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  • Mid-Infrared ultra-strong light-matter coupling for THz thermal emission
    ACS Photonics (IF 6.756) Pub Date : 2017-09-22
    Benjamin Askenazi, Angela Vasanelli, Yanko Todorov, Emilie Sakat, Jean-Jacques Greffet, Grégoire Beaudoin, Isabelle Sagnes, Carlo Sirtori

    In condensed matter, THz optical resonances (1 – 5 THz) are very sensitive to thermally activated phenomena that can either equate the populations between the levels or irremediably broaden the transition to a point where it disappears. It is therefore very difficult to exploit THz electronic transitions for thermal emission. To bypass this problem, we have used a transition in the mid-infrared, (10 – 50 THz) ultra-strongly coupled to a resonant mode of a highly subwavelength microcavity. The coupling strength in our system reaches 90% of the energy of the matter resonance, and becomes so high that the lower-polariton state lies in the THz region. This mixed light-matter resonance is therefore issued from an optical transition that is much less sensitive to thermal effects, as we have experimentally demonstrated. Our system has been optimized by tailoring the cavity thickness and engineering the matter resonance, which arises from a set of heavily doped quantum wells, in order to increase the THz emissivity. By injecting a lateral current in the quantum wells that raises the electronic temperature, we have observed THz emission up to room temperature.

    更新日期:2017-09-23
  • Plasmonic Interference in Superstructured Metal Photonic Crystals
    ACS Photonics (IF 6.756) Pub Date : 2017-09-22
    S. C. Lee, S. R. J. Brueck
    更新日期:2017-09-22
  • Correlating Light Absorption with Various Nanostructure Geometries in Vertically Aligned Si Nanowire Arrays
    ACS Photonics (IF 6.756) Pub Date : 2017-09-22
    Yi-Seul Park, Jin Seok Lee
    更新日期:2017-09-22
  • Flexible Three-Dimensional Anti-Counterfeiting Plasmonic Security Label: Utilizing Z-Axis-Dependent SERS Readouts to Encode Multi-Layered Molecular Information
    ACS Photonics (IF 6.756) Pub Date : 2017-09-21
    Yejing Liu, Yih Hong Lee, Mian Rong Lee, Yijie Yang, Xing Yi Ling

    Current surface-enhanced Raman scattering (SERS)-based anti-counterfeiting strategies primarily encode molecular information in single two-dimensional (2D) planes and under-utilize the three-dimensionality (3D) of plasmonic hot spots. Here, we demonstrate a 3D SERS anti-counterfeiting platform to extend “layered security” capabilities from 2D to 3D. We achieve this capability by combining 3D candlestick microstructures with 3D SERS imaging to fully resolve a at least three layers of encoded information within the same 2D area along the z-axis, notably using only a single probe molecule. Specific pre-designed covert images can only be fully recovered via hyperspectral SERS imaging at pre-determined z values. Furthermore, our 3D SERS anti-counterfeiting security labels can be fabricated on both rigid and flexible substrates, widening their potential usages to curved product surfaces and banknotes.

    更新日期:2017-09-21
  • Three-Dimensionally Coupled THz Octagrams as Isotropic Metamaterials
    ACS Photonics (IF 6.756) Pub Date : 2017-09-21
    Kriti Agarwal, Chao Liu, Daeha Joung, Hyeong-Ryeol Park, Jeeyoon Jeong, Dai-Sik Kim, Jeong-Hyun Cho
    更新日期:2017-09-21
  • Solid Ligand-Assisted Storage of Air-Stable Formamidinium Lead Halide Quantum Dots via Restraining the Highly Dynamic Surface Towards Brightly Luminescent Light Emitting Diodes
    ACS Photonics (IF 6.756) Pub Date : 2017-09-21
    Qinghua Li, Haiyang Li, Huaibin Shen, Fangfang Wang, Feng Zhao, Feng Li, Xugu Zhang, Danyang Li, Xiao Jin, Weifu Sun

    Although organometal halide perovskites have garnered enormous interest in solar cells, nonetheless limited attention has been paid to light emitting devices fabricated from formamidinium lead halide perovskite. Highly luminescent and air-stable formamidinium lead halide perovskite quantum dots using high melting point ligands have been synthesized. Through compositional engineering, the emission spectra are readily tunable over the entire visible spectral region of 409−817 nm. The photoluminescence of FAPbX3 nanocrystals are characteristic of narrow emission line-widths of 21~34 nm, high quantum yields of up to 88% and a photoluminescence lifetime of 54.6-68.6 ns for single halide FAPbBr3 that could be stable for several months. We have demonstrated the fabrication of highly efficient perovskite quantum dot-based green light emitting diodes with the highest luminance of 33993 cd m-2, the highest current efficiency of 20.3 cd A-1 and moderately high max external quantum efficiency of 4.07%.

    更新日期:2017-09-21
  • Halide Perovskite 3D Photonic Crystals for Distributed Feedback Lasers
    ACS Photonics (IF 6.756) Pub Date : 2017-09-20
    Stefan Schünemann, Sarah Brittman, Kun Chen, Erik C. Garnett, Harun Tüysüz
    更新日期:2017-09-20
  • Nonlocal Effects In Transition Hyperbolic Metamaterials
    ACS Photonics (IF 6.756) Pub Date : 2017-09-19
    Brian M Wells, Zhaxylyk A Kudyshev, Natalia M. Litchinitser, Viktor A. Podolskiy

    Light-matter interactions at a particular point in a material may be dominated by properties of the medium at this point or they could be affected by the electromagnetic properties of the medium in the surrounding regions. In the former case, the medium is said to be local, while in the latter, it is nonlocal. Recent studies of light-matter interactions in composite optical metamaterials showed that nonlocal effects enable new optical phenomena that are not acounted for by the conventional, local effective medium description. Up until now the majority of studies focused on metamaterials with spatially uniform material parameters. However, optical metamaterials with electromagnetic material parameters gradually changing from positive to negative values, so-called transition materials, have been predicted to induce a strong enhancement of the local electric or magnetic field in the vicinity of the zero referactive index point. This opens new opportunities for sensing and low-intensity nonlinear optical applications. Here, we analyze the field enhancement in realistic transition metamaterials consisting of an array of plasmonic cone-shaped rods embedded in dielectric matrix and demonstrate that optical nonlocality is required to adequately describe this optical response. This work enables design and practical applications of this new emerging metamaterial platform.

    更新日期:2017-09-20
  • Young’s double-slit, invisible objects and the role of noise in an optical epsilon-near-zero experiment
    ACS Photonics (IF 6.756) Pub Date : 2017-09-19
    Daniel Ploss, Arian Kriesch, Christoph Etrich, Nader Engheta, Ulf Peschel

    Epsilon-near-zero (ENZ) media disclose the peculiarities of electrodynamics in the limit of infinite wavelength but non-zero frequency for experiments and applications. Theory suggests that wave interaction with obstacles and disturbances dramatically changes in this domain. To investigate the optics of those effects we fabricated a nanostructured 2D optical ENZ multilayer waveguide that is probed with wavelength-tuned laser light via a nanoscale wave launch configuration. In this experimental framework we directly optically measure wave propagation and diffraction in a realistic system with the level and scale of imperfection that is typical in nanooptics. As we scan the wavelength from 1.0 µm to 1.7 µm, we approach the ENZ regime, and observe the interference pattern of a micro-scale Young’s double slit to steeply diverge. By evaluating multiple diffraction orders we experimentally determine the effective refractive index neff and its zero-crossing as an intrinsic measured reference, which is in agreement with theoretical predictions. We further verify that the double-slit and specifically placed scattering objects become gradually “invisible” when approaching the ENZ regime. We also observe that light-matter-interaction intensifies towards ENZ and quantify how speckle noise, caused by tiny random imperfections, increasingly dominates the optical response and blue-shifts the cut-off frequency.

    更新日期:2017-09-20
  • Magneto-Optical Response Enhanced by Mie Resonances in Nanoantennas
    ACS Photonics (IF 6.756) Pub Date : 2017-09-18
    Maria G. Barsukova, Alexander S. Shorokhov, Alexander I. Musorin, Dragomir N. Neshev, Yuri S. Kivshar, Andrey A. Fedyanin
    更新日期:2017-09-18
  • Highly Efficient and Stable Narrow-Band Red Phosphor Cs2SiF6:Mn4+ for High-Power Warm White LED Applications
    ACS Photonics (IF 6.756) Pub Date : 2017-09-15
    Enhai Song, Y. Y. Zhou, X. B. Yang, Z. F. Liao, Weiren Zhao, Ting-Ting Deng, L. Y. Wang, Y. Y. Ma, Shi Ye, Qinyuan Zhang

    Due to the unique narrow-band red emission and broadband blue light excitation, as well as milder synthesis conditions, Mn4+ ions activated fluoride red phosphors show great promising for white light emitting diodes (W-LEDs) applications. However, as the Mn4+ -emission belongs to a spin-forbidden transition (2Eg→4A2), it is a fundamental challenge to synthesize these phosphors with a high external quantum efficiency (EQE) above 60%. Herein, a highly efficient and thermally stable red fluoride phosphor Cs2SiF6:Mn4+ with a high internal quantum efficiency (IQE) of 89% and ultra-high EQE of 71% is demonstrated. Furthermore, nearly 95% of the room temperature IQE and EQE are maintained at 150 0C. The static and dynamic spectral measurements, as well as density functional theory (DFT) calculations show that the excellent performances of Cs2SiF6:Mn4+ is assigned to the Mn4+ ions tend to be evenly distributed in host lattice Cs2SiF6. By employing Cs2SiF6:Mn4+ as red light component, stable 10-W high-power warm W-LEDs with luminous efficiency of ~110 lm/W could be obtained. These findings indicate that red phosphor Cs2SiF6:Mn4+ may be highly suitable candidate for fabricating high-performance high-power warm white LEDs.

    更新日期:2017-09-15
  • Hybridized Plasmons in 2D Nano-slits: From Graphene to Anisotropic 2D Materials
    ACS Photonics (IF 6.756) Pub Date : 2017-09-15
    P. A. D. Gonçalves, Sanshui Xiao, N. M. R. Peres, N. Asger Mortensen

    Plasmon coupling and hybridization in complex nanostructures constitutes a fertile playground for controlling light at the nanoscale. Here, we present a semi-analytical model to describe the emergence of hybrid plasmon modes guided along 2D nano-slits. In particular, we find two new coupled plasmonic resonances arising from symmetric and antisymmetric hybridizations of the edge plasmons of the constituent half-sheets. These give rise to an antibonding and a bonding mode, lying above and below the energy of the bare edge plasmon. Our treatment is notably generic, being able to account for slits of arbitrary width, and remains valid irrespective of the 2D conductive material (e.g., doped graphene, 2D transition metal dichalcogenides, or phosphorene). We derive the dispersion relation of the hybrid modes of a 2D nano-slit along with the corresponding induced potential and electric field distributions. We also discuss the plasmonic spectrum of a 2D slit together with the one from its complementarity structure, that is, a ribbon. Finally, the case of a nano-slit made from an anisotropic 2D material is considered. Focusing on black phosphorus (which is highly anisotropic), we investigate the features of its plasmonic spectrum along the two main crystal axes. Our results offer insights into the interaction of plasmons in complex 2D nanostructures, thereby expanding the current toolkit of plasmonic resonances in 2D materials, and paving the way for the emergence of future compact devices based on atomically thin plasmonics.

    更新日期:2017-09-15
  • Spatiotemporal Dynamics and Control of Strong Coupling in Plasmonic Nanocavities
    ACS Photonics (IF 6.756) Pub Date : 2017-09-15
    Angela Demetriadou, Joachim M. Hamm, Yu Luo, John B. Pendry, Jeremy J. Baumberg, Ortwin Hess
    更新日期:2017-09-15
  • On-Chip Single Mode Distributed Feedback Colloidal Quantum Dot Laser under Nanosecond Pumping.
    ACS Photonics (IF 6.756) Pub Date : 2017-09-14
    Yunpeng Zhu, Weiqiang Xie, Suzanne Bisschop, Tangi Aubert, Edouard Brainis, Pieter Geiregat, Zeger Hens, Dries Van Thourhout

    We report on a hybrid integrated distributed feedback (DFB) laser fabricated using the colloidal quantum dots (QDs) /silicon nitride (SiN) integration platform. The DFB laser is fabricated with a CMOS compatible process and consists of a waveguide stack in which a QD layer is embedded between two SiN layers to enhance the coupling of the QD to the optical waveguide mode. Following characterization of the intrinsic properties of the CdSe/CdS core/shell QDs using transient absorption spectroscopy, we demonstrate single mode lasing upon nanosecond optical pumping. With a 7 nanosecond pump pulse, the lasing threshold is 270 μJ//cm2. This result attests of the potential of colloidal QDs as an enabling gain material for integrated SiN photonics and it showcases the design versatility of hybrid integrated photonics platforms based on colloidal QDs.

    更新日期:2017-09-15
  • Magneto-optical response enhanced by Mie resonances in nanoantennas
    ACS Photonics (IF 6.756) Pub Date : 2017-09-14
    Maria Barsukova, Alexander S. Shorokhov, Alexander Musorin, Dragomir Neshev, Yuri S. Kivshar, Andrey A. Fedyanin

    We demonstrate both experimentally and numerically multifold enhancement of magneto-optical effects in subwavelength dielectric nanostructures with magnetic surrounding exhibiting localized magnetic Mie resonances. We employ amorphous silicon nanodisks covered with a thin nickel film and achieve the fivefold enhancement of the magneto-optical response of the hybrid magnetophotonic array of nanodisks in comparison with a thin nickel film deposited on a flat silica substrate. Our findings allows for a new basis for active and nonreciprocal photonic nanostructures and metadevices, which could be tuned by an external magnetic field.

    更新日期:2017-09-15
  • Plasmonics in topological insulators: Spin-charge separation, the influence of the inversion layer, and phonon-plasmon coupling
    ACS Photonics (IF 6.756) Pub Date : 2017-09-13
    Tobias Stauber, Guillermo Gómez-Santos, Luis Brey

    We demonstrate via three examples that topological insulators (TI) offer a new platform for plasmonics. Firstly, we show that the collective excitations of a thin slab of a TI display spin-charge separation. This gives rise to purely charge-like optical and purely spin-like acoustic plasmons, respectively. Secondly, we argue that the depletion layer mixes Dirac and Schrödinger electrons which can lead to novel features such as high modulation depths and interband plasmons. The analysis is based on an extension of the usual formula for optical plasmons that depends on the slab width and on the dielectric constant of the TI. Thirdly, we discuss the coupling of the TI surface phonons to the plasmons and find strong hybridisation especially for samples with large slab widths.

    更新日期:2017-09-13
  • Infrared nano-imaging reveals the surface metallic plasmons in topological insulator
    ACS Photonics (IF 6.756) Pub Date : 2017-09-13
    Jian Yuan, Weiliang Ma, Lei Zhang, Yao Lu, Meng Zhao, Hongli Guo, Jin Zhao, Wenzhi Yu, Yupeng Zhang, Kai Zhang, Hui Ying Hoh, Xiaofeng Li, Kian Ping Loh, Shaojuan Li, Chengwei Qiu, Qiaoliang Bao

    Surface plasmons make a high degree of localization of electromagnetic fields achievable at the vicinity of metal surfaces. Topological insulators (TIs) are a family of materials which are insulating in the bulk but have metallic surfaces caused by the strong spin−orbit coupling. Surface plasmons supported by the surface state on topological insulators have attracted incredible interests from ultra violet to mid-infrared frequencies. In this work, we experimentally investigate the near-field properties of Bi2Te3 nanosheets using scattering-type scanning near-field optical microscopy (s-SNOM). The s-SNOM tip enables to detect significantly enhanced intensity in its near field at precisely controlled positions with regards to Bi2Te3 structure. With the help of highly position-selective excitation and high-pixel real-space mapping, we discover near-field patterns of bright outside fringes which are associated with its surface-metallic, plasmonic behavior at mid-infrared frequency. Thereby, we experimentally demonstrate that the scattered signal responses and near-field amplitudes of outside fringes can be tailored via mechanical (sheet thickness of Bi2Te3), electric (electrostatic gating), and optical (incident wavelength) fashions. The discovery of outside fringes in TI nanosheets may enable the development of strongly enhanced light–matter interactions for quantum optical devices, mid-infrared (MIR) and terahertz detectors or sensors.

    更新日期:2017-09-13
  • Piezo-phototronic Effect Enhanced Responsivity of Photon Sensor Based on Composition-tunable Ternary CdSxSe1-x Nanowires
    ACS Photonics (IF 6.756) Pub Date : 2017-09-13
    Guozhang Dai, Haiyang Zou, Xingfu Wang, Yuankai Zhou, Peihong Wang, Yong Ding, Yan Zhang, Junliang Yang, Zhong Lin Wang

    The study of piezotronics effect and piezo-phototronics effect on materials and devices are have been widely studied in binary semiconductors. Wide-band ternary semiconductor are a great class of materials with potential application in nano/microdevices, because of their continuously tunable physical properties with composition. Here, we first demonstrate the piezo-photronics effect of ternary wurtzite structured nanowires (NWs), opening an innovative materials system. Single crystal ternary CdSxSe1-x (x=0.85, 0.60 and 0.38) NWs were synthesized with site-controlled compositions via chemical vapor deposition process and high-performance visible photodetectors (PDs) with fast respond speed (< 2 ms), high photosensitivity, high responsivity and broaden photoresponse region (than CdS NW) were fabricated based on the these ternary materials. By introducing an external tensile strain, the performance of PDs is enhanced by 76.7% upon 0.2 mW/cm2 442 nm light illumination for CdS0.85Se0.15 by piezo-phototronic effect. The composition effect of materials in ternary materials on light detecting and piezo-phototronic was also first investigated systematically. The results indicate that in the CdSxSe1-x system, as the value of x decreases, the photocurrent and responsivity experience an increase, while the enhancement of piezo-phototronic effect was weakened. The change in piezoelectric coefficient and carries screening effect are proposed for the observed phenomenon. This study reported a high quality of ternary CdSxSe1-x NWs system used for high performance PDs, broadens the family of piezotronic materials, offers an innovative material for high-performance visible PD, and provides a new pathway to modulate the performance of piezo-phototronic devices by tuning the atomic ratios of the ternary wurtzite semiconducting materials. This is essential for developing a full understanding about piezotronics on a broader scope and it also enables the development of the better performance of optoelectronics devices.

    更新日期:2017-09-13
  • Multi-Level Nonvolatile Organic Photomemory based on Vanadyl-Phthalocyanine/para-Sexiphenyl Heterojunctions
    ACS Photonics (IF 6.756) Pub Date : 2017-09-13
    Chuan Qian, Jia Sun, Ling-An Kong, Ying Fu, Yang Chen, Juxiang Wang, Shitan Wang, Haipeng Xie, Han Huang, Junliang Yang, Yongli Gao

    Organic photomemory based on heterojunction phototransistor has been fabricated utilizing vanadyl-phthalocyanine (VOPc) on para-sexiphenyl (p-6P) thin films. Under 365 nm ultraviolet light irradiation, the ratio of photocurrent and dark current (Iph/Idark) and photoresponsivity of phototransistors are about 1.5×105 and 87 A/W, respectively. Such devices can transduce the input light signals into electrical signals and the output signals can be stored for recording the light simulation. After applying a light pulse (4.2 mW/cm2, 100 ms) on the device, the stored current level lasted for ~5000 s with only a 20% decrease, indicating a good photomemory behavior. Importantly, the photomemory behavior is effectively modulated by gate voltage. Multi-level photomemory behaviors are observed by modulating light pulse duration and light power intensity. Because of the construction of type-I heterojunction, the superior photomemory characteristics are mainly originated from efficient charge trapping at VOPc/p-6P interface. In-situ current sensitive atomic force microscopy (CSAFM) is used for monitoring surface current of the VOPc/p-6P heterojucntions. A change of conductivity in grains is observed upon 365 nm light illumination. After turning off the light, the current of grains did not rapidly decrease, but displayed the behavior of photomemory. This study provides a guide for designing high-performance organic photomemory devices.

    更新日期:2017-09-13
  • Manifestation of planar and bulk chirality mixture in plasmonic λ-shaped nanostructures caused by symmetry breaking defects}
    ACS Photonics (IF 6.756) Pub Date : 2017-09-12
    Aline Pham, Quanbo Jiang, Airong Zhao, Joel Bellessa, Cyriaque Genet, Aurélien Drezet

    We report on the coexistence of planar and bulk chiral effects in plasmonic Λ-shaped nanostructure arrays arising from symmetry breaking defects. The manifestation of bi-(2D) and three-(3D) dimensional chiral effects are revealed by means of polarization tomography and confirmed by symmetry considerations of the experimental Jones matrix. Notably, investigating the antisymmetric and symmetric parts of the Jones matrix points out the contribution of 2D and 3D chirality in the polarization conversion induced by the system whose eigenpolarizations attest of the coexistence of planar and bulk chirality. Furthermore, we introduce a generalization of the microscopic model of Kuhn, yielding to a physical picture of the origins of the observed planar chirality, circular birefringence and dichroism, theoretically prohibited in symmetric Λ-shaped nanostructures.

    更新日期:2017-09-13
  • Constructing “designer atoms” via resonant graphene-induced Lamb shifts
    ACS Photonics (IF 6.756) Pub Date : 2017-09-12
    Cyuan-Han Chang, Nicholas Rivera, John D. Joannopoulos, Marin Soljacic, Ido Kaminer

    The properties of an electron in an atom or molecule are not fixed; rather they are a function of the optical environment of the emitter. Not only is the spontaneous emission a function of the optical environment but also the underlying wavefunctions and energy levels, which are modified by the potential induced by quantum fluctuations of the electromagnetic field. In free space, this modification of atomic levels and wavefunctions is very weak and generally hard to observe due to the prevalence of other perturbations like fine structure. Here, we explore the possibility of highly tailorable electronic structure by exploiting large Lamb shifts in tunable electromagnetic environments such as graphene, whose optical properties are dynamically controlled via doping. The Fermi energy can be chosen so that the Lamb shift is very weak, but it can also be chosen so that the the shifts become more prominent than the fine structure of the atom and even potentially the Coulomb interaction with the nucleus. Potential implications of this idea include being able to electronically shift an unfavorable emitter structure into a favorable one, a new approach to probe near-field physics in fluorescence, and a way to access regimes of physics where vacuum fluctuations are not a weak perturbation but rather the dominant physics.

    更新日期:2017-09-13
  • Understanding Hot-Electron Generation and Plasmon Relaxation in Metal Nanocrystals: Quantum and Classical Mechanisms
    ACS Photonics (IF 6.756) Pub Date : 2017-09-12
    Lucas Vazquez Besteiro, Xiang-Tian Kong, Zhiming Wang, Gregory V Hartland, Alexander O. Govorov

    Generation of energetic (hot) electrons is an intrinsic property of any plasmonic nanostructure under illumination. Simultaneously, a striking advantage of metal nanocrystals over semiconductors lies in their very large absorption cross sections. Therefore, metal nanostructures with strong and tailored plasmonic resonances are very attractive for photocatalytic applications in which excited electrons play an important role. However, the central questions in the problem of plasmonic hot electrons are the number of optically-excited energetic electrons in a nanocrystal and how to extract such electrons. Here we develop a theory describing the generation rates and the energy-distributions of hot electrons in nanocrystals with various geometries. In our theory, hot electrons are generated owing to surfaces and hot spots. As expected, the formalism predicts that large optically-excited nanocrystals show the excitation of mostly low-energy Drude electrons, whereas plasmons in small nanocrystals involve mostly high-energy (hot) electrons. We obtain analytical expressions for the distribution functions of excited carriers for simple shapes. For complex shapes and for small quantum nanocrystals, our results are computational. By looking at the energy distributions of electrons in an optically-excited nanocrystal, we see how the quantum many-body state in small particles evolves towards the classical state described by the Drude model when increasing nanocrystal size. We show that the rate of surface decay of plasmons in nanocrystals is directly related to the rate of generation of hot electrons. Based on a detailed many-body theory involving kinetic coefficients, we formulate a simple scheme describing how the plasmon in a nanocrystal dephases over time. In most nanocrystals, the main decay mechanism of a plasmon is the Drude friction-like process and the secondary path comes from generation of hot electrons due to surfaces and electromagnetic hot spots. The hot-electron path strongly depends on the material system and on its shape. Correspondingly, the efficiency of hot-electron production in a nanocrystal strongly varies with size, shape and material. The results in the paper can be used to guide the design of plasmonic nanomaterials for photochemistry and photodetectors.

    更新日期:2017-09-13
  • Energy Transport State Resolved Raman for Probing Interface Energy Transport and Hot Carrier Diffusion in Few-Layered MoS2
    ACS Photonics (IF 6.756) Pub Date : 2017-09-12
    Pengyu Yuan, Ridong Wang, Hong Tan, Tianyu Wang, Xinwei Wang

    Quantitative understanding of 2D atomic layer interface thermal resistance (R) based on Raman characterization is significantly hindered by unknown sample-to-sample optical properties variation, interface-induced optical interference, off-normal laser irradiation, and large thermal-Raman calibration uncertainties. In this work, we develop a novel energy transport state resolved Raman (ET-Raman) to resolve these critical issues, and also consider the hot carrier diffusion, which is crucial but has been rarely considered during interface energy transport study. In ET-Raman, by constructing two steady heat conduction states with different laser spot sizes, we differentiate the effect of R and hot carrier diffusion coefficient (D). By constructing an extreme state of zero/negligible heat conduction using a picosecond laser, we differentiate the effect of R and material’s specific heat. In the end, we precisely determine R and D without need of laser absorption and temperature rise of the 2D atomic layer. Seven MoS2 samples (6.6~17.4 nm) on c-Si are characterized using ET-Raman. Their D is measured in the order of 1.0 cm2/s, increasing against the MoS2 thickness. This is attributed to the weaker in-plane electron-phonon interaction in thicker samples, enhanced screening of long-range disorder, and improved charge impurities mitigation. R is determined as 1.22~1.87×10-7 K·m2/W, decreasing with the MoS2 thickness. This is explained by the interface spacing variation due to thermal expansion mismatch between MoS2 and Si, and increased stiffness of thicker MoS2. The local interface spacing is uncovered by comparing the theoretical Raman intensity and experimental data, and is correlated with the observed R variation.

    更新日期:2017-09-13
  • Direct Coupling of Coherent Emission from Site-Selectively Grown III–V Nanowire Lasers into Proximal Silicon Waveguides
    ACS Photonics (IF 6.756) Pub Date : 2017-09-12
    T. Stettner, T. Kostenbader, D. Ruhstorfer, J. Bissinger, H. Riedl, M. Kaniber, G. Koblmüller, J. J. Finley
    更新日期:2017-09-12
  • Spontaneous emission inside a hyperbolic metamaterial waveguide
    ACS Photonics (IF 6.756) Pub Date : 2017-09-12
    Diane Roth, Alexey V Krasavin, Alexander Wade, Wayne Dickson, Antony Murphy, Stéphane Kéna-Cohen, Robert J. Pollard, Gregory Wurtz, David Richards, Stefan A. Maier, Anatoly V Zayats

    The ability to control the rate of spontaneous emission via the design of nanostructured materials with appropriate electromagnetic properties is important in the development of novel fast sources of incoherent illumination, single photon emitters for quantum optical applications, laser physics and de-excitation of electronic states leading to photodegradation in organic materials. Here, for an emitter placed inside a hyperbolic metamaterial slab of finite thickness comprised of an array of gold nanorods, we experimentally demonstrate an enhancement of the fluorescence coupled to the waveguided plasmon-polariton modes of the metamaterial. We show that fluorescence properties in such finite-size metamaterial design behave differently from commonly studied infinite metamaterials or when the emitters are placed near the metamaterial interface. The emitters inside the metamaterial waveguide exhibit an almost 50-fold reduction of their lifetime, whereas a much smaller reduction (a factor of 2-3) is observed for emitters placed on top of the metamaterial. While in both cases the emission from the metamaterial can be radiated in the far field (up to 18% of the total emitted intensity, depending on the emitter position with respect to the nanorods), the coupling to waveguided modes of the metamaterial slab provide an efficient mean to shape the emission spectrum for each polarization. The considered geometry is ideal for designing integrated, fast optical sources for data communications, sensing or quantum photonic applications.

    更新日期:2017-09-12
  • Wavelength-Selective Diffraction from Silica Thin-Film Gratings
    ACS Photonics (IF 6.756) Pub Date : 2017-09-12
    Ijaz Rashid, Haider Butt, Ali K. Yetisen, Bruno Dlubak, James E. Davies, Pierre Seneor, Aymeric Vechhiola, Faycal Bouamrane, Stephane Xavier
    更新日期:2017-09-12
  • Electrically Tunable Optical Nonlinearities in Graphene-Covered SiN Waveguides Characterized by Four-Wave Mixing
    ACS Photonics (IF 6.756) Pub Date : 2017-09-11
    Koen Alexander, Nadja A. Savostianova, Sergey A. Mikhailov, Bart Kuyken, Dries Van Thourhout
    更新日期:2017-09-11
  • Correlating Light Absorption with Various Nanostructure Geometries in Vertically Aligned Si Nanowire Arrays
    ACS Photonics (IF 6.756) Pub Date : 2017-09-11
    Yi-Seul Park, Jin Seok Lee

    Exploring the interactions between light and nanostructures contributes greatly to understanding and engineering nanoscale optical phenomena related to device performance. However, this often involves a compromise between uniformity and scalability. Given that optical properties, and especially light absorption, are governed by the geometries of nanostructures, this study investigated the correlation between light absorption and vertically aligned silicon nanowire (v-SiNW) arrays syn-thesized using KrF stepper lithography. Controlled growth experiments of the v-SiNW arrays indicated that their geometrical parameters strongly influence their corresponding light absorption properties, as confirmed by reflection measurements and finite difference time domain (FDTD) simulations, which showed specific wavelength-dependent absorption. Moreover, the extent of tapering the v-SiNW arrays was modulating to achieve broad absorption of visible light resulting from the gradual change in diameter and to optimize their optical characteristics, based on diameter-dependent nanophotonic resonance, for use in various applications.

    更新日期:2017-09-11
  • Generating Optical Birefringence and Chirality in Silicon Nanowire Dimers
    ACS Photonics (IF 6.756) Pub Date : 2017-09-11
    Xin Zhao, M. H. Alizadeh, Björn M. Reinhard
    更新日期:2017-09-11
  • Real-Time Analysis of Molecular Conformation Using Silicon Electrophotonic Biosensors
    ACS Photonics (IF 6.756) Pub Date : 2017-09-11
    José Juan-Colás, Thomas F. Krauss, Steven D. Johnson
    更新日期:2017-09-11
  • Highly Sensitive Graphene–Semiconducting Polymer Hybrid Photodetectors with Millisecond Response Time
    ACS Photonics (IF 6.756) Pub Date : 2017-09-11
    Po-Han Chang, Yi-Chen Tsai, Shin-Wei Shen, Shang-Yi Liu, Kuo-You Huang, Chia-Shuo Li, Hei-Ping Chang, Chih-I Wu
    更新日期:2017-09-11
  • In Situ Planarization of Huygens Metasurfaces by Nanoscale Local Oxidation of Silicon
    ACS Photonics (IF 6.756) Pub Date : 2017-09-11
    Jonathan Bar-David, Noa Mazurski, Uriel Levy
    更新日期:2017-09-11
  • Deterministic Placement of Quantum-Size Controlled Quantum Dots for Seamless Top-Down Integration
    ACS Photonics (IF 6.756) Pub Date : 2017-09-11
    Arthur J. Fischer, P. Duke Anderson, Daniel D. Koleske, Ganapathi Subramania
    更新日期:2017-09-11
  • Revisiting Quantum Optics with Surface Plasmons and Plasmonic Resonators
    ACS Photonics (IF 6.756) Pub Date : 2017-09-08
    Francois Marquier, Christophe Sauvan, Jean-Jacques Greffet
    更新日期:2017-09-08
  • Large Band-Edge Photocurrent Peak in Thick Methylammonium Lead Iodide Photosensors with Symmetric Metal Electrodes
    ACS Photonics (IF 6.756) Pub Date : 2017-09-07
    Péter Hantz, Ferenc Sarlós, István Jalsovszky, Balázs Plesz
    更新日期:2017-09-07
  • Cavity QED in the Ultrastrong Coupling Regime: Photon Bunching from the Emission of Individual Dressed Qubits
    ACS Photonics (IF 6.756) Pub Date : 2017-09-07
    Luigi Garziano, Alessandro Ridolfo, Simone De Liberato, Salvatore Savasta
    更新日期:2017-09-07
  • Subfemtosecond and nanometer plasmon dynamics with photoelectron microscopy: theory and efficient simulations
    ACS Photonics (IF 6.756) Pub Date : 2017-09-07
    Timothy J. Davis, Bettina Frank, Daniel Podbiel, Philip Kahl, Frank J. Meyer zu Heringdorf, Harald Giessen

    We develop a theoretical model of the excitation and interference of surface plasmon polariton (SPP) waves with femtosecond laser pulses and use the model to understand the features in images from subfemtosecond time-resolved two-photon photoelectron microscopy (2PPE- PEEM). The numerically efficient model is based on the optics of SPP modes on multi-layer thin films and takes account of the excitation and interference by the incident light, its polarization, the boundary shape on the film where the plasmons are generated, the pulsed form of the excitation and the time integration associated with the PEEM method. The model explains the dominant features observed in the images including the complex patterns formed in experiments involving orbital angular momentum. The model forms the basis of an efficient numerical method for simulating time-resolved 2PPE-PEEM images of SPP wave propagation. The numerics is extremely fast, efficient and accurate, so that each image can takes as little as a few seconds to calculate on a laptop computer, enabling entire PEEM movies to be calculated within minutes.

    更新日期:2017-09-07
  • Halide Perovskite 3D Photonic Crystals for Distributed Feedback Lasers
    ACS Photonics (IF 6.756) Pub Date : 2017-09-07
    Stefan Schünemann, Sarah Brittman, Kun Chen, Erik C. Garnett, Harun Tüysüz

    Halide perovskites are under intense investigation for light harvesting applications in solar cells. Their outstanding optoelectronic properties such as long charge carrier diffusion lengths, high absorption coefficients, and defect tolerance also triggered interest in laser and LED applications. Here, we report on the lasing properties of 3D distributed feedback halide perovskite nanostructures prepared via an all-solution process. A colloidal crystal templating approach was developed to precisely control the hybrid halide perovskite structure on the nanoscale. The prepared CH3NH3PbBr3 thin films with inverse opal morphology show narrow lasing emissions with a full width half maximum as low as 0.15 nm and good long term stability under pulsed laser excitation above the lasing threshold of 1.6 mJ cm-2 in ambient atmosphere. Furthermore, lasing emission was also observed for CH3NH3PbI3 inverse opals under excitation with a focused laser beam. Unlike other protocols for the fabrication of distributed feedback perovskite lasers, control of the nanostructure of hybrid halide perovskites is achieved without the use of expensive and elaborate lithography techniques or high temperatures. Therefore, the presented protocol opens a route to the low cost fabrication of hybrid halide perovskite lasers.

    更新日期:2017-09-07
  • Light-Emission Mechanism in CuInS2 Quantum Dots Evaluated by Spectral Electrochemistry
    ACS Photonics (IF 6.756) Pub Date : 2017-09-07
    Addis Fuhr, Hyeong Jin Yun, Nikolay S. Makarov, Hongbo Li, Hunter McDaniel, Victor I. Klimov

    Luminescent CuInS2 (CIS) quantum dots (QDs) exhibit highly efficient intra-gap emission and long, hundreds-of-nanoseconds radiative lifetimes. These spectral properties, distinct from structurally similar II-VI QDs, can be explained by the involvement of intra-gap defect states containing a localized hole capable of coupling with a conduction band electron for a radiative transition. However, the absolute energies of the intra-gap and band-edge states, the structure of the emissive defect(s), and the role and origin of non-emissive decay channels still remain poorly understood. Here, we address these questions by applying methods of spectral electrochemistry. Cyclic voltammetry measurements reveal a well-defined intra-gap state whose redox potential is close to that of the Cux defect state (where x = 1+ or 2+). The energy offset of this state from the valence band accounts well for the apparent photoluminescence (PL) Stokes shift observed in optical spectra. These results provide direct evidence that Cu-related defects serve as emission centers responsible for strong intra-gap emission from CIS QDs. We then use in-situ spectroelectrochemistry to reveal two distinct emission pathways based on the differing oxidation states of Cu-defects, which can be controlled by altering QD stoichiometry (1+ for stoichiometric QDs and 2+ for Cu-poor QDs).

    更新日期:2017-09-07
  • Three-Dimensionally Coupled THz Octagrams as Isotropic Metamaterials
    ACS Photonics (IF 6.756) Pub Date : 2017-09-07
    Kriti Agarwal, Chao Liu, Daeha Joung, Hyeong-Ryeol Park, Jeeyoon Jeong, Dai-Sik Kim, Jeong-Hyun Cho

    Split-ring resonator (SRR) based metamaterials have been studied for the development of highly sensitive, small-sized, low-power chemical and biomolecular sensors. However, the anisotropic behavior arising from their two-dimensional (2D) structure presents substantial challenges leading to ambiguity in their transmission spectra. In this paper, we present the design of a three-dimensional (3D) isotropic octagram split-ring resonator (OSRR) demonstrating a three-dimensionally coupled resonance behavior that overcomes the anisotropic response of conventional 2D SRRs, leading to a strong, distortion-free, and polarization invariant transmission response. The OSRR undergoes 3D coupling through the splits at the corners of the 3D structure (cube) which remains invariant under any polarization along the coordinate axes. The strong coupling between resonant segments provides the OSRR with 25 times higher sensitivity than the corresponding 2D structure, allowing the resonant frequency to be reliably monitored for small changes in concentration of a targeted substance. The isotropic frequency response of the 3D OSRR, without ambiguity in the amplitude caused by the polarization dependence, also allows monitoring the amplitude for minute changes in concentration which are too small to cause any shift in resonant frequency. Thus, the detection range for the presented 3D OSRR stretches from large to minute variations of targeted substance.

    更新日期:2017-09-07
  • Ultrashort Tilted-Pulse-Front Pulses and Nonparaxial Tilted-Phase-Front Beams
    ACS Photonics (IF 6.756) Pub Date : 2017-09-06
    Liang Jie Wong, Ido Kaminer
    更新日期:2017-09-07
  • Octave-Spanning Broadband Absorption of Terahertz Light using Metasurface Fractal-Cross Absorbers
    ACS Photonics (IF 6.756) Pub Date : 2017-09-06
    Mitchell Kenney, James Grant, Yash D Shah, Ivonne Escorcia-Carranza, Mark Humphreys, David R.S. Cumming

    Synthetic fractals inherently carry spatially encoded frequency information that renders them as an ideal candidate for broadband optical structures. Nowhere is this more true than in the terahertz (THz) band where there is a lack of naturally occurring materials with valuable optical properties. One example are perfect absorbers that are a direct step towards the development of highly sought after detectors and sensing devices. Metasurface absorbers that can be used to substitute for natural materials suffer from poor broadband performance, whilst those with high absorption and broadband capability typically involve complex fabrication and design and are multilayered. Here, we demonstrate a polarization-insensitive ultrathin (~λ/6) planar metasurface THz absorber composed of supercells of fractal crosses capable of spanning one optical octave in bandwidth, whilst still being highly-efficient. A sufficiently thick polyimide interlayer produces a unique absorption mechanism based on Salisbury screen and anti-reflection responses, which lends to the broadband operation. Experimental peak absorption exceeds 93%, whilst the average absorption is 83% from 2.82 THz to 5.15 THz. This new ultrathin device architecture, achieving an absorption-bandwidth of one optical octave, demonstrates a major advance towards a synthetic metasurface blackbody absorber in the THz band.

    更新日期:2017-09-07
  • Anderson Localization of Visible Light on a Nanophotonic Chip
    ACS Photonics (IF 6.756) Pub Date : 2017-09-06
    Tom Crane, Oliver Joe Trojak, Juan Pablo Vasco, Stephen Hughes, Luca Sapienza
    更新日期:2017-09-06
  • High-Efficiency Semitransparent Organic Solar Cells with Non-Fullerene Acceptor for Window Application
    ACS Photonics (IF 6.756) Pub Date : 2017-09-06
    Mushfika Baishakhi Upama, Matthew Wright, Naveen Kumar Elumalai, Md Arafat Mahmud, Dian Wang, Cheng Xu, Ashraf Uddin
    更新日期:2017-09-06
  • Meta-Holograms with Full Parameter Control of Wavefront over a 1000 nm Bandwidth
    ACS Photonics (IF 6.756) Pub Date : 2017-09-06
    Zhenwei Xie, Ting Lei, Guangyuan Si, Xianyou Wang, Jiao Lin, Changjun Min, Xiaocong Yuan
    更新日期:2017-09-06
  • Visual Understanding of Light Absorption and Waveguiding in Standing Nanowires with 3D Fluorescence Confocal Microscopy
    ACS Photonics (IF 6.756) Pub Date : 2017-09-05
    Rune Frederiksen, Gozde Tutuncuoglu, Federico Matteini, Karen L. Martinez, Anna Fontcuberta i Morral, Esther Alarcon-Llado
    更新日期:2017-09-06
  • Granular Permittivity Representation in Extremely Near-Field Light–Matter Interaction Processes
    ACS Photonics (IF 6.756) Pub Date : 2017-09-05
    Alexey S. Kadochkin, Alexander S. Shalin, Pavel Ginzburg
    更新日期:2017-09-05
  • Meta-Holograms with Full Parameter Control of Wavefront over a 1000-nm Bandwidth
    ACS Photonics (IF 6.756) Pub Date : 2017-09-04
    Zhenwei Xie, Ting Lei, Guangyuan Si, Xianyou Wang, Jiao Lin, changjun min, Xiaocong Yuan

    Metasurfaces offer promising structures for controlling the wavefront of light. The development of such structures is evidence for numerous ways to alter on demand light properties such as amplitude, phase, and polarization. However, the simultaneous control of all parameters of light over a wide bandwidth is still a great challenge. With polarization multiplexing, we have achieved the lesser goal of simultaneous control of phase and amplitude over a 1000-nm bandwidth using a plasmonic nano-slit array associated with the traditional detour phase. In a proof-of-concept experiment, we demonstrate 3D object reconstruction and polarization multiplexing images at various prescribed wavelengths from 473 nm to 1550 nm using a specially designed meta-hologram. Benefiting from high controllability of amplitude, phase, and polarization, meta-holograms offer great potential in future applications such as 3D displays, optical communications, and beam shaping.

    更新日期:2017-09-05
  • Free-space optical beam tapping with an all-silica metasurface
    ACS Photonics (IF 6.756) Pub Date : 2017-09-04
    Qitong Li, Fengliang Dong, Bo Wang, Weiguo Chu, Qihuang Gong, Mark L. Brongersma, Yan Li

    Extraction of information about the multi-dimensional optical properties of free-space and guided optical beams is critical in modern photonics. To date, planar, most beam-information detection systems destroy or substantially modify the original wave fronts of an incident beam in the detection process. Here, we demonstrate all-silica beam information detection system that effectively taps into a free space optical beam while leaving the original wavefronts virtually unaffected. This is accomplished by diverting a small (few percent) fraction of the light through the interaction with a silica metasurface based on the Pancharatnam-Berry phase. A chiroptical spectrometer and a multi-channel angular momentum detector are proposed to demonstrate the multifunctionality of this design principle. The concept and device proposed here may pave the way to in-situ beam monitoring and may provide a novel method to collect optical information for emerging augmented reality technologies.

    更新日期:2017-09-05
  • Nonlinear Anisotropic Dielectric Metasurfaces for Ultrafast Nanophotonics
    ACS Photonics (IF 6.756) Pub Date : 2017-09-01
    Giuseppe Della Valle, Ben Hopkins, Lucia Ganzer, Tatjana Stoll, Mohsen Rahmani, Stefano Longhi, Yuri S. Kivshar, Costantino De Angelis, Dragomir N. Neshev, Giulio Cerullo
    更新日期:2017-09-04
  • Plasmon Generation through Electron Tunneling in Graphene
    ACS Photonics (IF 6.756) Pub Date : 2017-09-01
    Sandra de Vega, F. Javier García de Abajo
    更新日期:2017-09-04
  • Terahertz Nanoscopy of Plasmonic Resonances with a Quantum Cascade Laser
    ACS Photonics (IF 6.756) Pub Date : 2017-08-31
    Riccardo Degl’Innocenti, Robert Wallis, Binbin Wei, Long Xiao, Stephen J. Kindness, Oleg Mitrofanov, Philipp Braeuninger-Weimer, Stephan Hofmann, Harvey E. Beere, David A. Ritchie
    更新日期:2017-09-04
  • Spatio-temporal dynamics and control of strong coupling in plasmonic nano-cavities
    ACS Photonics (IF 6.756) Pub Date : 2017-09-02
    Angela Demetriadou, Joachim M Hamm, Yu Luo, John B. Pendry, Jeremy J. Baumberg, Ortwin Hess

    In the light-matter strong coupling regime, the excited state of quantum emitters is inextricably linked to a photonic mode, leading to hybrid states that are part-light and part-matter. Recently, there has been huge effort to realize strong coupling with nanoplasmonics, since it provides a versatile environment to study and control molecules in ambient conditions. Amongst the most promising designs are plasmonic nano-cavities that confine light to unprecedentedly small volumes. Such nano-cavities though support multiple types of modes, with different field profiles and radiative decay rates (bright and dark modes). Here, we show theoretically that the different nature of these modes leads to mode beating within the nano-cavity and the Rabi-oscillations, which alters the spatio-temporal dynamics of the hybrid system. By specifically designing the illumination set-up, we decompose and control the dark and bright plasmon mode excitation and therefore their coupling with quantum emitters. Hence, this work opens new routes for dynamically dressing emitters, to tailor their hybrid states with external radiation.

    更新日期:2017-09-04
  • Direct coupling of coherent emission from site-selectively grown III-V nanowire lasers into proximal silicon waveguides
    ACS Photonics (IF 6.756) Pub Date : 2017-09-02
    Thomas Stettner, Tobias Kostenbader, Daniel Ruhstorfer, Jochen Bissinger, Hubert Riedl, Michael Kaniber, Gregor Koblmueller, Jonathan J. Finley

    Semiconductor nanowire (NW) lasers are nanoscale coherent light sources that exhibit a small footprint, low-threshold lasing characteristics, and properties suitable for monolithic and site-selective integration onto Si photonic circuits. An important milestone on the way towards novel on-chip photonic functionalities, such as injection locking of laser emission and all-optical switching mediated by coherent optical coupling and feedback, is the integration of individual, deterministically addressable NW lasers on Si waveguides with efficient coupling and mode propagation in the underlying photonic circuit. Here, we demonstrate the monolithic integration of single GaAs-based NW lasers directly onto lithographically defined Si ridge waveguides (WG) with low threshold power densities of 19.8 µJ/cm² when optically excited. The lasing mode of individual NW lasers is shown to couple efficiently into propagating modes of the underlying orthogonal Si WG, preserving the lasing characteristics during mode propagation in the WG in good agreement with Finite-Difference Time-Domain (FDTD) simulations. Using a WG structure with a series of mask openings along the central mode propagation axis, we further illustrate the out-coupling properties of both spontaneous and stimulated emission and demonstrate propagation of the lasing mode over distances > 60 µm, despite absorption in the silicon dominating the propagation losses.

    更新日期:2017-09-04
  • Real-time analysis of molecular conformation using silicon electrophotonic biosensors
    ACS Photonics (IF 6.756) Pub Date : 2017-08-31
    José Juan-Colás, Thomas F. Krauss, Steven D. Johnson

    Silicon microring resonators are widely used as optical biosensors because of their high sensitivity and promise of low-cost mass-manufacturing. Typically, they only measure the adsorbed molecular mass via the refractive index change they detect. Here, we propose and demonstrate a silicon microring biosensor that can measure molecular thickness and density as well as electrochemical activity simultaneously, thereby enabling quantification of the conformation of sur-face-immobilized biological and molecular layers in real time. Insight into the molecular conformation is obtained by recording the resonance shift from two geometrically distinct ring-resonators connected to a single access waveguide. The resonant cavities both support a single TE polarized optical mode but have different widths (480 and 580 nm); the extent of their evanescent fields is thus very different providing different depth-resolution of the interaction with a molecular layer on the sensor surface. By combining the optical shift from these two measurements, we demonstrate unambiguous quantification of the thickness and the refractive index of a molecular layer assembled on the waveguide. The precision of the technique is 0.05 nm and 0.005 RIU in the molecular layer thickness and refractive index, respec-tively. We demonstrate the cascaded electrophotonic ring resonator system using two exemplar systems, namely a) physisorption of a bovine serum albumin monolayer and b) an electroactive DNA oligonucleotide hairpin, where we uniquely show the ability to monitor electrochemical activity and conformational change with the same device. This novel sensor geometry provides a new approach for monitoring the conformation and conformational changes in an inexpensive and miniaturised platform that is amenable to multiplexed, high-throughput measurements.

    更新日期:2017-09-04
  • Highly Sensitive Graphene–Semiconducting Polymer Hybrid Photodetectors with Millisecond Response Time
    ACS Photonics (IF 6.756) Pub Date : 2017-08-31
    Po-Han Chang, Yi-Chen Tsai, Shin-Wei Shen, Shang-Yi Liu, Kuo-You Huang, Chia-Shuo Li, Hei-Ping Chang, Chih-I Wu

    Graphene–semiconducting light absorber hybrid photodetectors have attracted increasing attention because of their ultrahigh photoconductive gain and superior sensitivity. However, most graphene-based hybrid photodetectors reported previously have shown a relatively long response time (in the order of seconds) caused by numerous long-lived traps in these hybrid systems, which greatly restricts device speed. In this work, graphene–thieno[3,4-b]thiophene/benzodithiophene polymer hybrid photodetectors fabricated on self-assembled monolayer (SAM)-functionalized SiO2 substrates are demonstrated with a maximum responsivity of ~1.8×105 A W−1 and a relatively short photocurrent response time of ~7.8 ms. The fast and highly sensitive device characteristics provide great potential in low light imaging applications. The hybrid photodetector on the SAM-coated SiO2 substrate shows better performance in responsivities and response times as compared with those of the device on the bare SiO2 substrate. The improved responsivities are attributed to a significant increase in carrier mobility in graphene channels by introducing SAM-modified substrates. In addition, SAM functionalization is capable of effectively removing multiple surface traps and charged impurities between graphene sheets and SiO2 substrates, which prevents the long-lived trapping of photo-carriers at graphene/SiO2 interfaces and remarkably decreases device response time.

    更新日期:2017-09-04
  • Controlling Spoof Plasmons in a Metal Grating Using Graphene Surface Plasmons
    ACS Photonics (IF 6.756) Pub Date : 2017-08-31
    Eduardo J. C. Dias, N. M. R. Peres
    更新日期:2017-08-31
  • Edge States in Dynamical Superlattices
    ACS Photonics (IF 6.756) Pub Date : 2017-08-29
    Yiqi Zhang, Yaroslav V. Kartashov, Feng Li, Zhaoyang Zhang, Yanpeng Zhang, Milivoj R. Belić, Min Xiao
    更新日期:2017-08-29
  • Organic Exciton in Strong Coupling with Long-Range Surface Plasmons and Waveguided Modes
    ACS Photonics (IF 6.756) Pub Date : 2017-08-29
    Kevin Chevrier, Jean-Michel Benoit, Clementine Symonds, Julien Paparone, Julien Laverdant, Joel Bellessa
    更新日期:2017-08-29
  • In-Situ planarization of Huygens metasurfaces by nanoscale local oxidation of silicon
    ACS Photonics (IF 6.756) Pub Date : 2017-08-29
    Jonathan Bar-David, Noa Mazurski, Uriel Levy

    Metasurfaces are becoming a flourishing field of research, with diverse applications, such as planar optical components and structural colors. While metallic metasurfaces are typically few tens of nanometers in their thickness, their dielectric counterparts typically span few hundreds of nanometers in thickness variations. This makes the stacking of multilayers a bit challenging. To mitigate this challenge, we have developed a new approach for the realization of dielectric metasurfaces. Our approach is based on the nanoscale local oxidation of silicon (LOCOS), allowing to achieve planar metasurface structures. We have utilized this approach for the design, fabrication and characterization of amorphous silicon based all-dielectric Huygens metasurfaces. This metasurfaces show clear electric and magnetic resonances, which can be structurally tuned. The obtained results are in good agreement with numerical simulations taking into account the unique shape of the nanoantennas. Relying on a robust approach for their realization, and combined with the important feature of in-situ planarization, we believe that such planarized metasurfaces will become a viable technology for future applications.

    更新日期:2017-08-29
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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