Browsing by Author "Aydogdu, G. H."

Now showing 1 - 3 of 3

Citation - WoS: 1
Enhancement of Laser Damage Resistance at 1064 Nm of High and Anti-Reflective Optical Multilayers by Tailoring the Electric Field Distribution and Post-Annealing
(Soc Vacuum Coaters, 2016) Aydogdu, G. H.; Batman, H.; Cosar, M. B.; Ozhan, A. E. S.; Computer Engineering
In this study, multilayer Ta2O5/SiO2 and HfO2/SiO2 films were deposited on glass substrates by ion beam sputtering and physical vapor deposition methods, respectively. The effect of electric field distribution and heat treatment of these oxide multilayers on laser damage resistance were investigated systematically. Optical performance was characterized by spectrophotometer. Electric field analysis and optic system design were performed by thin film design software. LIDT (laser-induced damage threshold) measurements were applied at 1064 nm to obtain laser damage values of optical coatings. Damage images were characterized by a Nomarski (with dark field type) microscope. It was observed that the LIDT value of HfO2/SiO2 anti-reflective optical films increases to 34 J/cm(2) when they are post-annealed at 350 degrees C. On the other hand, measured LIDTs as high as 26 J/cm(2) were achieved by tailoring the electric field distribution of high reflective coatings.
Citation - WoS: 9
Citation - Scopus: 10
Improving the Laser Damage Resistance of Oxide Thin Films and Multilayers Via Tailoring Ion Beam Sputtering Parameters
(Elsevier Science Bv, 2015) Cosar, M. B.; Coşar, Batuhan Mustafa; Ozhan, A. E. S.; Aydogdu, G. H.; Coşar, Batuhan Mustafa; Computer Engineering; Computer Engineering
Ion beam sputtering is one of the widely used methods for manufacturing laser optical components due to its advantages such as uniformity, reproducibility, suitability for multilayer coatings and growth of dielectric materials with high packing densities. In this study, single Ta2O5 layers and Ta2O5/SiO2 heterostructures were deposited on optical quality glass substrates by dual ion beam sputtering. We focused on the effect of deposition conditions like substrate cleaning, assistance by 12 cm diameter ion beam source and oxygen partial pressure on the laser-induced damage threshold of Ta2O5 single layers. After-wards, the obtained information is employed to a sample design and produces a Ta2O5/SiO2 multilayer structure demonstrating low laser-induced damage without a post treatment procedure. (C) 2014 Elsevier B.V. All rights reserved.
A Solution To the Adhesion Problem of Oxide Thin Films on Zinc Selenide Optical Substrates
(Soc Vacuum Coaters, 2016) Cosar, M. B.; Aydogdu, G. H.; Batman, H.; Ozhan, A. E. S.; Computer Engineering
Zinc selenide optical substrates have high transparency within the 0.5- to 14.0-mu m wavelength range. This makes them an attractive candidate for multiband imaging applications in optical components. In order to minimize reflection loss in visible, near-infrared, and mid-infrared applications, zinc selenide lenses are coated with multi-layered oxide thin films by physical vapor deposition method or ion beam deposition. In this study, a four-layer anti-reflective filter at 1.064 gm and between 3.6 and 4.9 gm is applied to zinc selenide using an ion beam deposition system. The filter is used for a dual-beam optical application. The filter is composed of metal oxide layers that have an adhesion problem on zinc selenide. In order to solve this adhesion problem they were heat-treated at 300 degrees C for varying amounts of time prior to metal oxide coating. Treated samples were characterized in terms of their roughness, contact angle, morphology, refractive index, transparency, crystallography and chemical composition. Results show that it is possible to manufacture durable oxide thin film coatings on zinc selenide, by using a well-designed pre-treatment processes.