Gestalt Optics: Three-Dimensional Transparent Ceramics
Zachary Seeley | 19-ERD-006
Additive manufacturing (AM) of optical elements, where the part is built-up layer by layer until complete, has begun to have a significant impact in the scientific community. This LDRD expands beyond Lawrence Livermore National Laboratory's previous use of AM techniques into printing of specific functionalities into laser gain media, which would not otherwise be available by conventional means of fabrication. The main focus of the effort was the use of material jet printing of both colloidal and solution-based inks to print fine-featured optical waveguides with tailored laser gain profiles in polycrystalline yttrium aluminum garnet (YAG) optics.
While nearly impossible to fabricate such optical components via traditional methods, jet printing was successful in creating planar waveguides as thin as 25 microns that supported single mode laser propagation. Additionally, multiple layers of different ink compositions were printed to independently control the index and laser gain across the width of the waveguide. A "mode-stable" laser output was successfully demonstrated in a planar waveguide fabricated by depositing the active laser gain ion (ytterbium or Yb3+) only in the central portion of the waveguide and compensating the refractive index increase with a non-laser-active ion (lutetium) near the edges of the waveguide. And finally, the ability to stack multiple gain/no-gain structures into a ribbon structure was demonstrated with the potential to increase the waveguide size without losing mode stability, which could ultimately lead to increased power output for a given laser gain element volume. While planar waveguides are a step toward compact, lightweight laser gain elements, ribbon waveguides can further improve the power/volume by a factor directly correlated with the effective fill-factor of the planar structure.
The ability to print such fine tailored structures into a laser gain element is now a new capability developed at Livermore that has opened the potential for new laser designs that have never before been considered. Additive manufacturing allows rapid fabrication of intricate structures that can be multiplied by layering one on top of another in a small volume, potentially allowing scaling to higher laser powers. Development of new high-power lasers is a disruptive technology for lightweight laser applications. Additionally, the ability to print small channel waveguides of dimensions less than 100 microns in YAG provides an opportunity for printing integrated optics in a YAG-based substrate, potentially of interest as a new route to fabrication of photonic integrated circuits, currently a topic of active interest at the Defense Advanced Research Projects Agency. Furthermore, this work contributes to the science and technology required for novel approaches to support NNSA missions.
Publications, Presentations, and Patents
Seeley, Z. et al. 2019. "Additive manufacturing of transparent ceramics." American Ceramic Society global forum on advanced materials and technologies for sustainable development, Toronto Canada, 21-26 July 2019. LLNL-PRES-782323.
Seeley, Z. et al. 2019. "Additive manufacturing of transparent ceramics." MS&T19 conference, Portland OR, 29 Sept - 3 Oct 2019. LLNL-PRES-791018.
Seeley, Z. et at. 2020. "Additive manufacturing of transparent ceramics laser gain media - rods, thin disks, and planar waveguides." Optical Society of America - Advanced solid-state laser conference, October 2020.
Rudzik, T. et al. 2020. "Single and Multi-dopant diffusion in YAG ceramics for lasers." MS&T conference, virtual, 2-6 November 2020. LLNL-POST-816031.
Seeley, Z. et al. 2021. "Material jet printing of transparent ceramic Yb:YAG planar waveguides," Optics Lett. 46(10):2433-2436. Doi:10.1364/OL.420504. LLNL-JRNL-818899.
Seeley, Z. et al. 2021. "3D printed ceramics laser gain media." SPIE Defense and Commercial Sensing conference, virtual, April 2021, LLNL-PRES-820868.