Optical second-harmonic waves are generated from the electric quadrupole contribution in a centrosymmetric magnetic Weyl semimetal Co₃Sn₂S₂. Two magnetic orders and phase transitions are explored in temperature-dependent rotational anisotropy measurements by second-harmonic generation.

Combining random illumination microscopy with coherent anti-Stokes Raman scattering and sum-frequency generation contrasts, a robust wide-field nonlinear microscope with a 3 µm axial sectioning capability and a 300 nm transverse resolution is demonstrated.

Introduction of a starch-based layer inhibits ion migration and repairs defects generated on light/dark cycles in perovskite solar cells. Cells retain 98.0% of the initial power conversion efficiency after 42 illumination cycles, and achieve a certified power conversion efficiency of 23.9%.

Thanks to the unique properties of twisted double bilayer graphene heterostructures, an ultra-broadband photoconductivity spanning the spectral range of 2–100 μm with internal quantum efficiencies of approximately 40% at speeds of 100 kHz is reported.

Time reflection and refraction are experimentally observed in ultracold atoms. To this end, the time boundary is formed by imposing an abrupt change in the coupling strength of the atomic chain. Time boundary effects are robust against material disorder.

A self-contained ring laser interferometre measures length-of-day variations due to global mass transport phenomena with a precision of a few milliseconds over several months of measurements.

Light sheet microscopy offers rapid 3D imaging of biological specimens while limiting photodamage. Nature Photonics spoke with Elizabeth Hillman of Columbia University about its capabilities, promising applications and present limitations.

Mansoor Sheik-Bahae, an exceptionally inventive scientist who made important contributions to nonlinear optics, optical refrigeration and laser science, passed away in July 2023, aged 67. He will be cherished for his sharp intellect, good humour, warm heart and the scientific legacy he leaves.

Activity in using photonics for subsea wireless communications and power generation is starting to make waves.

Optics is now going beneath the waves to give remote-operated vehicles and divers fast optical wireless data links. Nature Photonics spoke with Boon Ooi from KAUST, a leading researcher into underwater photonics research.

Benjamin Palmer from Ben-Gurion University in Israel talks to Nature Photonics about the intriguing optical properties found in molecular crystals in the living world. His latest paper on the topic can be found in this issue.