Publications without Fulltext
Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
Browse
84 results
Filters
Advanced Search
Filter by
Settings
Search Results
Publication Metadata only Contrast improvement through a Generative Adversarial Network (GAN) by utilizing a dataset obtained from a line-scanning confocal microscope(SPIE, 2024) Department of Physics; Kiraz, Alper; Morova, Berna; Bavili, Nima; Ketabchi, Amir Mohammad; Department of Physics; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); College of Sciences; Graduate School of Sciences and EngineeringConfocal microscopy offers enhanced image contrast and signal-to-noise ratio compared to wide-field illumination microscopy, achieved by effectively eliminating out-of-focus background noise. In our study, we initially showcase the functionality of a line-scanning confocal microscope aligned through the utilization of a Digital Light Projector (DLP) and a rolling shutter CMOS camera. In this technique, a sequence of illumination lines is projected onto a sample using a DLP and focusing objective (50X, NA=0.55). The reflected light is imaged with the camera. Line-scanning confocal imaging is accomplished by synchronizing the illumination lines with the rolling shutter of the sensor, leading to a substantial enhancement of approximately 50% in image contrast. Subsequently, this setup is employed to create a dataset comprising 500 pairs of images of paper tissue. This dataset is employed for training a Generative Adversarial Network (cGAN). Roughly 45% contrast improvement was measured in the test images for the trained network, in comparison to the ground-truth images.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 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 Resonance fluorescence in a waveguide geometry(IEEE, 2012) Rephaeli, Eden; Fan, Shanhui; Department of Electrical and Electronics Engineering; Kocabaş, Şükrü Ekin; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; N/AWe show how to calculate the first-and second-order statistics of the scattered fields for an arbitrary intensity coherent-state light field interacting with a two-level system in a waveguide geometry. Specifically, we calculate the resonance fluorescence from the qubit, using input-output formalism. We derive the transmission and reflection coefficients, and illustrate the bunching and antibunching of light that is scattered in the forward and backward directions, respectively. Our results agree with previous calculations on one-and two-photon scattering as well as those that are based on the master equation approach.Publication Metadata only Dynamical properties of a coupled nonlinear dielectric waveguide - surface-plasmon system as a new type of josephson junction(IEEE, 2011) N/A; Department of Physics; N/A; Department of Physics; Müstecaplıoğlu, Özgür Esat; Özok, Yasa Ekşioğlu; Güven, Kaan; Faculty Member; PhD Student; Faculty Member; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; 1674; 237974; 52290We demonstrate that a weakly-coupled nonlinear dielectric waveguide surface-plasmon (DWSP-JJ) system can be formulated as in analogy to bosonic Josephson junction of atomic condensates, yet the inherently dynamic coupling parameter generates novel features in the phase space.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.Publication Metadata only Newton-cartan connections with torsion(Istanbul Technical University, 2004) Koçak, Şahin; Limoncu, Murat; Department of Physics; Dereli, Tekin; Faculty Member; Department of Physics; College of Sciences; 201358We re-formulate the notion of a Newton-Cartan manifold and clarify the compatibility conditions of a connection with torsion with the Newton-Cartan structure.Publication Metadata only Determination of the stimulated emission cross section from laser-induced pump saturation data in Cr4+-doped solid-state lasers(Optical Soc america, 2001) Department of Physics; Department of Physics; Sennaroğlu, Alphan; Yaman, Fatih; Faculty Member; Undergraduate Student; Department of Physics; College of Sciences; College of Sciences; 23851; N/AWe describe a novel method for the determination of the stimulated emission cross section in Cr4+-doped solid-state lasers from laser-induced pump saturation data. the technique uses the fact that increasing intra-cavity laser intensity stimulates a faster decay of excited atoms and reduces the saturation of pump absorption. a numerical model was developed to analyze the experimental data collected from Cr4+:YaG and Cr4+:forsterite lasers. the best-fit values of the stimulated emission cross section agree with previous results. To demonstrate the applicability of the method to other solid-state lasers, the same technique was also used to determine the emission cross section in a Cr2+:ZnSe laser.Publication Metadata only Physics of spectral singularities(Trends in Mathematics, 2015) N/A; Department of Mathematics; Mostafazadeh, Ali; Faculty Member; Department of Mathematics; College of Sciences; 4231Spectral singularities are certain points of the continuous spectrum of generic complex scattering potentials. We review the recent developments leading to the discovery of their physical meaning, consequences, and generalizations. In particular, we give a simple definition of spectral singularities, provide a general introduction to spectral consequences of ��-symmetry (clarifying some of the controversies surrounding this subject), outline the main ideas and constructions used in the pseudo-Hermitian representation of quantum mechanics, and discuss how spectral singularities entered in the physics literature as obstructions to these constructions. We then review the transfer matrix formulation of scattering theory and the application of complex scattering potentials in optics. These allow us to elucidate the physical content of spectral singularities and describe their optical realizations. Finally, we survey some of the most important results obtained in the subject, drawing special attention to the remarkable fact that the condition of the existence of linear and nonlinear optical spectral singularities yield simple mathematical derivations of some of the basic results of laser physics, namely the laser threshold condition and the linear dependence of the laser output intensity on the gain coefficient.Publication Metadata only High average-power diode-pumped femtosecond Cr3+: LiCAF laser(Association for Computational Linguistics, 2008) Kärtner, Franz X.; Fujimoto, James G.; Demirbaş, Ümit; Benedick, Andrew; Siddiqui, Aleem; Department of Physics; Sennaroğlu, Alphan; Faculty Member; Department of Physics; College of Sciences; 2385167-fs pulses with an average power of 300 mW and pulse repetition rate of 120 MHz were obtained from a diode-pumped Cr3+: PLiCAF laser. A semiconductor saturable absorber mirror enabled stable and self-starting mode-locked operation.