Perovskite–polymer LEDs with external quantum efficiencies exceeding 20% are demonstrated. Ultrafast spectroscopy reveals that non-radiative losses are fully eliminated leading to near-100% internal electroluminescence quantum efficiencies. The perovskite–polymer light emitter shows significant potential for display, lighting and communications applications.

See Di et al.

Artist’s impression of triple-frequency-comb laser spectroscopy. Three different repetition-rate frequency combs are used to generate a high-resolution multidimensional coherent spectrum of a mixture of 87Rb and 85Rb isotopes in under one second. The approach is promising for remote chemical sensing applications.

See Cundiff et al.

A 3D nonlinear photonic crystal in lithium niobate is realized by using a laser erasing technique to spatially control the crystal’s nonlinearity, locally switching it ‘on’ or ‘off’. The achievement provides a promising platform to fully control nonlinearity and interacting waves for applications in beam shaping, holography and quantum information processing.

See Zhang et al. and Ellenbogen.

Harnessing multiple round-trips through an optical cavity enables radical possibilities for time-of-flight cameras. This concept of time-folding an optical path yields new camera designs capable of functions such as ultrafast multispectral imaging.

See Heshmat et al.

Artistic impression of a tailored plasma structure that frequency downshifts a near-infrared laser pulse to efficiently generate intense, single-cycle infrared pulses in the spectral range of 5–14 μm. Such long-wavelength single-cycle pulses are potentially useful for many applications including coherent control, metrology and attosecond generation.

See Lu et al.

Artist’s impression of a new form of non-invasive, laser-based vision correction that uses a femtosecond laser to induce mechanical and refractive changes in the eye’s cornea.

See Vukelic et al.

Artistic image of an electron accelerator that operates by the interaction between single-cycle terahertz pulses and electron bunches. The accelerator is composed of arrays of parallel metal waveguides that feature a dielectric filling in order to phase match the terahertz–electron interaction. It can perform complex, high gradient operations on ultrashort electron bunches.

See Zhang et al.

Triangular combs of frequencies generated in optical fibres are observed to reappear with or without temporal shift due to broken symmetry of the Fermi–Pasta–Ulam recurrence phenomenon. This behaviour is revealed by a novel non-destructive optical technique that allows full characterization of the optical phase evolution.

See Mussot et al.

Depiction of an ‘angular streaking’ scheme that enables the attosecond details of individual X-ray pulses to be read by a detector, akin to reading the face of a clock. Performed at the Linac Coherent Light Source in Stanford, US, ultrashort X-ray pulses photoionize neon while the circular polarization of an infrared laser field modulates the corresponding photoelectron energy and angle of the emission.

See Helml et al.

X-ray diffraction pattern generated from two different-sized spherical objects in close proximity to each other. The curvature and modulation of the dark fringes in the pattern provide useful information related to the relative position of the two objects and can be interpreted for image reconstruction. The result is a scheme that can perform ultrafast X-ray imaging of nanoscale systems such as a virus.

See Gorkhover et al.

Photograph of a number of electromechanically pumped optical isolators on an aluminium nitride chip. These magnet-free isolators use sound waves to break time-reversal symmetry for light propagation. The devices are fabricated by electron-beam photolithography and the isolation band for each device can be lithographically defined. The isolators are designed for operation near 1,550 nm with a bandwidth exceeding 1 GHz.

See Sohn et al.

Mid-infrared surface phonon polariton resonances in InP and 4H-SiC nanopillars are optically tuned by using green laser light to create photoinjected carriers. Photocarrier-induced blue-shifts of several cm−1 are observed. The ability to optically tune and modulate such resonances could be useful for realizing on-chip devices that operate in the mid-infrared.

See Dunkelberger et al.