Dr. Tobias Utikal

  • Wissenschaftlicher Referent (Research Coordinator)
  • Room: A.3.232
  • Telephone: +49 9131 7133316
  • E-mail

My research interest ranges from cryogenic Nano-Quantum-Optics with single emitters to Nano-Bio-Photonics using iSCAT microscopy. As research coordinator of the division I am involved in many research projects pushing the experiments forward, coordinating resources, and preserving the knowledge in the group. In various exploratory side-projects I am breaking new ground for future experiments.

I am always interested in the latest technology developments of narrow-band lasers, cryogenics, nano-positioning, microscopy at and beyond the diffraction limit, single photon detectors, and scientific cameras.

2024

iSCAT microscopy and particle tracking with tailored spatial coherence

Mahdi Mazaheri, Kiarash Kasaian, David Albrecht, Jan Renger, Tobias Utikal, Cornelia Holler, Vahid Sandoghdar

Optica 11 1030-1038 (2024) | Journal | PDF

Interferometric scattering (iSCAT) microscopy has demonstrated unparalleled performance among label-free optical methods for detecting and imaging isolated nanoparticles and molecules. However, when imaging complex structures such as biological cells, the superposition of the scattering fields from different locations of the sample leads to a speckle-like background, posing a significant challenge in deciphering fine features. Here, we show that by controlling the spatial coherence of the illumination, one can eliminate the spurious speckle without sacrificing sensitivity. We demonstrate this approach by positioning a rotating diffuser coupled with an adjustable lens and an iris in the illumination path. We report on imaging at a high frame rate of 25 kHz and across a large field of view of 100µm×100µm, while maintaining diffraction-limited resolution. We showcase the advantages of these features by three-dimensional (3D) tracking over 1000 vesicles in a single COS-7 cell and by imaging the dynamics of the endoplasmic reticulum (ER) network. Our approach opens the door to the combination of label-free imaging, sensitive detection, and 3D high-speed tracking using wide-field iSCAT microscopy.

High-Resolution Cryogenic Spectroscopy of Single Molecules in Nanoprinted Crystals

Mohammad Musavinezhad, Jan Renger, Johannes Zirkelbach , Tobias Utikal, Claudio U. Hail, Thomas Basché, Dimos Poulikakos, Stephan Götzinger, Vahid Sandoghdar

ACS Nano 18 21886-21893 (2024) | Journal | PDF

We perform laser spectroscopy at liquid helium temperatures (T = 2 K) to investigate single dibenzoterrylene (DBT) molecules doped in anthracene crystals of nanoscopic height fabricated by electrohydrodynamic dripping. Using high-resolution fluorescence excitation spectroscopy, we show that zero-phonon lines of single molecules in printed nanocrystals are nearly as narrow as the Fourier-limited transitions observed for the same guest–host system in the bulk. Moreover, the spectral instabilities are comparable to or less than one line width. By recording super-resolution images of DBT molecules and varying the polarization of the excitation beam, we determine the dimensions of the printed crystals and the orientation of the crystals’ axes. Electrohydrodynamic printing of organic nano- and microcrystals is of interest for a series of applications, where controlled positioning of quantum emitters with narrow optical transitions is desirable.

Tobias Utikal studied Physics at University of Bonn from 2001 to 2007. For his Diploma thesis on “Ultrafast Spectroscopy of Metallic Photonic Crystals” he moved to University of Stuttgart where he worked in the group of Prof. Harald Giessen. The following PhD thesis on “Ultrafast Nonlinear Spectroscopy of Hybrid Plasmonic Systems” he partially conducted at the Max Planck Institute for Solid State Research in Stuttgart. In 2011 he joined the Group of Prof. Vahid Sandoghdar at ETH Zurich as a postdoc. After the move of the group to the Max Planck Institute for the Science of Light (MPL) in Erlangen he became a permanent senior scientist and is acting as research coordinator of the division. In his function as safety officer he is member of the work safety council of the institute. Tobias has been elected as the scientific staff representative of MPL from 2015 – 2021.

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