Gerhard Spindler

Thin-disk laser - Power scaling to the kW regime in fundamental mode operation

A significant reduction of the influence of the thermal lens in thin-disk lasers in high power laser operation mode could be achieved, using dynamically stable resonators. For designing the resonator, investigations of thermally induced phase distortions of thin-disks as well as numerical simulations of the field distribution in the resonator were performed. This characterization was combined with thermo-mechanical computations. On the basis of these studies, about 500 W output power with an averaged M2 = 1.55 could be demonstrated, using one disk. Almost 1 kW output power with good beam quality could be extracted, using two disks. For the purpose of further power scaling in nearly fundamental mode operation, experiments using more than two disks are in preparation.

L-band microwave pumped XeCl laser without preionization

A peak power of 300 W of a microwave pumped XeCl laser has been obtained without preionization techniques. So far the system operates at a repetition frequency of 10 Hz. The pulse width was determined to be 65 ns.

Thin-Disk Lasers with Dynamically Stable Resonators

A significant reduction of the influence of the thermal lens for high power laser operation could be achieved in a thin-disk laser by systematic characterization of the thin-disk laser medium and the utilization of a dynamically stable resonator. Furthermore, the power scalability of the thin-disk laser concept could be demonstrated with two disks in one resonator and with large pump spot radii, realizing an output power of approximately 1 kW with nearly diffraction limited beam quality.

Simulations of wavefront correction of distorted laser beams

The transverse beam profile of solid-state lasers is a key issue for determining its propagation properties. Herein, we address laser beam distortions caused by thermal lensing and birefringence. For the simulations a finite difference method is used for the description of beam propagation problems. The method is an improved approach to the solution of the wave equation in paraxial approximation. Provided that steady-state conditions prevail, in comparison with the Fresnel-Kirchhoff integral description this method allows for a fully 3 D treatment of the aforementioned laser-optical phenomena.

Power scaling of high power thin-disk lasers with high beam quality

Since the invention of the thin-disk laser 16 years ago [1], high output power and high optical efficiency made this type of solid-state lasers a common tool for industrial applications like cutting and welding. Nowadays, thin-disk lasers for material processing with an output power up to 16 kW are commercially available. The highest published output power of an Yb:YAG single-disk laser is 5.3 kW in multi-mode operation [2].