Stuttgart University researchers develop a new high-power 3D printed micro optical device for compact lasers

Researchers from the Fourth Institute of Physics at the University of Stuttgart have demonstrated the feasibility of 3D printed polymer based micro optical devices in harsh laser environments.

This study was detailed in the Journal of Optics, outlining the use of 3D printing technology to directly manufacture microscale optical devices on fibers, seamlessly integrating fibers and laser crystals into a single laser oscillator. To maintain stability, the resulting hybrid laser produces a consistent output of over 20 mW at 1063.4 nm, reaching a peak of 37 mW. The uniqueness of this laser lies in its combination of the compactness, durability, and cost-effectiveness of fiber lasers, as well as the multifunctional characteristics of crystal based solid-state lasers, including various powers and colors. This research represents significant progress in creating affordable, compact and reliable lasers, especially for the lidar system in autonomous vehicle.

"By using 3D printing to manufacture high-quality micro optical devices directly on glass fibers used inside the laser, we have significantly reduced the size of the laser," said Simon Angstenberger, head of the research team at the Fourth Institute of Physics at the University of Stuttgart. This is the first implementation of this 3D printed optical device in real-world lasers, highlighting their high damage threshold and stability.

The Fourth Institute of Physics at the University of Stuttgart has been actively involved in promoting the development of 3D printing micro optical technology, especially in direct printing onto optical fibers. Using the two-photon aggregation 3D printing method, researchers have achieved the creation of high-precision miniaturized optical devices and introduced new features such as free-form surface optical devices and complex lens systems.

In this study, a Nanoscribe 3D printer was used to manufacture a lens with a diameter of 0.25 millimeters and a height of 80 micrometers directly on a size matched fiber through two-photon polymerization. This process involves designing optical components using commercial software, inserting optical fibers into a 3D printer, and performing complex structure printing at the end of the fiber. The accuracy of aligning printing with fibers and ensuring the accuracy of the printing process are key aspects of this meticulous process.

After printing, the researchers assembled the laser and its cavity, choosing fibers instead of traditional mirrors. This method produces a hybrid fiber crystal laser, where the printed lens focuses and collects light entering and exiting the laser crystal. Then fix the fiber optic cable on the bracket to enhance system stability and reduce sensitivity to air turbulence, thus forming a compact 5 x 5 cm2 laser system.

Within a few hours, continuous monitoring of laser power was conducted to confirm that the printed optical components did not deteriorate or have any adverse effects on the long-term performance of the laser. The scanning electron microscope images of the optical components used in the laser cavity show no visible damage. Researchers are currently focused on optimizing the efficiency of printed optical devices, exploring larger fibers and different lens designs to improve output power and customized options for specific applications.

"So far, 3D printed optical devices have been mainly used for low-power applications such as endoscopy," Angstenberger said. For example, the ability to use them for high-power applications may be useful for lithography and laser marking. We demonstrate that these 3D micro optical devices printed on fibers can be used to focus a large amount of light onto a single point, which is very useful for medical applications.

During an interview with the 3D printing industry, Philipp Kohlwes, head of L-PBF at Fraunhofer IAPT, shared the institute's research on beam shaping to improve the stability and productivity of metal 3D printing. The focus of this study is to adjust the laser profile to optimize the energy input of the molten pool in the laser powder bed melting, and to solve the problems caused by traditional Gaussian profiles. Beam shaping is crucial for laser contour adjustment, ensuring a uniform temperature distribution. This technology has advantages such as enhanced microstructure control, potential cost savings, and up to 2.5 times printing speed, which can help improve productivity.

Last January, 3DM Digital Manufacturing launched a technology that allows users to customize their selective laser sintering 3D printing lasers for specific materials or applications. Using quantum cascade lasers, the company's proprietary lasers can provide adjustable wavelengths, faster laser absorption, and high surface finish. With its application in polymer manufacturing, this scalable technology aims to expand the market share of industrial 3D printing.

Source: Laser Net