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Permanent URI for this communityhttps://hdl.handle.net/20.500.14288/2
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Publication Open Access Compact and broadband silicon photonic multiplexers based on fast adiabatic structures(Optica Publishing Group, 2021) Department of Electrical and Electronics Engineering; Mağden, Emir Salih; Görgülü, Kazım; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 276368; N/AWe present the theory and experimental demonstration for compact integrated spectral multiplexers utilizing fast adiabatic structures. The demonstrated 1x2 multiplexers effectively separate/combine broadband long-pass and short-pass signals, with compact footprint and low loss.Publication Restricted Deep photonic networks with arbitrary and broadband functionality(Koç University, 2023) Amiri, Ali Najjar; Mağden, Emir Salih; 0000-0001-7680-6818; Koç University Graduate School of Sciences and Engineering; Electrical and Electronics Engineering; 276368Publication Restricted Design and optimization of broadband silicon photonic devices(Koç University, 2023) Görgülü, Kazım; Mağden, Emir Salih; 0000-0001-7680-6818; Koç University Graduate School of Sciences and Engineering; Electrical and Electronics Engineering; 276368Publication Restricted Design of microheater for thermo-optic tuning of silicon photonic filters(Koç University, 2022) Koral, Ahmet Kağan; Mağden, Emir Salih; 0000-0001-7680-6818; Koç University Graduate School of Sciences and Engineering; Electrical and Electronics Engineering; 276368Publication Open Access Detection of aflatoxin M1 by fiber cavity attenuated phase shift spectroscopy(Optical Society of America (OSA), 2021) Ghauri, M. Daniyal; Hussain, Syed Zajif; Ullah, Ubaid; Saleem, Rahman Shah Zaib; Cheema, M. Imran; N/A; Department of Physics; Ayaz, Rana Muhammed Armaghan; Kiraz, Alper; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; N/A; 22542Aflatoxin M1 (AFM1) is a carcinogenic compound commonly found in milk in excess of the WHO permissible limit, especially in developing countries. Currently, state-of-the-art tests for detecting AFM1 in milk include chromatographic systems and enzyme-linked-immunosorbent assays. Although these tests provide fair accuracy and sensitivity, they require trained laboratory personnel, expensive infrastructure, and many hours to produce final results. Optical sensors leveraging spectroscopy have a tremendous potential of providing an accurate, real-time, and specialist-free AFM1 detector. Despite this, AFM1 sensing demonstrations using optical spectroscopy are still immature. Here, we demonstrate an optical sensor that employs the principle of cavity attenuated phase shift spectroscopy in optical fiber cavities for rapid AFM1 detection in aqueous solutions at 1550 nm. The sensor constitutes a cavity built by two fiber Bragg gratings. We splice a tapered fiber of < 10 μm waist inside the cavity as a sensing head. For ensuring specific binding of AFM1 in a solution, the tapered fiber is functionalized with DNA aptamers followed by validation of the conjugation via FTIR, TGA, and EDX analyses. We then detect AFM1 in a solution by measuring the phase shift between a sinusoidally modulated laser input and the sensor output at resonant frequencies of the cavity. Our results show that the sensor has the detection limit of 20 ng/L (20 ppt), which is well below both the U.S. and the European safety regulations. We anticipate that the present work will lead towards a rapid and accurate AFM1 sensor, especially for low-resource settings.Publication Restricted Development of aerogel based optofluidic microreactors(Koç University, 2018) Özbakır, Yaprak; Erkey, Can; Kiraz, Alper; 0000-0001-6539-7748; 0000-0001-7977-1286; Koç University Graduate School of Sciences and Engineering; Chemical and Biological Engineering; 29633; 22542Publication Restricted Elastic light scattering, fluorescence, and raman spectroscopy of a diamond microsphere(Koç University, 2017) Bayer, Mustafa Mert; Serpengüzel, Ali; 0000-0002-0676-8817; Koç University Graduate School of Sciences and Engineering; Optoelectronics and Photonics Engineering; 27855
Publication Metadata only Exactness of the first born approximation in electromagnetic scattering(Oxford Univ Press Inc, 2024) Loran, Farhang; Department of Mathematics; Mostafazadeh, Ali; Department of Mathematics; College of SciencesFor the scattering of plane electromagnetic waves by a general possibly anisotropic stationary linear medium in three dimensions, we give a condition on the permittivity and permeability tensors of the medium under which the first Born approximation yields the exact expression for the scattered wave whenever the incident wavenumber k does not exceed a preassigned value alpha. We also show that under this condition the medium is omnidirectionally invisible for k <= alpha/2, i.e. it displays broadband invisibility regardless of the polarization of the incident wave.Publication Restricted Excitation of silicon and diamond microsphere whispering gallery modes by femtosecond laser written glass and diamond waveguides, and a glass fiber coupler(Koç University, 2017) Çirkinoğlu, Hüseyin Ozan; Serpengüzel, Ali; 0000-0002-0676-8817; Koç University Graduate School of Sciences and Engineering; Optoelectronics and Photonics Engineering; 27855Publication Restricted Integrated photonic studies of silicon meandering distributed feedback structures: a model system for biological ligands(Koç University, 2019) Chaudhry, Muhammad Rehan; Serpengüzel, Ali; 0000-0002-0676-8817; Koç University Graduate School of Sciences and Engineering; Bio-Medical Sciences and Engineering; 27855