Femtosecond Laser Modulation on Luminescence Properties of CdS Quantum Dot Glasses

CdS quantum dots have a quantum size effect, while photoluminescence wavelength can be regulated by manipulating their sizes, both of which show application potentials in many fields such as 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, photoluminescence modulation of CdS quantum dots by the femtosecond lasers has never been achieved. This work aims at preparation and photoluminescence modulation of CdS quantum dots based on glass matrix by using femtosecond laser direct writing, and explores 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. Morphology, microstructure size and dispersion of CdS quantum dots precipitated inside the glass were analyzed by transmission electron microscopy. By changing the laser parameters to regulate size of the precipitated quantum dot spot, continuous regulation of the spot size of laser-induced processing within the range of 5.33-12.28 μm and modulation of the emission wavelength within the range of 540-610 nm were achieved. Finally, it was demonstrated that femtosecond lasers could direct write on the CdS quantum dots in fields such as information encryption and storage.