A new laser material that is capable of emitting ultra-short, high-power pulses was engineered at University of California San Diego. The advance could potentially yield smaller, more powerful lasers with superior thermal shock resistance, broad tunability and high-duty cycles.

New materials processing strategies were devised to dissolve high concentrations of neodymium ions into alumina crystals. The resulting neodymium-alumina laser gain medium is the first in the field of laser Neodymium-alumina (left) shows no signs of cracking at 40 W applied voltage, while neodymium-YAG (right) cracks at 25 W. Source: Elias Penilla, University of California San Diegomaterials research. It has 24 times higher thermal shock resistance than one of the leading solid-state laser gain materials.

Neodymium and alumina are two of the most widely used components in state-of-the-art solid-state laser materials. Light-emitting neodymium ions are used to make high-power lasers while alumina crystals, a type of host material for light-emitting ions, can yield lasers with ultra-short pulses. These crystals also feature high thermal shock resistance, enabling them to withstand rapid changes in temperature and high heat loads.

Combining neodymium and alumina to make a lasing medium is challenging as they are incompatible in size. Alumina crystals typically host small ions like titanium or chromium. Neodymium ions are too big and are typically hosted inside a yttrium aluminum garnet (YAG) crystal.

The key to the materials merger was to rapidly heat a pressurized mixture of neodymium and alumina powders at a rate of 300 C per minute until it reaches 1,260 C, which is sufficiently hot to dissolve a high concentration of neodymium into the alumina lattice. The solid solution is held at that temperature for five minutes and then rapidly cooled, also at a rate of 300 C per minute.

To demonstrate lasing capability, the crystals were optically pumped with infrared light (806 nm). The material emitted amplified light (gain) at a lower frequency infrared light at 1064 nm. Construction of a laser with this new material is underway.

The research is published in the journal Light: Science & Applications.