Nature Photonics

Guide for the perplexed to the Shockley–Queisser model for solar cells   pp501 - 505  Jean-Francois Guillemoles, Thomas Kirchartz, David Cahen & Uwe Rau doi:10.1038/s41566-019-0479-2
In memory of Mikhail Gorodetsky    pp506 - 508  Igor Bilenko, Vladimir Ilchenko, Farid Khalili & Tobias J. Kippenberg doi:10.1038/s41566-019-0490-7
NEWS & VIEWS
Striving for extreme solitons    pp509 - 511  Benjamin Wetzel & Fetah Benabid  doi:10.1038/s41566-019-0497-0  T-ray modulation of light for future THz radios    pp511 - 513  Guillaume Ducournau  doi:10.1038/s41566-019-0499-y  Towards coherent X-ray free-electron lasers    pp513 - 515  Li Hua Yu & Timur Shaftan  doi:10.1038/s41566-019-0495-2  Overcoming the colour barrier    pp515 - 516  Shoujun Zhu & Xiaoyuan Chen  doi:10.1038/s41566-019-0500-9
LETTERS
THz-to-optical conversion in wireless communications using an ultra-broadband plasmonic modulator    pp519 - 524  S. Ummethala, T. Harter, K. Koehnle, Z. Li, S. Muehlbrandt et al.  doi:10.1038/s41566-019-0475-6  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.
High-sensitivity imaging of time-domain near-infrared light transducer   pp525 - 531  Yuyang Gu, Zhiyong Guo, Wei Yuan, Mengya Kong, Yulai Liu et al.  doi:10.1038/s41566-019-0437-z  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.
ARTICLES
Controlling competing photochemical reactions stabilizes perovskite solar cells    pp532 - 539  Silvia G. Motti, Daniele Meggiolaro, Alex J. Barker, Edoardo Mosconi, Carlo Andrea Riccardo Perini et al.  doi:10.1038/s41566-019-0435-1  The photo-instability of perovskite solar cells is investigated and controlled by the use of a passivation strategy.
Highly efficient blue thermally activated delayed fluorescence emitters based on symmetrical and rigid oxygen-bridged boron acceptors    pp540 - 546 Dae Hyun Ahn, Si Woo Kim, Hyuna Lee, Ik Jang Ko, Durai Karthik et al.  doi:10.1038/s41566-019-0415-5  The discovery of two deep-blue organic emitters of light could aid the development of next-generation organic light-emitting devices.
High-energy pulse self-compression and ultraviolet generation through soliton dynamics in hollow capillary fibres    pp547 - 554  John C. Travers, Teodora F. Grigorova, Christian Brahms & Federico Belli doi:10.1038/s41566-019-0416-4  Optical soliton dynamics in large-core hollow capillary fibres is demonstrated. The findings enable the scaling of soliton effects by several orders of magnitude to the multi-millijoule energy and terawatt peak power levels, and open up opportunities for new-generation table-top light sources for ultrafast strong-field physics and advanced spectroscopy.
Coherent soft X-ray pulses from an echo-enabled harmonic generation free-electron laser    pp555 - 561  Primož Rebernik Ribič, Alessandro Abrami, Laura Badano, Maurizio Bossi, Hans-Heinrich Braun et al.  doi:10.1038/s41566-019-0427-1  Echo-enabled harmonic generation in a free-electron laser enables 45th harmonic pulses from a 264 nm wavelength seed, yielding 5.9 nm wavelength coherent output.
Retrieval of phase relation and emission profile of quantum cascade laser frequency combs    pp562 - 568  Francesco Cappelli, Luigi Consolino, Giulio Campo, Iacopo Galli, Davide Mazzotti et al.  doi:10.1038/s41566-019-0451-1  The combined technique of dual-comb multi-heterodyne detection and Fourier-transform analysis allows simultaneous acquisition and monitoring of the phase pattern of a generic frequency comb demonstrating the high degree of coherence of the emission of two quantum cascade laser frequency combs.
Knotting fractional-order knots with the polarization state of light    pp569 - 574  Emilio Pisanty, Gerard J. Machado, Verónica Vicuña-Hernández, Antonio Picón, Alessio Celi et al.  doi:10.1038/s41566-019-0450-2  The polarization structure around polarization singularities can exhibit arbitrary fractional rotations when tracing around the singularity, due to an underlying topology of a torus knot imprinted by the chosen ratio of frequencies contained in the light beam.
Computational time-of-flight diffuse optical tomography    pp575 - 579  Ashley Lyons, Francesco Tonolini, Alessandro Boccolini, Audrey Repetti, Robert Henderson et al.  doi:10.1038/s41566-019-0439-x  By combining a single-photon time-of-flight camera with computational processing of the spatial and full temporal photon distribution data, an object embedded inside a strongly diffusive medium can be imaged over more than 80 transport mean free paths in a contactless manner on the timescale of the order of 1 s.
AMENDMENTS & CORRECTIONS
Author Correction: Silicon–plasmonic integrated circuits for terahertz signal generation and coherent detection    p580  T. Harter, S. Muehlbrandt, S. Ummethala, A. Schmid, S. Nellen et al.  doi:10.1038/s41566-019-0487-2
Publisher Correction: High-sensitivity imaging of time-domain near-infrared light transducer    p580  Yuyang Gu, Zhiyong Guo, Wei Yuan, Mengya Kong, Yulai Liu et al.  doi:10.1038/s41566-019-0491-6