Papers by Mustafa M Aslan
Proceedings of SPIE - The International Society for Optical Engineering, 1998
ABSTRACT
SPIE Proceedings, 2011
An analytical study of the sensitivity enhancement of an angularly interrogated long range surfac... more An analytical study of the sensitivity enhancement of an angularly interrogated long range surface plasmon (LRSP) sensor, with a closed symmetric transducer structure consisting of a prism, Teflon and gold layers, is presented. The effects of the sensor design parameters, such as wavelength and the thicknesses of the gold and Teflon layers, on the angular (Stheta) and intrinsic (IStheta) sensitivities
SPIE Proceedings, 2000
The conventional methods of measuring displacement and strain are severely taxed especially when ... more The conventional methods of measuring displacement and strain are severely taxed especially when long-term stability is needed in a situation involving temperatures above 1000 degrees Celsius. Optical techniques are attractive for measurements in these difficult situations ...
SPIE Newsroom, 2011
A straightforward and economic method for nanostructuring alumina waveguides for molecular sensin... more A straightforward and economic method for nanostructuring alumina waveguides for molecular sensing applications yields promising results. Molecular sensing is performed using either optical, electrochemical, electrical, thermal, magnetic, or piezo-electric sensors. Optical sensors are preferred and represent the most powerful approach because of their speed, safety, sensitivity, and robustness. In addition, they allow in situ sensing and real-time, nondestructive measurements. Further advantages include their suitability for component miniaturization and their remote and multi-analyte sensing capabilities. 1 Although optical sensors come in many different forms, evanescent-wave-based sensors-in which surface-plasmon and/or waveguide mode(s) can be exited to detect molecular changes in the evanescent-wave field on the sensor's surfacerepresent an innovative approach. Very small variations in the molecular layer (see Figure 1) may alter the spatial and spectral characteristics of the incident light (such as its intensity, polarization, phase, or frequency). Although measurable outputs of an optical sensor include fluorescence/phosphorescence, biochemical luminescence, reflectance, or Raman scattering, 2 label-free measurements can generally be performed. Likely sensor outputs may be intrinsic-such as total internal reflection (TIR)or extrinsic, such as scattering and Raman scattering. Most evanescent-wave sensors are characterized by intrinsic output. This is easy to detect and not affected by external factors. However, in some cases, understanding complex molecular events is limited-due to the characteristics of the reflected lightwhen available data is based solely on angular or spectral TIR measurements. Scattering measurements must be accompanied by reflection measurements to determine the concentration and organization of molecules on a sensor's surface.
AIP Conference Proceedings, 2000
The electronics industry relies on alumina (Al2O3) substrates to isolate, electrically and therma... more The electronics industry relies on alumina (Al2O3) substrates to isolate, electrically and thermally, the computer chip from the rest of the circuit. In order to improve the manufacturing process of these chips, it is desirable to machine the substrates with a laser rather than the conventional techniques. Unfortunately, the high thermal stresses due to the intensity of the laser cause
Transactions of the ASAE, 2005
In this article, we present an experimental approach to determine the milk fat content using scat... more In this article, we present an experimental approach to determine the milk fat content using scattered light intensity profiles. The elements of the scattering (Mueller) matrix have been shown to provide valuable information about variation of the optical properties of scattering particles. The scattering behavior of fat and casein in terms of the scattering matrix elements was experimentally determined for milk with varying fat levels ranging from 0.05 wt% (skim) to 3.20 wt% (whole). Three of the scattering Mueller matrix elements, specifically S 11 , S 12 /S 11 , and S 33 /S 11 , were found to be sensitive to the number of fat particles in milk. These results indicate that it should be possible to develop a reliable sensor based on the measurement of these scattering elements, which will allow for the development of a robust, in-line sensor to be used in food processing. In addition, an attempt was made to model the phenomena using a relatively simple approach based on single scattering with a size distribution. The disagreement between the model and experiments suggests that a more comprehensive model is needed which can account for multiple scattering.
8th AIAA/ASME Joint Thermophysics and Heat Transfer Conference, 2002
We present a detailed experimental/theoretical study on understanding tile fundamental nature of ... more We present a detailed experimental/theoretical study on understanding tile fundamental nature of individual cotton fibers from light scattering experiments. For this purpose, we built a new precision nephelometer and calibrated it with quartz fibers. The results were ...
Heat Transfer, Part B, 2005
Metallic nanoparticles display considerably different optical properties than those of their bulk... more Metallic nanoparticles display considerably different optical properties than those of their bulk counterparts. They have long been of interest in several novel applications, from colored glass production of medieval times to molecular-level sensors of today. Recently, there has ...
Design, Synthesis, and Applications, 2004
In this paper, we introduce a novel methodology to determine the size and structure of nano-parti... more In this paper, we introduce a novel methodology to determine the size and structure of nano-particles on a surface. We present an analysis, dubbed Elliptically Polarized Surface-Wave Scattering (EPSWS) approach, to show that 5–10 nm size particles on or above an interface can be characterized by using the scattered surface plasmon (SP) or evanescent waves. We present an analysis to show that the scattering matrix elements of the evanescent waves scattered by the nano-particles on or near an interface can be used for characterization of nano-size particles.
Advanced Environmental, Chemical, and Biological Sensing Technologies XI, 2014
ABSTRACT Today evanescent wave based fiber optic (F/O) platforms are in favor of the use for moni... more ABSTRACT Today evanescent wave based fiber optic (F/O) platforms are in favor of the use for monitoring molecular interactions since they are practical, economic and easy to operate which make them ideal turnkey systems for clinical, pharmaceutical, environmental and security applications. The side polishing is one of techniques for reshaping the geometry of the waveguide to make the F/O sensor more sensitive to surrounding refractive index (RI) in evanescent field. In this study D-type F/O sensors with a 25 mm-long interaction lengths are fabricated. In addition to that, effects of the critical parameters such as the polishing depth, the wavelength, and the temperature on the sensor response are determined for the RI in the range of 1.33 -1.47. The developing key of these F/O sensors is reaching high strength and penetration depth of evanescent wave in varying RI of the surrounding bio-layer. Development steps of D-type F/O sensors are; fabrication of supporting elements -silicon V channels, F/O cable preparation, adhesion, lapping and polishing, fusing the FC connectors, construction of the optical system, and RI measurements. Details of these steps are explained and the general characteristics of the D-type F/O sensor are presented. Results indicate that the sensor's responses in three different RI ranges can be improved by the polishing depth. A maximum sensitivity of around 2x10 5 for the D-type F/O sensors is demonstrated in the RI range of 1.44-1.46.
Biennial University/Government/Industry Microelectronics Symposium - Proceedings, 2008
AbstractThe fabrication of integrated grating couplers for planar optical waveguides is presente... more AbstractThe fabrication of integrated grating couplers for planar optical waveguides is presented. Holographic gratings with spatial period of 300-400 nm are produced in photoresist films using a Lloyd's mirror setup. The periodic modulations of the gratings are transferred ...
2009 IEEE/LEOS International Conference on Optical MEMS and Nanophotonics, 2009
Page 1. Spectroscopic Studies in Protein Films with Highly Sensitive Single-Mode Guided-Wave Plat... more Page 1. Spectroscopic Studies in Protein Films with Highly Sensitive Single-Mode Guided-Wave Plataforms Rodrigo S. Wiederkehr, Geoffrey C. Hoops, Mustafa M. Aslan, Courtney L. Byard, and Sergio B. Mendes Department ...
Advanced Photonics, 2014
ABSTRACT
SPIE Proceedings, 2012
Coupling surface plasmon resonance mode to waveguide mode(s) by simply forming a dielectric layer... more Coupling surface plasmon resonance mode to waveguide mode(s) by simply forming a dielectric layer on top of the metallic layer can improve the sensor's response to molecular variations. In this.
Thin Solid Films, 2010
In this work, we report low-loss single-mode integrated optical waveguides in the near ultraviole... more In this work, we report low-loss single-mode integrated optical waveguides in the near ultraviolet and visible spectral regions with aluminum oxide (Al 2 O 3) films using an atomic layer deposition (ALD) process. Alumina films were deposited on glass and fused silica substrates by the ALD process at substrate/chamber temperatures of 200 °C and 300 °C. Transmission spectra and waveguide measurements were performed in our alumina films with thicknesses in the range of 210-380 nm for the optical characterization. Those measurements allowed us to determine the optical constants (n w and k w), propagation loss, and thickness of the alumina films. The experimental results from the applied techniques show good agreement and demonstrate a lowloss optical waveguide. Our alumina thin-film waveguides is well transparent in the whole visible spectral region and also in an important region of the UV; the measured propagation loss is below 4 dB/cm down to a wavelength as short as 250 nm. The low propagation loss of these alumina guiding films, in particular in the near ultraviolet region which lacks materials with high optical performance, is extremely useful for several integrated optic applications.
Thin Solid Films, 2012
A study of the nanostructuring of alumina integrated optical waveguides by means of hot water tre... more A study of the nanostructuring of alumina integrated optical waveguides by means of hot water treatment to tune their outputs, namely, total internal reflection and scattering, is presented. Homogeneous alumina thin films fabricated by atomic layer deposition were exposed to hot water to form surface nano-pillars of various heights and densities. The 135-, 232-and 307-nm thick alumina films were immersed in hot water at 50, 60, and 80°C for 2, 5, 10, 15, 20 and 30 min. Topology measurements of the nanostructured integrated optical waveguides (n-IOWs) were made using an atomic force microscope and a scanning electron microscope. Optical transmission and coupling measurements for n-IOWs were taken. Average pillar height and density, controlled by adjusting the water temperature and exposure time, act to tune the scattered and guided fractions of the coupled light. Well controlled fabrication of nanopillars (up to 110-nm-tall) as well as fine tuning of the scattered component of sensor output is possible. Fabricated n-IOW sensors with dual outputs, total internal reflection and scattering, could be quite useful for the enhanced sensing of surface-adsorbed molecular species.
The Journal of Physical Chemistry C, 2009
In this work, we report experimental results on the molar absorptivity of cytochrome c adsorbed a... more In this work, we report experimental results on the molar absorptivity of cytochrome c adsorbed at different submonolayer levels onto an aluminum oxide waveguide surface; our data show a clear dependence of the protein optical properties on its surface density. The measurements were performed using the broadband, single-mode, integrated optical waveguide spectroscopic technique, which is an extremely sensitive tool able to reach submonolayer levels of detection required for this type of studies. This investigation focuses on the molar absorptivity at the Q-band (centered at 525 nm) and, for the first time to our knowledge, the weak charge transfer (CT) band (centered at 695 nm) of surface-adsorbed cyt c. Polarized light in the spectral region from 450 to 775 nm was all-coupled into an alumina thin film, which functioned as a single-mode planar optical waveguide. The alumina thin-film waveguide used for this work had a thickness of 180 nm and was deposited on a glass substrate by the atomic layer deposition process. The protein submonolayer was formed on the alumina waveguide surface through electrostatic adsorption from an aqueous buffer solution at neutral pH. The optical properties of the surface-adsorbed cyt c were investigated for bulk protein concentrations ranging from 5 nM to 8200 nM in the aqueous buffer solution. For a protein surface density of 2.3 pmol/cm 2 , the molar absorptivity measured at the charge transfer band was 335 M −1 cm −1 , and for a surface density of 15 pmol/cm 2 was 720 M −1 cm −1 , which is much closer to the value of cyt c dissolved in an aqueous neutral buffer (830 M −1 cm −1). The modification of the protein molar absorptivity and its dependence on the surface density can most likely be attributed to conformational changes of the surface-adsorbed species.
Journal of Thermophysics and Heat Transfer, 2003
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Papers by Mustafa M Aslan