune the microdroplet radius with a precision reaching 1 angstrom. We combine this effect with fluorescence excitation spectroscopy using a fixed wavelength laser to measure Q-factors of up to similar to 10(5). Conversely, focusing the heating laser to the microdroplet rim reveals absorption resonances, leading to a hysteretic behavior when cycling the laser power. We show that this behavior can be used to lock the size of a microdroplet and make it exhibit optical bistability. WGM resonances of locked microdroplets are probed using a tunable laser, showing a spectral locking precision reaching <0.01 nm over tens of minutes. these results indicate that the wavelength stability and positioning challenges inherent to liquid microdroplets in air can be overcome, providing an easily tunable and lockable alternative to solid optical microcavities and making them potential candidates for studies in cavity optomechanics.
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    High precision size tuning and stabilization of single salt-water microdroplets on a superhydrophobic surface
    (2009) N/A; Department of Physics; N/A; Department of Physics; Gündoğan, Mustafa; Kiraz, Alper; Yorulmaz, Saime Çiğdem; Mestre, Michael; Master Student; Faculty Member; Master Student; Researcher; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; N/A; 22542; N/A; N/A
    While their spherical geometry is mostly preserved, salt-water microdroplets can be studied in stable experimental conditions when standing on a superhydrophobic surface. Here, we report how the photothermal effect can be used to continuously tune or lock the whispering gallery mode (WGM) spectrum (therefore the size) of salt-water microdroplets on a superhydrophobic surface. The microdroplets are kept in the controlled atmosphere of a humidity chamber. Local heating by an infrared laser focused at the center of the microdroplet causes it to depart from its equilibrium size, shifting the WGM spectrum. This photothermal tuning effect is fully reversible and can be used to tune the microdroplet radius with a precision reaching 1 Å by finely controlling the heating laser power. We demonstrate a new spectroscopy method based on this effect, and use it to measure Q-factors of WGM resonances of up to - 10 5. Conversely, focusing the heating laser to the microdroplet rim causes it to experience absorption resonances, leading to a hysteretic behavior when increasing and decreasing the laser power. We show that this behavior can be used to lock the size of a microdroplet and make it function as an optically bistable element. WGM resonances of microdroplets locked in such a way are probed using a tunable laser, showing a locking precision reaching andlt; 0.01 nm over tens of minutes. These results indicate that the challenges in terms of position and wavelength stability inherent to liquid microdroplets surrounded by air can be overcome, and that they provide an easily tunable and lockable alternative to solid optical microcavities. © 2009 IEEE.