A new series of high power diode laser line sources is reported. The modules are designed for the industrial materials
processing market and include both fiber coupled and direct beam configurations. Typical applications include welding,
hardening and semiconductor processing. The biggest challenge in delivering line sources lies in the variety of
application specific requirements. This problem is approached with modular concepts that allow for power scaling and
custom beam shaping. All modules are available either as an OEM laser head or as a turn-key solution including power
supply and chiller.
Fiber coupled diode laser modules are available at power levels ranging from 600W to 4kW at various wavelengths.
New developments include a 1kW module with a single wavelength and 400um / 0.22NA fiber and a 2kW module based
on two wavelengths. Dilas offers up to 5kW from a 1mm / 0.22NA fiber with a single wavelength. At 200 μm fiber
diameter, power levels of 850W are available with a single wavelength.
While fiber coupled modules allow for easy power scaling, free space systems are capable of even higher overall electrooptical
efficiencies and lower cost. Based on modular building blocks, Dilas provides customized solutions that are
optimized for individual applications. Two modules will be described in detail. The first module is a 600W line source
with line dimensions of 10.5mm x 350 μm at a working distance of 160mm. The second module operates at 3kW output
power and creates a homogenized line with dimensions of 9mm x 1.3mm at a working distance of 200mm.
Optical design trade-offs will be discussed and concepts for the modules described above are shown. Experimental
results are presented.
The Beam Parameter Product (BPP) of a passive, lossless system is a constant and cannot be improved upon but the
beams may be reshaped for enhanced coupling performance. The function of the optical designer of fiber coupled diode
lasers is to preserve the brightness of the diode sources while maximizing the coupling efficiency. In coupling diode
laser power into fiber output, the symmetrical geometry of the fiber core makes it highly desirable to have symmetrical
BPPs at the fiber input surface, but this is not always practical. It is therefore desirable to be able to know the 'diagonal'
(fiber) BPP, using the BPPs of the fast and slow axes, before detailed design and simulation processes. A commonly
used expression for this purpose, i.e. the square root of the sum of the squares of the BPPs in the fast and slow axes, has
been found to consistently under-predict the fiber BPP (i.e. better beam quality is predicted than is actually achievable in
practice). In this paper, using a simplified model, we provide the proof of the proper calculation of the diagonal (i.e. the
fiber) BPP using BPPs of the fast and slow axes as input. Using the same simplified model, we also offer the proof that
the fiber BPP can be shown to have a minimum (optimal) value for given diode BPPs and this optimized condition can
be obtained before any detailed design and simulation are carried out. Measured and simulated data confirms satisfactory
correlation between the BPPs of the diode and the predicted fiber BPP.
Tobias Koenning, Kim Alegria, Zuolan Wang, Armin Segref, Dean Stapleton, Wilhelm Faßbender, Marco Flament, Karsten Rotter, Axel Noeske, Jens Biesenbach
We report on a new series of fiber coupled diode laser modules exceeding 1.2kW of single wavelength optical power
from a 400um / 0.2NA fiber. The units are constructed from passively cooled laser bars as opposed to other comparably
powered, commercially available modules that use micro-channel heat-sinks. Micro-channel heat sinks require cooling
water to meet demanding specifications and are therefore prone to failures due to contamination and increase the overall
cost to operate and maintain the laser. Dilas' new series of high power fiber coupled diode lasers are designed to
eliminate micro channel coolers and their associated failure mechanisms.
Low-smile soldering processes were developed to maximize the brightness available from each diode laser bar. The
diode laser brightness is optimally conserved using Dilas' recently developed propriety laser bar stacking geometry and
optics. A total of 24 bars are coupled into a single fiber core using a polarization multiplexing scheme. The modular
design permits further power scaling through wavelength multiplexing. Other customer critical features such as
industrial grade fibers, pilot beams, fiber interlocks and power monitoring are standard features on these modules.
The optical design and the beam parameter calculations will be presented to explain the inherit design trade offs. Results
for single and dual wavelengths modules will be presented.
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