Printable microlaser arrays with programmable modes for information encryption

Lasing emissions with multiple and tunable modes are promising in coding field as a novel cryptographic primitive. With the advantages of simple fabrication, full-color and high-quality-factor whispering gallery mode lasing inside a circular cross-section, polymer microfibers are attractive for photonic devices. However, polymer lasing microfibers for information encryption have never been reported. Herein, we propose a design of printable lasing microfiber encryption chip by in-situ tuning the effective refractive index of the microresonator arrays via a facile approach. Through inkjet printing high-refractive-index nanoparticles on the designated position of lasing microfiber arrays, the effective refractive index of the microcavities is regulated, and the ratio of wavenumber spacing between transverse electric and transverse magnetic mode to the free spectral range can be modulated, particularly with neglectable influence by the size factor. Thus, the programmable region selective encoding process can be conducted simply by a printing program within several minutes. Besides, the encoded microfiber arrays are encapsulated into polydimethylsiloxane to reduce the scattering loss and environmental interference, and a printable encryption chip is realized. This work is expected to provide a platform for the printable encrypted devices.