Defect Engineering for Lower Thresholds in Nd:YAG Microcavity

Reducing the laser threshold, as a crucial objective in the development of Whispering Gallery Mode (WGM) resonator lasers, often requires increasing the microcavity Q‐factor, which in turn complicates the fabrication process. Achieving a lower threshold without employing more complex fabrication techniques poses a notable challenge. In this work, a reduced threshold in a Nd:YAG microcavity laser through defect engineering is demonstrated. The defects within the Nd:YAG film are generated through 6 MeV carbon implantation, where the carbon ions penetrate the film and create defects along their tracks. These defects induce strain in the direction of ion implantation, resulting in enhanced and polarization‐dependent fluorescence of the Nd ions. The defect‐engineered Nd:YAG reduces the threshold of the microcavity laser to 1.15 µW. These results highlight the significant impact of defect engineering as an effective method to tailor the optical properties of crystalline films, opening up a new path for optimizing the performance of WGM lasers components based on crystalline films.