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 — Single stack element of a 3.5 kW laser stack

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

Stack elements before assembly into a pump module stack

High-power laser stack with lenses, providing 3.5 kW of optical output power

High-power micromodule integrating six diode lasers by wavelength multiplexing.

SAMBA: 780 nm direct diode laser module for additive manufacturing

Laser diode stacks consist of vertically arranged laser bars 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 spectrally-combined laser systems for direct material processing. Other applications include free-space communication, printing and medical technology.

Wavelength

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

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 and large-aperture single emitters on passive CuW heat sinks
Stacking of CuW heat sinks 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

QCW operation t_P= 1 ms f = 10...200 Hz
Tailored single emitters with 1.2 mm aperture
- reliable output power > 120 W
- power density ~ 1 kW/cm
- lateral far field 12° (95% power)
- efficiency > 60%
Stack of 28 bars and FACs
- output power 3.5 kW with efficiency > 60%
- simple and efficient coupling into fibers possible
  - vertical divergence (> 95% power level) < 2 mrad
  - vertical beam parameter product < 90 mm·mrad
  - lateral divergence (> 95% power level) < 210 mrad
  - lateral beam parameter product < 90 mm·mrad

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.

In the BriSCL project, diode lasers at wavelengths around 915 nm with higher brilliance are being developed for industrial use.

The focus in this project lies on components that enable high output yield and high power at the same time, as well as on novel techniques of steel merging, optical resonators and leading technologies for stronger laser diode modules. Thereby, FBH's BRIS (buried regrown implant structure) semiconductor technology is also used.
Click here to visit the project website.

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.

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