Ultrashort-pulse fiber laser systems, which offer, due to their high peak
pulse intensity in combination with high pulse frequencies (repetition rate), an
innovative technology of nonlinear interaction with materials, help to fabricate
components with unprecedented quality, precision and speed. Also due to the
short pulse duration, laser energy can be introduced into the material in a shorter
time than heat transfer occurs, which thus prevents thermal damage to the part. It
is not surprising that industrial laser systems with a sub-nanosecond pulse length
are widely used in the markets of precision processing, medical devices and in
many other applications. The most critical component of such systems is the seed
laser source. To date, the existing devices in the commercial market do not fully
satisfy the industrial requirements.
In this thesis I describe a new concept for the generation of ultrashort laser
pulses using an all-passive, fiber-ring, mode-locked laser with at least two passive
spectral filters incorporated. Also presented is a full theoretical model of the
operation of the laser. I report on the development and the comprehensive
characterization of a fully optimized laser configuration, finding excellent
agreement of the theoretical model and the experimental results. Various practical
configurations and their application were demonstrated. During the period of the
project, a fully commercially developed laser scheme was implemented in a variety
of IPG Photonics picosecond and femtosecond laser systems.