A reconfigurable metasurface constitutes an important block of future adaptive and smart nanophot... more A reconfigurable metasurface constitutes an important block of future adaptive and smart nanophotonic applications, such as adaptive cooling in spacecraft. In this paper, we introduce a new modeling approach for the fast design of tunable and reconfigurable metasurface structures using a convolutional deep learning network. The metasurface structure is modeled as a multilayer image tensor to model material properties as image maps. We avoid the dimensionality mismatch problem using the operating wavelength as an input to the network. As a case study, we model the response of a reconfigurable absorber that employs the phase transition of vanadium dioxide in the mid-infrared spectrum. The feed-forward model is used as a surrogate model and is subsequently employed within a pattern search optimization process to design a passive adaptive cooling surface leveraging the phase transition of vanadium dioxide. The results indicate that our model delivers an accurate prediction of the metasurface response using a relatively small training dataset. The proposed patterned vanadium dioxide metasurface achieved a 28% saving in coating thickness compared to the literature while maintaining reasonable emissivity contrast at 0.43. Moreover, our design approach was able to overcome the non-uniqueness problem by generating multiple patterns that satisfy the design objectives. The proposed adaptive metasurface can potentially serve as a core block for passive spacecraft cooling applications. We also believe that our design approach can be extended to cover a wider range of applications.
European Conference on Antennas and Propagation, May 13, 2015
A fast analytical technique based on T-matrix approach is formulated to solve the problem of dire... more A fast analytical technique based on T-matrix approach is formulated to solve the problem of direct electromagnetic scattering by an infinite circular cylinder buried in a dielectric half-space and illuminated by a normally incident transverse magnetic (TM) plane wave. The technique employs the signal-flow graph (SFG) model to include all multiple reflections that take place during the scattering process. The selection of the truncation order of the obtained T-matrix is also discussed. Index Terms-scattering, buried cylinder, signal-flow graph.
With the growing need for portable, compact, low-cost, and efficient biosensors, plasmonic materi... more With the growing need for portable, compact, low-cost, and efficient biosensors, plasmonic materials hold the promise to meet this need owing to their label-free sensitivity and deep light–matter interaction that can go beyond the diffraction limit of light. In this review, we shed light on the main physical aspects of plasmonic interactions, highlight mainstream and future plasmonic materials including their merits and shortcomings, describe the backbone substrates for building plasmonic biosensors, and conclude with a brief discussion of the factors affecting plasmonic biosensing mechanisms. To do so, we first observe that 2D materials such as graphene and transition metal dichalcogenides play a major role in enhancing the sensitivity of nanoparticle-based plasmonic biosensors. Then, we identify that titanium nitride is a promising candidate for integrated applications with performance comparable to that of gold. Our study highlights the emerging role of polymer substrates in the ...
Abstract Wearable real-time, non-invasive personalized health monitoring sensors and low-power el... more Abstract Wearable real-time, non-invasive personalized health monitoring sensors and low-power electronics critically necessitate alternative power supplies because batteries have proven insufficient due to their demerits of charging cycles and periodic degradation and replacement. Thermoelectric energy harnessing from human body heat via the Seebeck effect is an effective route to develop flexible thermoelectric generators that enables continuous power supply for the wearable devices. This review focuses on critically assessing the theory, the performance, fabrication, and future steps of thermoelectric generation using two-dimensional (2D) tellurene and aims to provide insights as to how to integrate 2D tellurene into practical, durable wearable generators. The literature survey shows that 2D Tellurene nanomaterial has exceptional thermoelectric properties including high thermoelectric figure of merit (ZT) as high as 2.9, and it possesses fabrication process-dependent thermoelectric properties and forms desirable electrical contacts. The flexible nature of 2D tellurene with high environmental stability and high strain resistance of up to 36% and Young's modulus of 27 GPa under bending conditions makes it an excellent material for especially wearable applications. Future research should focus on developing thermoelectric theory with computational methods for tellurene and its manufacturing methods to develop proof-of-concepts for thermoelectric devices. We hope this review would be a seminal work in the growing frontier of 2D tellurene wearable thermoelectrics for sensors for real-time monitoring of personalized health status.
Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected freq... more Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected frequency bands. It is thus necessary to decipher such behavior for many applications, including plasmonic energy harvesting, radiative cooling and thermal emitters. In this article, we propose a compact reconfigurable vanadium dioxide (VO2)-based metasurface absorber/emitter to demonstrate switching between dual and single-band absorption modes in the mid-infrared regime. The unit cell of the design employs a four-split gold circular ring resonator with gaps filled with VO2 patches. The phase-transition property of VO2 between semiconductor and metallic states is used to control the mode of operation of the metasurface absorber. When VO2 is in the semiconductor state, a dual-band absorption at 6 μm and 10.6 μm is obtained. When it attains a metallic state, the metasurface exhibits a single-band absorption at 8.25 μm. To achieve the maximum absorption efficiency in both single and dual-band ...
2021 International Applied Computational Electromagnetics Society Symposium (ACES), 2021
In this paper we introduce the design of a switchable metasurface waveplate using low-loss phase-... more In this paper we introduce the design of a switchable metasurface waveplate using low-loss phase-change material. The structure includes Antimony Triselenide grating deposited over a glass substrate, which can be easily fabricated using standard silicon fabrication technology. By employing the different birefringent effect induced, the grating operates as a quarter-wave plate when Antimony Triselenide is in the amorphous state, and operates as a half-wave plate when it is in the crystalline state. The grating parameters (thickness, height, and period) are optimized using global genetic algorithm. The design provides above 80% transmission for amorphous and crystalline states over the telecom band between 1.3 and 1.65 µm. The proposed design constitutes an important device for integrated silicon nanophotonics and flat optics applications.
Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected freq... more Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected frequency bands. It is thus necessary to decipher such behavior for many applications, including plasmonic energy harvesting, radiative cooling and thermal emitters. In this article, we propose a compact reconfigurable vanadium dioxide (VO2)-based metasurface absorber/emitter to demonstrate switching between dual and single-band absorption modes in the mid-infrared regime. The unit cell of the design employs a four-split gold circular ring resonator with gaps filled with VO2 patches. The phase-transition property of VO2 between semiconductor and metallic states is used to control the mode of operation of the metasurface absorber. When VO2 is in the semiconductor state, a dual-band absorption at 6 μm and 10.6 μm is obtained. When it attains a metallic state, the metasurface exhibits a single-band absorption at 8.25 μm. To achieve the maximum absorption efficiency in both single and dual-band ...
2021 International Applied Computational Electromagnetics Society Symposium (ACES), 2021
Reconfigurable metasurface constitutes an important block for future adaptive and smart nanophoto... more Reconfigurable metasurface constitutes an important block for future adaptive and smart nanophotonic applications. In this work we introduce a new modeling approach for the fast design of tunable and reconfigurable metasurface structures using convolutional deep learning network. The metasurface structure is modeled as a multilayer image tensor to model the material properties as image maps. The dimensionality mismatch problem is avoided by using the operating wavelength as an input to the network, so the model is used as single-point solver. As a case study, we model the response of a reconfigurable absorber employing phase transition of vanadium dioxide in the mid-infrared. The results show that our model provides accurate prediction of the metasurface response using small training dataset.
2021 International Applied Computational Electromagnetics Society Symposium (ACES), 2021
Reconfigurable metasurface constitutes an important block for future adaptive and smart nanophoto... more Reconfigurable metasurface constitutes an important block for future adaptive and smart nanophotonic applications. In this work we introduce a new modeling approach for the fast design of tunable and reconfigurable metasurface structures using convolutional deep learning network. The metasurface structure is modeled as a multilayer image tensor to model the material properties as image maps. The dimensionality mismatch problem is avoided by using the operating wavelength as an input to the network, so the model is used as single-point solver. As a case study, we model the response of a reconfigurable absorber employing phase transition of vanadium dioxide in the mid-infrared. The results show that our model provides accurate prediction of the metasurface response using small training dataset.
2021 International Applied Computational Electromagnetics Society Symposium (ACES), 2021
In this paper we introduce the design of a switchable metasurface waveplate using low-loss phase-... more In this paper we introduce the design of a switchable metasurface waveplate using low-loss phase-change material. The structure includes Antimony Triselenide grating deposited over a glass substrate, which can be easily fabricated using standard silicon fabrication technology. By employing the different birefringent effect induced, the grating operates as a quarter-wave plate when Antimony Triselenide is in the amorphous state, and operates as a half-wave plate when it is in the crystalline state. The grating parameters (thickness, height, and period) are optimized using global genetic algorithm. The design provides above 80% transmission for amorphous and crystalline states over the telecom band between 1.3 and 1.65 µm. The proposed design constitutes an important device for integrated silicon nanophotonics and flat optics applications.
Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected freq... more Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected frequency bands. It is thus necessary to decipher such behavior for many applications, including plasmonic energy harvesting, radiative cooling and thermal emitters. In this article, we propose a compact reconfigurable vanadium dioxide (VO2)-based metasurface absorber/emitter to demonstrate switching between dual and single-band absorption modes in the mid-infrared regime. The unit cell of the design employs a four-split gold circular ring resonator with gaps filled with VO2 patches. The phase-transition property of VO2 between semiconductor and metallic states is used to control the mode of operation of the metasurface absorber. When VO2 is in the semiconductor state, a dual-band absorption at 6 μm and 10.6 μm is obtained. When it attains a metallic state, the metasurface exhibits a single-band absorption at 8.25 μm. To achieve the maximum absorption efficiency in both single and dual-band ...
2015 9th European Conference on Antennas and Propagation (EuCAP), 2015
A fast analytical technique based on T-matrix approach is formulated to solve the problem of dire... more A fast analytical technique based on T-matrix approach is formulated to solve the problem of direct electromagnetic scattering by an infinite circular cylinder buried in a dielectric half-space and illuminated by a normally incident transverse magnetic (TM) plane wave. The technique employs the signal-flow graph (SFG) model to include all multiple reflections that take place during the scattering process. The selection of the truncation order of the obtained T-matrix is also discussed.
A plasmonic dual-band polarization-insensitive metasurface absorber is proposed. The design provi... more A plasmonic dual-band polarization-insensitive metasurface absorber is proposed. The design provides subwavelength and confined collection of the absorbed energy in the gaps of the structure. In this paper, we study the absorption behavior of the metasurface operating in a dual-band mode targeting the mid-infrared range suitable for energy harvesting applications such as thermophotovoltaics. The design is optimized using a global optimization technique.
The development of highly sensitive sensors and power generators that could function efficiently ... more The development of highly sensitive sensors and power generators that could function efficiently in extreme temperatures and contact with fire can be lifesaving but challenging to accomplish. Herein, we report, for the first time, a fire-retardant and self-extinguishing triboelectric nanogenerator (FRTENG), which can be utilized as a motion sensor and/or power generator in occupations such as oil drilling, firefighting or working in extreme temperature environments with flammable and combustible materials. The device takes advantage of the excellent thermal properties of carbon derived from resorcinol-formaldehyde aerogel whose electrical, mechanical and triboelectric properties have been improved via the introduction of Polyacrylonitrile nanofibers and graphene oxide nanosheets. This FRTENG is not flammable even after 90 s of trying, whereas conventional triboelectric materials were entirely consumed by fire under the same conditions. The developed device shows exceptional charge t...
A plasmonic switchable polarization-insensitive metasurface absorber is proposed. The design prov... more A plasmonic switchable polarization-insensitive metasurface absorber is proposed. The design provides two modes of operation by employing phase-change material in semiconductor and metallic phases. In this paper, we study the switchable absorption behavior of the metasurface operating in a dual-band and single-band modes targeting the mid-infrared range suitable for energy harvesting applications such as thermophotovoltaics. The design is optimized using a global optimization technique.
A reconfigurable metasurface constitutes an important block of future adaptive and smart nanophot... more A reconfigurable metasurface constitutes an important block of future adaptive and smart nanophotonic applications, such as adaptive cooling in spacecraft. In this paper, we introduce a new modeling approach for the fast design of tunable and reconfigurable metasurface structures using a convolutional deep learning network. The metasurface structure is modeled as a multilayer image tensor to model material properties as image maps. We avoid the dimensionality mismatch problem using the operating wavelength as an input to the network. As a case study, we model the response of a reconfigurable absorber that employs the phase transition of vanadium dioxide in the mid-infrared spectrum. The feed-forward model is used as a surrogate model and is subsequently employed within a pattern search optimization process to design a passive adaptive cooling surface leveraging the phase transition of vanadium dioxide. The results indicate that our model delivers an accurate prediction of the metasurface response using a relatively small training dataset. The proposed patterned vanadium dioxide metasurface achieved a 28% saving in coating thickness compared to the literature while maintaining reasonable emissivity contrast at 0.43. Moreover, our design approach was able to overcome the non-uniqueness problem by generating multiple patterns that satisfy the design objectives. The proposed adaptive metasurface can potentially serve as a core block for passive spacecraft cooling applications. We also believe that our design approach can be extended to cover a wider range of applications.
European Conference on Antennas and Propagation, May 13, 2015
A fast analytical technique based on T-matrix approach is formulated to solve the problem of dire... more A fast analytical technique based on T-matrix approach is formulated to solve the problem of direct electromagnetic scattering by an infinite circular cylinder buried in a dielectric half-space and illuminated by a normally incident transverse magnetic (TM) plane wave. The technique employs the signal-flow graph (SFG) model to include all multiple reflections that take place during the scattering process. The selection of the truncation order of the obtained T-matrix is also discussed. Index Terms-scattering, buried cylinder, signal-flow graph.
With the growing need for portable, compact, low-cost, and efficient biosensors, plasmonic materi... more With the growing need for portable, compact, low-cost, and efficient biosensors, plasmonic materials hold the promise to meet this need owing to their label-free sensitivity and deep light–matter interaction that can go beyond the diffraction limit of light. In this review, we shed light on the main physical aspects of plasmonic interactions, highlight mainstream and future plasmonic materials including their merits and shortcomings, describe the backbone substrates for building plasmonic biosensors, and conclude with a brief discussion of the factors affecting plasmonic biosensing mechanisms. To do so, we first observe that 2D materials such as graphene and transition metal dichalcogenides play a major role in enhancing the sensitivity of nanoparticle-based plasmonic biosensors. Then, we identify that titanium nitride is a promising candidate for integrated applications with performance comparable to that of gold. Our study highlights the emerging role of polymer substrates in the ...
Abstract Wearable real-time, non-invasive personalized health monitoring sensors and low-power el... more Abstract Wearable real-time, non-invasive personalized health monitoring sensors and low-power electronics critically necessitate alternative power supplies because batteries have proven insufficient due to their demerits of charging cycles and periodic degradation and replacement. Thermoelectric energy harnessing from human body heat via the Seebeck effect is an effective route to develop flexible thermoelectric generators that enables continuous power supply for the wearable devices. This review focuses on critically assessing the theory, the performance, fabrication, and future steps of thermoelectric generation using two-dimensional (2D) tellurene and aims to provide insights as to how to integrate 2D tellurene into practical, durable wearable generators. The literature survey shows that 2D Tellurene nanomaterial has exceptional thermoelectric properties including high thermoelectric figure of merit (ZT) as high as 2.9, and it possesses fabrication process-dependent thermoelectric properties and forms desirable electrical contacts. The flexible nature of 2D tellurene with high environmental stability and high strain resistance of up to 36% and Young's modulus of 27 GPa under bending conditions makes it an excellent material for especially wearable applications. Future research should focus on developing thermoelectric theory with computational methods for tellurene and its manufacturing methods to develop proof-of-concepts for thermoelectric devices. We hope this review would be a seminal work in the growing frontier of 2D tellurene wearable thermoelectrics for sensors for real-time monitoring of personalized health status.
Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected freq... more Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected frequency bands. It is thus necessary to decipher such behavior for many applications, including plasmonic energy harvesting, radiative cooling and thermal emitters. In this article, we propose a compact reconfigurable vanadium dioxide (VO2)-based metasurface absorber/emitter to demonstrate switching between dual and single-band absorption modes in the mid-infrared regime. The unit cell of the design employs a four-split gold circular ring resonator with gaps filled with VO2 patches. The phase-transition property of VO2 between semiconductor and metallic states is used to control the mode of operation of the metasurface absorber. When VO2 is in the semiconductor state, a dual-band absorption at 6 μm and 10.6 μm is obtained. When it attains a metallic state, the metasurface exhibits a single-band absorption at 8.25 μm. To achieve the maximum absorption efficiency in both single and dual-band ...
2021 International Applied Computational Electromagnetics Society Symposium (ACES), 2021
In this paper we introduce the design of a switchable metasurface waveplate using low-loss phase-... more In this paper we introduce the design of a switchable metasurface waveplate using low-loss phase-change material. The structure includes Antimony Triselenide grating deposited over a glass substrate, which can be easily fabricated using standard silicon fabrication technology. By employing the different birefringent effect induced, the grating operates as a quarter-wave plate when Antimony Triselenide is in the amorphous state, and operates as a half-wave plate when it is in the crystalline state. The grating parameters (thickness, height, and period) are optimized using global genetic algorithm. The design provides above 80% transmission for amorphous and crystalline states over the telecom band between 1.3 and 1.65 µm. The proposed design constitutes an important device for integrated silicon nanophotonics and flat optics applications.
Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected freq... more Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected frequency bands. It is thus necessary to decipher such behavior for many applications, including plasmonic energy harvesting, radiative cooling and thermal emitters. In this article, we propose a compact reconfigurable vanadium dioxide (VO2)-based metasurface absorber/emitter to demonstrate switching between dual and single-band absorption modes in the mid-infrared regime. The unit cell of the design employs a four-split gold circular ring resonator with gaps filled with VO2 patches. The phase-transition property of VO2 between semiconductor and metallic states is used to control the mode of operation of the metasurface absorber. When VO2 is in the semiconductor state, a dual-band absorption at 6 μm and 10.6 μm is obtained. When it attains a metallic state, the metasurface exhibits a single-band absorption at 8.25 μm. To achieve the maximum absorption efficiency in both single and dual-band ...
2021 International Applied Computational Electromagnetics Society Symposium (ACES), 2021
Reconfigurable metasurface constitutes an important block for future adaptive and smart nanophoto... more Reconfigurable metasurface constitutes an important block for future adaptive and smart nanophotonic applications. In this work we introduce a new modeling approach for the fast design of tunable and reconfigurable metasurface structures using convolutional deep learning network. The metasurface structure is modeled as a multilayer image tensor to model the material properties as image maps. The dimensionality mismatch problem is avoided by using the operating wavelength as an input to the network, so the model is used as single-point solver. As a case study, we model the response of a reconfigurable absorber employing phase transition of vanadium dioxide in the mid-infrared. The results show that our model provides accurate prediction of the metasurface response using small training dataset.
2021 International Applied Computational Electromagnetics Society Symposium (ACES), 2021
Reconfigurable metasurface constitutes an important block for future adaptive and smart nanophoto... more Reconfigurable metasurface constitutes an important block for future adaptive and smart nanophotonic applications. In this work we introduce a new modeling approach for the fast design of tunable and reconfigurable metasurface structures using convolutional deep learning network. The metasurface structure is modeled as a multilayer image tensor to model the material properties as image maps. The dimensionality mismatch problem is avoided by using the operating wavelength as an input to the network, so the model is used as single-point solver. As a case study, we model the response of a reconfigurable absorber employing phase transition of vanadium dioxide in the mid-infrared. The results show that our model provides accurate prediction of the metasurface response using small training dataset.
2021 International Applied Computational Electromagnetics Society Symposium (ACES), 2021
In this paper we introduce the design of a switchable metasurface waveplate using low-loss phase-... more In this paper we introduce the design of a switchable metasurface waveplate using low-loss phase-change material. The structure includes Antimony Triselenide grating deposited over a glass substrate, which can be easily fabricated using standard silicon fabrication technology. By employing the different birefringent effect induced, the grating operates as a quarter-wave plate when Antimony Triselenide is in the amorphous state, and operates as a half-wave plate when it is in the crystalline state. The grating parameters (thickness, height, and period) are optimized using global genetic algorithm. The design provides above 80% transmission for amorphous and crystalline states over the telecom band between 1.3 and 1.65 µm. The proposed design constitutes an important device for integrated silicon nanophotonics and flat optics applications.
Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected freq... more Reconfigurable metasurface absorbers enable collecting or emitting radiation within selected frequency bands. It is thus necessary to decipher such behavior for many applications, including plasmonic energy harvesting, radiative cooling and thermal emitters. In this article, we propose a compact reconfigurable vanadium dioxide (VO2)-based metasurface absorber/emitter to demonstrate switching between dual and single-band absorption modes in the mid-infrared regime. The unit cell of the design employs a four-split gold circular ring resonator with gaps filled with VO2 patches. The phase-transition property of VO2 between semiconductor and metallic states is used to control the mode of operation of the metasurface absorber. When VO2 is in the semiconductor state, a dual-band absorption at 6 μm and 10.6 μm is obtained. When it attains a metallic state, the metasurface exhibits a single-band absorption at 8.25 μm. To achieve the maximum absorption efficiency in both single and dual-band ...
2015 9th European Conference on Antennas and Propagation (EuCAP), 2015
A fast analytical technique based on T-matrix approach is formulated to solve the problem of dire... more A fast analytical technique based on T-matrix approach is formulated to solve the problem of direct electromagnetic scattering by an infinite circular cylinder buried in a dielectric half-space and illuminated by a normally incident transverse magnetic (TM) plane wave. The technique employs the signal-flow graph (SFG) model to include all multiple reflections that take place during the scattering process. The selection of the truncation order of the obtained T-matrix is also discussed.
A plasmonic dual-band polarization-insensitive metasurface absorber is proposed. The design provi... more A plasmonic dual-band polarization-insensitive metasurface absorber is proposed. The design provides subwavelength and confined collection of the absorbed energy in the gaps of the structure. In this paper, we study the absorption behavior of the metasurface operating in a dual-band mode targeting the mid-infrared range suitable for energy harvesting applications such as thermophotovoltaics. The design is optimized using a global optimization technique.
The development of highly sensitive sensors and power generators that could function efficiently ... more The development of highly sensitive sensors and power generators that could function efficiently in extreme temperatures and contact with fire can be lifesaving but challenging to accomplish. Herein, we report, for the first time, a fire-retardant and self-extinguishing triboelectric nanogenerator (FRTENG), which can be utilized as a motion sensor and/or power generator in occupations such as oil drilling, firefighting or working in extreme temperature environments with flammable and combustible materials. The device takes advantage of the excellent thermal properties of carbon derived from resorcinol-formaldehyde aerogel whose electrical, mechanical and triboelectric properties have been improved via the introduction of Polyacrylonitrile nanofibers and graphene oxide nanosheets. This FRTENG is not flammable even after 90 s of trying, whereas conventional triboelectric materials were entirely consumed by fire under the same conditions. The developed device shows exceptional charge t...
A plasmonic switchable polarization-insensitive metasurface absorber is proposed. The design prov... more A plasmonic switchable polarization-insensitive metasurface absorber is proposed. The design provides two modes of operation by employing phase-change material in semiconductor and metallic phases. In this paper, we study the switchable absorption behavior of the metasurface operating in a dual-band and single-band modes targeting the mid-infrared range suitable for energy harvesting applications such as thermophotovoltaics. The design is optimized using a global optimization technique.
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Papers by Ayman Negm