Researcher:
Yorulmaz, Saime Çiğdem

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Master Student

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Saime Çiğdem

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Yorulmaz

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Yorulmaz, Saime Çiğdem

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2008 - 20099

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Now showing 1 - 9 of 9
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    Controlled observation of nondegenerate cavity modes in a microdroplet on a superhydrophobic surface
    (Elsevier, 2009) Department of Physics; Department of Physics; Department of Mechanical Engineering; Department of Mechanical Engineering; Department of Physics; Yorulmaz, Saime Çiğdem; Mestre, Michael; Muradoğlu, Metin; Alaca, Burhanettin Erdem; Kiraz, Alper; Master Student; Researcher; Faculty Member; Faculty Member; Faculty Member; Department of Mechanical Engineering; Department of Physics; College of Engineering; College of Engineering; College of Engineering; College of Engineering; College of Sciences; N/A; N/A; 46561; 115108; 22542
    We demonstrate controlled lifting of the azimuthal degeneracy of the whispering gallery modes (WGMs) of single glycerol-water microdroplets standing on a superhydrophobic surface by using a uniform electric field. A good agreement is observed between the measured spectral positions of the nondegenerate WGMs and predictions made for a prolate spheroid. Our results reveal fewer azimuthal modes than expected from an ideal spherical microdroplet due to the truncation by the surface. We use this difference to estimate the contact angles of the microdroplets.
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    Reversible photothermal tuning of a salty water microdroplet
    (Royal Soc Chemistry, 2009) N/A; Department of Physics; N/A; N/A; Department of Mechanical Engineering; Kiraz, Alper; Karadağ, Yasin; Yorulmaz, Saime Çiğdem; Muradoğlu, Metin; Faculty Member; PhD Student; Master Student; Faculty Member; Department of Physics; Department of Mechanical Engineering; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; 22542; N/A; N/A; 46561
    A fully reversible photothermal tuning of an inorganic salt (NaCl)-water microdroplet standing on a superhydrophobic surface is demonstrated. The size change of the microdroplet is caused by a focused infrared laser beam in a humidity-controlled chamber and a fully reversible large spectral tuning up to similar to 40 nm is achieved. The evaporation and growth of the microdroplet are modeled using, a lumped system formulation of mass and energy conservations and a good agreement is observed between the experimental and theoretical results.
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    Reversible photothermal tuning of single salt-water microdroplets on a superhydrophobic surface
    (Optical Society of America, 2009) N/A; Department of Physics; Department of Physics; Department of Physics; Kiraz, Alper; Yorulmaz, Saime Çiğdem; Mestre, Michael; Faculty Member; Master Student; Researcher; Department of Physics; College of Sciences; College of Sciences; College of Sciences; 22542; N/A; N/A
    We demonstrate large (up to 15 nm) and reversible spectral tuning of the whispering gallery modes of single NaCl-water microdroplets standing on a superhydrophobic surface by local heating with an infrared laser.
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    Raman lasing near 650 nm from pure water microdroplets on a superhydrophobic surface
    (Elsevier Science Bv, 2009) N/A; Department of Physics; N/A; N/A; Department of Physics; Kiraz, Alper; Yorulmaz, Saime Çiğdem; Yorulmaz, Mustafa; Sennaroğlu, Alphan; Faculty Member; Master Student; Master Student; Faculty Member; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; 22542; N/A; N/A; 23851
    We demonstrate Raman lasing near 650 nm in pure water microdroplets located on a superhydrophobic surface. In the experiments, stationary, pure water microdroplets were prepared on a superhydrophobic surface and excited by a pulsed, frequency-doubled Nd:YAG laser at 532 nm. Intense laser emission was observed at frequencies corresponding to the whispering gallery mode resonances of the water microdroplets near 650 nm where Raman resonances due to OH-stretching bonds of water are located. On-off behavior was observed during lasing and the average temporal inter-burst separation was determined from the time-dependent intensity traces., Our results can find applications in the development of novel organic light emitters for short-haul communication systems, and in the spectroscopic characterization of water microdroplets on a surface.
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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.
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    PublicationOpen Access
    Large spectral tuning of liquid microdroplets by local heating with a focused infrared laser
    (Society of Photo-optical Instrumentation Engineers (SPIE), 2008) Department of Physics; Department of Electrical and Electronics Engineering; Kiraz, Alper; Karadağ, Yasin; Yorulmaz, Saime Çiğdem; Muradoğlu, Metin; Faculty Member; PhD Student; Faculty Member; Department of Physics; Department of Electrical and Electronics Engineering; College of Sciences; 22542; N/A; N/A; 46561
    Large deformations can easily be introduced in liquid microdroplets by applying relatively small external forces or controlling the evaporation/condensation kinetics. This makes liquid microdroplets attractive to serve as the building blocks of largely tunable optical switches or filters that are essential in optical communication systems based on wavelength division multiplexing. Solid optical microcavities have not found large use in these applications, mainly due to their rigid nature. The fact that liquid microdroplets are low-cost and disposable can also prove to be important in mass production of these photonic devices. Here, we show that local heating with an infrared laser can be used to largely tune the whispering gallery modes (WGMs) of water/glycerol or salty water microdroplets standing on a superhydrophobic surface. In the scheme presented, a liquid microdroplet kept in a humidity chamber is stabilized on a superhydrophobic surface, and an infrared laser beam is focused near tire center of the microdroplet. As a, result of the local treating, the temperature of the liquid microdroplet increases, and the water content in the liquid microdroplet evaporates until a new equilibrium is reached. At the new equilibrium state, the non-volatile component, (i.e. glycerol or salt) attains a higher concentration in the liquid microdroplet. We report tunability over large spectral ranges up to 30 run at around 590 nm. For salty water microdroplets the reported spectral timing mechanism is almost fully reversible, while for tire case of glycerol/water microdroplets the spectral timing mechanism can be made highly reversible when the chamber is saturated with glycerol vapor and the relative water humidity approaches unity.