Disk lasers combine high efficiency, excellent beam quality, high average and/or peak power with moderate cost and
high reliability at multiple wavelengths, ranging from the infrared over the green to the ultraviolet.
The demonstrated infrared average powers range from tens of kW in CW operation over >1 kW in ns pulses to >100 W
in ps pulses and > 70 W in fs pulses.
Wavelength conversion for nearly all modes of operation, e.g. 700 W@515nm in ns pulses, enlarges the fields of
applications, making the disk technology today's most versatile laser platform.
This paper demonstrates that disk-laser technology introduces advantages that increase efficiency and
allows for high productivity in micro-processing in both the nanosecond (ns) and picosecond (ps) regimes.
Some technical advantages of disk technology include not requiring good pump beam quality or special
wavelengths for pumping of the disk, high optical efficiencies, no thermal lensing effects and a possible
scaling of output power without an increase of pump beam quality. With cavity-dumping, the pulse
duration of the disk laser can be specified between 30 and hundreds of nanoseconds, but is independent of
frequency, thus maintaining process stability. TRUMPF uses this technology in the 750 watts average
power laser TruMicro 7050. High intensity, along with fluency, is important for high ablation rates in thinfilm
removal. Thus, these ns lasers show high removal rates, above 60 cm2/s, in thin-film solar cell
production. In addition, recent results in paint-stripping of aerospace material prove the green credentials
and high processing rates inherent with this technology as it can potentially replace toxic chemical
processes. The ps disk technology meanwhile is used in, for example, scribing of solar cells, wafer dicing
and drilling injector nozzles, as the pulse duration is short enough to minimize heat input in the laser-matter
interaction. In the TruMicro Series 5000, the multi-pass regenerative amplifier stage combines high
optical-optical efficiencies together with excellent output beam quality for pulse durations of only 6 ps and
high pulse energies of up to 0.25 mJ.
TRUMPF presents the flexibility of the thin disk laser technology in this paper. Used on CW lasers, short pulsed laser
based on cavity-dumping including intracavity frequency conversion and ultrafast MOPA systems, lasers based on disk
technology are important tools for a variety of industries. By employing a cavity-dumped thin disk laser, a wide range
of pulse durations and up to 750 watts is available. In addition, TRUMPF's TruMicro 7250 combines this technology
with intracavity frequency conversion. The compact generation of the TruMicro Series 5000 offers six picosecond pulse
duration and 50 W average power.
TRUMPF Laser has developed an advanced solid-state q-switched laser, designed specifically to meet the requirements
of industrial micro-processing. Pulse energies exceeding 4 mJ, pulse durations adapted to the application and a
diffraction limited beam (M2 < 1.2) are essential for micro-machining. A novel feature of the laser ensures its particularly
high performance and overall stability. The technical concept is based on a power oscillator, where the output power is
not set by adjusting the pump power, but rather by precise switching and attenuation of the pulses outside of the
resonator. This leads to a high stability and a fixed concentric beam profile, independent of the actual output power of
the system. In the field of micro-processing, laser light is primarily used for the precise ablation of various materials.
High intensities beyond 1011 W/cm2 enable the development of new laser processing strategies, e.g. sublimation-cutting
and -drilling. High stability in terms of beam quality, beam location (pointing stability < 10 &mgr;rad) and pulse energy
allows for both the improvement of well known laser processes as well as pushing forward new applications.
Additionally, the repetition rate of up to several hundred kilohertz and the high average power emphasizes the high
performance of the developed system, particularly with regard to the competition with alternative manufacturing
Further potential to increase the precision and to minimize the heat affected zone (HAZ) is given by the application of
ultrashort picosecond and femtosecond pulses. TRUMPF Laser has already demonstrated a CPA-free, diode-pumped all-solid-state laser, delivering picosecond pulses with an average power of 50 W.