Structured doping in laser ceramics

A great advantage of transparent ceramics is the flexibility of the ceramic shaping processes. While the single crystals production technology provides high-quality optical components, its limitation lies in the difficulty to prepare components with complex inner structure, i.e. composed of parts with different dopants, with different dopant concentrations, or with concentration gradients. Such components are particularly advantageous in the area of laser gain media, where controlled dopant distribution enhances thermal management and reduces undesired thermal and thermomechanical effects like thermal lensing, or in planar waveguides. The present work shows the production of structured Yb-doped transparent ceramics and their laser performance, and provides a comparison of different shaping processes: pressing and tape casting followed by vacuum sintering. Optical quality and uniformity are compared using transmission maps. Laser emission has been tested in an end pumped cavity, using various fiber coupled diode lasers as pumping sources. The beneficial effect of structured dopant distribution in laser gain media is clearly demonstrated on the case of increasing thermal load.