The Experts below are selected from a list of 13878 Experts worldwide ranked by ideXlab platform
Mária Csete - One of the best experts on this subject based on the ideXlab platform.
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optimization of plasmonic structure integrated single photon detector designs to enhance Absorptance
Novel Optical Materials and Applications, 2015Co-Authors: Mária Csete, Gabor Szekeres, Balazs Banhelyi, Andras Szenes, Tibor Csendes, Gabor SzaboAbstract:Plasmonic structure integrated SNSPD configurations were optimized for 1550 nm p-polarized light illumination to maximize Absorptance. Orientation dependent NbN Absorptance, spectral sensitivity and dispersion characteristics were investigated.
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Improvement of infrared single-photon detectors Absorptance by integrated plasmonic structures.
Scientific Reports, 2013Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Gabor Szabo, Anikó Szalai, Karl K BerggrenAbstract:Plasmonic structures open novel avenues in photodetector development. Optimized illumination configurations are reported to improve p-polarized light Absorptance in superconducting-nanowire single-photon detectors (SNSPDs) comprising short- and long-periodic niobium-nitride (NbN) stripe-patterns. In OC-SNSPDs consisting of ~quarter-wavelength dielectric layer closed by a gold reflector the highest Absorptance is attainable at perpendicular incidence onto NbN patterns in P-orientation due to E-field concentration at the bottom of nano-cavities. In NCAI-SNSPDs integrated with nano-cavity-arrays consisting of vertical and horizontal gold segments off-axis illumination in S-orientation results in polar-angle-independent perfect Absorptance via collective resonances in short-periodic design, while in long-periodic NCAI-SNSPDs grating-coupled surface waves promote EM-field transportation to the NbN stripes and result in local Absorptance maxima. In NCDAI-SNSPDs integrated with nano-cavity-deflector-array consisting of longer vertical gold segments large Absorptance maxima appear in 3p-periodic designs due to E-field enhancement via grating-coupled surface waves synchronized with the NbN stripes in S-orientation, which enable to compensate fill-factor-related retrogression.
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Optimized polar-azimuthal orientations for polarized light illumination of different superconducting nanowire single-photon detector designs
Journal of Nanophotonics, 2012Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Karl K BerggrenAbstract:The optimum orientations were determined for polarized light illumination of three superconducting nanowire single-photon detector (SNSPD) designs consisting of niobium-nitride (NbN) stripes with dimensions according to conventional devices in 200 nm periodic pattern: (1) standing in air (bare-SNSPD), (2) below ∼ quarter-wavelength hydrogen-silsesquioxane (HSQ) filled nano-cavity (DC-SNSPD), and (3) below HSQ-filled nano-cavity closed by a thin gold reflector (OC-SNSPD). Computations showed that the optical response and near-field distribution vary significantly with polar angle φ , and these variations are analogous across all azimuthal angles γ , but are fundamentally different in different device designs. Larger Absorptance is attainable due to p -polarized illumination of NbN patterns in P -orientation, while s -polarized illumination results in higher Absorptance in S -orientation. As a result of p-polarized illumination, a global NbN Absorptance maximum appears in bare-SNSPD at polar angle corresponding to attenuated total internal reflection (ATIR); in DC-SNSPD exactly at total internal reflection (TIR); and at perpendicular incidence in OC-SNSPD. S -polarized illumination results in a global NbN Absorptance maximum in bare-SNSPD at TIR; in DC-SNSPD at polar angle corresponding to ATIR phenomenon; while large and almost polar angle independent Absorptance is attainable in OC-SNSPD at small tilting.
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Improvement of infrared single-photon detectors Absorptance by integrated plasmonic structures
arXiv: Optics, 2012Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Anikó Szalai, Karl K BerggrenAbstract:The Absorptance of p-polarized light in superconducting-nanowire single-photon detectors (SNSPDs) was improved by integrating (1) ~quarter-wavelength nano-optical cavity closed by a gold reflector (OC-SNSPD), (2) nano-cavity-array closed by vertical and horizontal gold segments (NCAI-SNSPD), and (3) nano-cavity-deflector-array consisting of longer vertical gold segments (NCDAI-SNSPD) into short- (p-) and long- (3p-) periodic niobium-nitride (NbN) stripe-patterns. In OC-SNSPDs the highest Absorptance is observable at perpendicular incidence onto NbN stripes in P-orientation due to E-field concentration at the bottom of nano- cavities. In short-periodic NCAI-SNSPDs off-axis illumination results in almost polar-angle-independent perfect Absorptance due to collective resonances on plasmonic MIM nano-cavity-arrays in S-orientation. In long-periodic NCAI-SNSPDs the surface wave-excitation phenomena promote EM-field transportation to the NbN stripes in S-orientation and results in local Absorptance maxima. In NCDAI-SNSPDs with proper periodicity large Absorptance maxima appear due to synchronous E-field enhancement via deflected SPPs below NbN stripes in S-orientation, which make possible fill-factor-related loss compensation.
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polar azimuthal angle dependent efficiency of different infrared superconducting nanowire single photon detector designs
Proceedings of SPIE, 2011Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Karl K BerggrenAbstract:The illumination-angle-dependent Absorptance was determined for three types of superconducting-nanowire singlephoton detector (SNSPD) designs: 1. periodic bare niobium-nitride (NbN) stripes with dimensions of conventional SNSPDs, 2. the same NbN patterns integrated with ~quarter-wavelength hydrogensilsesquioxane-filled nano- cavity, 3. similar cavity-integrated structures covered by a thin gold reflector. A three-dimensional finite-element method was applied to determine the optical response and near-field distribution as a function of p-polarized light illumination orientations specified by polar-angle, φ, and azimuthal-angle, γ. The numerical results proved that the NbN Absorptance might be maximized via simultaneous optimization of the polar and azimuthal illumination angles. Complementary transfer-matrix-method calculations were performed on analogous film-stacks to uncover the phenomena contributing to the appearance of extrema on the optical response of NbN-patterns in P-structure-configuration. This comparative study showed that the Absorptance of bare NbN patterns is zero at the angle corresponding to total internal reflection (TIR). In cavity-integrated structures the NbN Absorptance curve indicates a maximum at the same orientation due to the phase shift introduced by the quarter-wavelength HSQ layer. The reflector promotes the NbN Absorptance at small polar angles, but the available Absorptance is limited by attenuated TIR in polar angle-intervals, where surface modes are excited on the gold film.
Karl K Berggren - One of the best experts on this subject based on the ideXlab platform.
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Improvement of infrared single-photon detectors Absorptance by integrated plasmonic structures.
Scientific Reports, 2013Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Gabor Szabo, Anikó Szalai, Karl K BerggrenAbstract:Plasmonic structures open novel avenues in photodetector development. Optimized illumination configurations are reported to improve p-polarized light Absorptance in superconducting-nanowire single-photon detectors (SNSPDs) comprising short- and long-periodic niobium-nitride (NbN) stripe-patterns. In OC-SNSPDs consisting of ~quarter-wavelength dielectric layer closed by a gold reflector the highest Absorptance is attainable at perpendicular incidence onto NbN patterns in P-orientation due to E-field concentration at the bottom of nano-cavities. In NCAI-SNSPDs integrated with nano-cavity-arrays consisting of vertical and horizontal gold segments off-axis illumination in S-orientation results in polar-angle-independent perfect Absorptance via collective resonances in short-periodic design, while in long-periodic NCAI-SNSPDs grating-coupled surface waves promote EM-field transportation to the NbN stripes and result in local Absorptance maxima. In NCDAI-SNSPDs integrated with nano-cavity-deflector-array consisting of longer vertical gold segments large Absorptance maxima appear in 3p-periodic designs due to E-field enhancement via grating-coupled surface waves synchronized with the NbN stripes in S-orientation, which enable to compensate fill-factor-related retrogression.
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Optimized polar-azimuthal orientations for polarized light illumination of different superconducting nanowire single-photon detector designs
Journal of Nanophotonics, 2012Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Karl K BerggrenAbstract:The optimum orientations were determined for polarized light illumination of three superconducting nanowire single-photon detector (SNSPD) designs consisting of niobium-nitride (NbN) stripes with dimensions according to conventional devices in 200 nm periodic pattern: (1) standing in air (bare-SNSPD), (2) below ∼ quarter-wavelength hydrogen-silsesquioxane (HSQ) filled nano-cavity (DC-SNSPD), and (3) below HSQ-filled nano-cavity closed by a thin gold reflector (OC-SNSPD). Computations showed that the optical response and near-field distribution vary significantly with polar angle φ , and these variations are analogous across all azimuthal angles γ , but are fundamentally different in different device designs. Larger Absorptance is attainable due to p -polarized illumination of NbN patterns in P -orientation, while s -polarized illumination results in higher Absorptance in S -orientation. As a result of p-polarized illumination, a global NbN Absorptance maximum appears in bare-SNSPD at polar angle corresponding to attenuated total internal reflection (ATIR); in DC-SNSPD exactly at total internal reflection (TIR); and at perpendicular incidence in OC-SNSPD. S -polarized illumination results in a global NbN Absorptance maximum in bare-SNSPD at TIR; in DC-SNSPD at polar angle corresponding to ATIR phenomenon; while large and almost polar angle independent Absorptance is attainable in OC-SNSPD at small tilting.
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Improvement of infrared single-photon detectors Absorptance by integrated plasmonic structures
arXiv: Optics, 2012Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Anikó Szalai, Karl K BerggrenAbstract:The Absorptance of p-polarized light in superconducting-nanowire single-photon detectors (SNSPDs) was improved by integrating (1) ~quarter-wavelength nano-optical cavity closed by a gold reflector (OC-SNSPD), (2) nano-cavity-array closed by vertical and horizontal gold segments (NCAI-SNSPD), and (3) nano-cavity-deflector-array consisting of longer vertical gold segments (NCDAI-SNSPD) into short- (p-) and long- (3p-) periodic niobium-nitride (NbN) stripe-patterns. In OC-SNSPDs the highest Absorptance is observable at perpendicular incidence onto NbN stripes in P-orientation due to E-field concentration at the bottom of nano- cavities. In short-periodic NCAI-SNSPDs off-axis illumination results in almost polar-angle-independent perfect Absorptance due to collective resonances on plasmonic MIM nano-cavity-arrays in S-orientation. In long-periodic NCAI-SNSPDs the surface wave-excitation phenomena promote EM-field transportation to the NbN stripes in S-orientation and results in local Absorptance maxima. In NCDAI-SNSPDs with proper periodicity large Absorptance maxima appear due to synchronous E-field enhancement via deflected SPPs below NbN stripes in S-orientation, which make possible fill-factor-related loss compensation.
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polar azimuthal angle dependent efficiency of different infrared superconducting nanowire single photon detector designs
Proceedings of SPIE, 2011Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Karl K BerggrenAbstract:The illumination-angle-dependent Absorptance was determined for three types of superconducting-nanowire singlephoton detector (SNSPD) designs: 1. periodic bare niobium-nitride (NbN) stripes with dimensions of conventional SNSPDs, 2. the same NbN patterns integrated with ~quarter-wavelength hydrogensilsesquioxane-filled nano- cavity, 3. similar cavity-integrated structures covered by a thin gold reflector. A three-dimensional finite-element method was applied to determine the optical response and near-field distribution as a function of p-polarized light illumination orientations specified by polar-angle, φ, and azimuthal-angle, γ. The numerical results proved that the NbN Absorptance might be maximized via simultaneous optimization of the polar and azimuthal illumination angles. Complementary transfer-matrix-method calculations were performed on analogous film-stacks to uncover the phenomena contributing to the appearance of extrema on the optical response of NbN-patterns in P-structure-configuration. This comparative study showed that the Absorptance of bare NbN patterns is zero at the angle corresponding to total internal reflection (TIR). In cavity-integrated structures the NbN Absorptance curve indicates a maximum at the same orientation due to the phase shift introduced by the quarter-wavelength HSQ layer. The reflector promotes the NbN Absorptance at small polar angles, but the available Absorptance is limited by attenuated TIR in polar angle-intervals, where surface modes are excited on the gold film.
Áron Sipos - One of the best experts on this subject based on the ideXlab platform.
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Improvement of infrared single-photon detectors Absorptance by integrated plasmonic structures.
Scientific Reports, 2013Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Gabor Szabo, Anikó Szalai, Karl K BerggrenAbstract:Plasmonic structures open novel avenues in photodetector development. Optimized illumination configurations are reported to improve p-polarized light Absorptance in superconducting-nanowire single-photon detectors (SNSPDs) comprising short- and long-periodic niobium-nitride (NbN) stripe-patterns. In OC-SNSPDs consisting of ~quarter-wavelength dielectric layer closed by a gold reflector the highest Absorptance is attainable at perpendicular incidence onto NbN patterns in P-orientation due to E-field concentration at the bottom of nano-cavities. In NCAI-SNSPDs integrated with nano-cavity-arrays consisting of vertical and horizontal gold segments off-axis illumination in S-orientation results in polar-angle-independent perfect Absorptance via collective resonances in short-periodic design, while in long-periodic NCAI-SNSPDs grating-coupled surface waves promote EM-field transportation to the NbN stripes and result in local Absorptance maxima. In NCDAI-SNSPDs integrated with nano-cavity-deflector-array consisting of longer vertical gold segments large Absorptance maxima appear in 3p-periodic designs due to E-field enhancement via grating-coupled surface waves synchronized with the NbN stripes in S-orientation, which enable to compensate fill-factor-related retrogression.
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Optimized polar-azimuthal orientations for polarized light illumination of different superconducting nanowire single-photon detector designs
Journal of Nanophotonics, 2012Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Karl K BerggrenAbstract:The optimum orientations were determined for polarized light illumination of three superconducting nanowire single-photon detector (SNSPD) designs consisting of niobium-nitride (NbN) stripes with dimensions according to conventional devices in 200 nm periodic pattern: (1) standing in air (bare-SNSPD), (2) below ∼ quarter-wavelength hydrogen-silsesquioxane (HSQ) filled nano-cavity (DC-SNSPD), and (3) below HSQ-filled nano-cavity closed by a thin gold reflector (OC-SNSPD). Computations showed that the optical response and near-field distribution vary significantly with polar angle φ , and these variations are analogous across all azimuthal angles γ , but are fundamentally different in different device designs. Larger Absorptance is attainable due to p -polarized illumination of NbN patterns in P -orientation, while s -polarized illumination results in higher Absorptance in S -orientation. As a result of p-polarized illumination, a global NbN Absorptance maximum appears in bare-SNSPD at polar angle corresponding to attenuated total internal reflection (ATIR); in DC-SNSPD exactly at total internal reflection (TIR); and at perpendicular incidence in OC-SNSPD. S -polarized illumination results in a global NbN Absorptance maximum in bare-SNSPD at TIR; in DC-SNSPD at polar angle corresponding to ATIR phenomenon; while large and almost polar angle independent Absorptance is attainable in OC-SNSPD at small tilting.
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Improvement of infrared single-photon detectors Absorptance by integrated plasmonic structures
arXiv: Optics, 2012Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Anikó Szalai, Karl K BerggrenAbstract:The Absorptance of p-polarized light in superconducting-nanowire single-photon detectors (SNSPDs) was improved by integrating (1) ~quarter-wavelength nano-optical cavity closed by a gold reflector (OC-SNSPD), (2) nano-cavity-array closed by vertical and horizontal gold segments (NCAI-SNSPD), and (3) nano-cavity-deflector-array consisting of longer vertical gold segments (NCDAI-SNSPD) into short- (p-) and long- (3p-) periodic niobium-nitride (NbN) stripe-patterns. In OC-SNSPDs the highest Absorptance is observable at perpendicular incidence onto NbN stripes in P-orientation due to E-field concentration at the bottom of nano- cavities. In short-periodic NCAI-SNSPDs off-axis illumination results in almost polar-angle-independent perfect Absorptance due to collective resonances on plasmonic MIM nano-cavity-arrays in S-orientation. In long-periodic NCAI-SNSPDs the surface wave-excitation phenomena promote EM-field transportation to the NbN stripes in S-orientation and results in local Absorptance maxima. In NCDAI-SNSPDs with proper periodicity large Absorptance maxima appear due to synchronous E-field enhancement via deflected SPPs below NbN stripes in S-orientation, which make possible fill-factor-related loss compensation.
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polar azimuthal angle dependent efficiency of different infrared superconducting nanowire single photon detector designs
Proceedings of SPIE, 2011Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Karl K BerggrenAbstract:The illumination-angle-dependent Absorptance was determined for three types of superconducting-nanowire singlephoton detector (SNSPD) designs: 1. periodic bare niobium-nitride (NbN) stripes with dimensions of conventional SNSPDs, 2. the same NbN patterns integrated with ~quarter-wavelength hydrogensilsesquioxane-filled nano- cavity, 3. similar cavity-integrated structures covered by a thin gold reflector. A three-dimensional finite-element method was applied to determine the optical response and near-field distribution as a function of p-polarized light illumination orientations specified by polar-angle, φ, and azimuthal-angle, γ. The numerical results proved that the NbN Absorptance might be maximized via simultaneous optimization of the polar and azimuthal illumination angles. Complementary transfer-matrix-method calculations were performed on analogous film-stacks to uncover the phenomena contributing to the appearance of extrema on the optical response of NbN-patterns in P-structure-configuration. This comparative study showed that the Absorptance of bare NbN patterns is zero at the angle corresponding to total internal reflection (TIR). In cavity-integrated structures the NbN Absorptance curve indicates a maximum at the same orientation due to the phase shift introduced by the quarter-wavelength HSQ layer. The reflector promotes the NbN Absorptance at small polar angles, but the available Absorptance is limited by attenuated TIR in polar angle-intervals, where surface modes are excited on the gold film.
Faraz Najafi - One of the best experts on this subject based on the ideXlab platform.
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Improvement of infrared single-photon detectors Absorptance by integrated plasmonic structures.
Scientific Reports, 2013Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Gabor Szabo, Anikó Szalai, Karl K BerggrenAbstract:Plasmonic structures open novel avenues in photodetector development. Optimized illumination configurations are reported to improve p-polarized light Absorptance in superconducting-nanowire single-photon detectors (SNSPDs) comprising short- and long-periodic niobium-nitride (NbN) stripe-patterns. In OC-SNSPDs consisting of ~quarter-wavelength dielectric layer closed by a gold reflector the highest Absorptance is attainable at perpendicular incidence onto NbN patterns in P-orientation due to E-field concentration at the bottom of nano-cavities. In NCAI-SNSPDs integrated with nano-cavity-arrays consisting of vertical and horizontal gold segments off-axis illumination in S-orientation results in polar-angle-independent perfect Absorptance via collective resonances in short-periodic design, while in long-periodic NCAI-SNSPDs grating-coupled surface waves promote EM-field transportation to the NbN stripes and result in local Absorptance maxima. In NCDAI-SNSPDs integrated with nano-cavity-deflector-array consisting of longer vertical gold segments large Absorptance maxima appear in 3p-periodic designs due to E-field enhancement via grating-coupled surface waves synchronized with the NbN stripes in S-orientation, which enable to compensate fill-factor-related retrogression.
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Optimized polar-azimuthal orientations for polarized light illumination of different superconducting nanowire single-photon detector designs
Journal of Nanophotonics, 2012Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Karl K BerggrenAbstract:The optimum orientations were determined for polarized light illumination of three superconducting nanowire single-photon detector (SNSPD) designs consisting of niobium-nitride (NbN) stripes with dimensions according to conventional devices in 200 nm periodic pattern: (1) standing in air (bare-SNSPD), (2) below ∼ quarter-wavelength hydrogen-silsesquioxane (HSQ) filled nano-cavity (DC-SNSPD), and (3) below HSQ-filled nano-cavity closed by a thin gold reflector (OC-SNSPD). Computations showed that the optical response and near-field distribution vary significantly with polar angle φ , and these variations are analogous across all azimuthal angles γ , but are fundamentally different in different device designs. Larger Absorptance is attainable due to p -polarized illumination of NbN patterns in P -orientation, while s -polarized illumination results in higher Absorptance in S -orientation. As a result of p-polarized illumination, a global NbN Absorptance maximum appears in bare-SNSPD at polar angle corresponding to attenuated total internal reflection (ATIR); in DC-SNSPD exactly at total internal reflection (TIR); and at perpendicular incidence in OC-SNSPD. S -polarized illumination results in a global NbN Absorptance maximum in bare-SNSPD at TIR; in DC-SNSPD at polar angle corresponding to ATIR phenomenon; while large and almost polar angle independent Absorptance is attainable in OC-SNSPD at small tilting.
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Improvement of infrared single-photon detectors Absorptance by integrated plasmonic structures
arXiv: Optics, 2012Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Anikó Szalai, Karl K BerggrenAbstract:The Absorptance of p-polarized light in superconducting-nanowire single-photon detectors (SNSPDs) was improved by integrating (1) ~quarter-wavelength nano-optical cavity closed by a gold reflector (OC-SNSPD), (2) nano-cavity-array closed by vertical and horizontal gold segments (NCAI-SNSPD), and (3) nano-cavity-deflector-array consisting of longer vertical gold segments (NCDAI-SNSPD) into short- (p-) and long- (3p-) periodic niobium-nitride (NbN) stripe-patterns. In OC-SNSPDs the highest Absorptance is observable at perpendicular incidence onto NbN stripes in P-orientation due to E-field concentration at the bottom of nano- cavities. In short-periodic NCAI-SNSPDs off-axis illumination results in almost polar-angle-independent perfect Absorptance due to collective resonances on plasmonic MIM nano-cavity-arrays in S-orientation. In long-periodic NCAI-SNSPDs the surface wave-excitation phenomena promote EM-field transportation to the NbN stripes in S-orientation and results in local Absorptance maxima. In NCDAI-SNSPDs with proper periodicity large Absorptance maxima appear due to synchronous E-field enhancement via deflected SPPs below NbN stripes in S-orientation, which make possible fill-factor-related loss compensation.
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polar azimuthal angle dependent efficiency of different infrared superconducting nanowire single photon detector designs
Proceedings of SPIE, 2011Co-Authors: Mária Csete, Áron Sipos, Faraz Najafi, Karl K BerggrenAbstract:The illumination-angle-dependent Absorptance was determined for three types of superconducting-nanowire singlephoton detector (SNSPD) designs: 1. periodic bare niobium-nitride (NbN) stripes with dimensions of conventional SNSPDs, 2. the same NbN patterns integrated with ~quarter-wavelength hydrogensilsesquioxane-filled nano- cavity, 3. similar cavity-integrated structures covered by a thin gold reflector. A three-dimensional finite-element method was applied to determine the optical response and near-field distribution as a function of p-polarized light illumination orientations specified by polar-angle, φ, and azimuthal-angle, γ. The numerical results proved that the NbN Absorptance might be maximized via simultaneous optimization of the polar and azimuthal illumination angles. Complementary transfer-matrix-method calculations were performed on analogous film-stacks to uncover the phenomena contributing to the appearance of extrema on the optical response of NbN-patterns in P-structure-configuration. This comparative study showed that the Absorptance of bare NbN patterns is zero at the angle corresponding to total internal reflection (TIR). In cavity-integrated structures the NbN Absorptance curve indicates a maximum at the same orientation due to the phase shift introduced by the quarter-wavelength HSQ layer. The reflector promotes the NbN Absorptance at small polar angles, but the available Absorptance is limited by attenuated TIR in polar angle-intervals, where surface modes are excited on the gold film.
Alexander Kaplan - One of the best experts on this subject based on the ideXlab platform.
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The Absorptance of metal surfaces to Nd:YAG/Nd:YLF laser light
Pacific International Conference on Applications of Lasers and Optics, 2008Co-Authors: David Bergstrom, John Powell, Alexander KaplanAbstract:The Absorptance of the metal surfaces used in Laser Material Processing depends strongly upon the particular surface conditions, including the degree of roughness and oxidation. In this paper the influence of surface topography on Nd:YAG/Nd:YLF laser Absorptance has been studied using 3D ray-tracing simulations. The results have increased the understanding of how surface roughness influences the laser-workpiece coupling efficiency.The Absorptance of the metal surfaces used in Laser Material Processing depends strongly upon the particular surface conditions, including the degree of roughness and oxidation. In this paper the influence of surface topography on Nd:YAG/Nd:YLF laser Absorptance has been studied using 3D ray-tracing simulations. The results have increased the understanding of how surface roughness influences the laser-workpiece coupling efficiency.
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Absorptance of nonferrous alloys to nd ylf and nd yag laser light at room temperature
Applied Optics, 2007Co-Authors: David Bergstrom, John Powell, Alexander KaplanAbstract:The measurement of Absorptance is important for the analysis and modeling of laser-material interactions. Unfortunately, most of the Absorptance data currently available consider only polished pure metals rather than the commercially available (unpolished, oxidized) alloys that are actually being processed in manufacturing. We present the results of Absorptance measurements carried out at room temperature on as-received engineering grade nonferrous metals (Al, Cu, and Zn alloys). The measurements were made using an integrating sphere with a Nd:YLF laser at two wavelengths (1053 and 527 nm, which means that the results are also valid for Nd:YAG radiation at 1064 and 532 nm). The Absorptance results obtained differ considerably from the existing data for polished, pure metals and should help improve the accuracy of laser-material interaction models. Some clear trends were identified. For all 22 cases studied the Absorptance was higher than for ideal pure, polished metals. For all Al and Cu samples the Absorptance was higher for the green than it was for the infrared wavelength, while for all Zn coatings this trend was reversed. No clear correlation between Absorptance and surface roughness was found at low roughness values (Sa 0.15-0.60), but one rougher set of samples (Sa 2.34) indicated a roughness-Absorptance correlation at higher roughness levels.
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The Absorptance of steels to Nd:YLF and Nd:YAG laser light at room temperature
Applied Surface Science, 2007Co-Authors: David Bergstrom, John Powell, Alexander KaplanAbstract:The measurement of Absorptance is important for the analysis and modelling of laser-material interactions. Unfortunately, most of the Absorptance data presently available considers only polished pure metals rather than the commercially available (unpolished, oxidised) alloys, which are actually being processed in manufacturing. This paper presents the results of Absorptance measurements carried out at room temperature on as-received engineering grade steels including hot and cold rolled mild steel and stainless steels of various types. The measurements were made using an integrating sphere with an Nd:YLF laser at two wavelengths (1053 and 527 nm, which means that the results are also valid for Nd:YAG radiation at 1064 and 532 nm). The Absorptance results obtained differ considerably from existing data for polished, pure metals and should help improve the accuracy of laser-material interaction models. Some clear trends were identified; for all materials studied, the Absorptance was considerably higher than the previously published values for the relevant pure metals with polished surfaces. For all 15 samples the Absorptance was higher for the green than for the infrared wavelength. No clear trend correlating the Absorptance with the roughness was found for mild steel in the roughness range Sa 0.4-5.6 μm. A correlation between Absorptance and roughness was noted for stainless steel for Sa values above 1.5 μm.
