Ofer Doron - Academia.edu (original) (raw)

Papers by Ofer Doron

Research paper thumbnail of Direct and cascaded collective third-harmonic generation in metasurfaces

Journal of The Optical Society of America B-optical Physics, Jun 14, 2019

We use collective interactions in plasmonic metasurfaces to manipulate the interplay between dire... more We use collective interactions in plasmonic metasurfaces to manipulate the interplay between direct and cascaded third-harmonic generation. We implement a simple case where in contrast to the direct contribution, which is mainly enhanced by the local plasmonic resonances, the cascaded contribution enhancement may be manipulated using the metasurface's geometry, in addition to the single nanoparticle's electrical response, by enabling the proper nonlocal interactions at the second-harmonic frequency. In addition, an anomalous phase relation of the single nanoparticle's linear polarizability at the second-harmonic region affects the relative phase between the direct and cascaded contributions, which results in a Fano-like asymmetrical line shape of the third-harmonic generation. We demonstrate that this can be used to enhance or contrarily completely eliminate third-harmonic generation from metasurfaces over a very narrow bandwidth. Such a unique fundamental observation of the interplay between direct and cascaded third-harmonic generation in periodic resonant systems may find new applications in sensing and to control nonlinear optical phenomena.

Research paper thumbnail of Composite bottlebrush mechanics: α-internexin fine-tunes neurofilament network properties

Soft Matter, 2015

Neuronal cytoplasmic intermediate filaments are principal structural and mechanical elements of t... more Neuronal cytoplasmic intermediate filaments are principal structural and mechanical elements of the axon. Their expression during embryonic development follows a differential pattern, while their unregulated expression is correlated to neurodegenerative diseases. The largest neurofilament proteins of medium (NF-M) and high molecular weight (NF-H) were shown to modulate the axonal architecture and inter-filament spacing. However, the individual roles of the remaining a-internexin (a-Inx) and neurofilament of low molecular weight (NF-L) proteins in composite filaments remained elusive. In contrast to previous predictions, we show that when co-assembled with NF-M, the shortest and the least charged a-Inx protein increases inter-filament spacing. These findings suggest a novel structural explanation for the expression pattern of neurofilament proteins during embryonic development. We explain our results by an analysis of ionic crosslinks between the disordered polyampholytic C-terminal tails and suggest that a collapsed conformation of the a-Inx tail domain interferes with tail cross-linking near the filament backbone.

Research paper thumbnail of Phosphorylation-Induced Mechanical Regulation of Intrinsically Disordered Neurofilament Proteins

Biophysical Journal, Mar 1, 2017

The biological function of protein assemblies was conventionally equated with a unique three-dime... more The biological function of protein assemblies was conventionally equated with a unique three-dimensional protein structure and protein-specific interactions. However, in the past 20 years it was found that some assemblies contain long flexible regions that adopt multiple structural conformations. These include neurofilament (NF) proteins that constitute the stressresponsive supportive network of neurons. Herein, we show that NF networks macroscopic properties are tuned by enzymatic regulation of the charge found on the flexible protein regions. The results reveal an enzymatic (phosphorylation) regulation of macroscopic properties such as orientation, stress-response and expansion in flexible protein assemblies. Together with a model explaining the attractive electrostatic interactions induced by enzymatically added charges, we demonstrate that phosphorylation-regulation is far richer and versatile than previously considered.

Research paper thumbnail of Rayleigh anomaly induced phase gradients in finite nanoparticle chains

Nanoscale

We find that the in-plane diffraction at the Rayleigh anomaly condition can induce anomalous phas... more We find that the in-plane diffraction at the Rayleigh anomaly condition can induce anomalous phase gradients in finite-nanoparticle chains. In turn, these gradients lead to angular anomalies of the diffraction.

Research paper thumbnail of Virtual lattice resonance of a single nanoresonator in a metal nanoslit

Physical Review A

We study the transmission through a subwavelength metallic slit loaded with a single nanoresonato... more We study the transmission through a subwavelength metallic slit loaded with a single nanoresonator. To gain physical insight into the problem a theoretical model combining the dipole approximation and image theory is developed. The model shows that the coupling between the single nanoresonator and the slit's cavity modes serves as a localized analog to an infinite nanoresonator array. This virtual array supports a surface image-lattice resonance due to the coherent self-scattering of the single nanoresonator. Thereby, it may lead to the ability to mimic many recently reported intriguing physical phenomena of real surface-lattice resonances in nanoresonator arrays, by a single-subwavelength system. We specifically show that it leads to enhanced light-matter interaction, and to the appearance of an extraordinary transmission window. The theoretical results are in good agreement with full-wave numerical simulations.

Research paper thumbnail of Virtual lattice resonance of a single nanoresonator in a metal nanoslit

Physical review, Mar 27, 2023

We study the transmission through a subwavelength metallic slit loaded with a single nanoresonato... more We study the transmission through a subwavelength metallic slit loaded with a single nanoresonator. To gain physical insight into the problem a theoretical model combining the dipole approximation and image theory is developed. The model shows that the coupling between the single nanoresonator and the slit's cavity modes serves as a localized analog to an infinite nanoresonator array. This virtual array supports a surface image-lattice resonance due to the coherent self-scattering of the single nanoresonator. Thereby, it may lead to the ability to mimic many recently reported intriguing physical phenomena of real surface-lattice resonances in nanoresonator arrays, by a single-subwavelength system. We specifically show that it leads to enhanced light-matter interaction, and to the appearance of an extraordinary transmission window. The theoretical results are in good agreement with full-wave numerical simulations.

Research paper thumbnail of Intermediate-filaments: from disordered building blocks to well-ordered cells

Bulletin of the American Physical Society, 2016

Research paper thumbnail of Phosphorylation-Induced Mechanical Regulation of Intrinsically Disordered Neurofilament Proteins

Biophysical journal, Jan 14, 2017

The biological function of protein assemblies has been conventionally equated with a unique three... more The biological function of protein assemblies has been conventionally equated with a unique three-dimensional protein structure and protein-specific interactions. However, in the past 20 years it has been found that some assemblies contain long flexible regions that adopt multiple structural conformations. These include neurofilament proteins that constitute the stress-responsive supportive network of neurons. Herein, we show that the macroscopic properties of neurofilament networks are tuned by enzymatic regulation of the charge found on the flexible protein regions. The results reveal an enzymatic (phosphorylation) regulation of macroscopic properties such as orientation, stress response, and expansion in flexible protein assemblies. Using a model that explains the attractive electrostatic interactions induced by enzymatically added charges, we demonstrate that phosphorylation regulation is far richer and versatile than previously considered.

Research paper thumbnail of Alpha - Soft Matter 2015 - Supp

Research paper thumbnail of Composite bottlebrush mechanics: α-internexin fine-tunes neurofilament network properties

Soft Matter, 2015

We measure the mechano-elastic properties of composite bottlebrush nematic hydrogels consisting o... more We measure the mechano-elastic properties of composite bottlebrush nematic hydrogels consisting of proteins originated from the central nervous system. We show that intra-brush interactions fine-tunes the network structure which may serve as a structural-regulatory mechanism in neuronal early developmental stages.

Research paper thumbnail of Direct and cascaded collective third-harmonic generation in metasurfaces

Journal of the Optical Society of America B, 2019

We use collective interactions in plasmonic metasurfaces to manipulate the interplay between dire... more We use collective interactions in plasmonic metasurfaces to manipulate the interplay between direct and cascaded third-harmonic generation. We implement a simple case where in contrast to the direct contribution, which is mainly enhanced by the local plasmonic resonances, the cascaded contribution enhancement may be manipulated using the metasurface's geometry, in addition to the single nanoparticle's electrical response, by enabling the proper nonlocal interactions at the second-harmonic frequency. In addition, an anomalous phase relation of the single nanoparticle's linear polarizability at the second-harmonic region affects the relative phase between the direct and cascaded contributions, which results in a Fano-like asymmetrical line shape of the third-harmonic generation. We demonstrate that this can be used to enhance or contrarily completely eliminate third-harmonic generation from metasurfaces over a very narrow bandwidth. Such a unique fundamental observation of the interplay between direct and cascaded third-harmonic generation in periodic resonant systems may find new applications in sensing and to control nonlinear optical phenomena.

Research paper thumbnail of Direct and cascaded collective third-harmonic generation in metasurfaces

Journal of The Optical Society of America B-optical Physics, Jun 14, 2019

We use collective interactions in plasmonic metasurfaces to manipulate the interplay between dire... more We use collective interactions in plasmonic metasurfaces to manipulate the interplay between direct and cascaded third-harmonic generation. We implement a simple case where in contrast to the direct contribution, which is mainly enhanced by the local plasmonic resonances, the cascaded contribution enhancement may be manipulated using the metasurface's geometry, in addition to the single nanoparticle's electrical response, by enabling the proper nonlocal interactions at the second-harmonic frequency. In addition, an anomalous phase relation of the single nanoparticle's linear polarizability at the second-harmonic region affects the relative phase between the direct and cascaded contributions, which results in a Fano-like asymmetrical line shape of the third-harmonic generation. We demonstrate that this can be used to enhance or contrarily completely eliminate third-harmonic generation from metasurfaces over a very narrow bandwidth. Such a unique fundamental observation of the interplay between direct and cascaded third-harmonic generation in periodic resonant systems may find new applications in sensing and to control nonlinear optical phenomena.

Research paper thumbnail of Composite bottlebrush mechanics: α-internexin fine-tunes neurofilament network properties

Soft Matter, 2015

Neuronal cytoplasmic intermediate filaments are principal structural and mechanical elements of t... more Neuronal cytoplasmic intermediate filaments are principal structural and mechanical elements of the axon. Their expression during embryonic development follows a differential pattern, while their unregulated expression is correlated to neurodegenerative diseases. The largest neurofilament proteins of medium (NF-M) and high molecular weight (NF-H) were shown to modulate the axonal architecture and inter-filament spacing. However, the individual roles of the remaining a-internexin (a-Inx) and neurofilament of low molecular weight (NF-L) proteins in composite filaments remained elusive. In contrast to previous predictions, we show that when co-assembled with NF-M, the shortest and the least charged a-Inx protein increases inter-filament spacing. These findings suggest a novel structural explanation for the expression pattern of neurofilament proteins during embryonic development. We explain our results by an analysis of ionic crosslinks between the disordered polyampholytic C-terminal tails and suggest that a collapsed conformation of the a-Inx tail domain interferes with tail cross-linking near the filament backbone.

Research paper thumbnail of Phosphorylation-Induced Mechanical Regulation of Intrinsically Disordered Neurofilament Proteins

Biophysical Journal, Mar 1, 2017

The biological function of protein assemblies was conventionally equated with a unique three-dime... more The biological function of protein assemblies was conventionally equated with a unique three-dimensional protein structure and protein-specific interactions. However, in the past 20 years it was found that some assemblies contain long flexible regions that adopt multiple structural conformations. These include neurofilament (NF) proteins that constitute the stressresponsive supportive network of neurons. Herein, we show that NF networks macroscopic properties are tuned by enzymatic regulation of the charge found on the flexible protein regions. The results reveal an enzymatic (phosphorylation) regulation of macroscopic properties such as orientation, stress-response and expansion in flexible protein assemblies. Together with a model explaining the attractive electrostatic interactions induced by enzymatically added charges, we demonstrate that phosphorylation-regulation is far richer and versatile than previously considered.

Research paper thumbnail of Rayleigh anomaly induced phase gradients in finite nanoparticle chains

Nanoscale

We find that the in-plane diffraction at the Rayleigh anomaly condition can induce anomalous phas... more We find that the in-plane diffraction at the Rayleigh anomaly condition can induce anomalous phase gradients in finite-nanoparticle chains. In turn, these gradients lead to angular anomalies of the diffraction.

Research paper thumbnail of Virtual lattice resonance of a single nanoresonator in a metal nanoslit

Physical Review A

We study the transmission through a subwavelength metallic slit loaded with a single nanoresonato... more We study the transmission through a subwavelength metallic slit loaded with a single nanoresonator. To gain physical insight into the problem a theoretical model combining the dipole approximation and image theory is developed. The model shows that the coupling between the single nanoresonator and the slit's cavity modes serves as a localized analog to an infinite nanoresonator array. This virtual array supports a surface image-lattice resonance due to the coherent self-scattering of the single nanoresonator. Thereby, it may lead to the ability to mimic many recently reported intriguing physical phenomena of real surface-lattice resonances in nanoresonator arrays, by a single-subwavelength system. We specifically show that it leads to enhanced light-matter interaction, and to the appearance of an extraordinary transmission window. The theoretical results are in good agreement with full-wave numerical simulations.

Research paper thumbnail of Virtual lattice resonance of a single nanoresonator in a metal nanoslit

Physical review, Mar 27, 2023

We study the transmission through a subwavelength metallic slit loaded with a single nanoresonato... more We study the transmission through a subwavelength metallic slit loaded with a single nanoresonator. To gain physical insight into the problem a theoretical model combining the dipole approximation and image theory is developed. The model shows that the coupling between the single nanoresonator and the slit's cavity modes serves as a localized analog to an infinite nanoresonator array. This virtual array supports a surface image-lattice resonance due to the coherent self-scattering of the single nanoresonator. Thereby, it may lead to the ability to mimic many recently reported intriguing physical phenomena of real surface-lattice resonances in nanoresonator arrays, by a single-subwavelength system. We specifically show that it leads to enhanced light-matter interaction, and to the appearance of an extraordinary transmission window. The theoretical results are in good agreement with full-wave numerical simulations.

Research paper thumbnail of Intermediate-filaments: from disordered building blocks to well-ordered cells

Bulletin of the American Physical Society, 2016

Research paper thumbnail of Phosphorylation-Induced Mechanical Regulation of Intrinsically Disordered Neurofilament Proteins

Biophysical journal, Jan 14, 2017

The biological function of protein assemblies has been conventionally equated with a unique three... more The biological function of protein assemblies has been conventionally equated with a unique three-dimensional protein structure and protein-specific interactions. However, in the past 20 years it has been found that some assemblies contain long flexible regions that adopt multiple structural conformations. These include neurofilament proteins that constitute the stress-responsive supportive network of neurons. Herein, we show that the macroscopic properties of neurofilament networks are tuned by enzymatic regulation of the charge found on the flexible protein regions. The results reveal an enzymatic (phosphorylation) regulation of macroscopic properties such as orientation, stress response, and expansion in flexible protein assemblies. Using a model that explains the attractive electrostatic interactions induced by enzymatically added charges, we demonstrate that phosphorylation regulation is far richer and versatile than previously considered.

Research paper thumbnail of Alpha - Soft Matter 2015 - Supp

Research paper thumbnail of Composite bottlebrush mechanics: α-internexin fine-tunes neurofilament network properties

Soft Matter, 2015

We measure the mechano-elastic properties of composite bottlebrush nematic hydrogels consisting o... more We measure the mechano-elastic properties of composite bottlebrush nematic hydrogels consisting of proteins originated from the central nervous system. We show that intra-brush interactions fine-tunes the network structure which may serve as a structural-regulatory mechanism in neuronal early developmental stages.

Research paper thumbnail of Direct and cascaded collective third-harmonic generation in metasurfaces

Journal of the Optical Society of America B, 2019

We use collective interactions in plasmonic metasurfaces to manipulate the interplay between dire... more We use collective interactions in plasmonic metasurfaces to manipulate the interplay between direct and cascaded third-harmonic generation. We implement a simple case where in contrast to the direct contribution, which is mainly enhanced by the local plasmonic resonances, the cascaded contribution enhancement may be manipulated using the metasurface's geometry, in addition to the single nanoparticle's electrical response, by enabling the proper nonlocal interactions at the second-harmonic frequency. In addition, an anomalous phase relation of the single nanoparticle's linear polarizability at the second-harmonic region affects the relative phase between the direct and cascaded contributions, which results in a Fano-like asymmetrical line shape of the third-harmonic generation. We demonstrate that this can be used to enhance or contrarily completely eliminate third-harmonic generation from metasurfaces over a very narrow bandwidth. Such a unique fundamental observation of the interplay between direct and cascaded third-harmonic generation in periodic resonant systems may find new applications in sensing and to control nonlinear optical phenomena.