The control of electromagnetic radiation in transformation optical metamaterials brings the development of vast variety of optical devices. Of a particular importance is the possibility to control the propagation of light with light. In this work, we use a structured planar cavity to enhance the thermo-optic effect in a transformation optical waveguide. In the process, a control laser produces apparent inhomogeneous refractive index change inside the waveguides. The trajectory of a second probe laser beam is then continuously tuned in the experiment. The experimental results agree well with the developed theory. The reported method can provide a new approach toward development of transformation optical devices where active all-optical control of the impinging light can be achieved.
{"title":"Active control of light beam in transformation optics (Presentation Recording)","authors":"Hui Liu","doi":"10.1117/12.2186132","DOIUrl":"https://doi.org/10.1117/12.2186132","url":null,"abstract":"The control of electromagnetic radiation in transformation optical metamaterials brings the development of vast variety of optical devices. Of a particular importance is the possibility to control the propagation of light with light. In this work, we use a structured planar cavity to enhance the thermo-optic effect in a transformation optical waveguide. In the process, a control laser produces apparent inhomogeneous refractive index change inside the waveguides. The trajectory of a second probe laser beam is then continuously tuned in the experiment. The experimental results agree well with the developed theory. The reported method can provide a new approach toward development of transformation optical devices where active all-optical control of the impinging light can be achieved.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121745340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. B. Barbosa Neira, Silvia Peruh, Giuseppe Marini, M. Nasir, A. Krasavin, N. Olivier, W. Dickson, G. Wurtz, A. Zayats
We will present experimental studies and numerical modeling of nonlinear optical processes in plasmonic metamaterials based on assemblies of metallic nanorods and other complex geometries. Second- and third-order nonlinear optical response originating from a plasmonic component of the metamaterial will be discussed. Such plasmonic metamaterials can be used for engineering enhanced nonlinear optical properties with the required spectral and temporal response. We will also discuss a novel concept of an on-chip ultrafast all-optical modulator based on a hyperbolic metamaterial integrated in a silicon waveguide.
{"title":"Nonlinearities in hyperbolic plasmonic metamaterials (Presentation Recording)","authors":"A. B. Barbosa Neira, Silvia Peruh, Giuseppe Marini, M. Nasir, A. Krasavin, N. Olivier, W. Dickson, G. Wurtz, A. Zayats","doi":"10.1117/12.2190133","DOIUrl":"https://doi.org/10.1117/12.2190133","url":null,"abstract":"We will present experimental studies and numerical modeling of nonlinear optical processes in plasmonic metamaterials based on assemblies of metallic nanorods and other complex geometries. Second- and third-order nonlinear optical response originating from a plasmonic component of the metamaterial will be discussed. Such plasmonic metamaterials can be used for engineering enhanced nonlinear optical properties with the required spectral and temporal response. We will also discuss a novel concept of an on-chip ultrafast all-optical modulator based on a hyperbolic metamaterial integrated in a silicon waveguide.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122088514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Shalaginov, S. Bogdanov, Jing Liu, A. Lagutchev, A. Kildishev, D. Peroulis, J. Irudayaraj, A. Boltasseva, V. Shalaev
Diamond based nitrogen-vacancy (NV) centers are promising solid state defects for applications in quantum information technologies. On the one hand, there is a growing interest in enhancing their single-photon emission by coupling them to plasmonic structures. On the other hand, the dependence of emission intensity on the electron spin state enables room temperature quantum information readout. We study the fluorescence contrast resulting from the spin resonance in the conditions of an increased photonic density of states. Fluorescence observations from NV center ensembles in diamond nanocrystals coupled to structures supporting plasmonic modes experimentally confirm the analytical results.
{"title":"Effect of photonic density of states on spin-flip induced fluorescence contrast in diamond nitrogen-vacancy center ensembles (Presentation Recording)","authors":"M. Shalaginov, S. Bogdanov, Jing Liu, A. Lagutchev, A. Kildishev, D. Peroulis, J. Irudayaraj, A. Boltasseva, V. Shalaev","doi":"10.1117/12.2187485","DOIUrl":"https://doi.org/10.1117/12.2187485","url":null,"abstract":"Diamond based nitrogen-vacancy (NV) centers are promising solid state defects for applications in quantum information technologies. On the one hand, there is a growing interest in enhancing their single-photon emission by coupling them to plasmonic structures. On the other hand, the dependence of emission intensity on the electron spin state enables room temperature quantum information readout. We study the fluorescence contrast resulting from the spin resonance in the conditions of an increased photonic density of states. Fluorescence observations from NV center ensembles in diamond nanocrystals coupled to structures supporting plasmonic modes experimentally confirm the analytical results.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"243 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124672680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Pelton, C. She, Igor Fedin, Dmitriy S. Dolzhnikov, S. Ithurria, Erfan Baghani, S. O’Leary, A. Demortière, R. Schaller, D. Talapin
Quantum wells (QWs) are thin semiconductor layers than confine electrons and holes in one dimension. They are widely used for optoelectronic devices, particularly semiconductor lasers, but have so far been produced using expensive epitaxial crystal-growth techniques. This has motivated research into the use of colloidal semiconductor nanocrystals, which can be synthesized chemically at low cost, and can be processed in the solution phase. However, initial demonstrations of optical gain from colloidal nanocrystals involved high thresholds. Recently, colloidal synthesis methods have been developed for the production of thin, atomically flat semiconductor nanocrystals, known as nanoplatelets (NPLs). We investigated relaxation of high-energy carriers in colloidal CdSe NPLs, and found that the relaxation is characteristic of a QW system. Carrier cooling and relaxation on time scales from picoseconds to hundreds of picoseconds are dominated by Auger-type exciton-exciton interactions. The picosecond-scale cooling of hot carriers is much faster than the exciton recombination rate, as required for use of these NPLs as optical gain and lasing materials. We therefore investigated amplified spontaneous emission using close-packed films of NPLs. We observed thresholds that were more than 4 times lower than the best reported value for colloidal nanocrystals. Moreover, gain in these films is 4 times higher than gain reported for other colloidal nanocrystals, and saturates at pump fluences more than two orders of magnitude above the ASE threshold. We attribute this exceptional performance to large optical cross-sections, relatively slow Auger recombination rates, and narrow ensemble emission linewidths.
{"title":"Semiconductor nanoplatelets: a new colloidal system for low-threshold high-gain stimulated emission (Presentation Recording)","authors":"M. Pelton, C. She, Igor Fedin, Dmitriy S. Dolzhnikov, S. Ithurria, Erfan Baghani, S. O’Leary, A. Demortière, R. Schaller, D. Talapin","doi":"10.1117/12.2186667","DOIUrl":"https://doi.org/10.1117/12.2186667","url":null,"abstract":"Quantum wells (QWs) are thin semiconductor layers than confine electrons and holes in one dimension. They are widely used for optoelectronic devices, particularly semiconductor lasers, but have so far been produced using expensive epitaxial crystal-growth techniques. This has motivated research into the use of colloidal semiconductor nanocrystals, which can be synthesized chemically at low cost, and can be processed in the solution phase. However, initial demonstrations of optical gain from colloidal nanocrystals involved high thresholds. Recently, colloidal synthesis methods have been developed for the production of thin, atomically flat semiconductor nanocrystals, known as nanoplatelets (NPLs). We investigated relaxation of high-energy carriers in colloidal CdSe NPLs, and found that the relaxation is characteristic of a QW system. Carrier cooling and relaxation on time scales from picoseconds to hundreds of picoseconds are dominated by Auger-type exciton-exciton interactions. The picosecond-scale cooling of hot carriers is much faster than the exciton recombination rate, as required for use of these NPLs as optical gain and lasing materials. We therefore investigated amplified spontaneous emission using close-packed films of NPLs. We observed thresholds that were more than 4 times lower than the best reported value for colloidal nanocrystals. Moreover, gain in these films is 4 times higher than gain reported for other colloidal nanocrystals, and saturates at pump fluences more than two orders of magnitude above the ASE threshold. We attribute this exceptional performance to large optical cross-sections, relatively slow Auger recombination rates, and narrow ensemble emission linewidths.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"9545 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129971028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Here, we show how the surface free energy of the electron-collecting oxide contact has a very pronounced effect on the nucleation free energy of solution-processed organolead halide perovskite thin films, which influences the crystal size/orientation, band-edge energies, conductivity and, ultimately, the performance of solar cell devices. While a great deal of the research community’s attention has been focused on the perovskite deposition methodology (e.g., starting precursors, annealing conditions, etc.), we demonstrate how the surface free energy of the oxide contact itself can be modified to control morphology and optoelectronic properties of the resulting hybrid perovskite thin films. The surface free energy of high-quality oxide contacts deposited by chemical vapor deposition (CVD) and atomic layer deposition (ALD) is modified by functionalization with a variety of self-assembled monolayers. We explore a number of deposition methodologies (e.g., a variety of single step and sequential step approaches) and their effect on the morphological and electronic properties of the resulting perovskite thin films deposited on these modified oxide contacts. Standard atomic force microscopy (AFM) and its conductive analog (cAFM) show how the oxide surface free energy ultimately affects the nanoscale morphology and charge transport characteristics of these semiconductor films. Photoelectron spectroscopy is used to elucidate the chemical composition (e.g., X-ray photoelectron spectroscopy - XPS), band edge energies (e.g., ultraviolet photoelectron spectroscopy - UPS), and the presence of gap states above the valence band (high sensitivity UPS measurements near the Fermi energy) of the hybrid perovskite materials as a function of the oxide surface free energy.
{"title":"Effect of substrate surface free energy on the optoelectronic and morphological properties of organolead halide perovskite solar cell materials (Presentation Recording)","authors":"R. C. Shallcross, James G. Stanfill, N. Armstrong","doi":"10.1117/12.2188843","DOIUrl":"https://doi.org/10.1117/12.2188843","url":null,"abstract":"Here, we show how the surface free energy of the electron-collecting oxide contact has a very pronounced effect on the nucleation free energy of solution-processed organolead halide perovskite thin films, which influences the crystal size/orientation, band-edge energies, conductivity and, ultimately, the performance of solar cell devices. While a great deal of the research community’s attention has been focused on the perovskite deposition methodology (e.g., starting precursors, annealing conditions, etc.), we demonstrate how the surface free energy of the oxide contact itself can be modified to control morphology and optoelectronic properties of the resulting hybrid perovskite thin films. The surface free energy of high-quality oxide contacts deposited by chemical vapor deposition (CVD) and atomic layer deposition (ALD) is modified by functionalization with a variety of self-assembled monolayers. We explore a number of deposition methodologies (e.g., a variety of single step and sequential step approaches) and their effect on the morphological and electronic properties of the resulting perovskite thin films deposited on these modified oxide contacts. Standard atomic force microscopy (AFM) and its conductive analog (cAFM) show how the oxide surface free energy ultimately affects the nanoscale morphology and charge transport characteristics of these semiconductor films. Photoelectron spectroscopy is used to elucidate the chemical composition (e.g., X-ray photoelectron spectroscopy - XPS), band edge energies (e.g., ultraviolet photoelectron spectroscopy - UPS), and the presence of gap states above the valence band (high sensitivity UPS measurements near the Fermi energy) of the hybrid perovskite materials as a function of the oxide surface free energy.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130003496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We have fabricated a metamaterial tunable filter for dynamic frequency selection in the terahertz region. The metamaterial consists of a sandwich of two meta-surfaces grown on high resistivity silicon wafers. The first meta-surface consists of a two-dimensional array of gold double split ring resonators and the second meta-surface consisits of an array of gold cut rods. Both meta-surfaces are fabricated for a response in the terahertz region. Our terahertz pulses are produced using the standard Austin switch technique. The terahertz pulse is focused onto the two meta-surfaces which are sandwiched together to produce a transmission window. Together, with the right orientation, translation, and parallelism of the two meta-surfaces, we achieve filtering of terahertz pulses. Since the unit cells for the inclusions are on the order of 100 microns, control of the translation, orientation, and parallelism of the two meta-surfaces with respect to each other and with respect to the orientation and direction of the impinging terahertz field is a challenge. We describe our technique for doing this and present data on our frequency filtering in the terahertz.
{"title":"Two layer metamaterials for selective frequency transmission in the terahertz region (Presentation Recording)","authors":"M. Landau","doi":"10.1117/12.2188966","DOIUrl":"https://doi.org/10.1117/12.2188966","url":null,"abstract":"We have fabricated a metamaterial tunable filter for dynamic frequency selection in the terahertz region. The metamaterial consists of a sandwich of two meta-surfaces grown on high resistivity silicon wafers. The first meta-surface consists of a two-dimensional array of gold double split ring resonators and the second meta-surface consisits of an array of gold cut rods. Both meta-surfaces are fabricated for a response in the terahertz region. Our terahertz pulses are produced using the standard Austin switch technique. The terahertz pulse is focused onto the two meta-surfaces which are sandwiched together to produce a transmission window. Together, with the right orientation, translation, and parallelism of the two meta-surfaces, we achieve filtering of terahertz pulses. Since the unit cells for the inclusions are on the order of 100 microns, control of the translation, orientation, and parallelism of the two meta-surfaces with respect to each other and with respect to the orientation and direction of the impinging terahertz field is a challenge. We describe our technique for doing this and present data on our frequency filtering in the terahertz.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134169734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mervin Zhao, Ziliang Ye, Yu Ye, Hanyu Zhu, Yuan Wang, Y. Iwasa, Xiang Zhang
The second harmonic generation (SHG) produced from two-dimensional atomic crystals have been utilized recently in studying the grain boundaries and electronic structure of such ultra-thin materials. However, the SHG in many of these crystals, such as transition metal dichalcogenides (TMDCs), only occur in odd numbered layers with limited intensity due to their noncentrosymmetric nature. Here, we probe the SHG from the bulk noncentrosymmetric molybdenum disulfide (MoS2). Whereas the commonly studied 2H crystal phase’s anti-parallel nonlinear dipoles in adjacent layers give an oscillatory SH response, the parallel nonlinear dipoles of each atomic layer in the 3R phase constructively interfere to amplify the nonlinear light. Due to this interference, we observed the atomically phase-matched condition yielding a quadratic dependence between the intensity and layer number. Additionally, we probed the layer evolution of the A and B excitonic transitions in 3R-MoS2 using SHG spectroscopy and found distinct electronic structure differences arising from the crystal geometry. These findings demonstrate the dramatic effect of the symmetry and layer stacking of these atomic crystals.
{"title":"Second-harmonic generation in an atomic phase-matched nonlinear 2D crystal (Presentation Recording)","authors":"Mervin Zhao, Ziliang Ye, Yu Ye, Hanyu Zhu, Yuan Wang, Y. Iwasa, Xiang Zhang","doi":"10.1117/12.2187575","DOIUrl":"https://doi.org/10.1117/12.2187575","url":null,"abstract":"The second harmonic generation (SHG) produced from two-dimensional atomic crystals have been utilized recently in studying the grain boundaries and electronic structure of such ultra-thin materials. However, the SHG in many of these crystals, such as transition metal dichalcogenides (TMDCs), only occur in odd numbered layers with limited intensity due to their noncentrosymmetric nature. Here, we probe the SHG from the bulk noncentrosymmetric molybdenum disulfide (MoS2). Whereas the commonly studied 2H crystal phase’s anti-parallel nonlinear dipoles in adjacent layers give an oscillatory SH response, the parallel nonlinear dipoles of each atomic layer in the 3R phase constructively interfere to amplify the nonlinear light. Due to this interference, we observed the atomically phase-matched condition yielding a quadratic dependence between the intensity and layer number. Additionally, we probed the layer evolution of the A and B excitonic transitions in 3R-MoS2 using SHG spectroscopy and found distinct electronic structure differences arising from the crystal geometry. These findings demonstrate the dramatic effect of the symmetry and layer stacking of these atomic crystals.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133523687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Quantum vacuum engineering is an active field of research. Here we use recent advances in the field of metasurface (2D-array of sub-wavelength scale nano-antennas) to construct an anisotropic quantum vacuum (AQV) in the vicinity of a quantum emitter located at some macroscopic distance from the metasurface. Such AQV can induce quantum interference among several atomic transitions, even when the transition dipole moment corresponding to the decay channels are orthogonal. Recently, there have been few theoretical proposal to use metamaterials to engineer the back-action. All these approaches, which works in the near field (few tens of nanometers from the surface), suffers from trapping an atom at these distance, surface interactions like quenching, Casimir force etc. Hence it’s pivotal to construct the back-action over macroscopic distance. We harness the polarization dependent response of a metasurface to engineer the back-action of the spontaneous emission from the atom to itself. We show strong anisotropy in the decay rate of a quantum emitter which is a manifestation of AQV. Engineering light-matter interaction over macroscopic distances opens new possibilities for long-range interaction between quantum emitters for quantum information processing, spin-optics/spintronics etc.
{"title":"Metasurface-enabled quantum vacuum effects over macroscopic distances (Presentation Recording)","authors":"P. Jha, X. Ni, Chihhui Wu, Y. Wang, Xiang Zhang","doi":"10.1117/12.2187434","DOIUrl":"https://doi.org/10.1117/12.2187434","url":null,"abstract":"Quantum vacuum engineering is an active field of research. Here we use recent advances in the field of metasurface (2D-array of sub-wavelength scale nano-antennas) to construct an anisotropic quantum vacuum (AQV) in the vicinity of a quantum emitter located at some macroscopic distance from the metasurface. Such AQV can induce quantum interference among several atomic transitions, even when the transition dipole moment corresponding to the decay channels are orthogonal. Recently, there have been few theoretical proposal to use metamaterials to engineer the back-action. All these approaches, which works in the near field (few tens of nanometers from the surface), suffers from trapping an atom at these distance, surface interactions like quenching, Casimir force etc. Hence it’s pivotal to construct the back-action over macroscopic distance. We harness the polarization dependent response of a metasurface to engineer the back-action of the spontaneous emission from the atom to itself. We show strong anisotropy in the decay rate of a quantum emitter which is a manifestation of AQV. Engineering light-matter interaction over macroscopic distances opens new possibilities for long-range interaction between quantum emitters for quantum information processing, spin-optics/spintronics etc.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132794882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Miri, Nicholas S. Nye, M. Khajavikhan, D. Christodoulides
Parity-time (PT) symmetric complex structures can exhibit peculiar properties which are otherwise unattainable in traditional Hermitian systems. This is achieved by judiciously involving balanced regions of gain and loss. Here we investigate the scattering properties of PT-symmetric diffraction gratings. The presence of the imaginary potential can modify the light transport properties in their far field. This is an outcome of a local power flow taking place between the gain and loss regions in the near field. We show that for a certain gain/loss contrast, all the negative diffraction orders can be eliminated while the positive diffraction orders can be amplified.
{"title":"PT-symmetric scatterers (Presentation Recording)","authors":"M. Miri, Nicholas S. Nye, M. Khajavikhan, D. Christodoulides","doi":"10.1117/12.2189863","DOIUrl":"https://doi.org/10.1117/12.2189863","url":null,"abstract":"Parity-time (PT) symmetric complex structures can exhibit peculiar properties which are otherwise unattainable in traditional Hermitian systems. This is achieved by judiciously involving balanced regions of gain and loss. Here we investigate the scattering properties of PT-symmetric diffraction gratings. The presence of the imaginary potential can modify the light transport properties in their far field. This is an outcome of a local power flow taking place between the gain and loss regions in the near field. We show that for a certain gain/loss contrast, all the negative diffraction orders can be eliminated while the positive diffraction orders can be amplified.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133040538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shu Zhang, D. Carberry, T. Nieminen, H. Rubinsztein-Dunlop
Boundary walls have a strong influence on the drag force on optically trapped object near surface. Faxen’s correction has shown how a flat surface modifies the hydrodynamic drag. However, to date, the effect of curved walls at microscopic scale on both translational and rotational movement of micro-objects has not been studied. Here we describe our experiments which aim to study the drag force on optically trapped particles moving near walls with different curvatures. The curved walls were made using 3D laser nano-printing (Nanoscribe), and optical tweezers were used to trap micro-objects near the walls. The translational and rotational motion of the optically trapped particle is related to the drag coefficients. By monitoring the change in the motion of particle, we determined the increase in drag force for particles translating or rotating at different distances from surfaces with different curvatures. These results are essential for calibrating the drag force on particles, and thus enable accurate rheology at the micron-scale. This opens the potential for microrheology under different conditions, such as within microdevices, biological cells and studies of biological processes
{"title":"Hydrodynamics of micro-objects near curved surfaces (Presentation Recording)","authors":"Shu Zhang, D. Carberry, T. Nieminen, H. Rubinsztein-Dunlop","doi":"10.1117/12.2190312","DOIUrl":"https://doi.org/10.1117/12.2190312","url":null,"abstract":"Boundary walls have a strong influence on the drag force on optically trapped object near surface. Faxen’s correction has shown how a flat surface modifies the hydrodynamic drag. However, to date, the effect of curved walls at microscopic scale on both translational and rotational movement of micro-objects has not been studied. Here we describe our experiments which aim to study the drag force on optically trapped particles moving near walls with different curvatures. The curved walls were made using 3D laser nano-printing (Nanoscribe), and optical tweezers were used to trap micro-objects near the walls. The translational and rotational motion of the optically trapped particle is related to the drag coefficients. By monitoring the change in the motion of particle, we determined the increase in drag force for particles translating or rotating at different distances from surfaces with different curvatures. These results are essential for calibrating the drag force on particles, and thus enable accurate rheology at the micron-scale. This opens the potential for microrheology under different conditions, such as within microdevices, biological cells and studies of biological processes","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116718314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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