High Power Ceramic Disk Lasers with Gradient Doping made by Direct Ink Writing

The power output of the high power lasers used in physics research is limited by the materials available for making gain media. Future increases in power require new and better materials. Operation at high power creates great thermal stresses that can lead to birefringence, thermal lensing or physical damage to the host. Effective cooling and small temperature gradients are critical for achieving higher powers. Disk lasers can mitigate these issues. The innovation in this proposed effort is to produce ceramic YAG disks with a radial gradient of absorption profile. This will improve the beam quality by “matching” the laser and pump profiles; optimize the efficiency by minimizing the pumped area that is not extracted, and minimize the ASE losses (amplified spontaneous emission) by limiting the (unextracted) lateral gain (i.e. perpendicular to the lasing axis). The graded disk will be fabricated by controlling the areal doping concentration radially within the disk. In Phase II, two methods will be examined and compared, one using additive manufacturing and one using a composite ceramic structure with an innovative doping structure formed during ceramic processing. Graded absorption will make possible the construction of a higher power, side-pumped, back-cooled solid state disk laser for accelerator applications. In Phase II, RMD, in collaboration with Lawrence Livermore National Laboratory, will develop ceramic components with a graded dopant concentration profile to replace the present crystalline, or even ceramic materials, now used in high power lasers. The issues addressed will include optimizing ceramic composition and dopant profile. By the end of Phase II we expect to have optimized ceramics disks containing a radial gradient dopant profile and constructed and tested a small scale prototype laser to demonstrate the approach. Lasers are used in every aspect of life. High power lasers are used for research, including accelerator facilities, laser ranging, and environmental sciences. Defense agencies use high power lasers for missile guiding and ranging and are developing high power laser weapons. Industrial applications include cutting and welding. In healthcare, high power lasers are used in areas like eye surgery and cosmetic surgery. Laser seeded coherent X-ray sources can be used for very high resolution imaging of fundamental events in biology and physics. The ability to produce higher power will enhance research, improve security, and increase the productivity of manufacturing processes that use high power lasers.