PhD & Postdoctoral Positions

We are continuously looking for talented and highly motivated Ph.D. students and postdocs. We also have short-term projects for internships and for M.S. students. Please contact Frank Vollmer for postdoctoral position, Ph.D. position (Doktorarbeit) and M.S. project (Diplomarbeit) here at the Laboratory for Nanophotonics & Biosensing at the Max Planck Institute for the Science of Light.

Positions are available in the following areas:

IMPRS projects offered by the Laboratory of Nanophotonics & Biosensing
Contact: Dr. Frank Vollmer, email: frank.vollmer(at)mpl.mpg(dot)de 



Plasmon-enhanced single molecule detection with optical microcavitie

free detection of single molecules has been a dream of biologists and biotechnologists. We have come one step closer towards achieving this goal by coupling optical resonators to nanoplasmonic structures. We use whispering gallery modes (WGM) in optical microsphere resonators to excite plasmon resonances in gold nanorods. Strong electromagnetic field enhancements are observed at the nanoparticle site - without significant losses to the quality factor of the resonator. When a molecule binds to the hotspot location it tunes the resonance frequency in proportion to the encountered field strength. The hotspots can provide large sensitivity enhancements – bringing label-free single molecule detection within reach. Here, we will investigate the physics of single molecule detection with plasmon enhanced microcavities, an endeavour that is essential for designing the next generation of biosensors and to elucidate intricate mechanisms of molecular machines.



Effects of polarization and scattering in disordered photonic crystal structures

Optical microcavities form in defects of 2D photonic crystals where the light field remains confined by Bragg reflection. Alternatively, optical microcavities can form by scattering (strong localization) in random media. Depending on these two confinement mechanisms, Bragg reflection or random scattering, the optical properties of the localized light fields are expected to differ significantly. Here, we will investigate a photonic crystal structure that confines light through the interplay of Bragg reflection AND random scattering. The lattice of the 2D photonic crystals is disordered which leads to strongly localized light fields resulting in high Q cavities, spectrally observed at the cut-off frequency of the waveguide mode. These microcavities are distributed randomly along the ~ 80 nm waveguide. We will characterize disordered W1 2D silicon photonic crystal waveguides.

Molecular interactions at a biosensor interface

We are interested in developing biosensing assays for clinically relevant biomarkers as well as for single cell analysis. Surface functionalization procedures of glass microsphere cavities have been developed to conjugate various antibodies which are used as recognition elements for detection of various biomarkers. The microspheres will be integrated in devices similar to the one shown here, for multiplexed chip-scale detection of various biomarkers from cell culture and engineered tissue. Here we are collaborating with colleagues from medicine and biology to develop on-chip molecular diagnostic tools. Such microchip devices will use DNA nanotechnology for improving nucleic acid detection limits, will monitor cells in culture and engineered tissue, and will detect kidney biomarkers in urine samples.

Optomechanics in biosensing

No abstract available yet, please send inquiries to Dr. Frank Vollmer.

Optical Resonator Physics:

We study the interaction of light with matter in optical microcavity structures such as microspheres, micro-rings, micro-toroids and photonic crystals. We use state-of-the art engineering tools to fabricate silicon photonic circuits on the micro- and nanoscale. We probe these structures in experiments ranging from non-linear optics to Anderson Localization. We study optical fields and forces in photonic microstructures and their interaction with nanoparticles and biomolecules. We construct microcavity-based devices such as highly sensitive optical biosensors, and one of our major efforts is focused on improving our label-free microcavity-based biosensing technology to reach single molecule detection capability. We also have an interest in understanding the interface between photonics and plasmonics. Required background in this area: physics (for example optics, atomic optics, photonics, optomechanics, plasmonics) or electrical engineering (for example nanofabrication, photonic crystals, photonics, biophotonics, plasmonics).

Molecular interactions at a biosensor interface

We use easy-to- fabricate, micron-size glass beads (microspheres) as highly sensitive optical biosensors. The microsphere sensors constitute optical resonators which allow for detection of minute changes in their respective optical resonance frequencies. Such frequency changes report on molecular binding events such as the binding of an antigen to a previously immobilized antibody. We use our biosensing technology to understand mechanisms of molecular recognition, conformational changes, affinity and avidity, protein and virus interactions, as well as protein denaturation and renaturation. We integrate our microsphere sensors with microfluidics and optical microscopy to achieve a) high-throughput detection and b) high sensitivity in many biological applications. We are particularly interested in developing biosensing assays for clinically relevant biomarkers as well as for single cell analysis. Required background in this area: bioengineering (for example biosensing, optical biosensor development, surface chemistry, basic cell biology and molecular biology) or chemical engineering (microfluidics, analytical chemistry, bioconjugation, optofluidics) or materials science (photonic plasmonic nanoparticles, micro- nanofabrication) or physics (optical sensor development, biophysics).

We are also seeking a postdoctoral fellow for collaborative work with Brigham and Women's Hospital (BWH) in Boston and with the Wyss Institute at Harvard University. Candidate will have background in bioengineering/optical microcavities/biosensing, will work at BWH in Boston (USA) and is willing to travel (30%-40%) to Max Planck Institute in Erlangen, Germany. This project is funded by NIH. Please send applications to Frank Vollmer. This position is also suitable for a senior researcher.



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