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  • Publisher Correction: Control of semiconductor emitter frequency by increasing polariton momenta
    Nat. Photon. (IF 32.521) Pub Date : 2018-07-16
    Yaniv Kurman, Nicholas Rivera, Thomas Christensen, Shai Tsesses, Meir Orenstein, Marin Soljačić, John D. Joannopoulos, Ido Kaminer

    Publisher Correction: Control of semiconductor emitter frequency by increasing polariton momenta Publisher Correction: Control of semiconductor emitter frequency by increasing polariton momenta, Published online: 16 July 2018; doi:10.1038/s41566-018-0214-4 Publisher Correction: Control of semiconductor emitter frequency by increasing polariton momenta

    更新日期:2018-07-18
  • A phonon laser operating at an exceptional point
    Nat. Photon. (IF 32.521) Pub Date : 2018-07-09
    Jing Zhang, Bo Peng, Şahin Kaya Özdemir, Kevin Pichler, Dmitry O. Krimer, Guangming Zhao, Franco Nori, Yu-xi Liu, Stefan Rotter, Lan Yang

    Non-Hermitian physical systems have attracted considerable attention lately for their unconventional behaviour around exceptional points (EPs)—spectral singularities at which eigenvalues and eigenvectors coalesce. In particular, many new EP-related concepts such as unidirectional lasing and invisibility, as well as chiral transmission, have been realized. Given the progress in understanding the physics of EPs in various photonic structures, it is surprising that one of the oldest theoretical predictions associated with them, a remarkable broadening of the laser linewidth at an EP, has been probed only indirectly so far. Here, we fill this gap by steering a phonon laser through an EP in a compound optomechanical system formed by two coupled resonators. We observe a pronounced linewidth broadening of the mechanical lasing mode generated in one of the resonators when the system approaches the EP.

    更新日期:2018-07-10
  • Publisher Correction: Mid-infrared frequency comb via coherent dispersive wave generation in silicon nitride nanophotonic waveguides
    Nat. Photon. (IF 32.521) Pub Date : 2018-07-04
    Hairun Guo, Clemens Herkommer, Adrien Billat, Davide Grassani, Chuankun Zhang, Martin H. P. Pfeiffer, Wenle Weng, Camille-Sophie Brès, Tobias J. Kippenberg

    Publisher Correction: Mid-infrared frequency comb via coherent dispersive wave generation in silicon nitride nanophotonic waveguidesPublisher Correction: Mid-infrared frequency comb via coherent dispersive wave generation in silicon nitride nanophotonic waveguides, Published online: 04 July 2018; doi:10.1038/s41566-018-0218-0Publisher Correction: Mid-infrared frequency comb via coherent dispersive wave generation in silicon nitride nanophotonic waveguides

    更新日期:2018-07-09
  • Macroscopic direct observation of optical spin-dependent lateral forces and left-handed torques
    Nat. Photon. (IF 32.521) Pub Date : 2018-07-02
    Hernando Magallanes, Etienne Brasselet

    Observing and taming the effects arising from non-trivial light–matter interaction has always triggered scientists to better understand nature and develop photonic technologies. However, despite tremendous conceptual advances1,2, so far there have been only a few experimental proposals to reveal unusual optomechanical manifestations that are hardly seen in everyday life, such as negative radiation pressure3,4, transverse forces5,6 or left-handed torques7. Here, we report naked-eye identification of spin-dependent lateral displacements of centimetre-sized objects endowed with structured birefringence. Left-handed macroscopic rotational motion is also reported. The unveiled effects ultimately rely on spin–orbit optical interactions and are driven by lateral force fields that are five orders of magnitude larger than those reported previously, as a result of the proposed design. By highlighting the spin–orbit optomechanics of anisotropic and inhomogeneous media, these results allow structured light–matter interaction to move from a scientific curiosity to a new asset for the optical manipulation toolbox.

    更新日期:2018-07-05
  • Single-source chip-based frequency comb enabling extreme parallel data transmission
    Nat. Photon. (IF 32.521) Pub Date : 2018-07-02
    Hao Hu, Francesco Da Ros, Minhao Pu, Feihong Ye, Kasper Ingerslev, Edson Porto da Silva, Md. Nooruzzaman, Yoshimichi Amma, Yusuke Sasaki, Takayuki Mizuno, Yutaka Miyamoto, Luisa Ottaviano, Elizaveta Semenova, Pengyu Guan, Darko Zibar, Michael Galili, Kresten Yvind, Toshio Morioka, Leif K. Oxenløwe

    The Internet today transmits hundreds of terabits per second, consumes 9% of all electricity worldwide and grows by 20–30% per year1,2. To support capacity demand, massively parallel communication links are installed, not scaling favourably concerning energy consumption. A single frequency comb source may substitute many parallel lasers and improve system energy-efficiency3,4. We present a frequency comb realized by a non-resonant aluminium-gallium-arsenide-on-insulator (AlGaAsOI) nanowaveguide with 66% pump-to-comb conversion efficiency, which is significantly higher than state-of-the-art resonant comb sources. This enables unprecedented high data-rate transmission for chip-based sources, demonstrated using a single-mode 30-core fibre. We show that our frequency comb can carry 661 Tbit s–1 of data, equivalent to more than the total Internet traffic today. The comb is obtained by seeding the AlGaAsOI chip with 10-GHz picosecond pulses at a low pump power (85 mW), and this scheme is robust to temperature changes, is energy efficient and facilitates future integration with on-chip lasers or amplifiers5,6.

    更新日期:2018-07-02
  • Electrically tuned nonlinearity
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-28
    Zhipei Sun

    Electrically tuned nonlinearity Electrically tuned nonlinearity, Published online: 28 June 2018; doi:10.1038/s41566-018-0201-9 The demonstration of broadband, electrically tunable third-order nonlinear optical responses in graphene is promising for a host of nonlinear optical applications.

    更新日期:2018-06-30
  • Twin-field QKD
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-28
    David F. P. Pile

    Twin-field QKD Twin-field QKD, Published online: 28 June 2018; doi:10.1038/s41566-018-0209-1 Twin-field QKD

    更新日期:2018-06-30
  • Molecular sensing
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-28
    Oliver Graydon

    Molecular sensing Molecular sensing, Published online: 28 June 2018; doi:10.1038/s41566-018-0211-7 Molecular sensing

    更新日期:2018-06-30
  • On our bookshelf
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-28
    Rachel Won

    On our bookshelf On our bookshelf, Published online: 28 June 2018; doi:10.1038/s41566-018-0207-3 On our bookshelf

    更新日期:2018-06-30
  • Measuring molecular mass with light
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-28
    Kyu Young Han, Taekjip Ha

    Measuring molecular mass with light Measuring molecular mass with light, Published online: 28 June 2018; doi:10.1038/s41566-018-0202-8 Interferometric analysis of the weak light scattered from proteins makes it possible to determine their mass.

    更新日期:2018-06-30
  • Tunable comb
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-28
    Rachel Won

    Tunable comb Tunable comb, Published online: 28 June 2018; doi:10.1038/s41566-018-0212-6 Tunable comb

    更新日期:2018-06-30
  • Triplet state brightens upconversion
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-28
    Jiajia Zhou, Dayong Jin

    Triplet state brightens upconversion Triplet state brightens upconversion, Published online: 28 June 2018; doi:10.1038/s41566-018-0188-2 Efficient photon upconversion is desired for applications ranging from molecular sensing to solar-energy harvesting. Now, the population of hidden triplet state electrons, created on dye antennas and rare-earth-doped nanoparticles, has been amplified to brighten upconversion by five orders of magnitude.

    更新日期:2018-06-30
  • Encouraging instability
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-28
    David F. P. Pile

    Encouraging instability Encouraging instability, Published online: 28 June 2018; doi:10.1038/s41566-018-0208-2 Encouraging instability

    更新日期:2018-06-30
  • Nonlinear charge oscillation driven by a single-cycle light field in an organic superconductor
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-25
    Y. Kawakami, T. Amano, Y. Yoneyama, Y. Akamine, H. Itoh, G. Kawaguchi, H. M. Yamamoto, H. Kishida, K. Itoh, T. Sasaki, S. Ishihara, Y. Tanaka, K. Yonemitsu, S. Iwai

    Application of an intense light field to solids produces enormous and ultrafast nonlinear phenomena such as high-harmonic generation1,2 and attosecond charge dynamics3,4. These are distinct from conventional photonics. However, the main targets for investigation have been limited to insulators and semiconductors, although theoretical approaches have also been developed for correlated metals and superconductors5. Here, in a layered organic superconductor, a nonlinear charge oscillation driven by a nearly single-cycle strong electric field of >10 MV cm−1 is observed as a stimulated emission. The charge oscillation is different from a linear response and ascribed to a polar charge oscillation with a period of ∼6 fs. This nonlinear polar charge oscillation is enhanced by critical fluctuations near a superconducting transition temperature and a critical end-point of first-order Mott transitions. Its observation on an ultrafast timescale of ∼10 fs clarifies that Coulomb repulsion plays an essential role in the superconductivity of organic superconductors.

    更新日期:2018-06-27
  • Giant optical anisotropy in a quasi-one-dimensional crystal
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-18
    Shanyuan Niu, Graham Joe, Huan Zhao, Yucheng Zhou, Thomas Orvis, Huaixun Huyan, Jad Salman, Krishnamurthy Mahalingam, Brittany Urwin, Jiangbin Wu, Yang Liu, Thomas E. Tiwald, Stephen B. Cronin, Brandon M. Howe, Matthew Mecklenburg, Ralf Haiges, David J. Singh, Han Wang, Mikhail A. Kats, Jayakanth Ravichandran

    Optical anisotropy is a fundamental building block for linear and nonlinear optical components such as polarizers, wave plates, and phase-matching elements1,2,3,4. In solid homogeneous materials, the strongest optical anisotropy is found in crystals such as calcite and rutile5,6. Attempts to enhance anisotropic light–matter interaction often rely on artificial anisotropic micro/nanostructures (form birefringence)7,8,9,10,11. Here, we demonstrate rationally designed, giant optical anisotropy in single crystals of barium titanium sulfide (BaTiS3). This material shows an unprecedented, broadband birefringence of up to 0.76 in the mid- to long-wave infrared, as well as a large dichroism window with absorption edges at 1.6 μm and 4.5 μm for light with polarization along two crystallographic axes on an easily accessible cleavage plane. The unusually large anisotropy is a result of the quasi-one-dimensional structure, combined with rational selection of the constituent ions to maximize the polarizability difference along different axes.

    更新日期:2018-06-18
  • Phase-matched extreme-ultraviolet frequency-comb generation
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-18
    Gil Porat, Christoph M. Heyl, Stephen B. Schoun, Craig Benko, Nadine Dörre, Kristan L. Corwin, Jun Ye

    Laser-driven high-order harmonic generation1,2 provides spatially3 and temporally4 coherent tabletop sources of broadband extreme-ultraviolet (XUV) light. These sources typically operate at low repetition rates, frep ≲ 100 kHz, where phase-matched HHG is readily achieved5,6. However, many applications demand the improved counting statistics or frequency-comb precision afforded by high repetition rates, frep > 10 MHz. Unfortunately, at such high frep, phase matching is prevented by steady-state plasma accumulated in the generation volume7,8,9,10,11, strongly limiting the XUV average power. Here, we use high-temperature gas mixtures as the generation medium to increase the gas translational velocity, thereby reducing the steady-state plasma in the laser focus. This allows phase-matched XUV emission inside a femtosecond enhancement cavity at frep = 77 MHz, enabling a record generated power of ~ 2 mW in a single harmonic order. This power scaling opens up many demanding applications, including XUV frequency-comb spectroscopy12,13 of few-electron atoms and ions for precision tests of fundamental physical laws and constants14,15,16,17,18,19,20.

    更新日期:2018-06-18
  • Strong-field optoelectronics in solids
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-18
    G. Vampa, T. J. Hammond, M. Taucer, Xiaoyan Ding, X. Ropagnol, T. Ozaki, S. Delprat, M. Chaker, N. Thiré, B. E. Schmidt, F. Légaré, D. D. Klug, A. Yu. Naumov, D. M. Villeneuve, A. Staudte, P. B. Corkum

    Perturbative optical nonlinearities induced by static electric fields1 have proven useful in visualizing dynamical function in systems including operating circuits2,3, electric and magnetic domain walls4, and biological matter5, and in controlling light for applications in silicon photonics6. Here, we extend field-induced second-harmonic generation to the non-perturbative regime. We demonstrate that static or transient fields up to terahertz (THz) frequencies applied to silicon and ZnO crystals generate even-order high harmonics. Images of the even harmonics confirm that static fields delivered with conventional electronics control the spatial properties of the high-harmonic emission. Extending our methodology to higher-harmonic photon energies7,8 paves the way for realizing active optics in the extreme ultraviolet and will allow imaging of operating electronic circuits9, of Si-photonic devices10 and of other functional materials11,12, with higher spatio-temporal resolution than perturbative methods. For THz spectroscopy, our method has the bandwidth to allow measurement of attosecond transients imprinted on THz waveforms.

    更新日期:2018-06-18
  • Relativistic single-cycle tunable infrared pulses generated from a tailored plasma density structure
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-11
    Zan Nie, Chih-Hao Pai, Jianfei Hua, Chaojie Zhang, Yipeng Wu, Yang Wan, Fei Li, Jie Zhang, Zhi Cheng, Qianqian Su, Shuang Liu, Yue Ma, Xiaonan Ning, Yunxiao He, Wei Lu, Hsu-Hsin Chu, Jyhpyng Wang, Warren B. Mori, Chan Joshi

    The availability of intense, ultrashort coherent radiation sources in the infrared region of the spectrum is enabling the generation of attosecond X-ray pulses via high-harmonic generation, pump–probe experiments in the ‘molecular fingerprint’ region and opening up the area of relativistic infrared nonlinear optics of plasmas. These applications would benefit from multi-millijoule single-cycle pulses in the mid- to long-wavelength infrared region. Here, we present a new scheme capable of producing tunable relativistically intense, single-cycle infrared pulses from 5 to 14 μm with a 1.7% conversion efficiency based on a photon frequency downshifting scheme that uses a tailored plasma density structure. The carrier-envelope phase of the long-wavelength infrared pulse is locked to that of the drive laser to within a few per cent. Such a versatile tunable infrared source may meet the demands of many cutting-edge applications in strong-field physics and greatly promote their development.

    更新日期:2018-06-12
  • Publisher Correction: Universal impedance matching and the perfect transmission of white light
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-05
    Ku Im, Ji-Hun Kang, Q-Han Park

    Publisher Correction: Universal impedance matching and the perfect transmission of white light Publisher Correction: Universal impedance matching and the perfect transmission of white light, Published online: 05 June 2018; doi:10.1038/s41566-018-0195-3 Publisher Correction: Universal impedance matching and the perfect transmission of white light

    更新日期:2018-06-05
  • Author Correction: Combined multi-plane phase retrieval and super-resolution optical fluctuation imaging for 4D cell microscopy
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-05
    A. Descloux, K. S. Grußmayer, E. Bostan, T. Lukes, A. Bouwens, A. Sharipov, S. Geissbuehler, A.-L. Mahul-Mellier, H. A. Lashuel, M. Leutenegger, T. Lasser

    Author Correction: Combined multi-plane phase retrieval and super-resolution optical fluctuation imaging for 4D cell microscopy Author Correction: Combined multi-plane phase retrieval and super-resolution optical fluctuation imaging for 4D cell microscopy, Published online: 05 June 2018; doi:10.1038/s41566-018-0198-0 Author Correction: Combined multi-plane phase retrieval and super-resolution optical fluctuation imaging for 4D cell microscopy

    更新日期:2018-06-05
  • Experimental observation of a polarization vortex at an optical bound state in the continuum
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-04
    Hugo M. Doeleman, Francesco Monticone, Wouter den Hollander, Andrea Alù, A. Femius Koenderink

    Optical bound states in the continuum (BICs) are states supported by a photonic structure that are compatible with free-space radiation, yet become perfectly bound for one specific in-plane momentum and wavelength1,2. Recently, it was predicted that light radiated by such modes around the BIC momentum–frequency condition should display a vortex in its far-field polarization profile, making the BIC topologically protected3. Here, we study a one-dimensional grating supporting a transverse magnetic mode with a BIC near 700 nm wavelength, verifying the existence of the BIC using reflection measurements, which show a vanishing reflection feature. Using k-space polarimetry, we measure the full polarization state of reflection around the BIC, highlighting the presence of a topological vortex. We use an electromagnetic dipole model to explain the observed BIC through destructive interference between two radiation channels, characteristic of a Friedrich–Wintgen-type BIC4. Our findings shed light on the origin of BICs and verify their topological nature.

    更新日期:2018-06-05
  • Control of semiconductor emitter frequency by increasing polariton momenta
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-04
    Yaniv Kurman, Nicholas Rivera, Thomas Christensen, Shai Tsesses, Meir Orenstein, Marin Soljačić, John D. Joannopoulos, Ido Kaminer

    Light emission and absorption is fundamentally a joint property of both an emitter and its optical environment. Nevertheless, because of the much smaller momenta of photons compared with electrons at similar energies, the optical environment typically modifies only the emission/absorption rates, leaving the emitter transition frequencies practically an intrinsic property. We show here that surface polaritons, exemplified by graphene plasmons, but also valid for other types of polariton, enable substantial and tunable control of the transition frequencies of a nearby quantum well, demonstrating a sharp break with the emitter-centric view. Central to this result is the large momenta of surface polaritons that can approach the momenta of electrons and impart a pronounced non-local behaviour to the quantum well. This work facilitates non-vertical optical transitions in solids and empowers ongoing efforts to access such transitions in indirect-bandgap materials, such as silicon, as well as enriching the study of non-locality in photonics.

    更新日期:2018-06-05
  • Topological protection of photonic mid-gap defect modes
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-04
    Jiho Noh, Wladimir A. Benalcazar, Sheng Huang, Matthew J. Collins, Kevin P. Chen, Taylor L. Hughes, Mikael C. Rechtsman

    Defect modes in two-dimensional periodic photonic structures have found use in diverse optical devices. For example, photonic crystal cavities confine optical modes to subwavelength volumes and can be used for enhancement of nonlinearity, lasing and cavity quantum electrodynamics. Defect-core photonic crystal fibres allow for supercontinuum generation and endlessly single-mode fibres with large cores. However, these modes are notoriously fragile: small structural change leads to significant detuning of resonance frequency and mode volume. Here, we show that photonic topological crystalline insulator structures can be used to topologically protect the mode frequency at mid-gap and minimize the volume of a photonic defect mode. We experimentally demonstrate this in a femtosecond-laser-written waveguide array by observing the presence of a topological zero mode confined to the corner of the array. The robustness of this mode is guaranteed by a topological invariant that protects zero-dimensional states embedded in a two-dimensional environment—a novel form of topological protection that has not been previously demonstrated.

    更新日期:2018-06-05
  • Publisher Correction: Massively parallel sensing of trace molecules and their isotopologues with broadband subharmonic mid-infrared frequency combs
    Nat. Photon. (IF 32.521) Pub Date : 2018-06-01
    A. V. Muraviev, V. O. Smolski, Z. E. Loparo, K. L. Vodopyanov

    Publisher Correction: Massively parallel sensing of trace molecules and their isotopologues with broadband subharmonic mid-infrared frequency combs Publisher Correction: Massively parallel sensing of trace molecules and their isotopologues with broadband subharmonic mid-infrared frequency combs, Published online: 01 June 2018; doi:10.1038/s41566-018-0196-2 Publisher Correction: Massively parallel sensing of trace molecules and their isotopologues with broadband subharmonic mid-infrared frequency combs

    更新日期:2018-06-01
  • Instability yields bright gamma emission
    Nat. Photon. (IF 32.521) Pub Date : 2018-05-29
    Andrea Macchi, Francesco Pegoraro

    Instability yields bright gamma emission Instability yields bright gamma emission, Published online: 29 May 2018; doi:10.1038/s41566-018-0181-9 The electromagnetic instability associated with a dense, ultra-relativistic electron beam propagating in a thin conductor could offer a new approach to realizing ultra-bright sources of gamma-rays.

    更新日期:2018-05-30
  • On our bookshelf
    Nat. Photon. (IF 32.521) Pub Date : 2018-05-29
    Rachel Won

    On our bookshelf On our bookshelf, Published online: 29 May 2018; doi:10.1038/s41566-018-0180-x On our bookshelf

    更新日期:2018-05-30
  • Intracellular movies
    Nat. Photon. (IF 32.521) Pub Date : 2018-05-29
    Oliver Graydon

    Intracellular movies Intracellular movies, Published online: 29 May 2018; doi:10.1038/s41566-018-0184-6 Intracellular movies

    更新日期:2018-05-30
  • Towards systems-on-a-chip
    Nat. Photon. (IF 32.521) Pub Date : 2018-05-29

    Towards systems-on-a-chip Towards systems-on-a-chip, Published online: 29 May 2018; doi:10.1038/s41566-018-0191-7 Progress in silicon photonics is delivering chips that can densely pack photonics and electronics together and perform multidimensional quantum information processing.

    更新日期:2018-05-30
  • Global position by polarization
    Nat. Photon. (IF 32.521) Pub Date : 2018-05-29
    Oliver Graydon

    Global position by polarization Global position by polarization, Published online: 29 May 2018; doi:10.1038/s41566-018-0187-3 Global position by polarization

    更新日期:2018-05-30
  • Payload success
    Nat. Photon. (IF 32.521) Pub Date : 2018-05-29
    Oliver Graydon

    Payload success Payload success, Published online: 29 May 2018; doi:10.1038/s41566-018-0182-8 Payload success

    更新日期:2018-05-30
  • Energy-efficient detector
    Nat. Photon. (IF 32.521) Pub Date : 2018-05-29
    Oliver Graydon

    Energy-efficient detector Energy-efficient detector, Published online: 29 May 2018; doi:10.1038/s41566-018-0185-5 Energy-efficient detector

    更新日期:2018-05-30
  • Ion string qubits
    Nat. Photon. (IF 32.521) Pub Date : 2018-05-29
    Noriaki Horiuchi

    Ion string qubits Ion string qubits, Published online: 29 May 2018; doi:10.1038/s41566-018-0183-7 Ion string qubits

    更新日期:2018-05-30
  • Publisher Correction: View from... MTSA 2017/Tera Nano 8/Opto X Nano: Terahertz surprises
    Nat. Photon. (IF 32.521) Pub Date : 2018-05-25
    Noriaki Horiuchi

    Publisher Correction: View from... MTSA 2017/Tera Nano 8/Opto X Nano: Terahertz surprises Publisher Correction: View from... MTSA 2017/Tera Nano 8/Opto X Nano: Terahertz surprises, Published online: 25 May 2018; doi:10.1038/s41566-018-0197-1 Publisher Correction: View from... MTSA 2017/Tera Nano 8/Opto X Nano: Terahertz surprises

    更新日期:2018-05-25
  • Publisher Correction: Spatiotemporal control of laser intensity
    Nat. Photon. (IF 32.521) Pub Date : 
    Dustin H. Froula, David Turnbull, Andrew S. Davies, Terrance J. Kessler, Dan Haberberger, John P. Palastro, Seung-Whan Bahk, Ildar A. Begishev, Robert Boni, Sara Bucht, Joseph Katz, Jessica L. Shaw

    Publisher Correction: Spatiotemporal control of laser intensity Publisher Correction: Spatiotemporal control of laser intensity, Published online: 22 May 2018; doi:10.1038/s41566-018-0192-6 Publisher Correction: Spatiotemporal control of laser intensity

    更新日期:2018-05-22
  • Gate-tunable third-order nonlinear optical response of massless Dirac fermions in graphene
    Nat. Photon. (IF 32.521) Pub Date : 2018-05-21
    Tao Jiang, Di Huang, Jinluo Cheng, Xiaodong Fan, Zhihong Zhang, Yuwei Shan, Yangfan Yi, Yunyun Dai, Lei Shi, Kaihui Liu, Changgan Zeng, Jian Zi, J. E. Sipe, Yuen-Ron Shen, Wei-Tao Liu, Shiwei Wu

    Graphene with massless Dirac fermions can have exceptionally strong third-order optical nonlinearities. Yet reported values of nonlinear optical susceptibilities for third-harmonic generation (THG), four-wave mixing (FWM) and self-phase modulation vary over six orders of magnitude. Such variation likely arises from frequency-dependent resonance effects of different processes in graphene under different doping. Here, we report an experimental study of THG and FWM in graphene using gate tuning to adjust the doping level and vary the resonant condition. We find that THG and sum-frequency FWM are strongly enhanced in heavily doped graphene, while the difference-frequency FWM appears just the opposite. Difference-frequency FWM exhibited a novel divergence towards the degenerate case in undoped graphene, leading to a giant enhancement of the nonlinearity. The results are well supported by theory. Our full understanding of the diverse nonlinearity of graphene paves the way towards future design of graphene-based nonlinear optoelectronic devices.

    更新日期:2018-05-22
  • Femtosecond laser crosslinking of the cornea for non-invasive vision correction
    Nat. Photon. (IF 32.521) Pub Date : 2018-05-14
    Chao Wang, Mikhail Fomovsky, Guanxiong Miao, Mariya Zyablitskaya, Sinisa Vukelic

    The prevalence of myopia has increased worldwide over the last 50 years. Its incidence in the United States and Europe is now almost twice that 50 years ago, and it is even more prevalent in East Asia. Spectacles and contact lenses remain the most common means of vision correction, but the permanent correction of refractive errors, by refractive surgery, has emerged as an attractive alternative. However, such surgery is an invasive procedure that may compromise corneal structure, and post-surgical complications have been reported. We propose a novel, non-invasive approach to permanent vision correction based on a different mode of laser–cornea interaction. Our approach induces the formation of a low-density plasma that produces reactive oxygen species, which react with the surrounding proteins, forming crosslinks and triggering spatially resolved changes in mechanical properties. We show that the proposed method changes the refractive power of the eye, and confirm its safety and stability.

    更新日期:2018-05-15
  • Adaptive wavefront shaping for controlling nonlinear multimode interactions in optical fibres
    Nat. Photon. (IF 32.521) Pub Date : 2018-05-07
    Omer Tzang, Antonio M. Caravaca-Aguirre, Kelvin Wagner, Rafael Piestun

    Recent progress in wavefront shaping has enabled control of light propagation inside linear media to focus and image through scattering objects. In particular, light propagation in multimode fibres comprises complex intermodal interactions and rich spatiotemporal dynamics. Control of physical phenomena in multimode fibres and its applications are in their infancy, opening opportunities to take advantage of complex nonlinear modal dynamics. Here, we demonstrate a wavefront shaping approach for controlling nonlinear phenomena in multimode fibres. Using a spatial light modulator at the fibre input, real-time spectral feedback and a genetic algorithm optimization, we control a highly nonlinear multimode stimulated Raman scattering cascade and its interplay with four-wave mixing via a flexible implicit control on the superposition of modes coupled into the fibre. We show versatile spectrum manipulations including shifts, suppression, and enhancement of Stokes and anti-Stokes peaks. These demonstrations illustrate the power of wavefront shaping to control and optimize nonlinear wave propagation.

    更新日期:2018-05-08
  • Continuous transition between weak and ultrastrong coupling through exceptional points in carbon nanotube microcavity exciton–polaritons
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-30
    Weilu Gao, Xinwei Li, Motoaki Bamba, Junichiro Kono

    Non-perturbative coupling of photons and excitons produces hybrid particles, exciton–polaritons, which have exhibited a variety of many-body phenomena in various microcavity systems. However, the vacuum Rabi splitting (VRS), which defines the strength of photon–exciton coupling, is usually a single constant for a given system. Here, we have developed a unique architecture in which excitons in an aligned single-chirality carbon nanotube film interact with cavity photons in polarization-dependent manners. The system reveals ultrastrong coupling (VRS up to 329 meV or a coupling-strength-to-transition-energy ratio of 13.3%) for polarization parallel to the nanotube axis, whereas VRS is absent for perpendicular polarization. Between these two extremes, VRS is continuously tunable through polarization rotation with exceptional points separating crossing and anticrossing. The points between exceptional points form equienergy arcs onto which the upper and lower polaritons coalesce. The demonstrated on-demand ultrastrong coupling provides ways to explore topological properties of polaritons and quantum technology applications.

    更新日期:2018-04-30
  • Hybrid perovskite films approaching the radiative limit with over 90% photoluminescence quantum efficiency
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-30
    Ian L. Braly, Dane W. deQuilettes, Luis M. Pazos-Outón, Sven Burke, Mark E. Ziffer, David S. Ginger, Hugh W. Hillhouse

    Reducing non-radiative recombination in semiconducting materials is a prerequisite for achieving the highest performance in light-emitting and photovoltaic applications. Here, we characterize both external and internal photoluminescence quantum efficiency and quasi-Fermi-level splitting of surface-treated hybrid perovskite (CH3NH3PbI3) thin films. With respect to the material bandgap, these passivated films exhibit the highest quasi-Fermi-level splitting measured to date, reaching 97.1 ± 0.7% of the radiative limit, approaching that of the highest performing GaAs solar cells. We confirm these values with independent measurements of internal photoluminescence quantum efficiency of 91.9 ± 2.7% under 1 Sun illumination intensity, setting a new benchmark for these materials. These results suggest hybrid perovskite solar cells are inherently capable of further increases in power conversion efficiency if surface passivation can be combined with optimized charge carrier selective interfaces.

    更新日期:2018-04-30
  • On our book shelf
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-26
    Rachel Won

    On our book shelf On our book shelf, Published online: 26 April 2018; doi:10.1038/s41566-018-0165-9 On our book shelf

    更新日期:2018-04-27
  • The super-resolution debate
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-26
    Rachel Won

    The super-resolution debate The super-resolution debate, Published online: 26 April 2018; doi:10.1038/s41566-018-0164-x In the quest for nanoscopy with super-resolution, consensus from the imaging community is that super-resolution is not always needed and that scientists should choose an imaging technique based on their specific application.

    更新日期:2018-04-27
  • Tight focusing
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-26
    Oliver Graydon

    Tight focusing Tight focusing, Published online: 26 April 2018; doi:10.1038/s41566-018-0171-y Tight focusing

    更新日期:2018-04-27
  • Monitoring mosquitoes
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-26
    David F. P. Pile

    Monitoring mosquitoes Monitoring mosquitoes, Published online: 26 April 2018; doi:10.1038/s41566-018-0168-6 Monitoring mosquitoes

    更新日期:2018-04-27
  • Tackling Africa’s digital divide
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-26
    Martin P. J. Lavery, Mojtaba Mansour Abadi, Ralf Bauer, Gilberto Brambilla, Ling Cheng, Mitchell A. Cox, Angela Dudley, Andrew D. Ellis, Nicolas K. Fontaine, Anthony E. Kelly, Christoph Marquardt, Selaelo Matlhane, Bienvenu Ndagano, Francesco Petruccione, Radan Slavík, Filippo Romanato, Carmelo Rosales-Guzmán, Filippus S. Roux, Kobus Roux, Jian Wang, Andrew Forbes

    Tackling Africa’s digital divide Tackling Africa’s digital divide, Published online: 26 April 2018; doi:10.1038/s41566-018-0162-z Innovations in ‘sustainable’ photonics technologies such as free-space optical links and solar-powered equipment provide developing countries with new cost-effective opportunities for deploying future-proof telecommunication networks.

    更新日期:2018-04-27
  • Shining light on an old problem
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-26
    Daniele Faccio, Fabio Biancalana

    Shining light on an old problem Shining light on an old problem, Published online: 26 April 2018; doi:10.1038/s41566-018-0160-1 The evolution of modulational instability sidebands in an optical fibre are shown to provide new insights into Fermi–Pasta–Ulam–Tsingou recurrences.

    更新日期:2018-04-27
  • Combating colour blindness
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-26
    Oliver Graydon

    Combating colour blindness Combating colour blindness, Published online: 26 April 2018; doi:10.1038/s41566-018-0173-9 Combating colour blindness

    更新日期:2018-04-27
  • Powerful X-rays
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-26
    David F. P. Pile

    Powerful X-rays Powerful X-rays, Published online: 26 April 2018; doi:10.1038/s41566-018-0169-5 Powerful X-rays

    更新日期:2018-04-27
  • Silicon Mie resonators for highly directional light emission from monolayer MoS2
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-23
    Ahmet Fatih Cihan, Alberto G. Curto, Søren Raza, Pieter G. Kik, Mark L. Brongersma

    Controlling light emission from quantum emitters has important applications, ranging from solid-state lighting and displays to nanoscale single-photon sources. Optical antennas have emerged as promising tools to achieve such control right at the location of the emitter, without the need for bulky, external optics. Semiconductor nanoantennas are particularly practical for this purpose because simple geometries such as wires and spheres support multiple, degenerate optical resonances. Here, we start by modifying Mie scattering theory developed for plane wave illumination to describe scattering of dipole emission. We then use this theory and experiments to demonstrate several pathways to achieve control over the directionality, polarization state and spectral emission that rely on a coherent coupling of an emitting dipole to optical resonances of a silicon nanowire. A forward-to-backward ratio of 20 was demonstrated for the electric dipole emission at 680 nm from a monolayer MoS2 by optically coupling it to a silicon nanowire.

    更新日期:2018-04-24
  • Complete polarization control
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-23
    Emma R. Simpson, Johan Mauritsson

    Complete polarization control Complete polarization control, Published online: 23 April 2018; doi:10.1038/s41566-018-0166-8 The polarization state of isolated attosecond pulses generated by high-order harmonic generation can now be manipulated at will. The development opens the door for a multitude of ultrafast experiments to investigate chiral media.

    更新日期:2018-04-24
  • Enrichment of molecular antenna triplets amplifies upconverting nanoparticle emission
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-23
    David J. Garfield, Nicholas J. Borys, Samia M. Hamed, Nicole A. Torquato, Cheryl A. Tajon, Bining Tian, Brian Shevitski, Edward S. Barnard, Yung Doug Suh, Shaul Aloni, Jeffrey B. Neaton, Emory M. Chan, Bruce E. Cohen, P. James Schuck

    Efficient photon upconversion at low light intensities promises major advances in technologies spanning solar energy harvesting to deep-tissue biophotonics. Here, we discover the critical mechanisms that enable near-infrared dye antennas to significantly enhance performance in lanthanide-doped upconverting nanoparticle (UCNP) systems, and leverage these findings to design dye–UCNP hybrids with a 33,000-fold increase in brightness and a 100-fold increase in efficiency over bare UCNPs. We show that increasing the lanthanide content in the UCNPs shifts the primary energy donor from the dye singlet to its triplet, and the resultant triplet states then mediate energy transfer into the nanocrystals. Time-gated phosphorescence, density functional theory, singlet lifetimes and triplet-quenching experiments support these findings. This interplay between the excited-state populations in organic antennas and the composition of UCNPs presents new design rules that overcome the limitations of previous upconverting materials, enabling performances now relevant for photovoltaics, biophotonics and infrared detection.

    更新日期:2018-04-24
  • Polarization control of isolated high-harmonic pulses
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-23
    Pei-Chi Huang, Carlos Hernández-García, Jen-Ting Huang, Po-Yao Huang, Chih-Hsuan Lu, Laura Rego, Daniel D. Hickstein, Jennifer L. Ellis, Agnieszka Jaron-Becker, Andreas Becker, Shang-Da Yang, Charles G. Durfee, Luis Plaja, Henry C. Kapteyn, Margaret M. Murnane, A. H. Kung, Ming-Chang Chen

    High-harmonic generation driven by femtosecond lasers makes it possible to capture the fastest dynamics in molecules and materials. However, thus far, the shortest isolated attosecond pulses have only been produced with linear polarization, which limits the range of physics that can be explored. Here, we demonstrate robust polarization control of isolated extreme-ultraviolet pulses by exploiting non-collinear high-harmonic generation driven by two counter-rotating few-cycle laser beams. The circularly polarized supercontinuum is produced at a central photon energy of 33 eV with a transform limit of 190 as and a predicted linear chirp of 330 as. By adjusting the ellipticity of the two counter-rotating driving pulses simultaneously, we control the polarization state of isolated extreme-ultraviolet pulses—from circular through elliptical to linear polarization—without sacrificing conversion efficiency. Access to the purely circularly polarized supercontinuum, combined with full helicity and ellipticity control, paves the way towards attosecond metrology of circular dichroism.

    更新日期:2018-04-24
  • Vacuum Bloch–Siegert shift in Landau polaritons with ultra-high cooperativity
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-16
    Xinwei Li, Motoaki Bamba, Qi Zhang, Saeed Fallahi, Geoff C. Gardner, Weilu Gao, Minhan Lou, Katsumasa Yoshioka, Michael J. Manfra, Junichiro Kono

    A two-level system resonantly interacting with an a.c. magnetic or electric field constitutes the physical basis of diverse phenomena and technologies. However, Schrödinger’s equation for this seemingly simple system can be solved exactly only under the rotating-wave approximation, which neglects the counter-rotating field component. When the a.c. field is sufficiently strong, this approximation fails, leading to a resonance-frequency shift known as the Bloch–Siegert shift. Here, we report the vacuum Bloch–Siegert shift, which is induced by the ultra-strong coupling of matter with the counter-rotating component of the vacuum fluctuation field in a cavity. Specifically, an ultra-high-mobility two-dimensional electron gas inside a high-Q terahertz cavity in a quantizing magnetic field revealed ultra-narrow Landau polaritons, which exhibited a vacuum Bloch–Siegert shift up to 40 GHz. This shift, clearly distinguishable from the photon-field self-interaction effect, represents a unique manifestation of a strong-field phenomenon without a strong field.

    更新日期:2018-04-17
  • Giant collimated gamma-ray flashes
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-16
    Alberto Benedetti, Matteo Tamburini, Christoph H. Keitel

    Bright sources of high-energy electromagnetic radiation are widely employed in fundamental research, industry and medicine1,2. This motivated the construction of Compton-based facilities planned to yield bright gamma-ray pulses with energies up to3 20 MeV. Here, we demonstrate a novel mechanism based on the strongly amplified synchrotron emission that occurs when a sufficiently dense ultra-relativistic electron beam interacts with a millimetre-thickness conductor. For electron beam densities exceeding approximately 3 × 1019 cm−3, electromagnetic instabilities occur, and the ultra-relativistic electrons travel through self-generated electromagnetic fields as large as 107–108 gauss. This results in the production of a collimated gamma-ray pulse with peak brilliance above 1025 photons s−1 mrad−2 mm−2 per 0.1% bandwidth, photon energies ranging from 200 keV to gigaelectronvolts and up to 60% electron-to-photon energy conversion efficiency. These findings pave the way to compact, high-repetition-rate (kilohertz) sources of short (≲30 fs), collimated (milliradian) and high-flux (>1012 photons s−1) gamma-ray pulses.

    更新日期:2018-04-17
  • Mid-infrared frequency comb via coherent dispersive wave generation in silicon nitride nanophotonic waveguides
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-16
    Hairun Guo, Clemens Herkommer, Adrien Billat, Davide Grassani, Chuankun Zhang, Martin H. P. Pfeiffer, Wenle Weng, Camille-Sophie Brès, Tobias J. Kippenberg

    Mid-infrared optical frequency combs are of significant interest for molecular spectroscopy due to the large absorption of molecular vibrational modes on the one hand, and the ability to implement superior comb-based spectroscopic modalities with increased speed, sensitivity and precision on the other hand. Here, we demonstrate a simple, yet effective, method for the direct generation of mid-infrared optical frequency combs in the region from 2.5 to 4.0 μm (that is, 2,500–4,000 cm−1), covering a large fraction of the functional group region, from a conventional and compact erbium-fibre-based femtosecond laser in the telecommunication band (that is, 1.55 μm). The wavelength conversion is based on dispersive wave generation within the supercontinuum process in an unprecedented large-cross-section silicon nitride (Si3N4) waveguide with the dispersion lithographically engineered. The long-wavelength dispersive wave can perform as a mid-infrared frequency comb, whose coherence is demonstrated via optical heterodyne measurements. Such an approach can be considered as an alternative option to mid-infrared frequency comb generation. Moreover, it has the potential to realize compact dual-comb spectrometers. The generated combs also have a fine teeth-spacing, making them suitable for gas-phase analysis.

    更新日期:2018-04-17
  • Author Correction: Single-molecule imaging by optical absorption
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-12
    Michele Celebrano, Philipp Kukura, Alois Renn, Vahid Sandoghdar

    Author Correction: Single-molecule imaging by optical absorption Author Correction: Single-molecule imaging by optical absorption, Published online: 12 April 2018; doi:10.1038/s41566-018-0159-7 Author Correction: Single-molecule imaging by optical absorption

    更新日期:2018-04-12
  • Hydroxypropyl cellulose photonic architectures by soft nanoimprinting lithography
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-09
    André Espinha, Camilla Dore, Cristiano Matricardi, Maria Isabel Alonso, Alejandro R. Goñi, Agustín Mihi

    As contamination and environmental degradation increase, there is a huge demand for new eco-friendly materials. Despite its use for thousands of years, cellulose and its derivatives have gained renewed interest as favourable alternatives to conventional plastics, due to their abundance and lower environmental impact. Here, we report the fabrication of photonic and plasmonic structures by moulding hydroxypropyl cellulose into submicrometric periodic lattices, using soft lithography. This is an alternative way to achieve structural colour in this material, which is usually obtained by exploiting its chiral nematic phase. Cellulose-based photonic crystals are biocompatible and can be dissolved in water or not depending on the derivative employed. Patterned cellulose membranes exhibit tunable colours and may be used to boost the photoluminescence of a host organic dye. Furthermore, we show how metal coating these cellulose photonic architectures leads to plasmonic crystals with excellent optical properties acting as disposable surface-enhanced Raman spectroscopy substrates.

    更新日期:2018-04-10
  • Improved photovoltaic performance from inorganic perovskite oxide thin films with mixed crystal phases
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-09
    Joyprokash Chakrabartty, Catalin Harnagea, Mert Celikin, Federico Rosei, Riad Nechache

    Inorganic ferroelectric perovskites are attracting attention for the realization of highly stable photovoltaic cells with large open-circuit voltages. However, the power conversion efficiencies of devices have been limited so far. Here, we report a power conversion efficiency of ~4.20% under 1 sun illumination from Bi–Mn–O composite thin films with mixed BiMnO3 and BiMn2O5 crystal phases. We show that the photocurrent density and photovoltage mainly develop across grain boundaries and interfaces rather than within the grains. We also experimentally demonstrate that the open-circuit voltage and short-circuit photocurrent measured in the films are tunable by varying the electrical resistance of the device, which in turn is controlled by externally applying voltage pulses. The exploitation of multifunctional properties of composite oxides provides an alternative route towards achieving highly stable, high-efficiency photovoltaic solar energy conversion.

    更新日期:2018-04-10
  • Segmented terahertz electron accelerator and manipulator (STEAM)
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-02
    Dongfang Zhang, Arya Fallahi, Michael Hemmer, Xiaojun Wu, Moein Fakhari, Yi Hua, Huseyin Cankaya, Anne-Laure Calendron, Luis E. Zapata, Nicholas H. Matlis, Franz X. Kärtner

    Acceleration and manipulation of electron bunches underlie most electron and X-ray devices used for ultrafast imaging and spectroscopy. New terahertz-driven concepts offer orders-of-magnitude improvements in field strengths, field gradients, laser synchronization and compactness relative to conventional radiofrequency devices, enabling shorter electron bunches and higher resolution with less infrastructure while maintaining high charge capacities (pC), repetition rates (kHz) and stability. We present a segmented terahertz electron accelerator and manipulator (STEAM) capable of performing multiple high-field operations on the six-dimensional phase space of ultrashort electron bunches. With this single device, powered by few-microjoule, single-cycle, 0.3 THz pulses, we demonstrate record terahertz acceleration of >30 keV, streaking with <10 fs resolution, focusing with >2 kT m–1 strength, compression to ~100 fs as well as real-time switching between these modes of operation. The STEAM device demonstrates the feasibility of terahertz-based electron accelerators, manipulators and diagnostic tools, enabling science beyond current resolution frontiers with transformative impact.

    更新日期:2018-04-03
  • Fibre multi-wave mixing combs reveal the broken symmetry of Fermi–Pasta–Ulam recurrence
    Nat. Photon. (IF 32.521) Pub Date : 2018-04-02
    Arnaud Mussot, Corentin Naveau, Matteo Conforti, Alexandre Kudlinski, Francois Copie, Pascal Szriftgiser, Stefano Trillo

    In optical fibres, weak modulations can grow at the expense of a strong pump to form a triangular comb of sideband pairs, until the process is reversed. Repeated cycles of such conversion and back-conversion constitute a manifestation of the universal nonlinear phenomenon known as Fermi–Pasta–Ulam recurrence. However, it remains a major challenge to observe the coexistence of different types of recurrences owing to the spontaneous symmetry-breaking nature of such a phenomenon. Here, we implement a novel non-destructive technique that allows the evolution in amplitude and phase of frequency modes to be reconstructed via post-processing of the fibre backscattered light. We clearly observe how control of the input modulation seed results in different recursive behaviours emerging from the phase-space structure dictated by the spontaneously broken symmetry. The proposed technique is an important tool to characterize other mixing processes and new regimes of rogue-wave formation and wave turbulence in fibre optics.

    更新日期:2018-04-03
  • Giant lasers in the US threatened with closure
    Nat. Photon. (IF 32.521) Pub Date : 2018-03-29

    Giant lasers in the US threatened with closure Giant lasers in the US threatened with closure, Published online: 29 March 2018; doi:10.1038/s41566-018-0158-8 Pressure on the US Department of Energy’s budget could see the Omega and Nike laser facilities being axed.

    更新日期:2018-03-30
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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