Laser induced third harmonic generation in δ-Bi1−xNdxB3O6 nanocomposites

• Tunable THG effect for polymer/Nd-doped δ-BiB3O6 nanocomposites was shown.
• THG features are strongly dependent not only on the pumping power but also on their relative polarizations.
• The effective anisotropic sixth rank tensor for description of such kind of photoinduced processes was introduced.

A possibility of optically operated third harmonic generation (THG) in polymer nanocomposites based on orthorhombic δ-Bi1−xNdxB3O6 powders (where x=0.025÷0.100) is presented. The nanoparticles were fabricated using polymeric precursor method. The particles were acoustically milled and then they were embedded into polyvinyl alcohol (PVA) photopolymer matrix. After solidification the additional photoinducing treatment was performed by two coherent 1064 nm Nd:YAG laser beams. The angle between the photoinducing beams and their polarization was varied in order to achieve the maximum of THG. THG efficiency was monitored immediately after Nd:YAG laser treatment at different temperatures. The photoinduced THG was explored versus the Nd3+ content and temperature. Origin of the effect is discussed within a framework of phenomenological description.