Laser operated optical features in β-BaTeMo₂O₉:Cr³⁺ nanocrystallites

An increase of second order nonlinear optical efficiency was established for Cr³⁺ doped β-BaTeMo₂O₉ (BTMO) nanocrystallites (with sizes varying within up to 150 nm range) under influence of two coherent beams of 532 nm nanosecond pulsed lasers at power densities up to 600 MW/cm². It was found that maximal enhancement of optical second harmonic generation was achieved for BTMO:Cr³⁺ nanocrystallites possessing sizes about 60–80 nm. Occurrence of some quasi-periodic space radial grating was observed as well. This is a consequence of competition between the photo-polarization and photo-thermal effects. Band structure simulations within a framework of the norm-conserving pseudopotential were performed. - Highlights: • BMTO nanocrystallites with the sizes 60 nm–120 nm were synthesized. • Photoinduced SHG is found. • The effect is caused by additional photopolarization