Fracture Mechanics and Self-Healing in Molecular Crystal Resonators for Lasing

Microscale damage poses a significant challenge to the reliability and longevity of miniaturized photonic devices; however, the mechanisms and repair of microscopic cracks and fractures in organic optical crystals remain largely unexplored. Here, we employ a mechanophotonic approach to induce microscale cracks and complete fractures in single crystals of 3-[4-(dimethylamino)phenyl]-1-(2-hydroxyphenyl)prop-2-en-1-one (HDMAC) using an atomic force microscopy (AFM) cantilever tip. We demonstrate the self-healing capability of these crystals while retaining their optical waveguiding and resonator properties, which are essential for lasing applications. HDMAC microcrystals exhibit self-healing of cracks introduced along the (010) and (001) crystallographic planes, demonstrating the versatility of this phenomenon across distinct crystal orientations. Furthermore, we identify different fracture mechanisms and establish a comprehensive assessment of healing efficiency by integrating optical loss measurements, resonator characteristics, and nanomechanical analyses. This multifaceted approach enables fair evaluation of the recovery of structural integrity and photonic functionality following self-healing.