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Your search keyword '"Obayya, Salah S.A."' showing total 32 results
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32 results on '"Obayya, Salah S.A."'

12. Numerical modeling of polarization conversion in semiconductor electro-optic modulators

Author

Obayya, Salah S.A., Haxha, Shyqyri, Rahman, B.M. Azizur, and Grattan, Kenneth T.V.

Subjects
Optical instruments, Semiconductor industry, Circuit components, Semiconductor industry, Semiconductor device, Astronomy, Physics
Abstract

An accurate numerical simulation study of a polarization conversion phenomenon in deeply etched semiconductor electro-optic waveguide modulators is presented. Based on a powerful and versatile finite element package, the effect of various imperfect fabrication conditions on unwanted and unexpected polarization conversion in electro-optic semiconductor modulators is, for the first time to our knowledge reported and explained in terms of its origin. OCIS codes: 230.4110, 130.3120, 230.5440.

Published
2005

13. Rigorous comparison of parabolically tapered and conventional multimode-interference-based 3-dB power splitters in InGaAsP/InP waveguides

Author

Themistos, Christos, Rajarajan, Muttukrishnan, Rahman, B.M. Azizur, Obayya, Salah S.A., and Grattan, Kenneth T.V.

Subjects
Optics -- Research, Astronomy, Physics
Abstract

Design issues such as optical transmission, interference mechanisms, the splitting ratio, the polarization dependence, and the fabrication tolerances of a compact parabolically tapered multimode-interference (MMI)-based 3-dB power splitter on an InP-based deeply etched ridge waveguide, by use of the finite-element-based beam-propagation method, are presented. The benefits and drawbacks of the use of the tapered structure, in comparison with an untapered MMI-based 3-dB splitter, have also been investigated. OCIS codes: 130.3120, 230.3120.

Published
2004

14. Velocity matching of a GaAs electro-optic modulator

Author

Haxha, Shyqyri, Rahman, B.M. Azizur, Obayya, Salah S.A., and Grattan, Kenneth T.V.

Subjects
Optics -- Research, Astronomy, Physics
Abstract

New designs for the velocity matching of a deep-etched semiconductor electro-optic modulator are presented. A tantalum pentoxide ([Ta.sub.2][O.sub.5]) coating is considered here for achieving velocity matching between the microwave and the optical signals. The effects of the velocity mismatch, the conductor loss, the dielectric loss, and the impedance mismatch are studied in relation to the optical bandwidth of a high-speed semiconductor modulator. It is shown that both the dielectric loss and the impedance matching play key roles for velocity-matched high-speed modulators with low conductor loss. The effects of [Ta.sub.2][O.sub.5] thickness on the overall bandwidth and on the half-wave voltage-length product [V.sub.[pi]]L are also reported. OCIS codes: 230.4110, 230.2090.

Published
2003

15. CuI as versatile hole-selective contact for organic solar cell based on anthracene-containing PPE–PPV

Author

Mohamed, Shaimaa A., Gasiorowski, Jacek, Hingerl, Kurt, Zahn, Dietrich R.T., Scharber, Markus C., Obayya, Salah S.A., El-Mansy, Mabrouk K., Sariciftci, Niyazi S., Egbe, Daniel A.M., and Stadler, Philipp

Subjects
Copper-iodide, Renewable Energy, Sustainability and the Environment, Organic photovoltaics, Inorganic–organic junction, Hole-selective contact, Electronic, Optical and Magnetic Materials, Surfaces, Coatings and Films
Abstract

An important issue in construction of organic photovoltaic cells concerns the selective contacts. Here, especially the modification of the hole-extraction is challenging, as energy levels have to match the polymer's highest occupied molecular orbital (HOMO). We took the view to the mutual anode interface and we sought for a solution-based alternative for commonly used PEDOT:PSS – with an eye on improving the hole-extraction with an inorganic interlayer. We present copper iodide (CuI) as a versatile inorganic p-type semiconductor that meets the requirements for enhanced charge extraction in donor polymers. We applied two types of anthracene-containing PPE–PPV block–copolymers that recently gained attention as efficient active absorbers in bulk heterojunction photovoltaic cells. We report on the advantages using CuI as hole-selective contact and show an improvement of the power conversion efficiency in polymer-based solar cells.

Published
2015
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29. Velocity Matching of a GaAs Electrooptic Modulator

Author

Haxha, Shyqyri, Rahman, B. M. Azizur, Obayya, Salah S.A., Grattan, Kenneth T. V., Haxha, Shyqyri, Rahman, B. M. Azizur, Obayya, Salah S.A., and Grattan, Kenneth T. V.

Abstract

New designs for the velocity matching of a deep-etched semiconductor electro-optic modulator are presented. A tantalum pentoxide (Ta2O5) coating is considered here for achieving velocity matching between the microwave and the optical signals. The effects of the velocity mismatch, the conductor loss, the dielectric loss, and the impedance mismatch are studied in relation to the optical bandwidth of a high-speed semiconductor modulator. It is shown that both the dielectric loss and the impedance matching play key roles for velocity-matched high-speed modulators with low conductor loss. The effects of Ta2O5 thickness on the overall bandwidth and on the half-wave voltage-length product VpiL are also reported.

Published
2003

32. Characterization of Photonic Devices by Finite Element Method

Author

Rahman, B. M. Azizur, Wongcharoen, T., Obayya, Salah S.A., Haxha, Shyqyri, Somasiri, N., Themistos, C., Rajarajan, M., Grattan, Kenneth T. V., Rahman, B. M. Azizur, Wongcharoen, T., Obayya, Salah S.A., Haxha, Shyqyri, Somasiri, N., Themistos, C., Rajarajan, M., and Grattan, Kenneth T. V.

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