Mechanically programmable whispering gallery mode microlasers for information encryption.

Microlasers featuring multiple emission degrees of freedom offer a unique physical platform for information encryption. However, conventional microlasers provide limited access to intrinsic mechanical properties of microcavities, leaving this mechanical dimension largely untapped for information encryption. Here, we propose mechanically programmable whispering gallery mode (WGM) microlasers to address this limitation. The microlasers were fabricated by inkjet printing a dye-doped solution on a superhydrophobic surface. The mechanical properties of the liquid microcavities can be programmed by changing the glycerol concentration. Ultrasound was applied to stimulate the microlaser, and the resulting dynamic laser spectra were used to read out the mechanical properties encoded in the microcavity. We found that the mechanical properties of microlasers establish a physically secure dimension orthogonal to conventional optical methods. We further employed these mechanically programmable WGM microlasers for information encryption. We envision that hybrid optical-mechanical encryption can be achieved through integration with conventional optical methods.