Abstract: CdS quantum dots have a quantum size effect, and the photoluminescence wavelength can be regulated by manipulating their sizes, of which show application potentials in many fields such as the fabrication of micro-nano optical devices. With the development of ultrafast laser technology, femtosecond lasers have gradually been delved in the micro-nano manufacturing and optical property regulation of the optoelectronic materials. However, the photoluminescence modulation of CdS quantum dot enabled by the femtosecond lasers has not been achieved. This work aims at the preparation and photoluminescence modulation of CdS quantum dots based on the glass matrix by using femtosecond laser direct writing, and also exploring their applications in fields such as optical storage and information encryption. In the experiment, five groups of borosilicate glasses with different CdS contents were prepared via a melt quenching method, and the glass samples were finely polished for the subsequent femtosecond laser processing. Due to the local thermal accumulation effect generated by the femtosecond laser, CdS quantum dots can be directly written and precipitate inside the glass. The morphology, microstructure size and dispersion of CdS quantum dots precipitated inside the glass are analyzed by the transmission electron microscopy. By changing the laser parameters to regulate the size of the precipitated quantum dot spot, continuous regulation of the spot size of laser-induced processing within the range of 5.33-12.33 μm and modulation of the emission wavelength within the range of 540-610 nm were achieved. Finally, the application of femtosecond laser direct writing of CdS quantum dots in fields such as information encryption and storage was also demonstrated.

Key words: CdS quantum dots, femtosecond laser, borosilicate glass, laser induction