Publications without Fulltext
Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
Browse
216 results
Search Results
Publication Metadata only Optical modulation with silicon microspheres(IEEE-Inst Electrical Electronics Engineers Inc, 2009) Gürlü, Oğuzhan; N/A; Department of Physics; Yüce, Emre; Serpengüzel, Ali; Master Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; 245435; 27855In this letter, a silicon microsphere coupled to a silica optical fiber half coupler has been characterized for electrooptical modulation in the L-band at 1.55 mu m. Electrooptical modulation of the transmitted and the 90 degrees elastic scattered signals for both the TE and the TM polarizations of the microsphere resonances has been observed.Publication Metadata only Resonant channel-dropping filter with integrated detector system based on optical fiber coupler and microsphere(IOP Publications, 2004) İşci, Şenol; Yılmaz, Yiğit; Department of Physics; Serpengüzel, Ali; Kurt, Adnan; Bilici, Temel; Faculty Member; Teaching Faculty; N/A; Department of Physics; College of Sciences; N/A; 27855; 194455; N/APublication Metadata only Motion of single terrylene molecules in confined channels of poly(butadiene)-poly(ethylene oxide) diblock copolymer(Amer Chemical Soc, 2009) N/A; Department of Physics; Department of Chemistry; Yorulmaz, Mustafa; Kiraz, Alper; Demirel, Adem Levent; Master Student; Faculty Member; Faculty Member; Department of Physics; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; 22542; 6568The motion of terrylene probe molecules in confined PB channels of an asymmetric PB-PEO diblock copolymer has been investigated by single molecule tracking. The one-dimensional diffusion coefficients were found to be significantly smaller and had a narrower distribution compared to two-dimensional diffusion coefficients in PB. The trajectories of some single molecules showed unusual behavior of directed motion where mean square displacement had a parabolic dependence oil lag time. The likely origin of this behavior is discussed in terms of local variations in the PB channel width and the resulting change in the local density. The results show the effect of nonuniformities and heterogeneities in the channels on the motion of single molecules and demonstrate the sensitivity of single molecule tracking in characterizing self-assembled block copolymer morphologies.Publication Metadata only Concentration dependence of the infrared luminescence efficiencies in TEO-CDCL2 : TM3+ glass(Optica Publishing Group, 2003) Özalp, M. Reha; Özen, Gönül; Department of Physics; Department of Physics; Sennaroğlu, Alphan; Kurt, Adnan; Faculty Member; Teaching Faculty; Department of Physics; College of Sciences; College of Sciences; 23851; 194455Using exper imental methods, the characteristics of the 1450-nm and 1800-nm luminescence bands of Tm3+ doped TeO2-CdCl2 glasses were studied as a function of the Tm3+ doping level.Publication Metadata only Ruby microsphere and liquid cyrstal based tunable optical filter(Ieee, 2009) Beccherelli, Romeo; Department of Physics; N/A; N/A; Serpengüzel, Ali; Murib, Mohammed Sharif; Hüseyinoğlu, Ersin; Faculty Member; PhD Student; Master Student; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 27855; N/AA microsphere placed in a liquid crystal is used as an optical filter. By changing the refractive index of the liquid cyrstal, the resonance frequency of the sphere is controlled.Publication Metadata only Effect of thermal lensing on the mode matching between pump and laser beams in Cr4+: forsterite lasers: a numerical study(IOP Publishing, 2000) Department of Physics; Sennaroğlu, Alphan; Faculty Member; Department of Physics; College of Sciences; 23851The numerical study presented in this paper investigates the role of thermal lensing on the mode matching between the pump beam and the cavity beam in continuous-wave end-pumped Cr4+:forsterite lasers. A suitable mode overlap function was first derived to calculate the degree of overlap between the pump beam and the fundamental mode of the resonator. The effect of thermal lensing on mode matching was then numerically investigated by calculating the changes in the average value of the mode overlap function due to variations in pump power and crystal boundary temperature. Thermal lensing was taken into account by calculating the pump-induced thermal gradients and by approximating the gain medium as a distributed quadratic lens. Finally, the model was used to offer guidelines about how one of the resonator lenses should be readjusted in order to maintain optimum mode matching as the boundary temperature and pump power are varied.Publication Metadata only Efficient continuous-wave radiatively cooled Cr4+: forsterite lasers at room temperature(Optical Soc Amer, 1998) Department of Physics; Sennaroğlu, Alphan; Faculty Member; Department of Physics; College of Sciences; 23851Results of a detailed experimental investigation aimed at reducing the thermal loading problem in a cw Cr4+:forsterite laser at elevated temperatures are presented. From a Cr4+:forsterite crystal with a differential absorption coefficient of 0.57 cm(-1), as much as 900 mW of cw output power has been obtained at 1.26 mu m and at a crystal boundary temperature of 15 degrees C with an absorbed pump power of only 4.5 W at 1.06 mu m. No chopping of the the pump beam was necessary. An efficient radiative cooling technique was further employed to cool the laser and no subsequent power fading was observed. To the author's knowledge, the measured absorbed power slope efficiency of 29.5% represents the highest cw power performance reported to date: from a Cr4+:forsterite laser pumped by a Nd:YAG laser around room temperature. The role of the low differential absorption coefficient in the reduction of thermal loading is further elucidated by presenting comparative cw power performance data with a second Cr4+:forsterite crystal having a differential absorption coefficient of 1.78 cm(-1) in the temperature range between 12 and 35 degrees C. Finally, some interesting multipulse effects of the laser observed in the millisecond regime during quasi-cw operation at 50% duty cycle are described.Publication Metadata only Minimizing earthquake damage by physical modulation of the soil structure(N/A, 2001) Ural, Derin N.; Department of Physics; Serpengüzel, Ali; Faculty Member; Department of Physics; College of Sciences; 27855The Bragg scattering phenomenon of solid state physics and photonic crystal concept of optics have been applied to geotechnical engineering to minimize earthquake damage. A theoretical one dimensional wave propagation model is developed and presented. A layered soil profile has been proposed and analyzed. The proposed layered soil profile reflects the incoming waves within the desired design frequency bandwidth.Publication Metadata only Broadly tunable continuous-wave orange-red source based on intracavity-doubled Cr4+: forsterite laser(Optical Soc Amer, 2002) Department of Physics; Sennaroğlu, Alphan; Faculty Member; Department of Physics; College of Sciences; 23851The operation of a room-temperature, continuous-wave, intracavity frequency-doubled Cr4+:forsterite laser capable of producing broadly tunable output in the orange-red region of the electromagnetic spectrum is described. Intracavity doubling was achieved in a periodically poled lithium niobate crystal that had gratings with different periods. Tunable second-harmonic output could be obtained between 613 and 655 am. At a wavelength of 630 nm, intracavity doubling yielded as much as 45 mW of continuous-wave output. To the author's knowledge, this represents the highest second-harmonic-power generation obtained to date with a continuous-wave Cr4+:forsterite laser.Publication Metadata only Silicon microspheres for optical modulation applications(SPIE-Soc Photoptical Instrumentation Engineers, 2009) Gürlü, Oǧuzhan; Department of Physics; Department of Physics; Department of Physics; Serpengüzel, Ali; Yüce, Emre; Murib, Mohammed Sharif; Faculty Member; Master Student; Master Student; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 27855; 245435; N/AA silicon microsphere coupled to a silica optical fiber half coupler is excited using a diode laser operating at 1.55 μm. The transmitted and the 90o elastically scattered light signals are modulated with an electrical square wave applied to the silicon microsphere.