Ba/Ma/PhD Projects

Nano-Opto-Electronics

Our group is among the pioneers in the field of electrically driven nano-antennas for light. We manufacture and characterize high-precision nano-opto-electronic systems made from gold single crystals. We are currently working on more complex antenna geometries to produce directional light emission (e.g. Yagi-Uda antennas, see figure) and on new concepts to improve the stability and efficiency of the antennas. We aim, for example, at the realization of a nanoscale directional radio link using light, applications in sensor technology, and the realization of very small pixels for displays in VR applications.

Contact:

   Bert Hecht
   Fabian Scheidler

Optical-Nanocircuitry

Using plasmonic waveguides, circuits can be implemented in which optical excitations can be controlled on the nanoscale - far below the wavelength of visible light. Recently, we developed ideas how to use plasmonic nanocircuitry to "immortalize" hybrid states of light and matter based on coherent perfect absorption. We would now like to realize such a system experimentally.

Contact:

Bert Hecht

Nano-Quantum-Optics

Nano-quantum optics deals with the quantum-optical properties of the light-matter interaction in optical nanosystems. Of particular interest are processes in which the presence of a single photon in the system has a noticeable effect on the interaction of a second photon. Such systems could lead to transistors that can be switched with individual photons.

Using unique, freely positionable gold nanostructures, we recently succeeded for the first time in observing strong coupling of quantum dots at room temperature which corresponds to observing individual light quanta hybridized optical modes. We are currently investigating other exciting phenomena in these systems and are also characterizing new material combinations.

Contact:

   Bert Hecht

Electrical excitation of nanostructures

A central part of our experiments is the electrical control of the nanostructures in order to generate, manipulate and detect light on a very small scale.

To realize this, we use a sophisticated sample layout in which the electrical wires and contacts pads are gradually expanded from the nanometer to the millimeter range. The samples are then placed on an optical microscope and electrically contacted using micromanipulators. This way it is possible to e.g. simultaneously apply a voltage and record spectra of the emitted light.

Surface investigation using atomic force microscopy

In order to better understand the surface properties of our nanostructures, we use extremely sharp tips, which are scanned over the sample like a cane.

This systematic scanning allows the topography of nanometer-sized objects to be precisely detected. Furthermore, advanced methods allow us not only to measure the topography, but also the magnetic and electrical properties of nanostructures, to manipulate them or to focus light on an almost atomic scale using special tips.

High-resolution confocal optical microscopy

For the investigation of the optical properties of our nanostructures, we have different, mostly self-made, highly optimized setups available.These allow the structures to be excited by means of laser or white light, so that on the one hand high-resolution imaging is also possible, but also optical spectroscopy can be performed. Important properties such as the optical resonances of the structures can thus be precisely determined or, for example, the photon statistics of quantum emitters can be determined.