Optothermally induced mechanical oscillation in a silk fibroin coated high- Q microsphere

Protein-based optical devices with biocompatibility and biodegradability have distinct advantages for applications in biomedical sensing. Silk fibroin with unique optical, thermal, and mechanical properties renders great flexibility in designing functional photonic platforms. Here, we report the experimental observation of optothermally induced mechanical oscillation in a silk-fibroin coated microcavity. Theoretical analysis reveals that the observed oscillation results from the interplay of several nonlinear effects in the silk-coated-microsphere as well as the coexistence of fast and slow thermal dynamic processes. The physics in our study breaks ground for the study of nonlinear dynamics of structural protein optical material that can be used for functional optical devices.