Laser Modules with High Power & Efficiency

We develop and assemble the appropriate light sources for applications that require high output powers with simultaneously high efficiency. For example, for use as pump lasers in space applications, we focus the laser beam by means of lenses in order to couple it into an optical fiber. Diode lasers (single emitters or laser bars), which are used in materials processing among other applications, are stacked to achieve output powers in the kilowatt range. In miniaturized micromodules, we combine the emission of several semiconductor lasers by means of wavelength multiplexing and/or polarization coupling.

Stack element with a paper clip for size comparison

Stack element with a lens and a paper clip for size comparison

Diode laser stacks

Laser diode stacks consist of vertically arranged laser bars, arrays or single emitters. The total optical power thus scales up with the number of emitters to the kilowatt range. Stacks can be used as pump sources for solid-state, fiber and alkali-gas lasers, for example in material processing applications or in high-energy solid-state laser systems. They are also suitable as beam sources for direct material processing. Other applications include free-space communication, printing and medical technology.

Wavelengths

650 to 1060 nm, e.g. 940 nm for pumping of Yb:YAG thin-disk amplifiers or 780 nm for aluminum processing

Chip technology

Semiconductor layers by means of MOVPE
Monolithic gratings via surface etch technology or two step-epitaxial techniques
Contact windows by
- projection lithography
- implantation and isolating layers
- deposition of metalization
Thinning
Scribing, breaking and cleaving
Facet coating and passivation with extremely long lifetimes

Assembly

Soldering of bars, arrays and large-aperture single emitters between passive CuW or CuDiamond heat sinks (stack elements)
Stacking of stack elements and fixing using AuSn solder suitable for extremely long lifetimes
Attaching of FAC (fast-axis collimator) lenses on the stack
Coupling into fiber

Typical data

CW or QCW operation t_P = 0.5…10 ms, f = 10...1000 Hz
Tailored emitter geometry, e.g. single emitters with 1.2 mm aperture or double emitters with 2x 200 µm aperture
- reliable output power / aperture size up to 1 kW/cm
- power density ~ 1 kW/cm
- efficiency up to > 60%
Stack of 28 layers, 1.2 mm aperture, λ = 9xx nm
- QCW output power 3.5 kW with efficiency > 60%
- simple and efficient coupling into fibers possible
  - vertical / lateral beam parameter product < 90 mm·mrad
- Stack of 24 layers, 0.8 mm aperture, λ = 780 nm
  - CW output power 600 W with efficiency ~ 50%
  - Direct material processing simple and efficient coupling into fibers possible
  - Vertical / lateral beam parameter product < 50 mm·mrad

High-power micromodules

In our compact high-power micromodules, we combine the emission of several semiconductor lasers by means of wavelength multiplexing and/or polarization coupling. This allows high optical output powers to be realized with excellent beam quality. These modules can be used as pump sources for solid-state lasers as well as for direct material processing.

In addition to the optical concept, the thermal design is decisive. The hybrid integration of active and passive elements is realized by means of precision assembly on individually adapted inlays. In addition, electronics for pulsed operation and fiber coupling (single-mode fibers, 20-µm low-mode-number fibers, or multi-mode fibers) can be integrated.

With a compact design, the micromodules deliver:

High optical output power of up to 35 W (free-space beam)
Excellent beam quality (M² < 3)

ProFIT Project SAMBA

Here you will find information on the SAMBA project, in which we are developing an innovative, direct beam source for Additive Manufacturing together with our project partners.

ProFIT Project HOTSTACK

As part of the HOTSTACK project, we are involved in the development of high-power diode laser stacks with a high duty cycle. These are key components for pulsed laser technology.