Ultrafast photonics articles within Nature Communications

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  • Article
    | Open Access

    The laser pulses that drive most laser wakefield accelerators have wavelengths near 1 micrometer and peak power > 100 terawatts. Here, the authors drive plasma wakes with 10 micrometer, 2-terawatt pulses, yielding relativistic electron beams with a collimated, narrow-energy-bandwidth component.

    • R. Zgadzaj
    • , J. Welch
    •  & M. C. Downer

  • Article
    | Open Access

    Photonic time crystal refers to a material whose dielectric properties oscillate in time. Here the authors theoretically show such behaviour in the excitonic insulator candidate Ta2NiSe5 under optical excitation and use it to explain the enhanced THz reflectivity recently observed in pump-probe experiments

    • Marios H. Michael
    • , Sheikh Rubaiat Ul Haque
    •  & Eugene Demler

  • Article
    | Open Access

    Correlated insulator states of moire excitons in transition metal dichalcogenide heterostructures have attracted significant attention recently. Here the authors use time-resolved pump-probe spectroscopy to demonstrate the effects of non-equilibrium correlations of moire excitons in WSe2/WS2 heterobilayers.

    • Jinjae Kim
    • , Jiwon Park
    •  & Hyunyong Choi

  • Article
    | Open Access

    Malakar et al. investigate the photochemical dynamics in the isomerization of bacteriorhodopsin light and dark-adapted forms and in the first photocycle intermediate, K. The results prompt a reevaluation of the counter ion model, revealing that a different protonation then that shown in the classic quadrupole so far considered must be employed to account for the experimental data.

    • Partha Malakar
    • , Samira Gholami
    •  & Sanford Ruhman

  • Article
    | Open Access

    Several recent works have highlighted the importance of the orbital currents in transferring angular momentum within materials. In combination with spin-orbit coupling, such orbital currents can be used to alter the magnetization of a material. Herein, the authors demonstrate the inverse effect, showing orbital current driven terahertz emission in Nickel based heterostructures.

    • Yong Xu
    • , Fan Zhang
    •  & Weisheng Zhao

  • Article
    | Open Access

    The researchers showcase swept-coded aperture real-time femtophotography—an all-optical single-shot computational imaging modality at up to 156.3 trillion frames per second—video-records transient absorption in a semiconductor and ultrafast demagnetization of a metal alloy.

    • Jingdan Liu
    • , Miguel Marquez
    •  & Jinyang Liang

  • Article
    | Open Access

    Differential absorption of polarized light, called dichroism, does not exist in amorphous solids due to the disordered arrangements of atoms. Here, the authors demonstrate that dichroism is intrinsic to all solids and can be controlled using helical light beams carrying orbital angular momentum.

    • Ashish Jain
    • , Jean-Luc Bégin
    •  & Ravi Bhardwaj

  • Article
    | Open Access

    The charge-density-wave Weyl semimetal (TaSe4)2I is a candidate for an axion insulator, however it may be obscured by polaron physics. Here, using ultrafast terahertz photocurrent spectroscopy, the authors realize phase switches from the polaronic state, to the charge density wave phase, and to the Weyl phase.

    • Bing Cheng
    • , Di Cheng
    •  & Jigang Wang

  • Article
    | Open Access

    Here, the authors report the generation and manipulation of transient hyperbolic plasmons in black phosphorus via ultrafast photocarrier injection, demonstrating a topological transition of the non-equilibrium iso-frequency contours and the coexistence of different transient plasmonic modes.

    • Rao Fu
    • , Yusong Qu
    •  & Jianing Chen

  • Article
    | Open Access

    Here the authors identify real-space contributions to the characteristics of high-harmonic generation in ReS2 and demonstrate the possibility of laser-controlled emission. They find that the spectrum is not just determined by the band structure, but also by the interference between HHG signals coming from different atoms within the unit cell.

    • Álvaro Jiménez-Galán
    • , Chandler Bossaer
    •  & Giulio Vampa

  • Article
    | Open Access

    Ultrafast laser excitation can generate metastable states in quantum materials, with no counterpart in equilibrium. Here the authors demonstrate a transient quadrupolar ordered state in Ca2RuO4 single crystals via excitation of a phonon mode coupled to the order parameter.

    • Honglie Ning
    • , Omar Mehio
    •  & David Hsieh

  • Article
    | Open Access

    Antiferromagnets exhibit high frequency magnons, in the THz regime, a point potentially useful for applications, however, it has meant that detecting spin-fluctuations in antiferromagnets is typically too fast for current experimental approaches. Here Weiss et al use femtosecond noise correlation spectroscopy to observe magnon fluctuations in Sm0.7Er0.3FeO3.

    • M. A. Weiss
    • , A. Herbst
    •  & T. Kurihara

  • Article
    | Open Access

    Nonlinear optical processes like higher-order harmonic generation in solids depend on several factors. Here the authors explore the optical nonlinearity of hexagonal boron nitride and find that enhanced nonlinearity is due to electron-phonon and phonon-polariton couplings.

    • Jared S. Ginsberg
    • , M. Mehdi Jadidi
    •  & Alexander L. Gaeta

  • Article
    | Open Access

    The authors provide an experimental demonstration of magnetic field generation in graphene disks via the inverse Faraday effect. When the disks are illuminated with circularly polarized radiation in resonance with the graphene plasmon frequency, the corresponding rotational motion of the charge carriers gives rise to a unipolar magnetic field.

    • Jeong Woo Han
    • , Pavlo Sai
    •  & Martin Mittendorff

  • Article
    | Open Access

    Strong optical excitation near band extrema can drive novel correlated states. Here the authors report a non-equilibrium many-body state in graphite driven by a strong excitation near van Hove singularity, yielding a tenfold increase in optical conductivity attributed to carrier excitations in the flat bands.

    • T. P. H. Sidiropoulos
    • , N. Di Palo
    •  & J. Biegert

  • Article
    | Open Access

    Here the authors provide the experimental demonstration of a widely tunable integrated frequency comb source unlocking the spectrum from the visible to the mid-infrared in a thin-film lithium niobate platform.

    • Arkadev Roy
    • , Luis Ledezma
    •  & Alireza Marandi

  • Article
    | Open Access

    THz pulses with tuneable properties are desirable for manipulating electronic states in materials. The authors report generation of THz pulses with phase, frequency, and amplitude control by tuning exciton interference in a 1D Mott insulator of transition metal complex and provide insight into exciton dynamics.

    • Tatsuya Miyamoto
    • , Akihiro Kondo
    •  & Hiroshi Okamoto

  • Article
    | Open Access

    Here the authors demonstrate the active control of an all-optical switch harnessing the interaction of light with the constituent materials. The response speeds up by two orders of magnitude and scales accordingly with the strength of the light matter interaction.

    • Soham Saha
    • , Benjamin T. Diroll
    •  & Alexandra Boltasseva

  • Article
    | Open Access

    Measurement and control of the carrier-envelope phase (CEP) is essential for applications of few-cycle laser beams. The authors present a compact on-chip, ambient-air, CEP scanning probe and show a 3D map of spatial changes of CEP and demonstrate CEP control in the focal volume with a spatial light modulator.

    • Václav Hanus
    • , Beatrix Fehér
    •  & Péter Dombi

  • Article
    | Open Access

    Pump-probe spectroscopy is routinely used to interrogate ultrafast valence electronic and vibrational dynamics in complex systems. Here, the authors extend this technique to the X-ray regime using a sequence of femtosecond X-ray pulses to understand core-valence interactions in a solvated molecular complex.

    • Robert B. Weakly
    • , Chelsea E. Liekhus-Schmaltz
    •  & Munira Khalil

  • Article
    | Open Access

    The authors present a moving-parts-free approach for visualizing soliton motion in optical cavities that lifts the wavelength and speed constraints of contemporary pulsed laser diagnostic techniques.

    • Łukasz A. Sterczewski
    •  & Jarosław Sotor

  • Article
    | Open Access

    Lead halide perovskites host bright triplet excitons which have applications in optospintronic devices. Here the authors observe quantum coherence between exciton sublevels without magnetic field and clarify the mechanisms of exciton spin relaxation in ensembles of CsPbBr3 nanocrystals.

    • Rui Cai
    • , Indrajit Wadgaonkar
    •  & Tze Chien Sum

  • Article
    | Open Access

    Exciton-polaritons present opportunities for quantum photonics, next generation qubits, and tuning material photophysics. Here Laitz et al. study the temperature dependence of 2D perovskite microcavity polaritons, revealing material-specific relaxation mechanisms towards the control of polariton momentum.

    • Madeleine Laitz
    • , Alexander E. K. Kaplan
    •  & Vladimir Bulović

  • Article
    | Open Access

    High-harmonic generation (HHG) is a nonlinear process and has been explored with different forms of plasma target. Here the authors report HHG using a liquid plasma mirror as a possible way for the generation of stable and intense attosecond pulses at a high-repetition rate.

    • Yang Hwan Kim
    • , Hyeon Kim
    •  & Kyung Taec Kim

  • Article
    | Open Access

    By placing an antiferromagnet next to a heavy metal such as platinum, magnetic excitations in the antiferromagnet drive a spin current in the heavy metal, leading to terahertz emission. Here, Kholid et al study the terahertz emission of two antiferromagnets, KCoF3 and KNiF3 with very different magnon frequencies, and find that the opening of a gap in the magnon density of states drastically alters the spin-transfer efficiency.

    • Farhan Nur Kholid
    • , Dominik Hamara
    •  & Chiara Ciccarelli

  • Article
    | Open Access

    Studies on the fractional Schrödinger equation (FSE) remain mostly theoretical, due to the lack of materials supporting fractional dispersion or diffraction. Here, the authors indirectly realized the FSE using two programmable holograms acting as an optical Lévy waveguide.

    • Shilong Liu
    • , Yingwen Zhang
    •  & Ebrahim Karimi

  • Article
    | Open Access

    There are many possible mechanisms of high-harmonic generation from crystals. Here the authors discuss the role of the Bloch oscillation to nonlinear response of the crystal and harmonic radiation from it.

    • Jan Reislöhner
    • , Doyeong Kim
    •  & Adrian N. Pfeiffer

  • Article
    | Open Access

    Holography recreates both the amplitude and wave front of a three dimensional object, meaning that the observer perceives the image in the nearly same way as they would the true object. Creating such holographic images is challenging computationally, and requires extremely fast display update. Here, the authors combine a fast memoryless computation algorithm with the ultra-rapid writing based on all-optical switching of a ferrimagnetic film.

    • M. Makowski
    • , J. Bomba
    •  & A. Stupakiewicz

  • Article
    | Open Access

    Floquet engineering aims at inducing new properties in materials with light. Here the authors have used pulses of variable durations, to investigate its applicability in the femtosecond domain. Surprisingly, they found that it holds to the few-cycle limit.

    • Matteo Lucchini
    • , Fabio Medeghini
    •  & Mauro Nisoli

  • Article
    | Open Access

    THz imaging and spectroscopy always request even more efficient components. Here the authors, thanks to a modified photoconductive switch that includes a graphene layer, demonstrate a high-speed photoconductive switch without sacrificing the generated power.

    • Dehui Zhang
    • , Zhen Xu
    •  & Zhaohui Zhong

  • Article
    | Open Access

    Deep understanding of defect physics, excitonic properties and the ultrafast carrier dynamics in the high mobility p-type transparent CuI is vital for its optoelectronic applications. Here, Liu et al. employ a synergistic approach to unveil these fundamental properties.

    • Zhan Hua Li
    • , Jia Xing He
    •  & Chao Ping Liu

  • Article
    | Open Access

    Energy transfer between the electromagnetic field and atoms or molecules is fundamentally interesting. Here the authors demonstrate stepwise energy transfer between broadband mid-infrared optical pulses and vibrating methylsulfonylmethane molecules in aqueous solution.

    • Martin T. Peschel
    • , Maximilian Högner
    •  & Ioachim Pupeza

  • Article
    | Open Access

    Understanding the photoelectron emission time after the interaction of photon with atoms and molecules is of fundamental interest. Here the authors examine the role of partial waves to the photoionization phase shift of atoms using an attosecond clock and electron-ion coincidence spectroscopy.

    • Wenyu Jiang
    • , Gregory S. J. Armstrong
    •  & Jian Wu

  • Article
    | Open Access

    Valley depolarization processes in 2D transition metal dichalcogenides have been linked to acoustic phonons, but optical verification is ambiguous, due to the nearly degenerate acoustic phonon frequencies at the zone-edge. Here, the authors determine the phonon momentum of the longitudinal acoustic (LA) phonons at the K point as responsible for the ultrafast valley depolarization in monolayer MoSe2.

    • Soungmin Bae
    • , Kana Matsumoto
    •  & Ikufumi Katayama

  • Article
    | Open Access

    Spintronic terahertz (THz) emitters are a class of magnetic heterostructure where femtosecond laser excitations generate THz radiation emission. While they have great potential, electric field control of spintronic emitter remains a challenge. Here, by combining a spintronic emitter with a piezoelectric substrate, Agarwal et al. demonstrate electric field control of THz emission through induced piezostrain.

    • Piyush Agarwal
    • , Lisen Huang
    •  & Ranjan Singh

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