Fabry–Perot(FP)modes are a class of fundamental resonances in photonic crystal(PhC)slabs.Owing to their low quality factors,FP modes are frequently considered as background fields with their resonance nature being ne...Fabry–Perot(FP)modes are a class of fundamental resonances in photonic crystal(PhC)slabs.Owing to their low quality factors,FP modes are frequently considered as background fields with their resonance nature being neglected.Nevertheless,FP modes can play important roles in some phenomena,as exemplified by their coupling with guided resonance(GR)modes to achieve bound states in the continuum(BIC).Here,we further demonstrate the genuine resonance mode capability of FP modes PhC slabs.Firstly,we utilize temporal coupled-mode theory to obtain the transmittance of a PhC slab based on the FP modes.Secondly,we construct exceptional points(EPs)in both momentum and parameter spaces through the coupling of FP and GR modes.Furthermore,we identify a Fermi arc connecting two EPs and discuss the far-field polarization topology.This work elucidates that the widespread FPs in PhC slabs can serve as genuine resonant modes,facilitating the realization of desired functionalities through mode coupling.展开更多
We have designed and fabricated two types of two-port resonant tunneling filters with a triangular air-hole lattice in two-dimensional photonic crystal slabs. In order to improve the filtering efficiency, a feedback m...We have designed and fabricated two types of two-port resonant tunneling filters with a triangular air-hole lattice in two-dimensional photonic crystal slabs. In order to improve the filtering efficiency, a feedback method is introduced by closing the waveguide. It is found that the relative position between the closed waveguide boundary and the resonator has an important impact on the dropping efficiency. Based on our analyses, two different types of filters are designed. The transmission spectra and scattering-light far-field patterns are measured, which agree well with theoretical prediction. In addition, the resonant filters are highly sensitive to the size of the resonant cavities, which are useful for practical applications.展开更多
Light extraction efficiency of organic light emitting diode （OLED） based on various photonic crystal slab （PCS） structures was studied. By using the finite-difference time-domain （FDTD） method, we investigated t...Light extraction efficiency of organic light emitting diode （OLED） based on various photonic crystal slab （PCS） structures was studied. By using the finite-difference time-domain （FDTD） method, we investigated the effect of several parameters, including filling factor and lattice constant, on the enhancement of light extraction efficiency of three basic PCSs, and got the most effective one. Two novel designs of ＂interlaced＂ and ＂double-interlaced＂ PCS structures based on the most effective basic PCS structure were introduced, and the ＂interlaced＂ one was proved to be even more efficient than its prototype. Large enhancement of light extraction efficiency resulted from the coupling to leaky modes in the expended light cone of a band structure, the diffraction in the space between columns, as well as the strong scattering at indium-tinoxide/glass interfaces.展开更多
Photonic crystal slabs integrated into organic light-emitting diodes(OLEDs) allow for the extraction of waveguide modes and thus an increase in OLED efficiency. We fabricated linear Bragg gratings with a 460-nm period...Photonic crystal slabs integrated into organic light-emitting diodes(OLEDs) allow for the extraction of waveguide modes and thus an increase in OLED efficiency. We fabricated linear Bragg gratings with a 460-nm period on flexible polycarbonate substrates using UV nanoimprint lithography. A hybrid organic–inorganic nanoimprint resist is used that serves also as a high refractive index layer. OLEDs composed of a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate(PEDOT:PSS) polymer anode, an organic emission layer [poly(p-phenylene vinylene)(PPV)-derivative 'Super Yellow'], and a metal cathode(Li F/Al) are deposited onto the flexible grating substrates. The effects of photonic crystal slab deformation in a flexible OLED are studied in theory and experiment. The substrate deformation is modeled using the finite-element method. The influence of the change in the grating period and the waveguide thickness under bending are investigated. The change in the grating period is found to be the dominant effect. At an emission angle of 20° a change in the resonance wavelength of 1.2% is predicted for a strain of 1.3% perpendicular to the grating grooves. This value is verified experimentally by analyzing electroluminescence and photoluminescence properties of the fabricated grating OLEDs.展开更多
We present a novel and simple design of an air-slot mode-gap photonic crystal(PC) nanocavity by introducing a linear air slot to the center of a line-defect waveguide in a two dimensional triangular-lattice silicon PC...We present a novel and simple design of an air-slot mode-gap photonic crystal(PC) nanocavity by introducing a linear air slot to the center of a line-defect waveguide in a two dimensional triangular-lattice silicon PC slab.A high quality factor(Q factor) of 8.42*105 and an ultrasmall mode volume of 0.998 cubic wavelength are achieved in an optimized air-slot nanocavity which is a suitable choice for the strong matter-field interaction in free space.The high Q cavities with ultrasmall mode volume are important for applications such as quantum computation and nonlinear optics.展开更多
We explore the behaviors of optically coupled topological corner states in supercell arrays composed of photonic crystal rods,where each supercell is a second-order topological insulator.Our findings indicate that the...We explore the behaviors of optically coupled topological corner states in supercell arrays composed of photonic crystal rods,where each supercell is a second-order topological insulator.Our findings indicate that the coupled corner states possess nondegenerate eigenfrequencies at theΓpoint,with coupled dipole corner states excited resonantly by incident plane waves and displaying a polarization-independent characteristic.The resonance properties of coupled dipole corner states can be effectively modulated via evanescently near-field coupling,while multipole decomposition shows that they are primarily dominated by electric quadrupole moment and magnetic dipole moment.Furthermore,we demonstrate that these coupled corner states can form surface lattice resonances driven by diffractively far-field coupling,leading to a dramatic increase in the quality factor.This work introduces more optical approaches to tailoring photonic topological states,and holds potential applications in mid-infrared topological micro-nano devices.展开更多
Trace elements, isotopic modeling and U-Th-Pb SHRIMP zircon age constraints are used to reconstruct the eruption history and magmatic processes of the Piedra Parada Caldera. In the early Eocene, the crystal-poor Barda...Trace elements, isotopic modeling and U-Th-Pb SHRIMP zircon age constraints are used to reconstruct the eruption history and magmatic processes of the Piedra Parada Caldera. In the early Eocene, the crystal-poor Barda Colorada ignimbrite(BCI), having >>15% micro-porphyritic crystals with respect to magmatic components, erupted a volume estimated in more than 300 km^3. The Piedra Parada caldera is located in the Patagonian Andes foreland, at the southern end of the calderas field of the Pilcaniyeu Volcanic Belt(PVB). This belt is related to an extensional tectonic setting as a result of the collision of the Farallon-Aluk ridge with South America, which enabled the development of a transform ocean/continental plate margin followed by the detachment of the Aluk plate and the opening of a slab window. The BCI extra-caldera Plateau is a >100 m thick deposit, having a lower unit with high silica(Si O_2> 76 wt.%),potassium poor rhyolitic composition(trondhjemitic like magma), and an upper unit with normal to high potassium rhyolitic composition(granitic like magma). A trace elements modeling of the BCI units shows that the BCI lower and upper units did not evolve from fractionation or immiscibility in the shallow magma reservoir. The BCI also have a primitive isotopic signature(initial87 Sr/86 Sr =0.7031-0.7049 and ε_(Nd)= +3.4 to +3.65). Thus, tectonic, compositional and isotopic constraints suggest the fast ascent of high silica magmas to a shallow reservoir, and point to an upper mantle origin for these rhyolitic magmas in a transitional(Orogenic-Anorogenic) tectono-magmatic setting. U-Th-Pb SHRIMP zircon crystallization ages of the Syn-caldera stage BCI units(56 -51.5 Ma) show a protracted life of 5 Ma for this caldera reservoir. The age of 52.9 ± 0.3 Ma is considered the best fit for the possible maximum age for the caldera collapse. The Late-caldera magmatism has trachyandesitic and rhyolitic compositions.The trace element modeling suggests that these rhyolites evolve from the trachyandesites and do not evolve from the BCI residual magma. The trachyandesites have U-Th-Pb SHRIMP zircon crystallization ages of 52 ± 1 Ma, suggesting that the caldera eruption was triggered by the arrival of the trachyandesitic magma.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12074049 and 12347101)。
文摘Fabry–Perot(FP)modes are a class of fundamental resonances in photonic crystal(PhC)slabs.Owing to their low quality factors,FP modes are frequently considered as background fields with their resonance nature being neglected.Nevertheless,FP modes can play important roles in some phenomena,as exemplified by their coupling with guided resonance(GR)modes to achieve bound states in the continuum(BIC).Here,we further demonstrate the genuine resonance mode capability of FP modes PhC slabs.Firstly,we utilize temporal coupled-mode theory to obtain the transmittance of a PhC slab based on the FP modes.Secondly,we construct exceptional points(EPs)in both momentum and parameter spaces through the coupling of FP and GR modes.Furthermore,we identify a Fermi arc connecting two EPs and discuss the far-field polarization topology.This work elucidates that the widespread FPs in PhC slabs can serve as genuine resonant modes,facilitating the realization of desired functionalities through mode coupling.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11004169)the National Basic Research Program of China (Grant No. 2011CB922002)the Doctoral Foundation of Shandong Province,China (Grant No. BS2009CL028)
文摘We have designed and fabricated two types of two-port resonant tunneling filters with a triangular air-hole lattice in two-dimensional photonic crystal slabs. In order to improve the filtering efficiency, a feedback method is introduced by closing the waveguide. It is found that the relative position between the closed waveguide boundary and the resonator has an important impact on the dropping efficiency. Based on our analyses, two different types of filters are designed. The transmission spectra and scattering-light far-field patterns are measured, which agree well with theoretical prediction. In addition, the resonant filters are highly sensitive to the size of the resonant cavities, which are useful for practical applications.
基金This work was supported by the 2005 Nano-Science and Technology Foundation of Science and Technology Committee of Shanghai Municipality under Grant No. 0452nm056.
文摘Light extraction efficiency of organic light emitting diode （OLED） based on various photonic crystal slab （PCS） structures was studied. By using the finite-difference time-domain （FDTD） method, we investigated the effect of several parameters, including filling factor and lattice constant, on the enhancement of light extraction efficiency of three basic PCSs, and got the most effective one. Two novel designs of ＂interlaced＂ and ＂double-interlaced＂ PCS structures based on the most effective basic PCS structure were introduced, and the ＂interlaced＂ one was proved to be even more efficient than its prototype. Large enhancement of light extraction efficiency resulted from the coupling to leaky modes in the expended light cone of a band structure, the diffraction in the space between columns, as well as the strong scattering at indium-tinoxide/glass interfaces.
基金support by the Bundesministerium fur Bildung und Forschung (BMBF) within the project Nano Futur under Project No. 03X5514
文摘Photonic crystal slabs integrated into organic light-emitting diodes(OLEDs) allow for the extraction of waveguide modes and thus an increase in OLED efficiency. We fabricated linear Bragg gratings with a 460-nm period on flexible polycarbonate substrates using UV nanoimprint lithography. A hybrid organic–inorganic nanoimprint resist is used that serves also as a high refractive index layer. OLEDs composed of a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate(PEDOT:PSS) polymer anode, an organic emission layer [poly(p-phenylene vinylene)(PPV)-derivative 'Super Yellow'], and a metal cathode(Li F/Al) are deposited onto the flexible grating substrates. The effects of photonic crystal slab deformation in a flexible OLED are studied in theory and experiment. The substrate deformation is modeled using the finite-element method. The influence of the change in the grating period and the waveguide thickness under bending are investigated. The change in the grating period is found to be the dominant effect. At an emission angle of 20° a change in the resonance wavelength of 1.2% is predicted for a strain of 1.3% perpendicular to the grating grooves. This value is verified experimentally by analyzing electroluminescence and photoluminescence properties of the fabricated grating OLEDs.
基金supported by the National Natural Science Foundation of China (11004169 and 10904176)the Doctoral Foundation of Shandong Province (BS2009CL028)
文摘We present a novel and simple design of an air-slot mode-gap photonic crystal(PC) nanocavity by introducing a linear air slot to the center of a line-defect waveguide in a two dimensional triangular-lattice silicon PC slab.A high quality factor(Q factor) of 8.42*105 and an ultrasmall mode volume of 0.998 cubic wavelength are achieved in an optimized air-slot nanocavity which is a suitable choice for the strong matter-field interaction in free space.The high Q cavities with ultrasmall mode volume are important for applications such as quantum computation and nonlinear optics.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.62275271,12272407,and 62275269)the National Key Research and Development Program of China (Grant No.2022YFF0706005)+1 种基金the Natural Science Foundation of Hunan Province,China (Grant Nos.2023JJ40683,2022JJ40552,and 2020JJ5646)the Program for New Century Excellent Talents in University,China (Grant No.NCET-12-0142)。
文摘We explore the behaviors of optically coupled topological corner states in supercell arrays composed of photonic crystal rods,where each supercell is a second-order topological insulator.Our findings indicate that the coupled corner states possess nondegenerate eigenfrequencies at theΓpoint,with coupled dipole corner states excited resonantly by incident plane waves and displaying a polarization-independent characteristic.The resonance properties of coupled dipole corner states can be effectively modulated via evanescently near-field coupling,while multipole decomposition shows that they are primarily dominated by electric quadrupole moment and magnetic dipole moment.Furthermore,we demonstrate that these coupled corner states can form surface lattice resonances driven by diffractively far-field coupling,leading to a dramatic increase in the quality factor.This work introduces more optical approaches to tailoring photonic topological states,and holds potential applications in mid-infrared topological micro-nano devices.
基金funded with research grants from projects of UNLP 11N/689 and 790, CONICET PID 00688the Spanish Ministry of Science and Innovation (Projects CGL2013-48408-C3-1-P) (LITHOS)
文摘Trace elements, isotopic modeling and U-Th-Pb SHRIMP zircon age constraints are used to reconstruct the eruption history and magmatic processes of the Piedra Parada Caldera. In the early Eocene, the crystal-poor Barda Colorada ignimbrite(BCI), having >>15% micro-porphyritic crystals with respect to magmatic components, erupted a volume estimated in more than 300 km^3. The Piedra Parada caldera is located in the Patagonian Andes foreland, at the southern end of the calderas field of the Pilcaniyeu Volcanic Belt(PVB). This belt is related to an extensional tectonic setting as a result of the collision of the Farallon-Aluk ridge with South America, which enabled the development of a transform ocean/continental plate margin followed by the detachment of the Aluk plate and the opening of a slab window. The BCI extra-caldera Plateau is a >100 m thick deposit, having a lower unit with high silica(Si O_2> 76 wt.%),potassium poor rhyolitic composition(trondhjemitic like magma), and an upper unit with normal to high potassium rhyolitic composition(granitic like magma). A trace elements modeling of the BCI units shows that the BCI lower and upper units did not evolve from fractionation or immiscibility in the shallow magma reservoir. The BCI also have a primitive isotopic signature(initial87 Sr/86 Sr =0.7031-0.7049 and ε_(Nd)= +3.4 to +3.65). Thus, tectonic, compositional and isotopic constraints suggest the fast ascent of high silica magmas to a shallow reservoir, and point to an upper mantle origin for these rhyolitic magmas in a transitional(Orogenic-Anorogenic) tectono-magmatic setting. U-Th-Pb SHRIMP zircon crystallization ages of the Syn-caldera stage BCI units(56 -51.5 Ma) show a protracted life of 5 Ma for this caldera reservoir. The age of 52.9 ± 0.3 Ma is considered the best fit for the possible maximum age for the caldera collapse. The Late-caldera magmatism has trachyandesitic and rhyolitic compositions.The trace element modeling suggests that these rhyolites evolve from the trachyandesites and do not evolve from the BCI residual magma. The trachyandesites have U-Th-Pb SHRIMP zircon crystallization ages of 52 ± 1 Ma, suggesting that the caldera eruption was triggered by the arrival of the trachyandesitic magma.
