Innovative High-Power 3D Printed Micro-Optics for Compact Lasers Developed by University of Stuttgart Researchers

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Researchers at the 4th Physics Institute at the University of Stuttgart have demonstrated the viability of 3D printed polymer-based micro-optics in a demanding laser environment.

Detailed in the Optics Journal, the study outlines the use of 3D printing technology to directly manufacture microscale optics onto optical fibers, seamlessly integrating fibers and laser crystals into a single laser oscillator. Maintaining stability, the resulting hybrid laser produces a consistent output exceeding 20 mW at 1063.4 nm, reaching a peak of 37 mW. What sets this laser apart is its combination of the compactness, durability, and cost-effectiveness of fiber-based lasers along with the versatile properties of crystal-based solid-state lasers, including various powers and colors. This research represents a significant advancement towards creating affordable, small, and reliable lasers, particularly beneficial for lidar systems in autonomous vehicles.

“We significantly reduced the size of a laser by using 3D printing to fabricate high-quality micro-optics directly on glass fibers used inside of lasers,” said research team leader Simon Angstenberger, 4th Physics Institute at the University of Stuttgart. “This is the first implementation of such 3D printed optics in a real-world laser, highlighting their high damage threshold and stability.”

Researchers printed microscale lenses directly onto optical fibers, allowing them to compactly combine fibers and laser crystals inside a single laser oscillator. The credit for this photographs goes to Moritz Floess and Simon Angstenberger, 4th Physics Institute at the University of Stuttgart in Germany.

From bulky lasers to compact powerhouses with 3D printed optics

The 4th Physics Institute at the University of Stuttgart has made significant strides in the advancement of 3D printed micro-optics, particularly printing directly onto fibers. By employing the two-photon polymerization 3D printing method, they have achieved high-precision miniaturized optics that feature innovative functionalities such as free-form optics and intricate lens systems.

In their research, a Nanoscribe 3D printer was utilized to forge lenses that were 0.25 mm in diameter and 80 microns in height directly onto a fiber of corresponding dimensions via two-photon polymerization. This intricate process encompasses the creation of an optical element using mainstream software, loading the fiber into the 3D printer, and executing the printing of the complex structure onto the fiber’s end. Accuracy in aligning the printing with the fiber and securing precision in the printing process were crucial to this intricate operation.

Upon completion of printing, the researchers designed the laser and its cavity, choosing fibers over traditional mirrors. This strategy led to the creation of a hybrid fiber-crystal laser, where the printed lenses were employed to hone and collect light into and out of the laser crystal. To increase system stability and decrease vulnerability to air turbulence, the fibers were secured in a mount, resulting in a compact 5 x 5 cm2 laser system.

Over several hours, the laser power underwent continuous monitoring, confirming that the printed optics exhibited no deterioration and did not adversely affect the long-term properties of the laser. Scanning electron microscopy images of the optics post-use in the laser cavity revealed no visible damage. The researchers are currently focusing on optimizing the efficiency of the printed optics, exploring larger fibers and different lens designs to enhance output power and customization options for specific applications.

“Until now, 3D printed optics have primarily been used for low-power applications such as endoscopy,” said Angstenberger. “The ability to use them with high-power applications could be useful for lithography and laser marking, for example. We showed that these 3D micro-optics printed onto fibers can be used to focus large amounts of light down to a single point, which could be useful for medical applications such as precisely destroying cancerous tissue.”

Advancements in laser technology

In an interview with 3D Printing Industry, Head of L-PBF at Fraunhofer IAPT, Philipp Kohlwes, shared insights into the institute’s beam shaping research for enhancing stability and productivity in metal 3D printing. The research focused on adapting laser profiles to optimize meltpool energy input in laser powder bed fusion (LPBF), addressing issues caused by traditional Gaussian profiles. Essential for laser profile adjustment, beam shaping ensures a uniform temperature distribution. The technology yields advantages like enhanced microstructure control, potential cost savings, and up to 2.5 times faster printing, contributing to increased productivity.

Last year in January, 3DM Digital Manufacturing unveiled a technology enabling users to customize their Selective Laser Sintering (SLS) 3D printing laser for specific materials or applications. Using Quantum Cascade Lasers, the company’s proprietary laser offers adjustable wavelengths, faster laser absorption, and high surface finish. With applications in polymer manufacturing, the scalable technology aims to expand industrial 3D printing’s market share.

Read all the 3D Printing Industry coverage from Formnext 2023.

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