Letters

  • Letter |

    A high-speed wireless THz communication link is seamlessly integrated into a fibre-optic network. The demonstration relies on an ultra-broadband modulator exploiting two-dimensionally localized gap plasmons for direct conversion of the THz signals to the optical domain.

    • S. Ummethala
    • , T. Harter
    • , K. Koehnle
    • , Z. Li
    • , S. Muehlbrandt
    • , Y. Kutuvantavida
    • , J. Kemal
    • , P. Marin-Palomo
    • , J. Schaefer
    • , A. Tessmann
    • , S. K. Garlapati
    • , A. Bacher
    • , L. Hahn
    • , M. Walther
    • , T. Zwick
    • , S. Randel
    • , W. Freude
    •  & C. Koos
  • Letter |

    By using a single-quantum-well active region with a unique well–cladding design to suppress non-radiative recombination and enhance radiative recombination, light-emitting diodes with close to unity internal quantum efficiency at a low current density of <10−4 A cm−2 are demonstrated.

    • Ning Li
    • , Kevin Han
    • , William Spratt
    • , Stephen Bedell
    • , John Ott
    • , Marinus Hopstaken
    • , Frank Libsch
    • , Qinglong Li
    •  & Devendra Sadana
  • Letter |

    A higher-order topological phase is demonstrated, manifesting as robust, topologically protected corner modes in a silicon photonics system.

    • Sunil Mittal
    • , Venkata Vikram Orre
    • , Guanyu Zhu
    • , Maxim A. Gorlach
    • , Alexander Poddubny
    •  & Mohammad Hafezi
  • Letter |

    By time-shifting short-pulse excitation photon energy into prolonged luminescent emission in the time domain, both the number of light signal transducers in sub-15 nm nanoparticles and the near-infrared-in to near-infrared-out conversion efficiency can be maximized, advancing in vivo optical bioimaging.

    • Yuyang Gu
    • , Zhiyong Guo
    • , Wei Yuan
    • , Mengya Kong
    • , Yulai Liu
    • , Yongtao Liu
    • , Yilin Gao
    • , Wei Feng
    • , Fan Wang
    • , Jiajia Zhou
    • , Dayong Jin
    •  & Fuyou Li
  • Letter |

    Transduction of valley information to mechanical states in a monolayer MoS2 resonator can be realized by optically pumping the valley carriers and applying an out-of-plane magnetic field gradient to induce a displacement-dependent valley splitting.

    • Hao-Kun Li
    • , King Yan Fong
    • , Hanyu Zhu
    • , Quanwei Li
    • , Siqi Wang
    • , Sui Yang
    • , Yuan Wang
    •  & Xiang Zhang
  • Letter |

    It is possible to regulate random lasers by controlling and manipulating their properties, including the number and spatial positions of their lasing modes, and the lasing wavelength and the modal size over wide ranges. Performances comparable with non-random optical cavities with 2D photonic crystals are reported.

    • Myungjae Lee
    • , Ségolène Callard
    • , Christian Seassal
    •  & Heonsu Jeon
  • Letter |

    Organic phosphors with ultra-long lifetimes and an emission colour that can be tuned by the excitation wavelength are reported.

    • Long Gu
    • , Huifang Shi
    • , Lifang Bian
    • , Mingxing Gu
    • , Kun Ling
    • , Xuan Wang
    • , Huili Ma
    • , Suzhi Cai
    • , Weihua Ning
    • , Lishun Fu
    • , He Wang
    • , Shan Wang
    • , Yaru Gao
    • , Wei Yao
    • , Fengwei Huo
    • , Youtian Tao
    • , Zhongfu An
    • , Xiaogang Liu
    •  & Wei Huang
  • Letter |

    A hybrid technique of stimulated Raman excited fluorescence that integrates superb detection sensitivity and fine chemical specificity is demonstrated, offering all-far-field single-molecule Raman spectroscopy and imaging without plasmonic enhancement.

    • Hanqing Xiong
    • , Lixue Shi
    • , Lu Wei
    • , Yihui Shen
    • , Rong Long
    • , Zhilun Zhao
    •  & Wei Min
  • Letter |

    A phonon laser based on an optically levitated silica nanosphere is demonstrated. A lasing threshold—a phase transition from Brownian motion to coherent oscillation—is observed when the modulation depth of the trapping beam power is increased.

    • Robert M. Pettit
    • , Wenchao Ge
    • , P. Kumar
    • , Danika R. Luntz-Martin
    • , Justin T. Schultz
    • , Levi P. Neukirch
    • , M. Bhattacharya
    •  & A. Nick Vamivakas
  • Letter |

    Nanometre thick metal films enable electrical tuning of plasmons.

    • Rinu Abraham Maniyara
    • , Daniel Rodrigo
    • , Renwen Yu
    • , Josep Canet-Ferrer
    • , Dhriti Sundar Ghosh
    • , Ruchirej Yongsunthon
    • , David E. Baker
    • , Aram Rezikyan
    • , F. Javier García de Abajo
    •  & Valerio Pruneri
  • Letter |

    Net gain of ~10 dB µm–1 and sub-picosecond switching time are shown at room temperature for optical transistors using polymers in a microcavity.

    • Anton V. Zasedatelev
    • , Anton V. Baranikov
    • , Darius Urbonas
    • , Fabio Scafirimuto
    • , Ullrich Scherf
    • , Thilo Stöferle
    • , Rainer F. Mahrt
    •  & Pavlos G. Lagoudakis
  • Letter |

    Pre-shaping image wavefronts with random phase to locally reduce Fresnel diffraction to Fourier holography results in Fresnel holograms that form on-axis with full depth control without any crosstalk. This produces large-volume, high-density, dynamic 3D projections with 1,000 simultaneous image planes.

    • Ghaith Makey
    • , Özgün Yavuz
    • , Denizhan K. Kesim
    • , Ahmet Turnalı
    • , Parviz Elahi
    • , Serim Ilday
    • , Onur Tokel
    •  & F. Ömer Ilday
  • Letter |

    By nesting a Kerr microresonator in a fibre loop with gain, 50-nm-wide bright microcavity-based soliton combs with a mode efficiency of 75% can be induced at average powers more than one order of magnitude lower than the Lugiato–Lefever soliton power threshold, facilitating real-world applications.

    • Hualong Bao
    • , Andrew Cooper
    • , Maxwell Rowley
    • , Luigi Di Lauro
    • , Juan Sebastian Totero Gongora
    • , Sai T. Chu
    • , Brent E. Little
    • , Gian-Luca Oppo
    • , Roberto Morandotti
    • , David J. Moss
    • , Benjamin Wetzel
    • , Marco Peccianti
    •  & Alessia Pasquazi
  • Letter |

    The implementation of optically reassigned scanning laser ophthalmoscopy enables in vivo photon reassignment super-resolution imaging and high-resolution imaging of living human retinal cone photoreceptor cells without adaptive optics or chemical dilation of the eye.

    • Theodore B. DuBose
    • , Francesco LaRocca
    • , Sina Farsiu
    •  & Joseph A. Izatt
  • Letter |

    A nearly Fourier-limited X-ray free-electron laser beam is generated by a self-seeding scheme. The beam in the first half of the undulators is monochromatized via Bragg reflection, and is subsequently amplified in the remaining undulators.

    • Ichiro Inoue
    • , Taito Osaka
    • , Toru Hara
    • , Takashi Tanaka
    • , Takahiro Inagaki
    • , Toru Fukui
    • , Shunji Goto
    • , Yuichi Inubushi
    • , Hiroaki Kimura
    • , Ryota Kinjo
    • , Haruhiko Ohashi
    • , Kazuaki Togawa
    • , Kensuke Tono
    • , Mitsuhiro Yamaga
    • , Hitoshi Tanaka
    • , Tetsuya Ishikawa
    •  & Makina Yabashi
  • Letter |

    Double-blind holography allows reconstruction of the missing spectral phases and characterization of the unknown signals in both isolated-pulse and double-pulse scenarios, facilitating the study of complex electron dynamics via a single-shot and linear measurement.

    • O. Pedatzur
    • , A. Trabattoni
    • , B. Leshem
    • , H. Shalmoni
    • , M. C. Castrovilli
    • , M. Galli
    • , M. Lucchini
    • , E. Månsson
    • , F. Frassetto
    • , L. Poletto
    • , B. Nadler
    • , O. Raz
    • , M. Nisoli
    • , F. Calegari
    • , D. Oron
    •  & N. Dudovich
  • Letter |

    Temporal dissipative soliton formation in a free-space femtosecond enhancement cavity with a thin Kerr medium is reported. Locking a 350-fs, 1,035-nm pulse train with a repetition rate of 100 MHz to this cavity-soliton state generates a 37-fs sech2-shaped pulse with a peak-power enhancement of 3,200.

    • N. Lilienfein
    • , C. Hofer
    • , M. Högner
    • , T. Saule
    • , M. Trubetskov
    • , V. Pervak
    • , E. Fill
    • , C. Riek
    • , A. Leitenstorfer
    • , J. Limpert
    • , F. Krausz
    •  & I. Pupeza
  • Letter |

    The entanglement of three remote quantum memories based on 87Rb atoms is created via three-photon interference by enhancing the memory–photon entanglement in ring cavities, demonstrating a genuine quantum network involving more than two quantum nodes.

    • Bo Jing
    • , Xu-Jie Wang
    • , Yong Yu
    • , Peng-Fei Sun
    • , Yan Jiang
    • , Sheng-Jun Yang
    • , Wen-Hao Jiang
    • , Xi-Yu Luo
    • , Jun Zhang
    • , Xiao Jiang
    • , Xiao-Hui Bao
    •  & Jian-Wei Pan
  • Letter |

    Direct laser writing is shown to dramatically enhance the chemical etch rate of laser crystals yttrium aluminium garnet and sapphire, allowing nanostructuring.

    • Airán Ródenas
    • , Min Gu
    • , Giacomo Corrielli
    • , Petra Paiè
    • , Sajeev John
    • , Ajoy K. Kar
    •  & Roberto Osellame
  • Letter |

    An interferometric homodyne method is employed to measure material-dependent intensity-induced phase shifts of extreme-ultraviolet high harmonics emerging from bulk magnesium oxide and quartz crystals, providing a robust platform for high-harmonic spectroscopy of solids.

    • Jian Lu
    • , Eric F. Cunningham
    • , Yong Sing You
    • , David A. Reis
    •  & Shambhu Ghimire
  • Letter |

    Coupled lithium niobate ring resonators enable control of a ‘photonic molecule’ by programmed microwave signals. An on-demand optical storage and retrieval system is demonstrated.

    • Mian Zhang
    • , Cheng Wang
    • , Yaowen Hu
    • , Amirhassan Shams-Ansari
    • , Tianhao Ren
    • , Shanhui Fan
    •  & Marko Lončar
  • Letter |

    A microphotonic astrocomb is demonstrated via temporal dissipative Kerr solitons in photonic-chip-based silicon nitride microresonators with a precision of 25 cm s–1 (radial velocity equivalent), useful for Earth-like planet detection and cosmological research.

    • Ewelina Obrzud
    • , Monica Rainer
    • , Avet Harutyunyan
    • , Miles H. Anderson
    • , Junqiu Liu
    • , Michael Geiselmann
    • , Bruno Chazelas
    • , Stefan Kundermann
    • , Steve Lecomte
    • , Massimo Cecconi
    • , Adriano Ghedina
    • , Emilio Molinari
    • , Francesco Pepe
    • , François Wildi
    • , François Bouchy
    • , Tobias J. Kippenberg
    •  & Tobias Herr
  • Letter |

    A soliton microcomb as an astronomical spectrograph calibrator is presented. It can ultimately have a footprint of a few cubic centimetres, and reduced weight and power consumption, attractive for precision radial velocity measurement.

    • Myoung-Gyun Suh
    • , Xu Yi
    • , Yu-Hung Lai
    • , S. Leifer
    • , Ivan S. Grudinin
    • , G. Vasisht
    • , Emily C. Martin
    • , Michael P. Fitzgerald
    • , G. Doppmann
    • , J. Wang
    • , D. Mawet
    • , Scott B. Papp
    • , Scott A. Diddams
    • , C. Beichman
    •  & Kerry Vahala
  • Letter |

    Quantum cascade laser frequency combs are coherently locked to an external radio-frequency source even in extremely high-feedback conditions. The internal phase-locking mechanism and the possibility of all-electric stabilization are investigated.

    • Johannes Hillbrand
    • , Aaron Maxwell Andrews
    • , Hermann Detz
    • , Gottfried Strasser
    •  & Benedikt Schwarz
  • Letter |

    A second harmonic with a conversion efficiency of 0.049% W−1, originating from surface nonlinearity and bulk multipole response in a silica whispering-gallery microcavity, is observed with a continuous-wave pump power below 1 mW.

    • Xueyue Zhang
    • , Qi-Tao Cao
    • , Zhuo Wang
    • , Yu-xi Liu
    • , Cheng-Wei Qiu
    • , Lan Yang
    • , Qihuang Gong
    •  & Yun-Feng Xiao
  • Letter |

    A direct wireless-to-optical receiver in a transparent optical link is achieved, thanks to a subwavelength two-dimensionally localized gap-plasmon mixer encoding wireless information directly onto optical signals.

    • Y. Salamin
    • , B. Baeuerle
    • , W. Heni
    • , F. C. Abrecht
    • , A. Josten
    • , Y. Fedoryshyn
    • , C. Haffner
    • , R. Bonjour
    • , T. Watanabe
    • , M. Burla
    • , D. L. Elder
    • , L. R. Dalton
    •  & J. Leuthold
  • Letter |

    A quantum walker on a hexagonal glued array of optical waveguides is made inside a glass substrate. The optimal hitting time increases linearly with the layer depth, giving a quadratic speed-up over the hitting performance by classical random walks.

    • Hao Tang
    • , Carlo Di Franco
    • , Zi-Yu Shi
    • , Tian-Shen He
    • , Zhen Feng
    • , Jun Gao
    • , Ke Sun
    • , Zhan-Ming Li
    • , Zhi-Qiang Jiao
    • , Tian-Yu Wang
    • , M. S. Kim
    •  & Xian-Min Jin
  • Letter |

    Self-organization far from thermal equilibrium in a thermo-optical feedback process occurring in a random array of Fabry–Pérot resonators is shown, adding new capability to dynamic self-assembly in creating materials with fine-tuned adaptive responses.

    • Chad Ropp
    • , Nicolas Bachelard
    • , David Barth
    • , Yuan Wang
    •  & Xiang Zhang
  • Letter |

    Optical non-reciprocity is experimentally realized with Rb atoms embedded in a ring cavity at room temperature. Random thermal motion of the atoms causes the probe-direction-dependent response assisted by a unidirectional control laser field.

    • Shicheng Zhang
    • , Yiqi Hu
    • , Gongwei Lin
    • , Yueping Niu
    • , Keyu Xia
    • , Jiangbin Gong
    •  & Shangqing Gong
  • Letter |

    A nonlinear coherent spectroscopy that uses three slightly different repetition-rate frequency combs is demonstrated. A 2D spectrum with comb resolution is generated using only 365 milliseconds of data, almost 600 times faster than previous approaches.

    • Bachana Lomsadze
    • , Brad C. Smith
    •  & Steven T. Cundiff
  • Letter |

    By selectively erasing the nonlinear coefficients in a lithium niobate crystal using a femtosecond laser, a 3D nonlinear photonic crystal, with an effective conversion efficiency comparable to that of the typical quasi-phase-matching processes, is demonstrated.

    • Dunzhao Wei
    • , Chaowei Wang
    • , Huijun Wang
    • , Xiaopeng Hu
    • , Dan Wei
    • , Xinyuan Fang
    • , Yong Zhang
    • , Dong Wu
    • , Yanlei Hu
    • , Jiawen Li
    • , Shining Zhu
    •  & Min Xiao
  • Letter |

    Spin-polarized photon absorption and photoluminescence are reported in reduced-dimensional chiral perovskite materials. The finding indicates that such materials may in the future be useful as a photonic interface for spintronics.

    • Guankui Long
    • , Chongyun Jiang
    • , Randy Sabatini
    • , Zhenyu Yang
    • , Mingyang Wei
    • , Li Na Quan
    • , Qiuming Liang
    • , Abdullah Rasmita
    • , Mikhail Askerka
    • , Grant Walters
    • , Xiwen Gong
    • , Jun Xing
    • , Xinglin Wen
    • , Rafael Quintero-Bermudez
    • , Haifeng Yuan
    • , Guichuan Xing
    • , X. Renshaw Wang
    • , Datong Song
    • , Oleksandr Voznyy
    • , Mingtao Zhang
    • , Sjoerd Hoogland
    • , Weibo Gao
    • , Qihua Xiong
    •  & Edward H. Sargent
  • Letter |

    A three-dimensional nonlinear photonic crystal in ferroelectric barium calcium titanate that enables phase matching of nonlinear processes along an arbitrary direction, thereby removing constraints imposed by low-dimensional structures, is experimentally realized.

    • Tianxiang Xu
    • , Krzysztof Switkowski
    • , Xin Chen
    • , Shan Liu
    • , Kaloian Koynov
    • , Haohai Yu
    • , Huaijin Zhang
    • , Jiyang Wang
    • , Yan Sheng
    •  & Wieslaw Krolikowski
  • Letter |

    Nanocrystals assembled into metal–insulator–metal junctions can boost the efficiency of light generation from enhanced inelastic tunnelling to ~2%, which is a two orders of magnitude improvement over previous work, paving the way to on-chip ultrafast and ultracompact light sources.

    • Haoliang Qian
    • , Su-Wen Hsu
    • , Kargal Gurunatha
    • , Conor T. Riley
    • , Jie Zhao
    • , Dylan Lu
    • , Andrea R. Tao
    •  & Zhaowei Liu
  • Letter |

    Linewidth broadening of a phonon laser operated at an exceptional point of a compound optomechanical system is experimentally demonstrated.

    • Jing Zhang
    • , Bo Peng
    • , Şahin Kaya Özdemir
    • , Kevin Pichler
    • , Dmitry O. Krimer
    • , Guangming Zhao
    • , Franco Nori
    • , Yu-xi Liu
    • , Stefan Rotter
    •  & Lan Yang
  • Letter |

    By seeding a non-resonant aluminium-gallium-arsenide-on-insulator nanowaveguide with 10-GHz picosecond pulses at a low pump power of 85 mW, a single energy-efficient frequency comb source carrying 661 Tbit s–1 of data, equivalent to more than the total Internet traffic today, is achieved.

    • 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
  • Letter |

    A nonlinear charge oscillation driven by a 6 fs light field of 11 MV cm–1 is observed in a layered organic superconductor. The initial response time of the oscillation on the timescale of 10 fs clarifies that Coulomb repulsion is essential for the superconductivity.

    • 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
  • Letter |

    Highly crystalline BaTiS3 has been shown to exhibit record-breaking birefringence of 0.76 in the wavelength range of 7–16 μm. The large anisotropy is a result of its quasi-one-dimensional structure.

    • 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
  • Letter |

    Using high-temperature gas mixtures as the generation medium to increase the translational velocity of Xe atoms through the focus of a femtosecond enhancement cavity, phase-matched extreme-ultraviolet emission at a repetition rate of 77 MHz and with an average power of ~ 2 mW in a single harmonic order is achieved.

    • Gil Porat
    • , Christoph M. Heyl
    • , Stephen B. Schoun
    • , Craig Benko
    • , Nadine Dörre
    • , Kristan L. Corwin
    •  & Jun Ye
  • Letter |

    Near-infrared femtosecond laser pulses are sent to a Si or ZnO crystal to generate high-harmonic waves via static or transient field-induced optical nonlinearities. The beam profile of the high-harmonic emission is controlled by electronic methods.

    • 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