Regenerative amplifier for generating laser pulses with individually adjustable pulse duration or wavelength
Abstract
By using suitable components, it is now possible to selectively switch the interaction of the laser pulses with the resonator elements on and off for each cycle of the pulses. Properties such as duration, power or wavelength of the laser pulse can now be selected for each individual pulse in discrete, fine steps.
Background
Regenerative laser amplifiers are used in industrial laser material processing for numerous different manufacturing processes such as welding, cutting, soldering, ablating, drilling and surface treatment.
Problem
Regenerative laser amplifiers are used to amplify the short laser pulses of low-power seed lasers. The seed pulses are amplified by coupling the seed light into a resonator where it passes through an amplifier medium. It is then coupled from the resonator in the form of an amplified laser pulse. The laser pulses are decoupled with a Pockels cell, for example. The characteristics of the pulses are essentially the same for all pulses.
Solution
Scientists at the Institut für Strahlwerkzeuge at the University of Stuttgart developed a concept of a regenerative laser amplifier where one or more dispersive elements or frequency conversion elements are integrated into the amplifier’s resonator. It is possible to activate or deactivate the interaction of the laser pulses with the optical elements for each resonator round trip of the pulses. This allows each individual pulse to be finely tuned in discrete steps. The Pockels cell already present for coupling the seed pulses into and from the resonator can be used as switching element. The decisive factor is the control of the Pockels cell’s switching times. Changing the laser frequency or the pulse duration and thus also the power of the pulses opens up new fields of application for regenerative lasers.
![Schematic drawing of an exemplary design of a regenerative amplifier resonator with additional polarization-dependent resonator component [source: University of Stuttgart].](/fileadmin/user_upload/img/Technologieangebote/10_061_Schema_Verst%C3%A4rkerresonator_en.png "Schematic drawing of an exemplary design of a regenerative amplifier resonator with additional polarization-dependent resonator component [University of Stuttgart].")
Schematic drawing of an exemplary design of a regenerative amplifier resonator with additional polarization-dependent resonator component [University of Stuttgart].
Advantages
- Variable pulse duration in the fs to ns range for each pulse individually adjustable with constant pulse energy
- Variable setting of the laser frequency individually adjustable for each pulse
- No mechanical components
Application
With the regenerative laser amplifier, properties such as pulse duration, power or wavelength of the laser pulse can now be set individually and even for each individual laser pulse.