Khaled Mnaymneh - Academia.edu (original) (raw)

Papers by Khaled Mnaymneh

Proceedings of SPIE, Feb 9, 2006

ABSTRACT The key feature that gives photonic crystals (PhCs) their ability to form a photonic ban... more ABSTRACT The key feature that gives photonic crystals (PhCs) their ability to form a photonic band structure (PBS) is their translational symmetry. Structures that do not have translational symmetries also have a PBS. One explanation as to how these structures generate a PBS involves long-range interactions resulting in fractal dispersion relations (e.g. 1-D quasi-crystals, Fibonacci layers, etc.) However, long-range interactions do not fully explain why 2-D quasi-crystals structures also exhibit a PBS. This paper proposes an explanation for such results: by applying rotation operators from the SO(2) group to 1-D quasi-crystal dispersion relations. This process mimics the way electronic state amplitudes are calculated when such states have an angular dependence. Simulations results are presented in this paper.

Proceedings of SPIE, Sep 28, 2005

ABSTRACT The key feature that gives photonic crystals (PhCs) their ability to form photonic band ... more ABSTRACT The key feature that gives photonic crystals (PhCs) their ability to form photonic band gaps (PBGs) analogous to electronic band gaps of semiconductors is their translation symmetries. In recent years, however, it has been found that structures that possess only rotational symmetries can also have PBGs. In addition, these structures, known as Photonic Quasicrystals (PhQs), have other interesting qualities that set them apart of their translational cousins. One interesting feature is how defect states can be created in PhQs. If the rotational symmetry is disturbed, defect states analogous to defects states that are created in PhCs can be obtained. Simulation results of these defect states and other propagation properties of planar 12-fold photonic quasicrystal patterns, and its physical implementations in Silicon-On-Insulator (SOI) are presented. The main mechanisms required to make any optical multiplexing system is propagation; stop bands and add/drop ports. With the rotationally symmetry of the PhQ causing the stop bands, line defects facilitating propagation and now these specially design defect states acting as add/drop ports, a physical implementation of an OADM can be presented. Theoretical, practical and manufacturing benefits of PhQs are discussed. Simulated transmission plots are shown for various fill factors, dielectric contrast and propagation direction. It is shown that low index waveguides can be produced using the quasi-crystal photonic crystal pattern. Fabrication steps and results are shown.

Proceedings of SPIE, Dec 20, 2004

We present a dual-beam multiple exposure technique that can generate complex 2-D and 3-D band gap... more We present a dual-beam multiple exposure technique that can generate complex 2-D and 3-D band gap template structures in a photosensitive material. The system parameters related to the planar interference pattern produced by two laser beams and reorientation e ect of the sample relative to these planes is presented. Structures such as the 2-D, square and hexagonal arrays of dielectric "rods" and "holes" and the 3-D, cubic, Yablonovite and other proÿles are given. We perform band gap calculations on these structures when the dielectric contrast has been increased using a backÿll process and discuss techniques for increasing the band gap by sculpting the dielectric proÿle.

Proceedings of SPIE, Feb 9, 2006

The FDTD technique is employed to examine the optical properties of 12-fold rotational order quas... more The FDTD technique is employed to examine the optical properties of 12-fold rotational order quasi-crystal structures. Bandgap and defect states are shown to exits in the quasi-crystal patterns for in-plane propagating light. Out-of-plane propagation is examined by infinitely extending the planar quasi-crystal in the third direction. The resulting micro-structured optical fiber guides show supported modes confined by index guiding. A stack and draw technique is presented making quasi-crystal core designs possible.

Optical Materials, Sep 1, 2008

The central region of a hexagonal array photonic crystal is replaced with the central region of a... more The central region of a hexagonal array photonic crystal is replaced with the central region of a higher rotational order photonic quasi-crystal pattern. The quasi-crystal, with band gaps and defect states now acts as the defect region of the hexagonal array. For the model system examined, different types of ''defect" states are identified, and the modal properties examined. The higher degree of defect state control provided by the mixing of photonic crystal types can find applications in resonator design for laser cavities and WDM as well as assist in the formation of non-conventional photonic crystal waveguide designs. Results are presented specifically for the hexagonal array and 12-fold quasi-crystal and can be extended to other photonic crystal combinations.

Optics Express, 2007

Defects in photonic crystals are local regions in which the translational symmetry is broken. The... more Defects in photonic crystals are local regions in which the translational symmetry is broken. The same definition can be applied to photonic quasicrystals except in this case the symmetry is the 2pi/n rotational symmetry, where n is the rotational fold number. In this context, if no such defects are present, the structure is called "defect-free". Even though photonic quasicrystal patterns can be defect-free, localized modes can still exist in such structures. These modes resemble those of a central potential that suggests that localization in photonic quasicrystals are actually "extended" modes of the rotational symmetry. A possible connection is suggested between these localized modes and short-range dependence of the photonic band gap (PBG). Such a connection implies a tight-binding description of PBG formation of photonic quasicrystals - making them more similar to electronic semiconductors than regular photonic crystals.

Optics Express, 2005

The TM propagation properties of planar 12-fold photonic quasi-crystal patterns are theoretically... more The TM propagation properties of planar 12-fold photonic quasi-crystal patterns are theoretically examined using FDTD. The patterns examined can be produced using a dual beam multiple exposure technique. Simulated transmission plots are shown for various fill factors, dielectric contrast and propagation direction. It is shown that low index waveguides can be produced using the quasi-crystal photonic crystal pattern.

Optics Communications, Aug 1, 2006

The TM bandgap features of the 2D 12-fold quasi-crystal are examined based on the width of the di... more The TM bandgap features of the 2D 12-fold quasi-crystal are examined based on the width of the dielectric strip and pattern central symmetry location within the quasi-crystal. Results indicate that the bandgap properties observed for a particular fill factor is independent of the rotational symmetry center when the dielectric strip is wide, and still observable when the strip width is considerably reduced, confirming the general belief that the bandgap generating properties of the quasi-crystal are a local dielectric effect for the lower frequency band. Thin strips are shown to posses defect states in the bandgap region of the thicker equivalent strips, defect states analogous to intentionally introduced defect states of translational symmetric photonic crystals. We explore the mode profiles of the defect state when the defect is coincidental with the rotational symmetry central pivot point of the quasi-crystal pattern. In addition we show that the rotational center ''defect'' may be used to enhance the optical guidance of light around a 90°bend in a waveguide implanted in the quasi-crystal.

The author has granted a nonexclusive license allowing Library and Archives Canada to reproduce, ... more The author has granted a nonexclusive license allowing Library and Archives Canada to reproduce, publish, archive, preserve, conserve, communicate to the public by telecommunication or on the Internet, loan, distribute and sell theses worldwide, for commercial or noncommercial purposes, in microform, paper, electronic and/or any other formats. AVIS: L'auteur a accorde une licence non exclusive permettant a la Bibliotheque et Archives Canada de reproduire, publier, archiver, sauvegarder, conserver, transmettre au public par telecommunication ou par I'lnternet, preter, distribuer et vendre des theses partout dans le monde, a des fins commerciales ou autres, sur support microforme, papier, electronique et/ou autres formats. Canada Bien que ces formulaires aient inclus dans la pagination, il n'y aura aucun contenu manquant.

IEEE Photonics Journal

We report on an optimization procedure for depositing low-loss silicon nitride films at temperatu... more We report on an optimization procedure for depositing low-loss silicon nitride films at temperatures of 760°C and 820°C using low-pressure chemical vapor deposition. They were characterized in terms of quality and compositional proximity to stoichiometric silicon nitride. Films deposited at 760°C showed a higher stoichiometry, with a silicon-to-nitrogen ratio of 0.744, when compared to the 820°C film, which had a ratio of 0.77. We found the film deposited at the lower temperature had a smoother surface and exhibited lower optical losses. We investigated the impact of film stress on the refractive index of the film and found that removing the backside nitride from the wafer after deposition has a major effect on refractive index values. When using these films for integrated nonlinear and quantum applications, such as frequency conversion or soliton generation, knowledge of how the index changes with wafer and fabrication processing is critical for predicting the correct geometries, and the concomitant group velocities, needed to realize such quantum technologies.

2022 Photonics North (PN)

For photonic devices, extending beyond the planar regime to the third dimension can allow a highe... more For photonic devices, extending beyond the planar regime to the third dimension can allow a higher degree of integration and novel functionalities for applications such as photonic crystals and integrated optical circuits. Although conventional photolithography can achieve both high quality and structural control, it is still costly and slow for three-dimensional (3D) fabrication. Moreover, as diverse functional polymers emerge, there is potential to develop new techniques for quick and economical fabrication of 3D structures. We present a 3D ...

Icarus, 1980

Abstract A mechanism is treated for the origin of the eccentricities of the asteroids and of Mars... more Abstract A mechanism is treated for the origin of the eccentricities of the asteroids and of Mars: secular resonances associated with the dissipation of a primitive solar nebula. The nebula is modeled as a two-dimensional disk; a closed-form, convergent integral is derived to represent its disturbing function. Dissipation of this nebula gives rise to “excitation waves”, produced by the variable location of the secular resonances, which can excite the eccentricity of Mars, and scatter asteroidal eccentricities through the observed ranges. By requiring that these ranges match the observed values as a functions of semimajor axis, one infers: (a) the primordial eccentricities of Jupiter and Saturn initially had amplitudes different from present-day values, but these amplitudes approached the present values toward the end of nebular dissipation; (b) the nebular dissipation time scale may have been of the order of (few) × 104 years as the dissipation neared completion (but this depends on the validity of linear equations which model the inherently nonlinear asteroidal eccentricity pumping); (c) it is reasonable to propose a common origin for the eccentricies of Mars and the asteroids. A simple extension of the model also accounts for the quasi-Gaussian distribution of the number density of asteroidal eccentricities.

2021 Photonics North (PN), 2021

2021 Photonics North (PN), 2021

Quantum dots embedded in photonic nanowires are a promising route for generating single photons w... more Quantum dots embedded in photonic nanowires are a promising route for generating single photons with high efficiency [1]. Integration of such sources on-chip offers enhanced stability and miniaturization, important in many applications involving the processing of quantum information. Here we demonstrate the efficient coupling of quantum light generated in a III-V photonic nanowire to a silicon-based photonic integrated circuit. The hybrid integration is based on a “pick & place” approach using a nanomanipulator in a scanning electron microscope. We demonstrate detected count rates of 1 Mcps and single photon purities >95%.

The author has granted a nonexclusive license allowing Library and Archives Canada to reproduce, ... more The author has granted a nonexclusive license allowing Library and Archives Canada to reproduce, publish, archive, preserve, conserve, communicate to the public by telecommunication or on the Internet, loan, distribute and sell theses worldwide, for commercial or noncommercial purposes, in microform, paper, electronic and/or any other formats. AVIS: L'auteur a accorde une licence non exclusive permettant a la Bibliotheque et Archives Canada de reproduire, publier, archiver, sauvegarder, conserver, transmettre au public par telecommunication ou par I'lnternet, preter, distribuer et vendre des theses partout dans le monde, a des fins commerciales ou autres, sur support microforme, papier, electronique et/ou autres formats. Canada Bien que ces formulaires aient inclus dans la pagination, il n'y aura aucun contenu manquant.

ECS Meeting Abstracts, 2012

Proceedings of SPIE, Feb 9, 2006

ABSTRACT The key feature that gives photonic crystals (PhCs) their ability to form a photonic ban... more ABSTRACT The key feature that gives photonic crystals (PhCs) their ability to form a photonic band structure (PBS) is their translational symmetry. Structures that do not have translational symmetries also have a PBS. One explanation as to how these structures generate a PBS involves long-range interactions resulting in fractal dispersion relations (e.g. 1-D quasi-crystals, Fibonacci layers, etc.) However, long-range interactions do not fully explain why 2-D quasi-crystals structures also exhibit a PBS. This paper proposes an explanation for such results: by applying rotation operators from the SO(2) group to 1-D quasi-crystal dispersion relations. This process mimics the way electronic state amplitudes are calculated when such states have an angular dependence. Simulations results are presented in this paper.

Proceedings of SPIE, Sep 28, 2005

ABSTRACT The key feature that gives photonic crystals (PhCs) their ability to form photonic band ... more ABSTRACT The key feature that gives photonic crystals (PhCs) their ability to form photonic band gaps (PBGs) analogous to electronic band gaps of semiconductors is their translation symmetries. In recent years, however, it has been found that structures that possess only rotational symmetries can also have PBGs. In addition, these structures, known as Photonic Quasicrystals (PhQs), have other interesting qualities that set them apart of their translational cousins. One interesting feature is how defect states can be created in PhQs. If the rotational symmetry is disturbed, defect states analogous to defects states that are created in PhCs can be obtained. Simulation results of these defect states and other propagation properties of planar 12-fold photonic quasicrystal patterns, and its physical implementations in Silicon-On-Insulator (SOI) are presented. The main mechanisms required to make any optical multiplexing system is propagation; stop bands and add/drop ports. With the rotationally symmetry of the PhQ causing the stop bands, line defects facilitating propagation and now these specially design defect states acting as add/drop ports, a physical implementation of an OADM can be presented. Theoretical, practical and manufacturing benefits of PhQs are discussed. Simulated transmission plots are shown for various fill factors, dielectric contrast and propagation direction. It is shown that low index waveguides can be produced using the quasi-crystal photonic crystal pattern. Fabrication steps and results are shown.

Proceedings of SPIE, Dec 20, 2004

We present a dual-beam multiple exposure technique that can generate complex 2-D and 3-D band gap... more We present a dual-beam multiple exposure technique that can generate complex 2-D and 3-D band gap template structures in a photosensitive material. The system parameters related to the planar interference pattern produced by two laser beams and reorientation e ect of the sample relative to these planes is presented. Structures such as the 2-D, square and hexagonal arrays of dielectric "rods" and "holes" and the 3-D, cubic, Yablonovite and other proÿles are given. We perform band gap calculations on these structures when the dielectric contrast has been increased using a backÿll process and discuss techniques for increasing the band gap by sculpting the dielectric proÿle.

Proceedings of SPIE, Feb 9, 2006

The FDTD technique is employed to examine the optical properties of 12-fold rotational order quas... more The FDTD technique is employed to examine the optical properties of 12-fold rotational order quasi-crystal structures. Bandgap and defect states are shown to exits in the quasi-crystal patterns for in-plane propagating light. Out-of-plane propagation is examined by infinitely extending the planar quasi-crystal in the third direction. The resulting micro-structured optical fiber guides show supported modes confined by index guiding. A stack and draw technique is presented making quasi-crystal core designs possible.

Optical Materials, Sep 1, 2008

The central region of a hexagonal array photonic crystal is replaced with the central region of a... more The central region of a hexagonal array photonic crystal is replaced with the central region of a higher rotational order photonic quasi-crystal pattern. The quasi-crystal, with band gaps and defect states now acts as the defect region of the hexagonal array. For the model system examined, different types of ''defect" states are identified, and the modal properties examined. The higher degree of defect state control provided by the mixing of photonic crystal types can find applications in resonator design for laser cavities and WDM as well as assist in the formation of non-conventional photonic crystal waveguide designs. Results are presented specifically for the hexagonal array and 12-fold quasi-crystal and can be extended to other photonic crystal combinations.

Optics Express, 2007

Defects in photonic crystals are local regions in which the translational symmetry is broken. The... more Defects in photonic crystals are local regions in which the translational symmetry is broken. The same definition can be applied to photonic quasicrystals except in this case the symmetry is the 2pi/n rotational symmetry, where n is the rotational fold number. In this context, if no such defects are present, the structure is called "defect-free". Even though photonic quasicrystal patterns can be defect-free, localized modes can still exist in such structures. These modes resemble those of a central potential that suggests that localization in photonic quasicrystals are actually "extended" modes of the rotational symmetry. A possible connection is suggested between these localized modes and short-range dependence of the photonic band gap (PBG). Such a connection implies a tight-binding description of PBG formation of photonic quasicrystals - making them more similar to electronic semiconductors than regular photonic crystals.

Optics Express, 2005

The TM propagation properties of planar 12-fold photonic quasi-crystal patterns are theoretically... more The TM propagation properties of planar 12-fold photonic quasi-crystal patterns are theoretically examined using FDTD. The patterns examined can be produced using a dual beam multiple exposure technique. Simulated transmission plots are shown for various fill factors, dielectric contrast and propagation direction. It is shown that low index waveguides can be produced using the quasi-crystal photonic crystal pattern.

Optics Communications, Aug 1, 2006

The TM bandgap features of the 2D 12-fold quasi-crystal are examined based on the width of the di... more The TM bandgap features of the 2D 12-fold quasi-crystal are examined based on the width of the dielectric strip and pattern central symmetry location within the quasi-crystal. Results indicate that the bandgap properties observed for a particular fill factor is independent of the rotational symmetry center when the dielectric strip is wide, and still observable when the strip width is considerably reduced, confirming the general belief that the bandgap generating properties of the quasi-crystal are a local dielectric effect for the lower frequency band. Thin strips are shown to posses defect states in the bandgap region of the thicker equivalent strips, defect states analogous to intentionally introduced defect states of translational symmetric photonic crystals. We explore the mode profiles of the defect state when the defect is coincidental with the rotational symmetry central pivot point of the quasi-crystal pattern. In addition we show that the rotational center ''defect'' may be used to enhance the optical guidance of light around a 90°bend in a waveguide implanted in the quasi-crystal.

The author has granted a nonexclusive license allowing Library and Archives Canada to reproduce, ... more The author has granted a nonexclusive license allowing Library and Archives Canada to reproduce, publish, archive, preserve, conserve, communicate to the public by telecommunication or on the Internet, loan, distribute and sell theses worldwide, for commercial or noncommercial purposes, in microform, paper, electronic and/or any other formats. AVIS: L'auteur a accorde une licence non exclusive permettant a la Bibliotheque et Archives Canada de reproduire, publier, archiver, sauvegarder, conserver, transmettre au public par telecommunication ou par I'lnternet, preter, distribuer et vendre des theses partout dans le monde, a des fins commerciales ou autres, sur support microforme, papier, electronique et/ou autres formats. Canada Bien que ces formulaires aient inclus dans la pagination, il n'y aura aucun contenu manquant.

IEEE Photonics Journal

We report on an optimization procedure for depositing low-loss silicon nitride films at temperatu... more We report on an optimization procedure for depositing low-loss silicon nitride films at temperatures of 760°C and 820°C using low-pressure chemical vapor deposition. They were characterized in terms of quality and compositional proximity to stoichiometric silicon nitride. Films deposited at 760°C showed a higher stoichiometry, with a silicon-to-nitrogen ratio of 0.744, when compared to the 820°C film, which had a ratio of 0.77. We found the film deposited at the lower temperature had a smoother surface and exhibited lower optical losses. We investigated the impact of film stress on the refractive index of the film and found that removing the backside nitride from the wafer after deposition has a major effect on refractive index values. When using these films for integrated nonlinear and quantum applications, such as frequency conversion or soliton generation, knowledge of how the index changes with wafer and fabrication processing is critical for predicting the correct geometries, and the concomitant group velocities, needed to realize such quantum technologies.

2022 Photonics North (PN)

For photonic devices, extending beyond the planar regime to the third dimension can allow a highe... more For photonic devices, extending beyond the planar regime to the third dimension can allow a higher degree of integration and novel functionalities for applications such as photonic crystals and integrated optical circuits. Although conventional photolithography can achieve both high quality and structural control, it is still costly and slow for three-dimensional (3D) fabrication. Moreover, as diverse functional polymers emerge, there is potential to develop new techniques for quick and economical fabrication of 3D structures. We present a 3D ...

Icarus, 1980

Abstract A mechanism is treated for the origin of the eccentricities of the asteroids and of Mars... more Abstract A mechanism is treated for the origin of the eccentricities of the asteroids and of Mars: secular resonances associated with the dissipation of a primitive solar nebula. The nebula is modeled as a two-dimensional disk; a closed-form, convergent integral is derived to represent its disturbing function. Dissipation of this nebula gives rise to “excitation waves”, produced by the variable location of the secular resonances, which can excite the eccentricity of Mars, and scatter asteroidal eccentricities through the observed ranges. By requiring that these ranges match the observed values as a functions of semimajor axis, one infers: (a) the primordial eccentricities of Jupiter and Saturn initially had amplitudes different from present-day values, but these amplitudes approached the present values toward the end of nebular dissipation; (b) the nebular dissipation time scale may have been of the order of (few) × 104 years as the dissipation neared completion (but this depends on the validity of linear equations which model the inherently nonlinear asteroidal eccentricity pumping); (c) it is reasonable to propose a common origin for the eccentricies of Mars and the asteroids. A simple extension of the model also accounts for the quasi-Gaussian distribution of the number density of asteroidal eccentricities.

2021 Photonics North (PN), 2021

2021 Photonics North (PN), 2021

Quantum dots embedded in photonic nanowires are a promising route for generating single photons w... more Quantum dots embedded in photonic nanowires are a promising route for generating single photons with high efficiency [1]. Integration of such sources on-chip offers enhanced stability and miniaturization, important in many applications involving the processing of quantum information. Here we demonstrate the efficient coupling of quantum light generated in a III-V photonic nanowire to a silicon-based photonic integrated circuit. The hybrid integration is based on a “pick & place” approach using a nanomanipulator in a scanning electron microscope. We demonstrate detected count rates of 1 Mcps and single photon purities >95%.

The author has granted a nonexclusive license allowing Library and Archives Canada to reproduce, ... more The author has granted a nonexclusive license allowing Library and Archives Canada to reproduce, publish, archive, preserve, conserve, communicate to the public by telecommunication or on the Internet, loan, distribute and sell theses worldwide, for commercial or noncommercial purposes, in microform, paper, electronic and/or any other formats. AVIS: L'auteur a accorde une licence non exclusive permettant a la Bibliotheque et Archives Canada de reproduire, publier, archiver, sauvegarder, conserver, transmettre au public par telecommunication ou par I'lnternet, preter, distribuer et vendre des theses partout dans le monde, a des fins commerciales ou autres, sur support microforme, papier, electronique et/ou autres formats. Canada Bien que ces formulaires aient inclus dans la pagination, il n'y aura aucun contenu manquant.

ECS Meeting Abstracts, 2012