Volume 12 Issue 2, February 2018

Metasurfaces can in principle provide a versatile platform for optical functionalities, but in practice designing and fabricating them to specifications can be difficult. Now, the realization of metasurfaces with engineered disorder allows for versatile optical components that combine the best features of periodic and random systems.

Implementing non-reciprocal elements with a bandwidth comparable to optical frequencies is a challenge in integrated photonics. Now, a phonon pump has been used to achieve optical non-reciprocity over a large bandwidth.

Irradiating arrays of metal nanowires with intense femtosecond laser pulses produces high-brightness picosecond X-ray pulses. By specifically tailoring the plasma properties, up to 20% conversion efficiency of optical light into X-rays can be achieved.

The ability to switch fluorophores on and off is key to performing super-resolution nanoscopy. To date, all switching schemes have been based on an incoherent response to the laser field. Now, a nanoscope that uses on–off coherent switching of quantum dots has been demonstrated.

The study of the complex, unstable dynamics of lasers is not just of scientific value but is also creating new opportunities for making secure lidar and generating high-frequency microwave signals.

A spatial resolution of 30 nm (=λ/31) exceeding the diffraction limit is achieved by super-resolution fluorescence microscopy. The nanoscopic imaging scheme can be applied to coherent quantum-mechanical systems such as quantum dots, as well as colour centres.

The magneto-optical Kerr effect is demonstrated in an antiferromagnetic metal. Large rotation angles, magnetic octupole domain imaging was enabled.

Enhanced nonlinear response of 50-nm-thick antennas in the vicinity of an epsilon-near-zero material enable an optically induced refractive index change of ±2.5 over a 200 nm spectral range.

Using designer-disordered metasurfaces, optical input–output characteristics, which are typically difficult to obtain, can be known a priori. The approach is used for wavefront shaping, high-numerical-aperture focusing and fluorescence imaging.

Time-reversal symmetry is broken via an acoustic pumping scheme enabling demonstration of a frequency shifting optical isolator with 15 dB asymmetry and 1 GHz bandwidth.

Near-infrared organic light-emitting diodes that operate in the 700 nm region with an external quantum efficiency of almost 10% are reported.

Multijunctions have long been used to enhance photovoltaic solar cell efficiency. Here, a large-area tandem luminescent solar concentrator is demonstrated using two types of quantum dot with low reabsorption.

Using an ultrafast, time-stretched frequency comb laser operating with repetition rates from 7.6 MHz to 18.9 MHz, a rapid and large-volumetric-field optical coherence tomography at an imaging rate of up to 7.5 volumes per second is demonstrated.