RESEARCH

Nano & quantum optics is a rapidly developing research area that deals with the generation, propagation, manipulation, and detection of photons in structures that are far below the scale of the wavelength. The generation, spread, and localization of photons and complex multi photon states on such small length scales is nontrivial since according to Abbe the wavelength of light in the appropriate medium limits the ultimate wave localization. Nowadays in nano optics one distinguishes between two main scenarios. Firstly, one can achieve localization of light in nanosized particles or interfaces that typically show a huge field enhancement at their surfaces. Typical examples are tiny single photonic components such as complex nano-waveguides, nano-apertures and nano-resonators. Tight localization is of great practical importance, e.g. for high resolution inspection, local modification of materials, high field concentration, intensity enhancement, increase of efficiency of nonlinear processes such as Raman scattering and harmonic generation. Secondly, one can design and create novel optical materials, whose properties are mainly derived from the nanogeometries and not from the intrinsic material properties and are therefore engineerable. Eventually quantum photonic nanosystems will consist of ensembles of nanoscaled photonic elements (e.g. photonic waveguides, photonic crystals, amorphous nanomaterials, optical metamaterials). Consequently nano optics in connection to quantum optics is considered to be a major area of innovation in research and development of the 21st century.

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The Nano & Quantum Optics group at the Institute of Applied Physics examines fundamental effects of nanostructured materials and quantum photonic systems  in close collaboration between scientists in theory, technology, and experimental characterization. In nano optics, the vectorial nature of the electro-magnetic field as well as scattering and reflection into almost every spatial direction rules the optical response of these structures. In quantum optics, the quantum properties of few photon states allow realizing applications which are relying directly on the entanglement of such states. Particularly, in our group we are able to cover the whole process chain of design, modeling, fabrication, characterization and functional evaluation of nano and quantum optical structures with the aim of realizing and using optical systems with added functionality.

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Four microdisk resonators which are coupled via their evanescent fields.

Beside our strong commitment to explore the fascinating field of nano & quantum optics, further main research directions of the group address a broad field of photonics-related topics. On the one hand, we study fundamental science phenomena such as linear and nonlinear properties of optical microresonators, photonic crystals, and spatio-temporal dynamics in discrete optical systems. On the other hand, we are strongly engaged in application-oriented research fields, where we investigate, e.g., innovative approaches in near-field microscopy, nonlinear imaging and spectroscopic techniques for biological specimen, photon management in solar cells and integrated optical solutions for astronomical instrumentation.