Featured
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Room-temperature sub-band gap optoelectronic response of hyperdoped silicon
Extending the optical response of silicon below the band gap towards infrared wavelengths is of interest for applications such as imaging. Here, Mailoa et al. achieve room-temperature infrared photoresponse from silicon doped with supersaturated concentrations of gold impurities.
- Jonathan P. Mailoa
- , Austin J. Akey
- & Tonio Buonassisi
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| Open AccessHeterovalent cation substitutional doping for quantum dot homojunction solar cells
To use colloidal quantum dots in applications such as p-n junction solar cells, doping of the quantum dots is needed. Here, Stavrinadis et al. achieve lead sulphide quantum dot p-n homojunctions by heterovalent cation substitution of lead using bismuth.
- Alexandros Stavrinadis
- , Arup K. Rath
- & Gerasimos Konstantatos
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| Open AccessDetermining the optimum morphology in high-performance polymer-fullerene organic photovoltaic cells
The morphology of organic solar cells is crucial to their performance but is difficult to measure. Using a variety of probes, Hedley et al.map the morphology of polymer-fullerene solar cells and find that elongated fibre-like polymer- and fullerene-rich domains are desirable for high performance.
- Gordon J. Hedley
- , Alexander J. Ward
- & Ifor D. W. Samuel
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All-back-contact ultra-thin silicon nanocone solar cells with 13.7% power conversion efficiency
Nanostructured solar cells should be designed to balance the photonic and electronic effects together to be highly efficient. Cui et al.demonstrate a solar cell with the all-back-contact design and nanocone structure that uses just 10-μm-thick silicon while achieving efficiencies up to 13.7%.
- Sangmoo Jeong
- , Michael D. McGehee
- & Yi Cui
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Lasing from individual GaAs-AlGaAs core-shell nanowires up to room temperature
Semiconductor nanowires are of practical interest as some of the smallest laser sources available. Here Mayer et al.demonstrate GaAs/AlGaAs core-shell nanowire lasers at infrared wavelengths that operate up to room temperature.
- Benedikt Mayer
- , Daniel Rudolph
- & Jonathan J. Finley
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Two-colour hard X-ray free-electron laser with wide tunability
To study the dynamics of materials and biological samples at ultrafast time scales it is beneficial to use two short laser pulses, ideally at different energies. Here, the authors demonstrate the generation of two femtosecond hard X-ray laser pulses in a free electron laser, with more than 30% energy separation.
- Toru Hara
- , Yuichi Inubushi
- & Tetsuya Ishikawa
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| Open AccessOptical sinc-shaped Nyquist pulses of exceptional quality
The rectangular spectral shape of sinc Nyquist pulses are ideal for data transmission as they make optimal use of the available frequency spectrum. Here Soto et al.develop a scheme for the optical generation of sinc-shaped Nyquist pulses with very high quality, based on the direct synthesis of rectangular, phase-locked frequency combs.
- Marcelo A. Soto
- , Mehdi Alem
- & Thomas Schneider
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| Open AccessLong-distance distribution of genuine energy-time entanglement
Practical implementations of quantum communication need to securely deliver information over long distances without line-of-sight. Towards this goal, Cuevas et al.use an actively stabilized interferometer to close the geometry loophole for a Bell inequality violation over 1 km of optical fibre.
- A. Cuevas
- , G. Carvacho
- & G.B. Xavier
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| Open AccessRole of domain walls in the abnormal photovoltaic effect in BiFeO3
The origin of the abnormal photovoltaic effect in bismuth ferrite thin films, which causes voltages larger than the band gap, is poorly understood. Bhatnagar et al.show that this effect can be attributed to a bulk photovoltaic effect and that it can be enhanced by controlling domain wall conductivity.
- Akash Bhatnagar
- , Ayan Roy Chaudhuri
- & Marin Alexe
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Efficient organometal trihalide perovskite planar-heterojunction solar cells on flexible polymer substrates
Low-cost, flexible solar cells offer new possibilities to harvest solar energy, for example on curved or movable surfaces. Here, Docampo and colleagues demonstrate the fabrication of efficient organometallic perovskite heterojunction solar cells on flexible substrates.
- Pablo Docampo
- , James M. Ball
- & Henry J. Snaith
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| Open AccessAn on-chip coupled resonator optical waveguide single-photon buffer
Photonic circuits are a promising route to developing scalable quantum technologies, if all the necessary components can be built. Using coupled resonator optical waveguides, Takesue et al.present an on-chip single-photon buffer that can delay one photon from a pair for 150 ps while preserving entanglement.
- Hiroki Takesue
- , Nobuyuki Matsuda
- & Masaya Notomi
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Quantum teleportation from a propagating photon to a solid-state spin qubit
Future quantum technologies will require interfaces between photons transmitting information and solid-state devices storing and manipulating it. Towards this aim, Gao et al.show the transfer of information from a single photon to a semiconductor quantum dot through quantum teleportation protocols.
- W.B. Gao
- , P. Fallahi
- & A. Imamoğlu
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| Open AccessRay-optics cloaking devices for large objects in incoherent natural light
Although many electromagnetic cloaking schemes exist at different wavelengths, realizing a broadband visible wavelength device is hard. By relaxing the need for phase preservation inherent to most methods, Chen et al.present a ray-optics scheme for cloaking large-scale objects from the human eye.
- Hongsheng Chen
- , Bin Zheng
- & Baile Zhang
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Harvesting singlet fission for solar energy conversion via triplet energy transfer
The efficiency of organic solar cells may be increased by the incorporation of materials capable of singlet fission. Here, Tritsch and colleagues identify strategies to enhance the extraction of multiple excitons from the desirable singlet fission process.
- John R. Tritsch
- , Wai-Lun Chan
- & X-Y. Zhu
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Sharply autofocused ring-Airy beams transforming into non-linear intense light bullets
The propagation of high-intensity light beams through transparent media can lead to unusual non-linear effects. Here Panagiotopoulos et al.show that a high-intensity ring-Airy beam transforms into a robust non-linear light bullet.
- P. Panagiotopoulos
- , D.G. Papazoglou
- & S. Tzortzakis
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| Open AccessIntegrated spatial multiplexing of heralded single-photon sources
Photonic quantum technologies will require efficient single-photon sources and spatial multiplexing has been explored as a route to achieve this. Here, the authors present a scheme to integrate several single-photon sources using spatial multiplexing for on-chip applications at telecommunications wavelengths.
- M.J. Collins
- , C. Xiong
- & B.J. Eggleton
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Virtual hyperbolic metamaterials for manipulating radar signals in air
Controlling the propagation of microwaves in air is hard because of their divergence and the lack of suitable optics. Kudyshev et al. show how this can be overcome using plasma channels to create virtual hyperbolic metamaterials to collimate and guide radar beams.
- Zhaxylyk A. Kudyshev
- , Martin C. Richardson
- & Natalia M. Litchinitser
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Demonstration of a novel focusing small-angle neutron scattering instrument equipped with axisymmetric mirrors
Small-angle neutron scattering is an important technique for a number of fields, but most instruments are inefficient in terms of neutron flux. Using a design based on axisymmetric focussing mirrors, Liu et al. build a compact small-angle neutron-scattering setup that could overcome the present limitations.
- Dazhi Liu
- , Boris Khaykovich
- & David E. Moncton
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| Open AccessTwo-colour pump–probe experiments with a twin-pulse-seed extreme ultraviolet free-electron laser
Free-electron lasers are a powerful new tool for studying properties and transient states of matter. Here, the authors use a novel seed scheme for generation of two XUV laser pulses of controlled wavelength and time separation that enables access to ultrafast phenomena with elemental sensitivity.
- E. Allaria
- , F. Bencivenga
- & M. Zangrando
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| Open AccessSpiral resonators for on-chip laser frequency stabilization
Optical reference cavities are important in precision time keeping and low-noise microwave generation. Here as a step towards their miniaturization, the authors demonstrate a chip-based reference cavity that uses a spiral geometry to improve stability by introducing thermal and mechanical immunity.
- Hansuek Lee
- , Myoung-Gyun Suh
- & Kerry J. Vahala
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An entanglement-enhanced microscope
In microscopy, the standard quantum limit represents the best achievable signal-to-noise ratio for a given light intensity. Here, the authors build an optical microscope that uses entanglement between photon pairs to overcome this barrier.
- Takafumi Ono
- , Ryo Okamoto
- & Shigeki Takeuchi
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Interaction of independent single photons based on integrated nonlinear optics
Nonlinear interactions of single photons are important for future quantum technologies, but they are weak and hard to detect. By performing sum-frequency generation between single photons and single-photon level coherent states, Guerreiro et al. show that high-efficiency waveguides can overcome this.
- T. Guerreiro
- , E. Pomarico
- & N. Gisin
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Doping of polycrystalline CdTe for high-efficiency solar cells on flexible metal foil
Flexible CdTe solar cells on metal foil substrates are promising for low-cost roll-to-roll fabrication, but their efficiency is usually low because of their inverted structure. By controlling the doping of the CdTe layer with copper, Kranz et al. show that efficiencies up to 13.6% can be obtained.
- Lukas Kranz
- , Christina Gretener
- & Ayodhya N. Tiwari
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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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| 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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| 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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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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| 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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| 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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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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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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| 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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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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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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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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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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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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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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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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Article
| 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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Improved heat dissipation in gallium nitride light-emitting diodes with embedded graphene oxide pattern
High-brightness light-emitting diodes require high operating currents, which generate significant Joule heating and subsequent heat dissipation is an issue. This work demonstrates the growth of GaN-based light-emitting diodes directly on graphene oxide with a low thermal resistance for efficient heat removal.
- Nam Han
- , Tran Viet Cuong
- & Chang-Hee Hong
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Photon-mediated interaction between distant quantum dot circuits
Controlling the interaction between distant quantum dots is important if they are to be used in quantum information devices. Delbecq et al. place two quantum dot circuits in a microwave cavity and show that they interact via cavity photons, even though they are separated by 200 times their own size.
- M.R. Delbecq
- , L.E. Bruhat
- & T. Kontos
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| Open AccessParallel photonic information processing at gigabyte per second data rates using transient states
Inspired by neural networks, reservoir computing uses nonlinear transient states to perform computations, offering faster parallel information processing. Brunner et al.show a photonic approach to reservoir computing capable of simultaneous spoken digit and speaker recognition at high data rates.
- Daniel Brunner
- , Miguel C. Soriano
- & Ingo Fischer
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