Editorial Cite This: ACS Photonics 2017, 4, 2959−2961
Special Issue “2D Materials for Nanophotonics” F. Javier García de Abajo*,†,‡ †
ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain ICREA-Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona, Spain
‡
T
carriers.20 The present issue is also contributed by fascinating examples of these areas of research.1,8,20 The papers selected in this issue have a multidisciplinary nature, as they rely on the new optical and electro-optical properties of 2D materials, combined with exciting optical phenomena to create new opportunities for controlling the generation and flow of light within unprecedentedly small regions, as well as the interaction of light with atoms and atomically small structures, including molecules and finite 2D islands. The following relevant fields of photonics are specifically addressed by this article collection: • Nonlinear optics: The issue presents an experimental demonstration of electrically tunable four-wave mixing in silicon-nitride telecom-wavelength waveguides decorated with gated graphene,6 a pioneering experimental study of saturable absorption in black phosphorus,12 and a fundamental theoretical study of nonlinear plasmons in graphene.14 • Light manipulation: The issue includes a visionary review on the use of 2D materials combined with metasurfaces for the exploration of new frontiers in optical signal processing.4 In a related context, this paper collection also contains an experimental study on birefringence in anisotropic 2D materials and its use for accurate manipulation of light polarization,17 as well as an experimental work on the change in optical phase by 2D materials and its application in the characterization and imaging of these materials.13 • Photovoltaics: An insightful perspective is published within this issue on the potential and adequacy of 2D semiconductor materials as a new platform for photovoltaics.1 • Ultrafast optics: The present collection includes an experimental study of energy transport due to hot-charge-carrier diffusion, and its relative contribution compared with other heat transport mechanisms in MoS2 supported on Si.20 • Graphene plasmonics: The issue features two excellent reviews on this field: one dealing with fundamental aspects of graphene plasmons and their interaction with different types of electronic boundaries;2 and another one presenting an overview of the general understanding, phenomenology, and applications of these excitations in infrared photonics.3 These reviews are accompanied by an experimental study on well confined plasmons in two oppositely charge graphene layers separated by 1 nm of boron nitride,16 as well as five theoretical studies on the
he availability of new two-dimensional (2D) materials with appealing mechanical, structural, chemical, electrical, and optical properties has experienced an impressive growth over the past decade that finds a prolific manifestation in numerous nanophotonics studies of both fundamental and applied nature. The present special issue comprises 1 perspective paper,1 4 review papers,2−5 and 15 original research articles6−20 that capture a wide representation of current scientific frontiers in this field. Initiated with the isolation of graphene,21 the single-atomthick carbon layer, and the discovery of its unique electrical22,23 and optical properties,24,25 a productive search for 2D materials was launched based upon exfoliation of other crystal surfaces26 in which atomically thin layers are bounded by weak van der Waals attraction, and therefore, amenable to detachment by, for example, sticking to scotch tape. Other techniques were also used to produce 2D materials, including chemical vapor deposition,27 wet chemistry,28 epitaxial growth,29 and chemical self-assembly,30 some of which are compatible with mass production, therefore raising expectations for viable commercial applications in the near future. The work invested in producing 2D materials and investigating their physical properties soon generated a plethora of 2D electronic band structures, which gave rise to a wealth of polaritonic behavior31 with multiple uses in photonics. In particular, graphene plasmons32,33 have been the subject of intense research, which is also contributed by several of the papers in the present collection,2,3,7,9−11,14−16,18,19 while plasmonic behavior with unique characteristics is also identified in other 2D materials.5 Part of the appeal of polaritonic modes in atomically thin layers lies precisely in the fact that they are sustained by a comparatively small number of charges, thus, offering great sensitivity to external stimuli (e.g., electrical doping,34 magnetic fields,35 and optical pumping36). Additionally, graphene plasmons combine these means of active tunability with long lifetimes and high spatial confinement.37 In a parallel effort, the modulation of light by light in 2D materials was extensively examined based on their relatively large nonlinear responses, as exemplified by several of the papers included in this issue,6,12,14 also in combination with metasurfaces.4 Additionally, the well-defined thickness of atomically thin 2D material layers offers a practical way of accurately controlling and exploiting the phase of light, as neatly illustrated by two of the current research articles.13,17 The ability to control the gap in 2D insulating and semiconducting films both through their composition and through the number of atomic layers has given rise to exciting opportunities for ultracompact light sources (e.g., photonic crystal lasers38 and directionally controlled emission8), opened important perspectives for application in light harvesting,1 and demanded a better understanding of fundamental aspects associated with the propagation and ultrafast dynamics of charge © 2017 American Chemical Society
Special Issue: 2D Materials for Nanophotonics Received: November 20, 2017 Accepted: November 21, 2017 Published: December 20, 2017 2959
DOI: 10.1021/acsphotonics.7b01399 ACS Photonics 2017, 4, 2959−2961
ACS Photonics
Editorial
extraordinary confinement of graphene plasmons and ensuing potential for sensing when placed close to a metal surface,9 the interaction of graphene plasmons with optical surface waves in metal gratings,10 plasmon hybridization through edge-to-edge interaction in neighboring ribbons,11 plasmon reflection by corrugations,15 and plasmon modeling through simple analytical expressions for islands of arbitrary morphology.18 • Plasmons in topological insulators: The issue incorporates an exciting review on the fundamentals and exotic properties of plasmons in these materials,5 as well as an experimental study of these excitations in structured Bi2Te3 islands.19 • Optical emitters: The collection also includes a report on the measured modulation of the rate and angle of redlight emission from single-layer WSe2 supported on a silicon grating.8 • Quantum optics: This field is represented by an inspiring work on the possibility and prospects of using the electro-optical tunability of graphene to engineer the Lamb shift of electronic states in atoms and molecules.7 In summary, photonics with and within 2D materials is consolidating as a fertile field of research, encompassing a large degree of multidisciplinarity, displaying an impressive pace of scientific production, and covering a broad scope of targets, ranging from fundamental studies to market-oriented applications. As an eager ACS Photonics reader, I have benefited from the publication of numerous papers on 2D materials for nanophotonics by this journal since its inception. On this occasion, it is my privilege to introduce the present paper collection, which constitutes a state-of-the-art representation of the field, to which I truly expect that ACS Photonics will continue to contribute by publishing some of the most outstanding discoveries. Finally, before concluding this editorial note, I want to thank all the contributing authors, the reviewers who helped improve the papers, and the ACS Photonics Managing Editor, Carlos Toro, and Editorin-Chief, Professor Harry Atwater, for making this journal possible and for suggesting, handling, and supporting this special issue.
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(5) Stauber, T.; Gomez-Santos, G.; Brey, L. Plasmonics in Topological Insulators: Spin?Charge Separation, the Influence of the Inversion Layer, and Phonon-Plasmon Coupling. ACS Photonics 2017, 4, na. (6) Alexander, K.; Savostianova, N. A.; Mikhailov, S. A.; Kuyken, B.; Van Thourhout, D. Electrically Tunable Optical Nonlinearities in Graphene-Covered SiN Waveguides Characterized by Four-Wave Mixing. ACS Photonics 2017, 4, na DOI: 10.1021/acsphotonics.7b00559. (7) Chang, C.-H.; Rivera, N.; Joannopoulos, J. D.; Soljačić, M.; Kaminer, I. Constructing “Designer Atoms” via Resonant GrapheneInduced Lamb Shifts. ACS Photonics 2017, 4, na DOI: 10.1021/ acsphotonics.7b00731. (8) Chen, H.; Nanz, S.; Abass, A.; Yan, J.; Gao, T.; Choi, D.-Y.; Kivshar, Y. S.; Rockstuhl, C.; Neshev, D. N. Enhanced Directional Emission from Monolayer WSe2 Integrated onto a Multiresonant Silicon-Based Photonic Structure. ACS Photonics 2017, 4, na DOI: 10.1021/acsphotonics.7b00550. (9) Chen, S.; Autore, M.; Li, J.; Li, P.; Alonso-Gonzalez, P.; Yang, Z.; Martin-Moreno, L.; Hillenbrand, R.; Nikitin, A. Y. Acoustic Graphene Plasmon Nanoresonators for Field-Enhanced Infrared Molecular Spectroscopy. ACS Photonics 2017, 4, na DOI: 10.1021/acsphotonics.7b00654. (10) Dias, E. J. C.; Peres, N. M. R. Controlling Spoof Plasmons in a Metal Grating Using Graphene Surface Plasmons. ACS Photonics 2017, 4, na DOI: 10.1021/acsphotonics.7b00629. (11) Gonçalves, P. A. D.; Xiao, S.; Peres, N. M. R.; Mortensen, N. A. Hybridized Plasmons in 2D Nanoslits: From Graphene to Anisotropic 2D Materials. ACS Photonics 2017, 4, na DOI: 10.1021/acsphotonics.7b00558. (12) Huang, J.; Dong, N.; Zhang, S.; Sun, Z.; Zhang, W.; Wang, J. Nonlinear Absorption Induced Transparency and Optical Limiting of Black Phosphorus Nanosheets. ACS Photonics 2017, 4, na DOI: 10.1021/acsphotonics.7b00598. (13) Khadir, S.; Bon, P.; Vignaud, D.; Galopin, E.; McEvoy, N.; McCloskey, D.; Monneret, S.; Baffou, G. Optical Imaging and Characterization of Graphene and Other 2D Materials Using Quantitative Phase Microscopy. ACS Photonics 2017, 4, na DOI: 10.1021/acsphotonics.7b00845. (14) Mikhailov, S. A. Influence of Optical Nonlinearities on Plasma Waves in Graphene. ACS Photonics 2017, 4, na DOI: 10.1021/ acsphotonics.7b00468. (15) Slipchenko, T. M.; Nesterov, M. L.; Hillenbrand, R.; Nikitin, A. Y.; Martín-Moreno, L. Graphene Plasmon Reflection by Corrugations. ACS Photonics 2017, 4, na DOI: 10.1021/acsphotonics.7b00656. (16) Woessner, A.; Misra, A.; Cao, Y.; Torre, I.; Mishchenko, A.; Lundeberg, M.; Watanabe, K.; Taniguchi, T.; Polini, M.; Novoselov, K. Propagating Plasmons in a Charge-Neutral Quantum Tunneling Transistor. ACS Photonics 2017, 4, na DOI: 10.1021/acsphotonics.7b01020. (17) Yang, H.; Jussila, H.; Autere, A.; Komsa, H.-P.; Ye, G.; Chen, X.; Hasan, T.; Sun, Z. Optical Waveplates Based on Birefringence of Anisotropic Two- Dimensional Layered Materials. ACS Photonics 2017, 4, na DOI: 10.1021/acsphotonics.7b00507. (18) Yu, R.; Cox, J. D.; Saavedra, J. R. M.; García de Abajo, F. J. Analytical Modeling of Graphene Plasmons. ACS Photonics 2017, 4, na DOI: 10.1021/acsphotonics.7b00740. (19) Yuan, J.; Ma, W.; Zhang, L.; Lu, Y.; Zhao, M.; Guo, H.; Zhao, J.; Yu, W.; Zhang, Y.; Zhang, K. Infrared Nanoimaging Reveals the Surface Metallic Plasmons in Topological Insulator. ACS Photonics 2017, 4, na DOI: 10.1021/acsphotonics.7b00568. (20) Yuan, P.; Wang, R.; Tan, H.; Wang, T.; Wang, X. Energy Transport State Resolved Raman for Probing Interface Energy Transport and Hot Carrier Diffusion in Few-Layered MoS2. ACS Photonics 2017, 4, na DOI: 10.1021/acsphotonics.7b00815. (21) Novoselov, K. S.; Geim, A. K.; Morozov, S. V.; Jiang, D.; Zhang, Y.; Dubonos, S. V.; Grigorieva, I. V.; Firsov, A. A. Electric Field Effect in Atomically Thin Carbon Films. Science 2004, 306, 666−669.
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. ORCID
F. Javier García de Abajo: 0000-0002-4970-4565 Notes
Views expressed in this editorial are those of the author and not necessarily the views of the ACS.
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REFERENCES
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