We are developing an innovative approach for fabricating laser gain media, such as laser rods, based on utilizing the direct ink write (DIW) additive manufacturing methodology, together with ceramics processing. For DIW, the key is to formulate the ink so that has three main properties: (1) experiences shear-thinning so that it can pass through a nozzle of 250-500 mm; (2) encounters considerable “gelation” after exiting the nozzle so that the structure remains relatively firm; and (3) must include ~50% loading of the gain medium by volume, e.g. YAG. In Fig. 1, we see the DIW instrument, an example of a laser rod written with both doped and undoped regions, and the rheology curve for a typical ink. After writing the part, the next steps include heating near 1000C to remove the solvents, cold isostatic pressing to a green body, sintering (usually near 1700⁰C) to about 95% density, and finally heating under pressure (HIP’ing) to generate a clear part. The main advantage of this optical design for a laser rod is that it will strongly induce the TEM₀₀ mode of the laser and thereby increase the beam quality. In this talk we will discuss both the laser physics and the materials issues associated with the new pathways for fabricating laser elements.

This work was performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.