Prof. Abdolnaser Zakery Profile

Prof. Abdolnaser Zakery

at Shiraz Univ

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Publications (6)

Proceedings Article | 1 April 1999 Paper

Modeling of erbium-doped fiber amplifiers (EDFAs) using a Gaussian profile for the doped ion concentration

Abdolnasser Zakery, A. Askarzadeh

Proceedings Volume 3622, (1999) https://doi.org/10.1117/12.344506

KEYWORDS: Ions, Optical amplifiers, Fiber amplifiers, Erbium, Numerical integration, Photonics, Wave propagation, Erbium lasers, Ultraviolet radiation, Silicon

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Proceedings Article | 24 September 1996 Paper

New coupled mode analysis of gain coupled DFB lasers

Abdolnasser Zakery, Aref Bakhtazad

Proceedings Volume 2886, (1996) https://doi.org/10.1117/12.251883

KEYWORDS: Refractive index, Polarization, Waveguides, Shape analysis, Matrix multiplication, Dielectric polarization, Aluminum, Physics, Dielectrics, Information operations

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Proceedings Article | 24 September 1996 Paper

Coupled mode analysis of second order loss-coupled DFB lasers

Abdolnasser Zakery, R. Zare, Aref Bakhtazad

Proceedings Volume 2886, (1996) https://doi.org/10.1117/12.251884

KEYWORDS: Absorption, Radiation effects, Laser scattering, Refractive index, Cladding, Waveguides, Wave propagation, Diffraction gratings, Teeth, Resonators

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Proceedings Article | 23 September 1996 Paper

Modeling of the performance of reflection gratings in As-S thin films photodissolved with silver

Abdolnasser Zakery, M. Hatami

Proceedings Volume 2885, (1996) https://doi.org/10.1117/12.251844

KEYWORDS: Diffraction gratings, Silver, Diffraction, Thin films, Arsenic, Metals, Performance modeling, Reflection, Dielectrics, Magnetism

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Proceedings Article | 20 April 1995 Paper

Modeling of the diffraction gratings produced in As-S thin films

Abdolnasser Zakery, M. Hatami

Proceedings Volume 2404, (1995) https://doi.org/10.1117/12.207467

KEYWORDS: Diffraction gratings, Diffraction, Metals, Refractive index, Modulation, Thin films, Arsenic, Holography, Chalcogenides, Silver

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Proceedings Article | 1 September 1991 Paper

Fabrication and properties of chalcogenide IR diffractive elements

Peter Ewen, Christopher Slinger, Abdolnasser Zakery, Abdelkarim Zekak, A. Owen

Proceedings Volume 1512, (1991) https://doi.org/10.1117/12.47152

KEYWORDS: Silver, Chalcogenides, Diffraction gratings, Metals, Chemical elements, Infrared radiation, Holography, Refractive index, Diffraction, Absorption

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The authors report on techniques used to manufacture IR diffractive elements in chalcogenide glasses and on measurements of the material properties relevant to the performance of these elements. The characteristics of the elements produced are also presented and compared with theoretical predictions. The fabrication process used is based on the photodissolution of Ag into amorphous As-S films. Both surface relief and volume phase modulated transmission elements have been made. The transmission of Ag photodoped and undoped As-S films was found to be >80% over the range 2-12 micrometers for films up to 2 micrometers thick, the main loss mechanism being reflection. The difference in refractive index between Ag photodoped and undoped As-S over the range 0.5-12 micrometers was 0.5 for the most heavily doped material, so that high modulations are achievable for phase gratings. Theory suggests that for these As-S materials, green illumination (e.g., 514.5 nm) is the most efficient for producing the deep structures required for many of these IR elements. Surface relief structures can be produced by removing undoped material with an alkali etchant (e.g., NaOH). For transmission gratings, any remaining metallic Ag must be removed, to avoid high losses: the most successful Ag etchant was found to be Fe(NO3)3 in water. For the bulk holographic transmission gratings produced, efficiencies of >33% were observed for first diffraction orders measured in air at 632.8 nm, the main loss mechanisms being absorption and reflection, with some scatter. Measurements at 1.5 micrometers have given efficiencies of >30%, stability requirements during holographic recording currently being the main limitation to higher efficiencies at these and longer wavelengths. The results of a theoretical analysis based on numerical solution of the appropriate coupled-wave equations and taking into account bulk losses with phase and absorption modulation are in good agreement with the observed diffraction efficiency data. Given the low material absorption in the IR, theoretical studies show that, with suitable coatings, >95% efficiency should be possible for properly optimized bulk gratings and blazed zone plates.

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