Cover Art

Scheme of a photonic metamaterial composed of three-dimensional gold helices, each about 1.4 micrometers in diameter, fading to an oblique-view electron micrograph of the helices as fabricated (blue). The illuminated spiral symbolizes circularly polarized light impinging on the chiral metamaterial. The structure works as a circular polarizer for a frequency range exceeding one octave.

Over the last decade, direct laser writing via two-photon absorption turned from a laboratory curiosity into a versatile technique for the fabrication of 3D nano-and microstructures. Especially, in the field of nanophotonics novel structures could be fabricated and tested for agreement with theory. G. von Freymann and co-workers review recent progress in the field. The cover image displays a potpourri of complex 3D nanostructures for photonics.

Martin Bastmeyer and co-workers report the fabrication of elastic structures with submicrometer thickness for cell culture that can be deformed by forces exerted by single cardiomyocytes. The cover illustrates a 3D reconstruction of cardiomyocytes labeled for f-actin (green) and a-actinin (red) growing in an Ormocomp scaffold consisting of posts connected by flexible beams. This method offers the possibility to study cell behavior in a 3D environment with defined geometries and physiologically-relevant stiffness values.

A grand challenge in 3D nanolithography is to place near-IR photoluminescent guests precisely where desired in a high-refractive-index nanostructured host. This objective has now been reduced to practice, as reported by Georg von Freymann, Sean Wong, and coworkers, by using direct laser writing in an As₂S₃ all-inorganic photoresist doped with Er³⁺ ions. Such precise placement is considered a key step towards miniaturized optical, electro-optical, and photonic devices.