Volume 11 Issue 12, December 2017

Nature Photonics spoke to Demetrios Christodoulides, of CREOL, The College of Optics & Photonics, University of Central Florida, about the birth of the parity–time-symmetry concepts in optics and the challenges and prospects on the path ahead.

Optically generated local phase changes in methylammonium lead iodide produce a transient quantum-well-like structure with robust optical gain. The result is a perovskite laser that supports continuous-wave lasing under optical pumping.

Plasmonic antennas store energy by localizing light to nanoscale volumes. A plasmon’s oscillating electrons can scatter directly into a semiconductor, transferring the captured energy in less than ten femtoseconds.

The field of machine learning potentially brings a new set of powerful tools to optical communications and photonics. However, to separate hype from reality it is vital that such tools are evaluated properly and used judiciously.

General concepts and recent developments of parity–time symmetry in classical photonics are reviewed.

Topological photonic structures offer unique features such as reflection-free and non-reciprocal devices. This Review highlights the experimental progress in the relatively new field of photonic topology.

The progress on non-reciprocal photonic devices enabled by temporal modulation is reviewed.

Optically pumped continuous-wave lasing is achieved in methylammonium lead iodide (MAPbI₃) distributed feedback lasers that are maintained below the MAPbI₃ tetragonal-to-orthorhombic phase transition temperature of 160 K.

Self-starting harmonic frequency comb generation with a THz repetition rate in a quantum cascade laser is demonstrated. The mode spacing uniformity is verified to within 5 × 10⁻¹² parts of the central frequency. The findings extend the range of applications of quantum cascade laser frequency combs.

Attosecond electron pulse trains in electron microscopy are demonstrated through the coupling of phase-locked multicolour optical fields with electron pulses. A new variant of quantum state tomography for free-electron ensembles is established.

Exploiting the peculiar properties of graphene, a series of high-performance glass-on-graphene devices, such as polarizers, thermo-optic switches and mid-infrared waveguide-integrated photodetectors and modulators are realized.

The role of direct plasmonic coupling in hot-electron generation at Ag/TiO₂ interfaces is clarified by two-photon photoemission spectroscopy.