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Prof. Dr. Martin Wegener

Optics & Photonics (Topic 3)

Throughout the last decade, the field of optics & photonics has not only tremendously benefited from progress in nanoscience and -fabrication but has in turn also become an important driver and toolbox of nanoscience and -fabrication.

In optical lithography, the Abbe diffraction limit has been overcome, but there still are other limitations such as photoresist resolution. Such progress in three-dimensional optical lithography is not only relevant for advancing photonic wire-bonding schemes or for fabricating novel architectures for photonics, e.g., artificial optical materials called metamaterials, but also for the life sciences, e.g., for cell-culture scaffolds. For the life sciences, progress in advanced optical microscopy is equally important.

Stimulated emission depletion (STED) optical laser lithography

In stimulated emission depletion (STED) optical laser lithography, a Gaussian laser focus (red) writes and a specially shaped depletion focus (green) erases the periphery such that the effectively exposed volume (blue) is smaller than given by the diffraction barrier.


Optical components for imaging are well established at visible frequencies, but at X-ray frequencies new concepts for static and time-resolved non-destructive material testing and medical diagnostics are necessary. Compound X-ray lens systems focus X-rays to dimensions less than 100 nm with high intensities thus opening up high-energy X-ray microscopy on samples in ambient environment. X-ray gratings for phase contrast imaging might revolutionise computer tomography for medical diagnosis.

Full-field microscopy image of an Xradia nano-test-pattern

Full-field microscopy image of an Xradia nano-test-pattern normalised to its flat field (outer diameter: 30 µm, largest bar width: 1 µm, smallest bar width 50 nm (not resolved in the image)); taken at P05 at PETRA III at an energy of 30 keV.


In Germany, more than 10% of the total electric energy is currently consumed by information and communications technology. The increase of data traffic in data centres and world-wide communication networks still continues to double about every 18 months. Energy-efficient data transmission at terabit/s rates is therefore a key challenge, and novel concepts for generating, processing, transmitting, and detecting terabit/s data streams and electromagnetic waveforms with terahertz bandwidths (“teratronics”) are required.

Photonic wire bond

Photonic wire bond (PWB) connecting two silicon-on-insulator (SOI) chips. The PWB waveguide is generated by direct-write two-photon lithography. Photonic wire bonding will enable teratronic systems which are based on photonic multi-chip integration.


Efficient conversion of sunlight to electricity and vice versa of electricity to artificial light is a major part of the grand challenge of sustainable energy supply. Thus, finding and implementing new and inexpensive ways for solar energy conversion and energy-efficient lighting, enabling solar cells with higher efficiencies at lower costs, are needed.

Organic tandem solar cell

Organic tandem solar cells with transparent inorganic intermediate contact, which can be processed by solution via precursor.