Researcher:
Demir, Abdullah

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Master Student

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Abdullah

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Demir

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Demir, Abdullah

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2005 - 200922010 - 20141

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Researcher Of Publications: search.filters.isAuthorOfPublication.6bd9c7ca-34cd-4abd-b883-cc5db6999b5a

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    Optical channel dropping with a silicon microsphere
    (Ieee-Inst Electrical Electronics Engineers Inc, 2005) N/A; N/A; Department of Physics; Department of Physics; Yılmaz, Yiğit Ozan; Demir, Abdullah; Kurt, Adnan; Serpengüzel, Ali; Master Student; Master Student; Teaching Faculty; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; N/A; 194455; 27855
    We report the observation of morphology-dependent resonances from silicon microspheres. The dropped channels are observed both in the transmission and elastic scattering spectra in the O-band. The filter drops approximately 23% of the power at the resonance wavelength. The highest observed quality factor for the morphology-dependent resonances was on the order of 10(5). These resonances have a linewidth of 0.007 nm and a mode spacing of 0.19 nm.
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    Silica microspheres for biomolecular detection applications
    (Institution of Engineering and Technology (IET), 2005) Department of Physics; N/A; Serpengüzel, Ali; Demir, Abdullah; Faculty Member; Master Student; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; 27855; N/A
    Microsphere-based biosensors have been attracting the attention of the photonics community due to their high sensitivity, selectivity and implementation. Microspheres, with their high quality-factor (Q-factor) morphology dependent resonances, are very sensitive to refractive index and size changes. The perturbation of the microsphere morphology dependent resonances can be used for the detection of biomolecules. Adsorption of different biomolecules on the surface of microspheres causes a change of effective size and refractive index leading to the shift of resonance wavelengths. A biosensor, based on this phenomenon, can detect a single molecule sensitively depending on the configuration that needs to be designed and optimised. Silica with a refractive index of 1.5, which is very close to that of bimolecular agents, is a suitable photonic material to use for biosensing applications. The transverse electric and transverse magnetic elastic scattering spectra at 90° and 0° are calculated at 1.55 μm with the associated shifts after adding a layer on it. 90° scattering is used to monitor the scattered signal, whereas 0° scattering is used to monitor the transmission signal.
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    Elastic scattering from a sapphire microsphere placed on a silica optical fiber coupler: possible applications to biosensing
    (Springer Heidelberg, 2014) Murib, M. S.; Wagner, P.; N/A; N/A; Department of Physics; Department of Physics; Yılmaz, Yiğit Ozan; Demir, Abdullah; İşçi, Şenol; Bilici, Temel; Kurt, Adnan; Serpengüzel, Ali; Master Student; Master Student; Other; Teaching Faculty; Teaching Faculty; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; N/A; 194455; 27855
    Elastic light scattering is performed in the original band of optical fiber communication at 1300 nm for a 500 mu m sapphire microsphere placed on a silica optical fiber half coupler. The morphology dependent resonances (MDRs) are observed in the transverse magnetically (TM) polarized and transverse electrically (TE) polarized 0. transmission and 90 degrees elastic scattering obtained from the sapphire microsphere. The TE and TM MDRs can be detected selectively with the use of a Glan polarizer. The TE and TM polarization selectivity provides the ability to select relative MDR to BG levels. The TM polarization provides higher MDR signal to background ratio (SBR) and is suitable for optical monitoring, biological sensing or any other optoelectronic application that requires a high resolution optical filter. The polar angular mode spacing of 0.36 nm of the resonances correlates well with the optical size of the sapphire microsphere. The autocorrelation of the 90 degrees elastic scattering spectra also shows peaks at 0.36 nm. The spectral linewidths of the resonances are on the order of 0.1 nm, which corresponds to quality factors on the order of 10(4.) A sapphire sphere with a radius of 500 mu m and relative refractive index of 1.31, resonances will red-shift by 1.01nm (0.077%). This shift is on the order of 10 linewidths, making sapphire biophotonic sensors an interesting alternative to silica biophotonic sensors.