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Selective contacts drive charge extraction in quantum dot solids via asymmetry in carrier transfer kinetics
Colloidal quantum dot solar cells represent a rapidly advancing class of photovoltaic devices, but their underlying physics remains to be fully elucidated. Mora-Sero et al. characterize the charge diffusion at various contacts and propose a hopping mechanism of charge carriers between quantum dots.
- Ivan Mora-Sero
- , Luca Bertoluzzi
- & Juan Bisquert
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A reconfigurable plasmofluidic lens
Plasmonics offers sub-diffraction limit optical devices, but multiple functionalities are difficult to build in the solid state. By combining it with fluidics, Zhao et al. present a tunable and reconfigurable plasmonic lens using laser-controllable bubble formation in a microfluidic environment.
- Chenglong Zhao
- , Yongmin Liu
- & Tony Jun Huang
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A digital laser for on-demand laser modes
Customizing the output from a laser is typically done by appropriate optical elements. Here Ngcobo et al.show that a digitally controlled holographic mirror placed within the laser cavity can be used to dynamically select the desired laser output modes.
- Sandile Ngcobo
- , Igor Litvin
- & Andrew Forbes
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Silicon-in-silica spheres via axial thermal gradient in-fibre capillary instabilities
Silicon nanospheres could be of interest for applications in electronics and optoelectronics. Here, Gumenniket al. demonstrate a nanosphere fabrication process based on an optical fibre drawing technique that is able to produce p and n-type spheres paired into rectifying bispherical junctions.
- Alexander Gumennik
- , Lei Wei
- & Yoel Fink
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Performance enhancement of fullerene-based solar cells by light processing
Bulk heterojunctions based on semiconducting polymers blended with fullerenes are promising for organic solar cells. Liet al.show that an additional light exposure step during fabrication increases their thermal stability and can lead to enhanced device performance.
- Zhe Li
- , Him Cheng Wong
- & João T. Cabral
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| Open AccessHypervalent surface interactions for colloidal stability and doping of silicon nanocrystals
Electrically insulating ligands and doping of colloidal semiconductor nanocrystals continue to be significant challenges for practical nanocrystal-based optoelectronics. Wheeler et al.demonstrate a new surface chemistry technique that confronts both of these challenges simultaneously.
- Lance M. Wheeler
- , Nathan R. Neale
- & Uwe R. Kortshagen
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| Open AccessVibrational near-field mapping of planar and buried three-dimensional plasmonic nanostructures
Near-field effects generated by nanoantennas provide insights into light–matter interactions and new ways of sensing at low concentrations. By measuring characteristic vibrations from molecular patches, Dregely et al.are able to characterize the field intensity of buried three-dimensional nanostructures.
- Daniel Dregely
- , Frank Neubrech
- & Harald Giessen
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Complete tomography of a high-fidelity solid-state entangled spin–photon qubit pair
Future quantum communication technologies require entanglement between stationary and flying qubits, in systems that are inherently scalable. To this end, De Greveet al.present full state tomography of a qubit pair formed by entangling a quantum dot spin and a photon, with a fidelity of over 90%.
- Kristiaan De Greve
- , Peter L. McMahon
- & Yoshihisa Yamamoto
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| Open AccessDynamics of a vertical cavity quantum cascade phonon laser structure
Phonon lasers are the acoustic equivalent to optical lasers. Here Maryam and colleagues study the dynamics of semiconductor phonon lasers operating in the terahertz frequency regime, and show that these dynamics are similar to that of comparable optical lasers.
- W. Maryam
- , A. V. Akimov
- & A. J. Kent
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Understanding the role of phase in chemical bond breaking with coincidence angular streaking
Ultrafast laser pulses are useful to study electron dynamics in chemical bonds, but their influence on bond breaking is not fully understood. Wu et al. study H2 bond breaking with coincidence techniques, and find a phase-dependent anisotropy of the H+fragmentation even for isotropic multicycle laser pulses.
- J. Wu
- , M. Magrakvelidze
- & R. Dörner
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A hybrid high-speed atomic force–optical microscope for visualizing single membrane proteins on eukaryotic cells
Scanning probe microscopy techniques are hard to apply to live cell membrane imaging at high resolution as the temporal and force sensitivity are insufficient to monitor the fast processes. Colom et al.present a solution to this problem by combining high-speed atomic force microscopy with optical microscopy.
- Adai Colom
- , Ignacio Casuso
- & Simon Scheuring
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Prolonged spontaneous emission and dephasing of localized excitons in air-bridged carbon nanotubes
Understanding the photophysics of excitons in carbon nanotubes is important if they are to be fully exploited in optoelectronic devices. Sarpkaya et al. perform photoluminescence spectroscopy of nanotubes across an airbridge, finding a new narrow linewidth regime of intrinsic exciton behaviour.
- Ibrahim Sarpkaya
- , Zhengyi Zhang
- & Stefan Strauf
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| Open AccessDemonstration of the spin solar cell and spin photodiode effect
Finding ways to accumulate electronic spins of a given polarization in a given location is important to the development of spintronics. Endres et al.demonstrate a device that uses light to drive the accumulation of spin using a similar principle that a solar cell uses to drive the accumulation of charge.
- B. Endres
- , M. Ciorga
- & C.H. Back
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Engineering p-wave interactions in ultracold atoms using nanoplasmonic traps
Controlling p-wave interactions between fermions would enable studies of interesting quantum phenomena. Towards this end, Juliá-Díaz et al. propose a combination of strongly confined nanoplasmonic traps and laser-induced gauge fields that could produce the necessary coupling of atomic states.
- B. Juliá-Díaz
- , T. Graß
- & M. Lewenstein
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| Open AccessMicrowave synthesizer using an on-chip Brillouin oscillator
Microwaves are of interest for applications such as communications, radar and metrology. Here, Li et al. demonstrate an on-chip microresonator device for the generation of microwaves by optical means, instead of the usual electronic devices.
- Jiang Li
- , Hansuek Lee
- & Kerry J. Vahala
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| Open AccessIntegrated Mach–Zehnder interferometer for Bose–Einstein condensates
Atom interferometers exploit wave-particle duality and can be used as sensitive measurement devices. Berrada et al.present a Mach–Zehnder interferometer for Bose–Einstein condensates trapped on an atom chip and demonstrate enhanced performance using non-classical states.
- T. Berrada
- , S. van Frank
- & J Schmiedmayer
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| Open AccessSolar spectral conversion for improving the photosynthetic activity in algae reactors
Algae beds are a promising resource for bio-energy and gas production, but their productivity is often limited by solar energy harvesting efficiency. Wondraczek et al. promote algal growth by using photoluminescent phosphor, which shifts the light spectrum to better match the algal adsorption band.
- Lothar Wondraczek
- , Miroslaw Batentschuk
- & Christoph J. Brabec
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| Open AccessThree-dimensional deep sub-diffraction optical beam lithography with 9 nm feature size
The fabrication of three-dimensional nanoscale structures is important to nanophotonic applications where light is guided and controlled. The optical beam lithography scheme developed by Gan and colleagues enables the fabrication of three-dimensional structures with feature sizes down to 9 nm.
- Zongsong Gan
- , Yaoyu Cao
- & Min Gu
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Broadly tunable terahertz generation in mid-infrared quantum cascade lasers
Compact, tunable terahertz sources are highly desired for sensing and imaging applications. Here Vijayraghavan et al. demonstrate room-temperature quantum cascade laser sources based on the non-linear optical conversion of mid-infrared light that provide a tunable output over a 3.5-THz bandwidth.
- Karun Vijayraghavan
- , Yifan Jiang
- & Mikhail A. Belkin
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| Open AccessNon-volatile memory based on the ferroelectric photovoltaic effect
Ferroelectric RAM is considered a promising candidate on the quest for a universal memory, but the concept is still problem prone. Here, the authors use the ferroelectric photovoltaic effect as a non-destructive read-out method for a new prototype memory, which shows good data retention and fatigue resistance.
- Rui Guo
- , Lu You
- & Junling Wang
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| Open AccessQuasi-monoenergetic laser-plasma acceleration of electrons to 2 GeV
Laser-plasma accelerators can produce high-energy electron bunches over just a few centimetres of distance, offering possible table-top accelerator capabilities. Wang et al.break the current 1 GeV barrier by applying a petawatt laser to accelerate electrons nearly monoenergetically up to 2 GeV.
- Xiaoming Wang
- , Rafal Zgadzaj
- & M. C. Downer
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Brillouin cavity optomechanics with microfluidic devices
Light–sound interactions in microcavities are used for optomechanical excitation and cooling, but have previously only been shown in solid-state devices. Here, Bahl et al. generate acoustic oscillations in microfluidic resonators to enable novel optomechanical interactions with liquid-phase materials.
- Gaurav Bahl
- , Kyu Hyun Kim
- & Tal Carmon
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All-solution processed polymer light-emitting diode displays
Polymer light-emitting diodes promise cheap and flexible lighting and displays, but their fabrication is hindered by high-vacuum methods for creating cathodes. Zheng et al.show an all-solution processing approach to polymer diodes that removes this obstacle, offering roll-to-roll fabrication of devices.
- Hua Zheng
- , Yina Zheng
- & Yong Cao
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Sensitive magnetic control of ensemble nuclear spin hyperpolarization in diamond
The transfer of spin polarization from electrons to nuclei is important for nuclear spin-based techniques such as nuclear magnetic resonance. Here Wang and colleagues achieve sensitive magnetic control of the hyperpolarization of nuclei near optically polarized nitrogen-vacancy centres in diamond.
- Hai-Jing Wang
- , Chang S. Shin
- & Vikram S. Bajaj
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Photocurrent in graphene harnessed by tunable intrinsic plasmons
By patterning graphene with sub-wavelength features to introduce plasmonic modes, its optical properties can be tailored. Freitag et al. show how tunable plasmons in graphene nanoribbons can be exploited to form polarization-sensitive graphene photodetectors in the mid-infrared spectral region.
- Marcus Freitag
- , Tony Low
- & Phaedon Avouris
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| Open AccessA nanometre-scale resolution interference-based probe of interfacial phenomena between microscopic objects and surfaces
Interferometric techniques can provide valuable contact and profile information of microscopic objects on surfaces. This work uses reflection interference contrast microscopy to directly observe contact phenomena and presents novel analytical methods offering high-accuracy nanoscale resolution.
- Jose C. Contreras-Naranjo
- & Victor M. Ugaz
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Photo-switchable molecular monolayer anchored between highly transparent and flexible graphene electrodes
The realization of molecular monolayers with graphene electrodes may allow for superior flexible, transparent and stable electronics. Here, a photo-switchable molecular monolayer device is demonstrated, which has one side physically attached, and the other chemically bonded, to graphene.
- Sohyeon Seo
- , Misook Min
- & Hyoyoung Lee
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Monodisperse silicon nanocavities and photonic crystals with magnetic response in the optical region
Metamaterials offer optical functionality, such as cloaking, that is impossible to achieve with natural bulk materials. Here, Shi and colleagues fabricate colloidal metamaterials made from silicon whose magneto-optical response considerably exceeds that of related bulk materials.
- Lei Shi
- , Justin T Harris
- & Francisco Meseguer
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Focusing light with a flame lens
Lenses are well-understood optical instruments to focus light. The flame lens realized here by Michaelis et al. offers light focusing with a damage threshold several orders of magnitude higher than that of most conventional lenses.
- Max M. Michaelis
- , Cosmas Mafusire
- & Andrew Forbes
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Picosecond pulses from wavelength-swept continuous-wave Fourier domain mode-locked lasers
Ultrafast lasers are important in many fields of science, but they typically have high power consumption. Here Eigenwillig et al.realize picosecond laser pulses directly from a semiconductor-based laser. Due to the low repetition rate, high-energy pulses are generated at low average power.
- Christoph M. Eigenwillig
- , Wolfgang Wieser
- & Robert Huber
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Photoconductive response in organic charge transfer interfaces with high quantum efficiency
Single-crystal organic semiconductors are potential materials for electronic applications, for example, as field-effect transistors. Here, the authors demonstrate photoconductivity of single-crystal charge-transfer interfaces, suggesting that they may also be used for photonic applications.
- Helena Alves
- , Rui M. Pinto
- & Ermelinda S. Maçôas
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Broadband high photoresponse from pure monolayer graphene photodetector
Graphene holds great potential for use in photodetectors, owing to its ability to absorb light over a wide range of wavelengths. Here Zhang et al. report a large photoresponsivity of 8.6 AW-1 over a broad wavelength range in pure monolayer graphene.
- By Yongzhe Zhang
- , Tao Liu
- & Qi Jie Wang
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All-optical polariton transistor
Exciton-polaritons—coupled states of excitons and photons—exhibit interesting properties that may make them suitable as information carriers for optical computing technologies. With this goal in mind, Ballarini et al. demonstrate an all-optical polariton transistor that also operates as a logic gate.
- D. Ballarini
- , M. De Giorgi
- & D. Sanvitto
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Large-scale organic nanowire lithography and electronics
The high-speed, large-area printing of aligned semiconducting nanowires is vital for practical device applications. Here, the authors use a high-speed printing technique to print semiconducting nanowire arrays onto device substrates with precise nanowire control, and high field-effect mobilities are observed.
- Sung-Yong Min
- , Tae-Sik Kim
- & Tae-Woo Lee
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Single-shot pulse duration monitor for extreme ultraviolet and X-ray free-electron lasers
Free-electron lasers offer exciting new possibilities for X-ray studies on ultrafast timescales, but their shot-to-shot variability requires new diagnostic tools. Using a plasma switch cross-correlator, Riedel et al. present a single-shot online diagnostic to retrieve the duration of extreme ultraviolet pulses.
- R. Riedel
- , A. Al-Shemmary
- & F. Tavella
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Optical solitons in graded-index multimode fibres
Solitons are waves, occurring in systems such as water channels and optical fibres that preserve their shape as they travel. Here the observation of solitons in multimode optical fibres offers a platform for studying spatiotemporal wave packets, and could allow high peak power transmission along with increased data rates in low-cost telecommunications.
- W. H. Renninger
- & F. W. Wise
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Enhancing far-field thermal emission with thermal extraction
The control of thermal radiation is important for applications such as energy conversion and radiative cooling. Here Fan et al. demonstrate a thermal extraction scheme that can enhance the emission of a finite-sized blackbody-like emitter.
- Zongfu Yu
- , Nicholas P. Sergeant
- & Shanhui Fan
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Soft X-ray spectromicroscopy using ptychography with randomly phased illumination
Ptychographic methods can retrieve the complex sample transmittance from diffraction patterns that may have a large dynamic range. For soft X-ray spectromicroscopy, Maiden et al. use a diffuser to randomize the probe phase, reducing the dynamic range of the diffraction data by an order of magnitude.
- A.M. Maiden
- , G.R. Morrison
- & J.M. Rodenburg
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A strong electro-optically active lead-free ferroelectric integrated on silicon
The strong electro-optical response of BaTiO3 could be useful for making high-speed switches for optical telecommunications. Abel et al. demonstrate the ability to maintain this response in BaTiO3films grown directly onto silicon, extending its potential to the development of silicon photonics.
- Stefan Abel
- , Thilo Stöferle
- & Jean Fompeyrine
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Diamond-integrated optomechanical circuits
Diamond is of interest for optical and electronic applications owing to its unique mechanical and optical properties. Here, Rath et al. demonstrate the use of small nanometre-sized beams etched from diamond thin films for integrated photonic circuits.
- Patrik Rath
- , Svetlana Khasminskaya
- & Wolfram H.P. Pernice
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Two-dimensional structure from random multiparticle X-ray scattering images using cross-correlations
A model-independent protocol is developed for reconstructing a two-dimensional particle from multiparticle diffraction images. The method is verified experimentally with gold nanostructures, paving the way towards single-molecule imaging using high-intensity X-ray free-electron laser pulses.
- B. Pedrini
- , A. Menzel
- & R. Abela
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High-resolution correlation spectroscopy of 13C spins near a nitrogen-vacancy centre in diamond
The spin states associated with nitrogen vacancies in diamond could be useful in the development of solid-state quantum information processing. Laraoui et al. resolve the temporal dynamics of spins associated with C-13 atoms near such vacancies to better understand and perhaps better exploit their behaviour.
- Abdelghani Laraoui
- , Florian Dolde
- & Carlos A. Meriles
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Narrowband photodetection in the near-infrared with a plasmon-induced hot electron device
Plasmons excited in gratings create strong resonant absorptions that depend on the nanostructure period. By patterning a gold grating on a silicon substrate, Sobhani et al. exploit plasmon-induced hot electron photocurrent generation to create a narrowband infrared photodetector with greatly enhanced absorption efficiency.
- Ali Sobhani
- , Mark W. Knight
- & Naomi J. Halas
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Significant performance enhancement in photoconductive terahertz optoelectronics by incorporating plasmonic contact electrodes
For terahertz optoelectronics to find broader applications, more efficient sources and detectors are needed. Towards this end, Berry et al. demonstrate the use of plasmonic contact electrodes for both terahertz emitters and detectors, finding large enhancement over standard photoconductive devices.
- C.W. Berry
- , N. Wang
- & M. Jarrahi
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| Open AccessNonreciprocal plasmonics enables giant enhancement of thin-film Faraday rotation
The Faraday effect rotates the polarization plane of light in magneto-optical materials and is used for optical isolators blocking unwanted backscattering of light. Usually a small effect, Chin et al. have observed a large enhancement of the optical rotation by magneto-plasmonics.
- Jessie Yao Chin
- , Tobias Steinle
- & Harald Giessen
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Photon-enhanced thermionic emission from heterostructures with low interface recombination
By having the electrons and lattice at high temperature, photon-enhanced thermionic emission offers improved electron extraction energy in solar conversion devices. Schwede et al.use a heterostructure design to introduce an internal interface, showing higher quantum efficiencies than previous experiments.
- J.W. Schwede
- , T. Sarmiento
- & Z.-X. Shen
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Directional visible light scattering by silicon nanoparticles
The scattering of light by nanoparticles could be useful for photonic nanoantenna or other light manipulation schemes. Here Kuznetsov et al. demonstrate directional light scattering from silicon nanoparticles for visible light.
- Yuan Hsing Fu
- , Arseniy I. Kuznetsov
- & Boris Luk’yanchuk
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Bright solid-state sources of indistinguishable single photons
For quantum technologies to become widespread and scalable, bright sources of indistinguishable single photons are essential. Through deterministic positioning of quantum dots in pillar cavities, Gazzano et al.present a solid-state single-photon source with brightness as large as 0.65 photons per pulse.
- O. Gazzano
- , S. Michaelis de Vasconcellos
- & P. Senellart
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| Open AccessNanoscale imaging and spontaneous emission control with a single nano-positioned quantum dot
The emission properties of quantum dots make them ideal for probing plasmonic nanostructures, but their small size makes them difficult to manipulate. Ropp et al.use a microfluidic system to accurately place single quantum dots around silver nanowires to probe the local density of optical states.
- Chad Ropp
- , Zachary Cummins
- & Edo Waks