Emerging topological semimetals offer promise of realizing topological electronics enabled by terahertz (THz) current persistent against impurity scattering. Yet most fundamental issues remain on how to image nanoscale conductivity inhomogeneity. Here we show noninvasive and contactless conductivity mapping at THz-nm limit of electronic heterogeneity and nanostrip junctions in a Dirac material ZrTe5. A clear Dirac Fermion density transition, manifested as the exclusive THz conductivity contrast, is quantitatively analyzed and profiled on both sides of the junction. This also allows the determination of variable junction width of ∼25–220 nm, depending on the THz conductivity contrast of adjacent strips. The unique THz-nm contrast is absent in mid-infrared nano-imaging measurements since topological semimetals with small Fermi pockets exhibit a better matching of their plasma frequency and scattering rate to the THz spectral region. The first-principles calculations provide two compelling implications: the conductivity nanocontrast can be induced by a small anisotropic strain, even less than 0.5%, due to an extreme strain sensitivity in ZrTe5; A nanoscale topological phase transition is realized across some junctions induced by the strain, between strong topological insulators (TIs) and weak TIs/Dirac semimetals (DSMs).
ACS Photonics July 21, 2021 Volume 8, Issue 7 摘要
Terahertz Nano-Imaging of Electronic Strip Heterogeneity in a Dirac Semimetal
Richard H. J. Kim,...Jigang Wang*
Emerging topological semimetals offer promise of realizing topological electronics enabLED by terahertz (THz) current persistent against impurity scattering. Yet most fundamental issues remain on how to image nanoscale conductivity inhomogeneity. Here we show noninvasive and contactless conductivity mapping at THz-nm limit of electronic heterogeneity and nanostrip junctions in a Dirac material ZrTe5. A clear Dirac fermion density transition, manifested as the exclusive THz conductivity contrast, is quantitatively analyzed and profiled on both sides of the junction. This also allows the determination of variable junction width of ∼25–220 nm, depending on the THz conductivity contrast of adjacent strips. The unique THz-nm contrast is absent in mid-infrared nano-imaging measurements since topological semimetals with small Fermi pockets exhibit a better matching of their plasma frequency and scattering rate to the THz spectral region. The first-principles calculations provide two compelling implications: the conductivity nanocontrast can be induced by a small anisotropic strain, even less than 0.5%, due to an extreme strain sensitivity in ZrTe5; A nanoscale topological phase transition is realized across some junctions induced by the strain, between strong topological insulators (TIs) and weak TIs/Dirac semimetals (DSMs).
Strong Coupling in a Self-Coupled Terahertz photonic crystal
Maria Kaeek, Ran Damari, Michal Roth, Sharly Fleischer, and Tal Schwartz*
Vibrational strong coupling is a phenomenon in which a vibrational transition in a material placed inside a photonic structure is hybridized with its optical modes to form composite light–matter excitations known as vibro-polaritons. Here we demonstrate a new concept of vibrational strong coupling: we show that a monolithic photonic crystal, made of a resonant material, can exhibit strong coupling between the optical modes confined in the structure and the terahertz vibrational excitations of the same material. We study this system both experimentally and numerically to characterize the dISPersion of the photonic modes for various sample thicknesses and reveal their coupling with the vibrational resonances. Finally, our time-domain THz measurements allow us to isolate the free induction decay signal from the grating modes as well as from the vibro-polaritons.
Temperature-Dependent Energy-level Shifts of Spin Defects in Hexagonal Boron Nitride
Wei Liu, Zhi-Peng Li, Yuan-Ze Yang, Shang Yu, Yu Meng, Zhao-An Wang, Ze-Cheng Li, Nai-Jie Guo, Fei-Fei Yan, Qiang Li, Jun-Feng Wang, Jin-Shi Xu, Yi-Tao Wang*, Jian-Shun Tang*, Chuan-Feng Li*, and Guang-Can Guo
Two-dimensional hexagonal boron nitride (hBN) has attracted much attention as a platform for realizing integrated nanophotonics, and a collective effort has been focused on spin defect centers. Here, the temperature dependence of the optically detected magnetic resonance (ODMR) spectrum of negatively charged boron vacancy (VB–) ensembles in the range of 5–600 K is investigated. The microwave transition energy is found to decrease monotonically with increasing temperature and can be described by the Varshni empirical equation very well. Considering the proportional relation between energy-level shifts and the reciprocal lattice volume (V–1), thermal expansion might be the dominant cause for energy-level shifts. We also demonstrate that the VB– defects are stable at up to 600 K. Moreover, we find that there are evident differences among different hBN nanopowders, which might originate from the local strain and distance of defects from the flake edges. Our results may provide insight into the spin properties of VB– and for the realization of miniaturized, integrated thermal sensors.
Nonlinear Wavy Metasurfaces with Topological Defects for Manipulating Orbital Angular Momentum States
Yang Ming, Wang Zhang, Jie Tang, Xifeng Yang, Yu-shen Liu, and Yan-qing Lu
Patterned surfaces with rationally designed nanostructures provide a flexible platform for beam shaping in both the linear and nonlinear optical regime. The properties of reflected or diffracted output depend on the Fourier transform of the surface profile. To obtain ideal effects, the profile should contain a desired sum of specially formed sinusoidal terms with predefined superposition coefficients. Such a kind of surface is vividly described as a “wavy” surface in certain contexts, which has been widely utilized for linear optical applications. However, the nonlinear counterparts are rarely demonstrated. Here, we present a design framework of nonlinear “wavy” surfaces based on hybrid nanostructures of metal and multi-quantum-well (MQW) for generating and steering second-harmonic beams. Giant second-order nonlinearity is available in MQWs; thus, an efficient up-conversion process can be ensured. In this system, the harmonic output is determined by the Fourier spectrum of spatially dependent second-order nonlinearity, which can be engineered through tailoring the shape, orientation, and arrangement of nanoelements known as “meta-atoms”. Compared with previously proposed nonlinear metasurfaces, the wavy design can be more flexible for manipulating orbital angular momentum (OAM) states through introducing topological defects. Besides choosing states with expected topological charges and controlling the relative weight, the rule in conventional binary χ(2) systems that the attached OAM value increases with the order of reflection/diffraction can be broken via suitable nanostructure design, which means that lower order is possible to have larger absolute topological charge. This proposed framework has tremendous potential for applications in emerging areas such as quantum nanophotonics and topological photonics.
Transient Tap Couplers for Wafer-Level Photonic Testing Based on Optical Phase Change Materials
Yifei Zhang*, Qihang Zhang, Carlos Ríos, Mikhail Y. Shalaginov, Jeffrey B. Chou, Christopher Roberts, Paul Miller, Paul Robinson, Vladimir Liberman, Myungkoo Kang, Kathleen A. Richardson, Tian Gu, Steven A. Vitale, and Juejun Hu*
Wafer-level testing is crucial for process monitoring, post-fabrication trimming, and understanding system dynamics in photonic integrated circuits (PICs). Waveguide tap couplers are usually used to provide testing access to the PIC components. These tap couplers however incur permanent parasitic losses, imposing a trade-off between PIC performance and testing demands. Here we demonstrate a transient tap coupler design based on optical phase change materials (O-PCMs). In their as-fabricated “on” state, the couplers enable broadband interrogation of PICs at the wafer level. Upon completion of testing, the tap couplers can be turned “off” with minimal residual loss (0.01 dB) via a simple low-temperature (280 °C) wafer-scale annealing process. We further successfully demonstrated transient couplers in both Si and SiN photonics platforms. The platform-agnostic transient coupler concept uniquely combines compact footprint, broadband operation, exceptionally low residual losses, and low thermal budget commensurate with post-fabrication treatment, thereby offering a facile solution to wafer-level photonic testing without compromising the final PIC performance.
Bright Near-Infrared to Visible Upconversion Double quantum dots Based on a Type-II/Type-I Heterostructure
Gaoling Yang*, Miri Kazes, Dekel Raanan, and Dan Oron*
Upconverting semiconductor quantum dots (QDs) combine the stability of an inorganic crystalline structure with the spectral tunability afforded by quantum confinement. Here, we present upconverting type-II/type-I colloidal double QDs that enable enhancement of the performance of near-infrared to visible photon upconversion in QDs and broadening the range of relevant materials used. The resulting ZnTe/CdSe@CdS@CdSe/ZnSe type-II/type-I double QDs possess a very high photoluminescence quantum yield, monoexponential decay dynamics, and a narrow line width, approaching those of state-of-the-art upconverting QDs. We quantitatively characterize the upconversion cross section by direct comparison with two-photon absorption when varying the pump frequency across the absorption edge. Finally, we show that these upconversion QDs maintain their optical performance in a much more demanding geometry of a dense solid film and can thus be incorporated in devices as upconversion films. Our design provides guidance for fabricating highly efficient upconverting QDs with potential applications such as security coding and bioimaging.
High-Sensitivity, High-Resolution Detection of Reactive Oxygen Species Concentration Using NV Centers
Yoav Ninio, Nir Waiskopf, Idan Meirzada, Yoav Romach, Galya Haim, Shira Yochelis, Uri Banin, and Nir Bar-Gill*
Nitrogen-vacancy (NV) color centers in diamond have been demonstrated as useful magnetic sensors, in particular for measuring spin fluctuations and achieving high sensitivity and spatial resolution. These abilities can be used to explore various biological and chemical processes, catalyzed by reactive oxygen species (ROS). Here we demonstrate a novel approach to measure and quantify hydroxyl radicals with high spatial resolution, using the fluorescence difference between NV charged states. According to the results, the achieved NV sensitivity is , realized in situ without spin labels and localized to a volume of ∼10 picoliters.
Single Nanoflake Hexagonal Boron Nitride Harmonic Generation with Ultralow Pump Power
Ghazal Hajisalem, Mirali Seyed Shariatdoust, Rana Faryad Ali, Byron D. Gates, Paul E. Barclay, and Reuven Gordon*
The strong nonlinear optical response of two-dimensional materials has applications in bioimaging and integrated optical information processing; however, past experiments were on diffraction limited samples or required intense pulsed lasers, which is a detriment to potential applications due to cost, power and complexity. Here we show that second harmonic generation can be achieved from single subwavelength two-dimensional material nanoflakes smaller than the diffraction limit using a plasmonic optical tweezer with a low-power (down to 3 mW) laser diode operating in continuous-wave mode. A double nanohole plasmonic tweezer enhances the local field and the local density of optical states to allow for trapping and significant nonlinear generation at the nanoscale. Also, the fact that it is a two-dimensional material means that it can be positioned closer to the highest field regions, realizing 2 orders of magnitude higher power second harmonic generation than other nonlinear materials like lithium niobate. The ability to have simple high efficiency nonlinear generation at the nanoscale will benefit future nonlinear optics applications of these emerging materials.
Anisotropic Off-Axis Laser Oscillator
Ming-Hsiung Wu, Yan-Jou Lin, Fredrik Laurell, and Yen-Chieh Huang*
Thanks to the anisotropic radiation of elementary dipoles, greatly enhanced laser gain can be achieved by simply adding side-reflection planes for the radiating waves. To verify this fundamental physics concept, we exploit the strong z-polarized Raman response of KTiOPO4 by resonating off-axis Stokes waves in the x–y plane of the crystal with reflection feedback from the y-surfaces. When pumped by a laser pulse with a length comparable to the crystal length, such an anisotropic off-axis Raman oscillator generates a single off-axis mode with 30% optical efficiency. The anisotropic gain enhancement factor of this Raman laser is about 1.3×104 compared with one oscillating the Stokes polarization in the x–z plane.
Electrically Tunable High-Quality Factor Silicon Microring Resonator Gated by High Mobility Conductive Oxide
Wei-Che Hsu, Cheng Zhen, and Alan X. Wang*
Silicon microring resonators play pivotal roles in photonic integration circuits due to the advantages of low power consumption, high bandwidth, and ultracompact size. However, silicon microring resonators also face great challenges to control the working wavelength due to fabrication errors and temperature variation. In this work, we demonstrate an electrically tunable silicon microring resonator driven by a titanium-doped indium oxide/hafnium oxide/silicon metal-oxide-semiconductor capacitor, achieving a high electro-optic tuning efficiency of 130 pm/V with a high quality factor between 11900 and 4700. The high electro-optic tuning efficiency can be used to compensate for the drift of resonance wavelength induced by temperature fluctuation up to 12 K with an extremely low power consumption of 11 pW/nm, which is superior to the conventional thermal tuning.
Statistical Nonlinear optical mapping of Localized and Delocalized Plasmonic Modes in Disordered Gold Metasurfaces
Gauthier Roubaud, Sébastien Bidault*, Sylvain Gigan, and Samuel Grésillon*
Using a statistical analysis of nonlinear luminescence images measured with randomly wavefront-shaped femtosecond excitations, we provide direct insight on both the localized and delocalized plasmonic modes featured by disordered gold metasurfaces. We can independently image areas where far-field wavefront shaping can control the optical properties and areas with strong subwavelength optical hotspots. In practice, the fraction of the disordered plasmonic surface on which wavefront control is feasible depends strongly on the nanoscale morphology of the sample. Close to the percolation threshold, the entire surface is sensitive to wave-front shaping, and we observe the largest densities of delocalized modes as well as the strongest optical hotspots. These results demonstrate how statistical imaging schemes can offset the complexity of disordered nanophotonic systems in order to characterize their optical properties.
Large Field-of-View Super-Resolution Optical Microscopy Based on Planar Polymer Waveguides
Anders Kokkvoll Engdahl, Stefan Belle, Tung-Cheng Wang, Ralf Hellmann, Thomas Huser, and Mark Schüttpelz*
Planar photonic waveguides enable ultrathin sample illumination in fluorescence microscopy over exceedingly large fields of view. Their fabrication has been based on hard coatings requiring sputter deposition and ion-beam lithography, making volume production cumbersome and thereby limiting their availability. Additionally, they are typically fabricated on top of opaque silicon wafers, which restricts the use to upright microscopes. Here, we present a low-cost photonic waveguide chip based on standard 170 μm thick glass coverslips coated with a micrometer-thin layer of EpoCore, a photoresist polymer with a high refractive index. These chips enable wide-field excitation for fluorescence microscopy and nanoscopy on inverted microscopes using fluorescence detection through the transparent substrate. channel waveguides with varying widths provide uniform near-field illumination by evanescent waves for fields of view up to the millimeter scale. We demonstrate multicolor fluorescence excitation resulting in high-contrast immunofluorescence and super-resolution imaging with a resolution of approximately 60 nm.
Silicon-Based Quantum Mechanical Tunnel Junction for Plasmon Excitation from Low-Energy Electron Tunneling
Fangwei Wang, Yan Liu, Thorin Jake Duffin, Vijith Kalathingal, Siping Gao, Wenrui Hu, Yongxin Guo, Soo-Jin Chua, and Christian A. Nijhuis*
Light emission from metal–insulator–semiconductor junctions (MISJs) has been explored for decades as a possible on-chip light source; however it is not clear whether the mechanism of light emission is plasmonic in nature or is dominated by electroluminescence. Previous studies only investigated silicon with low doping levels, but here we show that only highly doped silicon allows us to excite surface plasmon polaritons (SPPs) in MISJs via inelastic tunneling. This paper describes the mechanism of charge transport and light emission from silicon-based Au-SiO2-nSi MISJs as a function of the doping level Nd varying from 1.6 × 1015 cm–3 to 1.0 × 1020 cm–3. At low doping levels (Nd ∼ 1015 cm–3), the MISJs behave as Schottky diodes, and the mechanism of light emission involves a radiative recombination of electrons and holes from minority carrier injection under high applied bias (>5.5 V). With increasing doping levels, the current–voltage characteristics of the MISJs change, resulting in symmetrical current–voltage curves with parabolic conductance behavior characteristic of quantum mechanical tunneling. MISJs with the highest doping level (Nd ∼ 1020 cm–3) are dominated by quantum mechanical tunneling, and light emission originates from radiative decay of surface plasmon polaritons (SPPs) via scattering at threshold voltages as low as 1.5 V. Our simulations indicate that tunneling over the thin SiO2 barrier between the Au and highly doped nSi excites a hybrid-SPP mode localized to the Au whose dispersion depends on the effective index induced by the SiO2–nSi interface. Our studies show that Si needs to be sufficiently doped to be conductive enough to enable SPP excitation via inelastic tunneling.
nanoparticle Trapping in a Quasi-BIC System
Sen Yang, Chuchuan Hong, Yuxi Jiang, and Justus C. Ndukaife*
Plasmonic nanotweezers employing metallic nanoantennas provide a powerful tool for trapping nanoscale particles, but the strong heating effect resulting from light absorption limits widespread applications. Here, we propose an all-dielectric nanotweezer harnessing quasi-bound states in the continuum (quasi-BICs) to enable the trapping of nanoscale objects with low laser power and a negligible heating effect. The quasi-BIC system provides very high electromagnetic field intensity enhancement that is an order of magnitude higher than plasmonic systems as well as high-quality-factor resonances comparable to photonic crystal cavities. Furthermore, the quasi-BIC metasurface tweezer array provides multiple optical hotspots with high field confinement and enhancement, thereby generating multiple trapping sites for the high-throughput trapping of nanometer-scale objects. By purposefully truncating the tips of the constituent elliptical nanoantennas in the quasi-BIC system to leverage the asymmetric field distribution, we demonstrate that the optical gradient forces can be further enhanced by a factor of 1.32 in comparison to the intact elliptical nanoantenna, which has attractive potential in subwavelength particle trapping applications. In addition, we show that trapped particles can improve the resonance mode of the cavity rather than suppress it in a symmetry-broken system, which in turn enhances the trapping process. Our study paves the way for applying quasi-BIC systems to low-power particle trapping and sensing applications and provides a new mechanism to harness the self-induced back-action.
Light Absorption and Emission Dominated by Trions in the Type-I van der Waals Heterostructures
Hyemin Bae, Suk Hyun Kim, Seungmin Lee, Minji Noh, Ouri Karni, Aidan L. O’Beirne, Elyse Barré, Sangwan Sim, Soonyoung Cha, Moon-Ho Jo, Tony F. Heinz*, and Hyunyong Choi*
van der Waals (vdW) heterostructures provide a powerful method to control the alignment of energy bands of atomically thin 2D materials. Under light illumination, the optical responses are dominated by Coulomb-bound electron–hole quasiparticles, for example, excitons, trions, and biexcitons, whose contributions accordingly depend on the types of heterostructures. For type-II heterostructures, it has been well established that light excitation results in electrons and holes that are separated in different layers, and the radiative recombination is dominated by the interlayer excitons. On the contrary, little is known about the corresponding optical responses of type-I cases. Understanding the optical characteristics of type-I heterostructures is important to the full exploration of the quasiparticle physics of the 2D heterostacks. In this study, we performed optical spectroscopy on type-I vdW heterostacks composed of monolayer MoTe2 and WSe2. Photoluminescence and reflection contrast spectroscopy show that the light absorption and emission are dominated by the Coulomb-bound trions. Importantly, we observed that the MoTe2 trion emission gets stronger compared with the exciton emission under resonant light excitation to the WSe2 trion absorption state, especially in the WSe2/MoTe2/WSe2 heterotrilayer. A detailed study of photoluminescence excitation further reveals that the charge-transfer mechanism is likely responsible for our observation, which differs from the exciton-dominated dipole–dipole energy transfer in type-II structures. Our demonstration implies that the type-I vdW heterostack provides new opportunities to engineer the light–matter interactions through many-body Coulomb-bound states.
Ligand-Assisted Sulfide Surface Treatment of CsPbI3 Perovskite Quantum Dots to
Increase Photoluminescence and RecoveryKim Anh Huynh, Sa-Rang Bae, Tuan Van Nguyen, Ha Huu Do, Do Yeon Heo, Jinwoo Park, Tae-Woo Lee, Quyet Van Le*, Sang Hyun Ahn*, and Soo Young Kim*
CsPbI3 perovskite quantum dots (QDs) are more unstable over time as compared to other perovskite QDs, owing to ligand loss and phase transformation. The strong red emission from fresh CsPbI3 QDs gradually declines to a weak emission from aged QDs, which PLQY dropped by 93% after a 20 day storage; finally, there is no emission from δ-phase CsPbI3. The present study demonstrated a facile surface treatment method, where a sulfur–oleylamine (S-OLA) complex was utilized to passivate the defect-rich surface of the CsPbI3 QDs and then self-assembly to form a matrix outside the CsPbI3 QDs protected the QDs from environmental moisture and solar irradiation. The PLQY of the treated CsPbI3 QDs increased to 82.4% compared to initial value of 52.3% of the fresh QDs. Furthermore, there was a significant increase in the colloidal stability of the CsPbI3 QDs. Above 80% of the original PLQY of the treated QDs was reserved after a 20 day storage and the black phase could be maintained for three months before transforming to the yellow phase. The introduction of S-OLA induced the recovery of the lost photoluminescence of the nonluminous aged CsPbI3 QDs with time to 95% of that of the fresh QDs. Furthermore, the photoluminescence was maintained for one month. The increase in the stability and photoluminescence are critical for realizing high-performance perovskite-QD-based devices. Therefore, this work paves the way for increasing the performance of perovskite-based devices in the near future.
Polarization and Spatial Mode Structure of Mid-Infrared-Driven Terahertz-to-Microwave Radiation
A. V. Mitrofanov, A. A. Voronin, M. V. Rozhko, D. A. Sidorov-Biryukov, M. M. Nazarov, A. B. Fedotov, and A. M. Zheltikov*
Polarization and angle resolved analysis of microwave-to-terahertz (μWv/THz) radiation from gas-phase plasmas induced by ultrashort mid-infrared laser pulses reveals a complex vectorial electrodynamic picture of μWv/THz generation by a diverse manifold of laser-driven plasma currents and provides a powerful tool to distinguish between currents of different spatial symmetries as sources of μWv/THz radiation. In experiments with a single-color mid-IR driver, the spatial mode of μWv/THz radiation is found to retain a remarkably uniform, conical-emission structure across its entire spectral span, with angular dispersion and a spatial mode profile as dictated by Cherenkov-type phase matching. This spatial mode structure is consistent with its polarization properties of μWv/THz radiation, indicating the dominant role of radiation by ponderomotively driven longitudinal currents. In experiments with a two-color laser driver, the spatial-polarization mode structure of μWv/THz radiation is found to change across its spectrum and as a function of the gas pressure, revealing mixed symmetries of underlying electric currents and indicating the shifting roles of transverse and longitudinal currents as mechanisms behind μWv/THz generation.
Nonreciprocal Light Propagation in a Cascaded All-Silicon Microring Modulator
Awanish Pandey*, Sarvagya Dwivedi, Tang Zhenzhou, Shilong Pan, and Dries Van Thourhout
optical isolators and circulators are critical building blocks for large-scale photonic integrated circuits. Among the several methods proposed to realize such nonreciprocal devices, including heterogeneous integration with garnet-based materials or using nonlinearities, dynamic modulation of the waveguide properties is a potentially practical and easily accessible method. However, most proposals relying on this method rely on modulators with a very large footprint, limiting their practical applicability. This paper overcomes this issue by presenting a method to achieve nonreciprocal optical transmission taking advantage of compact ring modulators. We use a cascaded system of microring modulators with a footprint as small as 15 μm × 220 μm and propose that, by tuning the relative time delay between the RF driving signals and the optical delay between the modulators, nonreciprocal transmission can be achieved. We present a detailed theoretical analysis of our design and investigate the origin of the asymmetric transmission. The modulators were designed and fabricated on IMEC’s Silicon-on-Insulator platform iSiPP50G. We achieve a 16 dB difference between forward and backward optical signals at a driving voltage (Vpp) of 8 V at 6 GHz. Moreover, we analyze the impact of fabrication imperfections on the device performance. Our work leads to a significant reduction in device footprint compared to formerly explored solutions using dynamic modulation and is well suited for monolithic integration with photonic integrated circuits.
Analog Quantum Simulation of Non-Condon Effects in Molecular Spectroscopy
Hamza Jnane, Nicolas P. D. Sawaya, Borja Peropadre, Alan Aspuru-Guzik, Raul Garcia-Patron, and Joonsuk Huh*
In this work, we present a linear optical implementation for analog quantum simulation of molecular vibronic spectra, incorporating the non-Condon scattering operation with a quadratically small truncation error. To date, analog and digital quantum algorithms for achieving quantum speedup have been suggested only in the Condon regime, which refers to a transition dipole moment that is independent of nuclear coordinates. For analog quantum optical simulation beyond the Condon regime (i.e., non-Condon transitions), the resulting nonunitary scattering operations must be handled appropriately in a linear optical network. In this paper, we consider the first- and second-order Herzberg–Teller expansions of the transition dipole moment operator for the non-Condon effect for implementation on linear optical quantum hardware. We believe that the method opens a new way to approximate arbitrary nonunitary operations in analog and digital quantum simulations. We report in silico simulations of the vibronic spectra for naphthalene, phenanthrene, and benzene to support our findings.
Narrowband optical coupler Using Fano interference in First Order Diffraction
Giorgio Quaranta, Fabian Lütolf, Olivier J. F. Martin, and Benjamin Gallinet*
Light coupling in waveguides has been extensively investigated in a variety of contexts, from photonic integrated circuits to biosensing and near-eye displays for augmented reality. Here, narrowband diffraction is reported using a Fano interference effect in hybrid nanostructures. The excitation of hybrid plasmonic and bulk waveguides allows for a selectivity of 10 nm bandwidth in the first order and strong reduction of the entire zeroth order. A Fano formalism is used to predict the maximal diffraction efficiency at critical coupling, when external mode coupling balances intrinsic losses. It is found that the first order and zeroth order are related by a Fano-like spectral profile with similar spectral widths, resonance wavelengths, and modulation depths and differ only in the asymmetry parameter. The diffraction efficiency, angle, and wavelength can be solely tuned by the thin film thickness. A semianalytical dispersion model of the hybrid system is introduced and validated experimentally. Applications are foreseen in many optical devices that require color-selective coupling or dispersive properties such as optical document security or near-eye displays. The dispersion behavior under a divergent light source can also be utilized to design inexpensive, compact, and robust spectrometers or biosensors.
Scattering of Light with Orbital Angular Momentum from a Metallic Meta-Cylinder with Engineered Topological Charge
Yanyan Cao, Yangyang Fu, Jian-Hua Jiang, Lei Gao*, and Yadong Xu*
Planar metasurfaces with phase gradient exhibit unprecedented abilities in freely controlling light propagation. On the other hand, only a few studies have been devoted to unveiling the light scattering properties of cylindrical metasurfaces. Here we propose and study a metallic cylinder with a phase gradient obtained by engineering the gradient of grooves on its outer surface. We find that structural topological charges may be generated by the phase gradient in the meta-cylinder that, in turn, may be exploited to manipulate light scattering with orbital angular momentum (OAM) and obtain a new conservation law for OAM. Remarkably, at variance with results obtained by conventional core–shell structures, high-efficiency and multichannel OAM conversion/absorption may be realized with a single meta-cylinder, aswe prove by theoretical analysis and numerical simulations. Moreover, owing to the transition of the diffraction channel and Ohmic loss in metal, asymmetric response to light is observed for incident OAM with opposite helicity. Our results open up a new train of thought for manipulating light scattering with OAM and pave the way to further versatile applications involving the manipulation of OAM with meta-objects.
Direct Growth of Hexagonal Boron Nitride on Photonic Chips for High-Throughput Characterization
Evgenii Glushkov*, Noah Mendelson, Andrey Chernev, Ritika Ritika, Martina Lihter, Reza R. Zamani, Jean Comtet, Vytautas Navikas, Igor Aharonovich, and Aleksandra Radenovic*
Adapting optical microscopy methods for nanoscale characterization of defects in two-dimensional (2D) materials is a vital step for photonic on-chip devices. To increase the analysis throughput, waveguide-based on-chip imaging platforms have been recently developed. Their inherent disadvantage, however, is the necessity to transfer the 2D material from the growth substrate to the imaging chip, which introduces nonuniform material coverage and contamination, potentially altering the characterization results. Here we present a unique approach to circumvent these shortfalls by directly growing a widely used 2D material (hexagonal boron nitride, hBN) on silicon nitride chips and optically characterizing the defects in the intact as-grown material. We compare the direct growth approach to the standard PMMA-assisted wet transfer method and confirm the clear advantages of the direct growth. While demonstrated with hBN in the current work, the method can be extended to other 2D materials.
Direct Plasmonic Excitation of the Hybridized Surface States in Metal Nanoparticles
Jacob B Khurgin*, Alexander Petrov, Manfred Eich, and Alexander V. Uskov
Plasmon-driven chemical reactions are a subject that is currently capturing the attention of the research community and generates a fair amount of arguments about their origin. Taking into account that the lifetime of excited hot carriers in metals is very short, some mechanism is required to store carriers long enough and in sites that allow chemical reactions with the environment. One established mechanism is the injection of charges into either the valence or conduction band of a semiconductor, followed by a chemical reaction at the semiconductor surface. Here, we consider a somewhat less-explored pathway by which plasmon decay can cause a chemical reaction: the direct excitation of hybridized surface states by plasmons. Using a simple model, we evaluate theoretically the rate of direct excitation and find that it can be comparable and often exceed the rate of indirect excitation of surface states. Our findings correspond to prior experimental results. We also identify the conditions under which one can enhance the direct excitation efficiency and, thus, bring plasmon-driven photochemistry closer to practical applications.
Coherent Confocal Light Scattering Spectroscopic Microscopy Evaluates Cancer
Progression and Aggressiveness in Live Cells and TissueDouglas K. Pleskow, Lei Zhang, Vladimir Turzhitsky, Mark F. Coughlan, Umar Khan, Xuejun Zhang, Conor J. Sheil, Maria Glyavina, Liming Chen, Shweta Shinagare, Yuri N. Zakharov, Edward Vitkin, Irving Itzkan, Lev T. Perelman*, and Le Qiu*
The observation of biological structures in live cells beyond the diffraction limit with super-resolution fluorescence microscopy is limited by the ability of fluorescence probes to permeate live cells and the effect of these probes, which are often toxic, on cellular behavior. Here we present a coherent confocal light scattering and absorption spectroscopic microscopy that for the first time enables the use of large numerical aperture optics to characterize structures in live cells down to 10 nm spatial scales, well beyond the diffraction limit. Not only does this new capability allow high-resolution microscopy with light scattering contrast, but it can also be used with almost any light scattering spectroscopic application that employs lenses. We demonstrate that the coherent light scattering contrast based technique allows continuous temporal tracking of the transition from noncancerous to an early cancerous state in live cells, without exogenous markers. We also use the technique to sense differences in the aggressiveness of cancer in live cells and for label-free identification of different grades of cancer in resected tumor tissues.
Exploring the Limit of Multiplexed Near-Field optical trapping
Donato Conteduca, Giuseppe Brunetti, Giampaolo Pitruzzello, Francesco Tragni, Kishan Dholakia, Thomas F. Krauss, and Caterina Ciminelli*
Optical trapping has revolutionized our understanding of biology by manipulating cells and single molecules using optical forces. Moving to the near-field creates intense field gradients to trap very smaller particles, such as DNA fragments, viruses, and vesicles. The next frontier for such optical nanotweezers in biomedical applications is to trap multiple particles and to study their heterogeneity. To this end, we have studied dielectric metasurfaces that allow the parallel trapping of multiple particles. We have explored the requirements for such metasurfaces and introduce a structure that allows the trapping of a large number of nanoscale particles (>1000) with a very low total power P < 26 mW. We experimentally demonstrate the near-field enhancement provided by the metasurface and simulate its trapping performance. We have optimized the metasurface for the trapping of 100 nm diameter particles, which will open up opportunities for new biological studies on viruses and extracellular vesicles, such as studying heterogeneity, or to massively parallelize analyses for drug discovery.
Vacuum-Deposited microcavity Perovskite Photovoltaic Devices
Abhyuday Paliwal, Chris Dreessen, Kassio P. S. Zanoni, Benedikt Dänekamp, Beom-Soo Kim, Michele Sessolo, Koen Vandewal, and Henk J. Bolink*
The interaction between semiconductor materials and electromagnetic fields resonating in microcavities or the light–matter coupling is of both fundamental and practical significance for improving the performance of various photonic technologies. The demonstration of light–matter coupling effects in the emerging perovskite-based optoelectronic devices via optical pumping and electrical readout (e.g., photovoltaics) and vice versa (e.g., light-emitting diodes), however, is still scarce. Here, we demonstrate the microcavity formation in vacuum-deposited methylammonium lead iodide (CH3NH3PbI3, MAPI) p-i-n photovoltaic devices fabricated between two reflecting silver electrodes. We tune the position of the microcavity mode across MAPI’s absorption edge and study the effect on the microcavity absorption enhancement. Tuning the microcavity mode toward lower energies enhances the absorption of the lower energy photons and steepens the absorption onset which reduces the effective optical gap (Eg) of the devices. This leads to a reduction in the open circuit voltage deficit.
Ten-Port Unitary Optical Processor on a Silicon Photonic Chip
Rui Tang*, Ryota Tanomura, Takuo Tanemura*, and Yoshiaki Nakano
Unitary optical processors (UOPs) are task-specific computing units that can ultimately enable ultrafast and energy-efficient unitary matrix-vector multiplications based on the interference between coherent optical beams. The UOP using multiport directional couplers (MDCs) holds great promise in large-scale integration because of its unique robustness against fabrication errors. Here, we demonstrate a 10-port robust UOP on a silicon photonic chip, which is so far the largest-scale UOP using multiport directional couplers. We further show the unique flexibility of this architecture by demonstrating operations for both the transverse electric (TE) and the transverse magnetic (TM) polarizations, which has never been realized in previous UOPs. This flexible and robust architecture is suitable for various scenarios in deep learning, optical communication, and quantum information processing.
Stimulated Emission Depletion Microscopy with Color Centers in Hexagonal Boron Nitride
Prince Khatri*, Ralph Nicholas Edward Malein, Andrew J. Ramsay, and Isaac J. Luxmoore*
Stimulated emission depletion, or STED microscopy, is a well-established super-resolution technique, but is ultimately limited by the chosen fluorophore. Here we demonstrate STED microscopy with color centers in nanoscale flakes of hexagonal boron nitride using time-gated, continuous-wave STED. For color centers with zero phonon line emission around 580 nm, we measure a STED cross section of (5.5 ± 3.2) × 10–17 cm2, achieve a resolution of ∼50 nm, and resolve two color centers separated by 250 nm, which is less than the diffraction limit. The achieved resolution is limited by the numerical aperture of the objective lens (0.8) and the available laser power, and we predict that a resolution of sub-10 nm can be achieved with an oil immersion objective lens, similar to the state-of-the-art resolution obtained with nitrogen vacancy centers in diamond.
Multiphoton Photoluminescence in Hybrid Plasmon–Fiber Cavities with Au and Au@Pd Nanobipyramids: Two-Photon versus Four-Photon Processes and Rapid quenching
Qi Ai*, Han Zhang, Jianfang Wang, and Harald Giessen*
We investigate the multiphoton photoluminescence (MPPL) characteristics of bare and palladium-capped gold nanobipyramid particles deposited on microfibers with diameters around 1.7 μm. A broad luminescence emission with two evident peaks is detected when the coupled gold nanobipyramid particles are illuminated with a fem-tosecond laser. By employing multiple peak Lorentz fitting to each PL emission spectrum and performing nonlinear order analysis of the excitation power depend-ent measurement, we come to the conclusion that four-photon photoluminescence (4PPL) at around 520 nm and two-photon photoluminescence (2PPL) at longer wavelengths are the main constituents of the broad luminescence emission. Add-itionally, we observed unexpectedly that those two emission processes have different polarization characteristics. These characteristics can be understood and explained by taking into account the band and crystalline structure of the gold nanobipyram-ids. Furthermore, the L-band-related 4PPL emission is quenched for Au@Pd nano-bipyramids due to the fast transfer of electrons from the gold to the palladium. This provides us with a new way of modifying the photoluminescence in coupled hybrid bimetallic nanostructures. This deeper understanding of MPPL in gold nanoparticles paves the way to precise control of the luminescence emission from plasmonic nano-particles, which is crucial for further applications in biological imaging and phototh-ermal therapy.
Generation and Tunability of Supermodes in Tamm Plasmon Topological Superlattices
Tong Qiao, Mengying Hu, Xi Jiang, Qiang Wang, Shining Zhu, and Hui Liu*
In this study, we propose and experimentally demonstrate a novel kind of Tamm plasmon topological superlattice (TTS) by engineering Tamm photonic crystals (TPCs) belonging to a different class of topology. Utilizing specifically designed double-layer metasurfaces etching on planar multilayered photonic structures, the TPC that supports the Tamm plasmon photonic bandgap is realized in the visible regime. Through the coupling of topological interface states existing between diff-erent TPCs, hybrid topological interface states of Tamm plasmon, called supermo-des, are obtained that can be fully described by a tight-binding model. Meanwhile, we can achieve a tunable bandwidth of supermodes via varying the etching depth difference between double-layer metasurfaces. We show that the bandwidth decre-ases with the increase of etching depth difference, resulting in a nearly flat dispersi-on of supermodes with strong localization, regardless of excitation angles. All the results are experimentally verified by measuring angular-resolved reflectance spe-ctra. The TTS and supermodes proposed here open a new pathway for the manipu-lation of Tamm plasmons based on which various promising applications such as integrated photonic devices, optical sensing, and enhancing light–matter intera-ctions can be realized.
Co-Design of Free-Space Metasurface Optical Neuromorphic Classifiers for High Performance
François Léonard*, Adam S. Backer, Elliot J. Fuller, Corinne Teeter, and Craig M. Vineyard
Classification of features in a scene typically requires conversion of the incoming photonic field into the electronic domain. Recently, an alternative approach has emerged whereby passive structured materials can perform classification tasks by directly using free-space propagation and diffraction of light. In this manuscript, we present a theoretical and computational study of such systems and establish the basic features that govern their performance. We show that system architecture, material structure, and input light field are intertwined and need to be co-designed to maximize classification accuracy. Our simulations show that a single layer meta-surface can achieve classification accuracy better than conventional linear classifiers, with an order of magnitude fewer diffractive features than previously reported. For a wavelength λ, single layer metasurfaces of size 100λ × 100λ with an aperture density λ–2 achieve ∼96% testing accuracy on the MNIST data set, for an optimized distance ∼100λ to the output plane. This is enabled by an intrinsic nonlinearity in photodete-ction, despite the use of linear optical metamaterials. Furthermore, we find that once the system is optimized, the number of diffractive features is the main determinant of classification performance. The slow asymptotic scaling with the number of apert-ures suggests a reason why such systems may benefit from multiple layer designs. Finally, we show a trade-off between the number of apertures and fabrication noise.
Probing the Redox Selectivity on Au@Pd and Au@Pt Bimetallic Nanoplates by Tip-Enhanced Raman spectroscopy
Zhandong Li and Dmitry Kurouski*
Bimetallic nanostructures possess unique catalytic reactivity and selectivity in plas-mondriven reactions. Such nanostructures are typically composed of plasmonic and catalytic metals. A growing body of evidence suggests that unique catalytic reactivity and selectivity of bimetallic nanostructures are determined by the intensity of the rectified electric field, the nature of the catalytic metals, and the interplay between catalytic and plasmonic metals at the nanoscale. However, the actual impact of all these factors remains unclear. In this study, we use tip-enhanced Raman spectros-copy (TERS) to determine the underlying physical cause of catalytic reactivity and selectivity of gold–platinum (Au@PtNPs) and gold–palladium (Au@PdNPs) bimeta-llic nanoplates. We perform nanoscale imaging of plasmon-driven oxidation of 4-mercapto-phenyl-methanol (MPM) to 4-mercaptobenzoic acid (MBA) and a reversed plasmon-driven reduction of MBA to MPM on Au@PtNPs, Au@PdNPs, and their monometallic analogues, AuNPs. Our results show that plasmon-driven reduction of MBA to MPM is evident only for Au@PdNPs, whereas Au@PtNPs exclusively poss-ess oxidation properties enabling MPM to MBA conversion. These results show that the nature of the catalytic metal determines redox properties of bimetallic nanostru-ctures. At the same time, none of these redox reactions are evident for AuNPs. Instead, we observe only C–C cleavage of both MPM and MBA that yields thiophe-nol. These findings suggest that the rectified electric field determines the reactivity of plasmon-driven reactions, whereas its intensity can be used to predict chemical tran-sformations on these mono- and bimetallic nanostructures.
Efficient Amplified Spontaneous Emission from Solution-Processed CsPbBr3 nanocrystal Microcavities under Continuous Wave Excitation
Modestos Athanasiou*, Paris Papagiorgis, Andreas Manoli, Caterina Bernasconi, Maryna I. Bodnarchuk, Maksym V. Kovalenko, and Grigorios Itskos*
Solution-processed lasers are cost-effective, compatible with a vast range of photonic resonators, and suited for a mass production of flexible, lightweight, and disposable devices. The emerging class of lead halide perovskite nanocrystals (LHP NCs) can serve as a highly suitable active medium for such lasers, owing to their outstanding optical gain properties and the suppressed optical nonradiative recombination losses stemming from their defect-tolerant nature. In this work, CsPbBr3 NCs are embed-ded within polymeric Bragg reflectors to produce fully solution-processed microc-avities. By a systematic parametric optimization of the polymer mirrors, resonators with Q-factors up to 110 can be produced in the green, supporting amplified sponta-neous emission (ASE) under continuous wave excitation, with a threshold as low as 140 mW/cm2. Angle-dependent reflectivity and luminescence studies performed below the ASE threshold demonstrate the strong spectral and angular redistribution of the CsPbBr3 NC spontaneous emission when coupled to the cavity mode. Under resonance, amplification of the output intensity by a factor of 9 in the vicinity of the cavity mode and by a factor of 5 in the whole integrated emission along with an incr-ease of the radiative rate accounted by a Purcell factor of 2 is obtained with respect to NCs deposited in reference microcavity structures.
Mg2+-Assisted Passivation of Surface Defects of Perovskite Polymer Composite Films for White Light-Emitting Diodes
Feiyang Ren, Fan Chen, Enrou Mei, Xiaojuan Liang*, Peng-cheng Qian*, and Weidong Xiang*
The instability of perovskites is the most critical unsolved problem that limits their practical application. In this work, magnesium oxide (MgO) was introduced into perovskite nanocrystals (PNCs) by the traditional hot injection strategy (HI), resul-ting in a decrease in the defects PNCs; therefore the photoluminescence quantum yield (PLQY) can be effectively improved. CsPb(Br/I)3-Mg@styrene-ethylene-butylene-styrene (SEBS) composite films were prepared by mixing perovskite nano-crystals and a SEBS toluene solution. Benefiting from the effective protection of the SEBS matrix, the blue light exposure, and thermal and water stability of PNCs are greatly improved. By combining a red composite film with a Ce:YAG phosphor and an InGaN blue chip, the color rendering index (CRI) of the assembled white light-emitting diodes (WLEDs) can exceed 90 (Ra > 90). Additionally, a light emit-ting device with a wide color gamut of 128% of the National Television Standards Com-mittee (NTSC) was achieved by combining green and red composite films with blue chips. The stable and flexible composite film will promote the application of PNCs in the field of general lighting applications and thin-film displays.
1D Self-Healing Beams in Integrated Silicon Photonics
Zhuoran Fang*, Rui Chen, Albert Ryou, and Arka Majumdar*
Since the first experimental observation of optical Airy beams, various applications ranging from particle and cell micromanipulation to laser micromachining have ex-ploited their nondiffracting and accelerating properties. The later discovery that Airy beams can self-heal after being blocked by an obstacle further proved their robust-ness to propagate under a scattering and disordered environment. Here, we report the generation of an Airy-like accelerating beam on an integrated silicon photonic chip and demonstrate that the on-chip 1D Airy-like accelerating beams preserve the same properties as the 2D Airy beams. The 1D synthetic-phase meta-optics used to create the accelerating beam has the size of only 3 μm × 16 μm, at least 3 orders of magnitude smaller than the conventional optic. The on-chip self-healing beams demonstrated here could potentially enable diffraction-free light routing for on-chip optical networks and high-precision micromanipulation of biomolecules on an integrated photonic chip.
Identification of Microplastics Based on the Fractal Properties of Their Holographic Fingerprint
Vittorio Bianco*, Daniele Pirone, Pasquale Memmolo, Francesco Merola, and Pietro Ferraro
Water plastic pollution is a serious problem affecting sealife, marine habitats, and the food chain. Artificial intelligence-enabled coherent imaging has recently shown exciting advances in the field of environmental monitoring, and portable holographic microscopes are good candidates to map the microparticles content of marine waters. The “holographic fingerprint” due to coherent light diffraction is rich in information, fully encoded into the complex wavefront scattered by the sample. Hence, proper analysis of the wavefronts reconstructed from digital holograms can unlock new possibilities in the fields of diagnostics and environmental monitoring. Fractal geometry well describes natural objects and allows inferring added-value information on the way these fill 2D spaces and 3D volumes. The most abundant micron-scale class of objects that populate marine waters consists of microalgae named diatoms, which are of interest as bioindicators of water quality. Here we inve-stigate the fractal properties of holographic patterns of diatoms and microplastics, considering a heterogeneous mixture of five types of plastic materials and 55 different species of microalgae. We show that, different from the case of weak scat-tering objects, a small set of fractal parameters is able to characterize these two large ensembles. As an applicative example, we carry out classification tests to show the possibility to identify the two classes with high accuracy. This new holographic frac-tal description of scattering micro-objects could be used in the near future for in situ automatic mapping of microplastic pollutants and for taxonomy of diatoms as water quality bioindicators, screened onboard holographic systems.
Asymmetric Quantum-Dot Pixelation for Color-Converted white balance
Enguo Chen*, Jianyao Lin, Tao Yang, Yu Chen, Xiang Zhang, Yun Ye, Jie Sun*, Qun Yan, and Tailiang Guo
Pixelated quantum-dot color conversion film (QDCCF) is attractive for next-generation, high-pixel-density, full-color displays. However, how to achieve white balance of these QD converted displays puts forward a new challenge, because the final light-emitting area is redefined by the apertures of the QD formed subpixels. Based on this, this paper presents an effective white-balance realization approach by precisely defining an asymmetric aperture ratio among three primary-color subpixels of the QDCCF. Based on the measured photoluminescence characteristic of quantum-dot photoresist (QDPR), the theoretical aperture ratio can be derived by the spectral radiation energy and external quantum efficiency (EQE) of QDCCFs for the target D65 white-balance state. A bilayered device architecture, combining a blue mini-LED backlight and a pixelated QDCCF, was simulated and experimentally assembled to verify the theoretical design. The simulated chromatic coordinates obtained from the QDCCF precisely agree with the target white-balance point. Experimental patterning and pixelation of the designed QDCCF were achieved by a precise photolithography process. Measured results show that a white-light output was achieved with the chromatic coordinates of (0.2822, 0.2951) and the color gamut of 115.09% NTSC (National television system Committee) standard. The deviation of the experimental chromatic coordinates is within ±0.05 to the D65 standard light source. The proposed white-balance realization approach featured by the aperture adjustable subpixels of a chromatic QDCCF may open up a new route for color reproduction in emerging display technologies.
cmos-Compatible Bias-Tunable Dual-Band Detector Based on GeSn/Ge/Si Coupled photodiodes
Enrico Talamas Simola*, Vivien Kiyek, Andrea Ballabio, Viktoria Schlykow, Jacopo Frigerio, Carlo Zucchetti, Andrea De Iacovo, Lorenzo Colace, Yuji Yamamoto, Giovanni Capellini, Detlev Grützmacher, Dan Buca*, and Giovanni Isella
Infrared (IR) multispectral detection is attracting increasing interest with the rising demand for high spectral sensitivity, room temperature operation, CMOS-compatible devices. Here, we present a two-terminal dual-band detector, which provides a bias-switchable spectral response in two distinct IR bands. The device is obtained from a vertical GeSn/Ge/Si stack, forming a double junction n-i-p-i-n structure, epitaxially grown on a Si wafer. The photoresponse can be switched by inverting the bias polarity between the near and the short-wave IR bands, with specific detectivities of 1.9 × 1010 and 4.0 × 109 cm·(Hz)1/2/W, respectively. The possibility of detecting two spectral bands with the same pixel opens up interesting applications in the field of IR imaging and material recognition, as shown in a solvent detection test. The continuous voltage tuning, combined with the nonlinear photoresponse of the detector, enables a novel approach to spectral analysis, demonstrated by identifying the wavelength of a monochromatic beam.
Deep-Learning-Based Virtual Refocusing of Images Using an Engineered Point-Spread Function
Xilin Yang, Luzhe Huang, Yilin Luo, Yichen Wu, Hongda Wang, Yair Rivenson, and Aydogan Ozcan*
We present a virtual refocusing method over an extended depth of field (DOF) enabled by cascaded neural networks and a double-helix point-spread function (DH-PSF). This network model, referred to as W-Net, is composed of two cascaded generator and discriminator network pairs. The first generator network learns to virtually refocus an input image onto a user-defined plane, while the second generator learns to perform a cross-modality image transformation, improving the lateral resolution of the output image. Using this W-Net model with DH-PSF engineering, we experimentally extended the DOF of a fluorescence microscope by ∼20-fold. In addition to DH-PSF, we also report the application of this method to another spatially engineered imaging system that uses a tetrapod point-spread function. This approach can be widely used to develop deep-learning-enabled reconstruction methods for localization microscopy techniques that utilize engineered PSFs to considerably improve their imaging performance, including the spatial resolution and volumetric imaging throughput.
参考文献：July 21, 2021 Volume 8, Issue 7 Pages 1873-2182
期刊链接：https://pubs.acs.org/toc/apchd5/8/7
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