Permanent volume Bragg grating fabrication in pure lithium niobate crystal using direct laser writing technique

In this work the authors present the results of volume Bragg grating (VBG) fabrication in pure congruent LN crystal using direct laser writing technique. The authors used Yb:KGW laser system that produces high intensity pulses at 1030-nm wavelength, with 300 fs duration at 100 kHz pulse repetition rate as femtosecond laser source. Laser pulses were focused with 0.42 numerical-aperture lens into the bulk of the sample crystal mounted on a 3-axis nanopositioning system.