Electron-beam written optical circuits on a 4-inch silicon wafer.

Advanced Fabrication Technologies for Micro- and Nano-Optics

apl. Prof. Dr. Uwe ZEITNER
Electron-beam written optical circuits on a 4-inch silicon wafer.
Image: Jan-Peter Kasper (University of Jena)
Uwe ZEITNER Uwe ZEITNER Image: Private

apl. Prof. Uwe ZEITNER

Email: uwe.zeitner@iof.fraunhofer.de
Phone: +49 3641-8-07403

Prof. Zeitner is the head of the research group MicroStructure Technology at the Institute of Applied Physics. Simultaneously, Prof. Zeitner is Senior Director for Opto-Mechanical Systems at the Fraunhofer Institute for Applied Optics and Precision Engineering, Jena.

The main goal of the Zeitner research group is the creation of a scientific and technological basis to make novel diffractive approaches for a highly flexible fabrication of micro- and nanostructures for optical applications available. The knowledge gained is used for the consistent development of innovative technological methods for the precise realization of very small optical structures on application-relevant areas. Furthermore, those techniques can be transferred with reasonable investments onto the existing infrastructure of the optical industry.

Research Areas

Prof. Zeitner’s research is focused on novel fabrication technologies for optical micro- and nano-structures with a strong emphasis on the exploitation of their application potential. Research fields include:

  • Plasmonic resonant nano-structures
  • High-resolution lithographic fabrication technologies
  • Nano-structures for quantum devices
  • Gratings for high end applications
  • High-precision computer-generated-holograms (CGHs)
  • Effective-refractive index structures
  • 3D structuring of crystals by ion-beam enhanced etching

Teaching Fields

Prof. Zeitner gives lectures in:

  • Optical modeling and design
  • Micro- and nano-structure technology for optics

Research Methods

The laboratories led by Prof. Zeitner offer a wide range of methods for the fabrication and characterization of optical micro- and nanostructures. Methods and facilities include:

  • Electron beam lithography on large areas
  • Optical and grayscale lithography
  • Various reactive ion etching (RIE) facilities
  • Scanning electron microscopy (SEM), focused ion beam (FIB) and He-ion microscopy (HIM)
  • Tactile and optical profilometry
  • Optical characterization lab

Recent Research Results

High resolution spectroscopic diffraction grating encapsulated between two prisms by adhesive-free direct bonding. High resolution spectroscopic diffraction grating encapsulated between two prisms by adhesive-free direct bonding. Image: Fraunhofer IOF

Our research group has demonstrated the use of diffractive photo-masks in mask-aligner lithography for the realization of high-resolution microstructures with feature dimensions well below 500 nm [1]. We proposed different exposure strategies for periodic and non-periodic structures, developed proper design methods for the diffractive photo-masks and considerably improved the mask-aligner exposure tools [2]. Parallel to the activities in the field of novel photolithography methods, the group is working to improve the photo-mask fabrication technology via special exposure regimes in the field of electron beam lithography. Together with the company Vistec, a new cell-projection writing principle has been incorporated into the work group’s electron beam writer. It allows for an extremely time-efficient exposure of complex high-resolution patterns [3]. This is not only a mandatory step for the fabrication of diffractive photo-masks, but also enables both the realization of optical metamaterials and, alternatively, effective refractive index structures on large areas. An additional thrust of the Micro- and Nano-Structure Technology group is the development of novel grating concepts for spectroscopic- and laser applications [4]. High diffraction efficiencies near the 100 % limit at large bandwidths and, at the same time, low wave-front errors and stray light levels are the main challenges for these devices [5]. Such gratings are required e.g. for the stretching or compression of ultrashort laser pulses or in high-performance spectrometers for space applications. A number of novel grating concepts have been successfully developed in recent years. These concepts include special configurations for the suppression of undesired spectral resonances, highly efficient transmission gratings on the basis of dielectric layer stacks, the combination of gratings and prisms by direct bonding techniques, and the use of atomic layer deposition techniques (ALD) for bandwidth tailoring and improved manufacturability. The ALD processes have been developed in close cooperation with other groups from the Abbe Center of Photonics. The Zeitner research group delivers such gratings for different European space missions such as GAIA, Sentinel-4, or next generation CO2-monitoring satellites (see Figure).

[1] Bourgin et al., Opt. Lett. 42, 3816 (2017).
[2] Weichelt et al., Opt. Express 25, 20983 (2017).
[3] Zeitner et al., Proc. SPIE Vol. 8974, 89740G (2014).
[4] Zeitner et al., Appl. Physics A 109, 789 (2012).
[5] Heusinger et al., Opt. Express 26, 28104 (2018).

Link to the Group of Advanced Fabrication Technologies for Micro- and Nano-Optics