Polarization-oriented LiNbO₃ nanocrystals by femtosecond laser irradiation in LiO₂–Nb₂O₅–SiO₂–B₂O₃ glasses

Abstract

This work investigates the role of a B 2 O 3 addition (up to 21 mole %) into a lithium niobium silicate glass matrix, focusing on the orientational dependency of second harmonic generation (SHG), induced after femtosecond laser irradiation. We detected the sharp emission of light at 515 nm, characteristic of SHG, in both static and scanning configurations, using pulse energy, repetition rate, and laser polarization as varying parameters. Among the results to highlight, the SHG signature appears within a few seconds in highly doped B 2 O 3 glass, i.e., one order of magnitude smaller than in B 2 O 3 -free glass. Additionally, we found that the orientability of the polar axis of LiNbO 3 nanocrystals by writing laser polarization can be obtained in glasses when SiO 2 is substituted with B 2 O 3 . These preliminary results open the door to the fabrication of crystal / glass based photonic devices with lower laser power deposited and much faster crystallization kinetics.