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ULTRAFAST OPTICS

The Ultrafast Optics Group has a strong expertise in scientific and technical aspects associated with ultrashort laser pulses including their generation, amplification, tailoring and application. A main focus is the interaction of intense ultrashort laser pulses with matter. On the one hand, this allows building innovative high power ultrafast THz sources; on the other hand, it opens the possibility for defined material modification. Here, driven by industrial demands, ultrashort pulses are used for material processing, allowing highly precise and practically damage and melting-free structuring.

In addition, transparent media can be structured within the volume without damaging the surface. The Ultrafast Optics Group was one of the first to demonstrate the true 3D capabilities of this direct writing technique for the fabrication of waveguides within the bulk of glasses. Based on the extension of this work to crystalline media, efficient frequency waveguide converters have been realized in LiNbO3 and also PPLN. In addition, waveguides buried within the bulk of crystalline silicon have been demonstrated for the first time giving rise to new options for connecting optics and electronics on one chip.

Interesting and promising phenomena have been observed when producing 2D coupled waveguide arrays within the bulk of different glasses, which open the potential for new routing and switching applications. These structures are among today's best model systems for investigating linear and nonlinear discrete propagation effects.

By applying the femtosecond direct writing technique to existing waveguides, the "Ultrafast Optics" group was one of the first to demonstrate the realization of fiber Bragg gratings (FBG) in non-photosensitive fibers using a point-by-point method. In addition, a phase mask scanning technique was developed to allow for the inscription of long and efficient FBGs in various types of fibers (e.g. non-photosensitive, polarization maintaining, active fibers). Recently, an efficient and stable integrated high-power fiber laser was realized using such FBGs.

The ultrafast materials processing knowledge is also used for medical applications. The current focus is on the use of ultrashort pulses for the treatment of presbyopia. Here, the goal is to regain the elasticity of the human lens by inducing defined cuts with a femtosecond laser.

Research areas

The research topic of Prof. Nolte is ultrashort laser pulses with the main focus on ultrashort pulse micromachining and material modification for industrial and medical applications, areas where he has been actively engaged in since the field's inception in the mid-1990s. Current research interests include:

  • linear and nonlinear interaction of light and matter
  • micro- and nanostructuring by ultrashort laser pulses
  • ultrashort pulse laser welding
  • 3D-volume structuring of glasses and crystals
  • fiber Bragg gratings, volume Bragg gratings
  • linear and nonlinear optics in discrete systems
  • medical applications of ultrashort laser pulses in ophthalmology
  • THz technology

Teaching fields

Stefan Nolte is teaching courses ranging from fundamental aspects of physics to state-of-the-art research. He is also responsible for the Abbe School of Photoncis experimental optics course, including internships. He gives courses in:

  • atomic and molecular physics (also for teachers)
  • laser physics and ultrashort pulse optics

Research methods

Our laboratories are equipped with a wide variety of lasers, handling equipment and characterization technology. They include:

  • high repetition rate ultrashort pulse laser systems (25 fs to 20 ps) including wavelength conversion covering the range from 300 nm to 10 μm
  • high-precision positioning and laser scanner systems
  • equipment for sample preparation and characterization (optical microscopes, electron microscope, Raman microscope, etc.)
  • characterization of spectral and spatial properties of micro- and nanostructured samples
  • characterization of nonlinear spatio-temporal dynamics

>> link to the Ultrafast Optics Group

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