for Students

In recent decades, the computer and telecommunications industry has developed rapidly. However, data transmission and processing still take place on fundamentally different platforms. The closer we can bring electronic circuits and optical fiber technology together, the shorter latencies and higher bandwidths can be achieved. The bachelor thesis deals with the characterization of waveguides written in silicon using ultra-short pulse lasers. The applied methods are manifold and range from near-field microscopy to Raman spectroscopy and electron microscopy. After successful training, it is also possible to produce your own waveguides.

The high intensities of ultrashort laser pulses allow precise structuring of transparent materials. With suitable parameters, these structures can be used as waveguides. Light, propagated by the waveguides, acts as information carrier. By inserting further structures into the waveguides, the information in the light can be changed. In this project, liquid crystals are to be used for this purpose, whose birefringence properties can be used to change the polarization of light. The main task will be the characterization of functionalized waveguides.

The aim of this work is the inscription of fiber Bragg gratings with adapted transmission or dispersion profiles. For this purpose, the "line-by-line" technique is used to individually generate the desired lattice profiles in the fiber. Subsequently, the gratings generated in this way are to be analyzed with regard to their spectral properties. Based on these results, the inscription can then be optimized so that the required parameters are best achieved.

The project includes the inscription of different femtosecond fiber gratings, which are investigated for their polarization dependence in a specially developed measuring setup.

Selective laser melting is a common method for additive manufacturing from CAD-data, where the usage of ultrashort laser systems with high repetition rates increases the number of process parameters and enables the application of new materials.
The comprehension of thermal conductivity, melting processes and heat accumulation effects in the MHz repetition regime is crucial for the further improvement of crucial properties like surface roughness and porosity of the parts produced.
This thesis aims for the simulation of the temporal evolution of the temperature in the powder bed of various materials using COMSOL Multiphysics and the comparison to experimental results.