Crystal growth and properties of pure L-alanine and boric acid doped L-alanine nonlinear optical single crystals for frequency conversion

Frequency conversion materials such as pure and 5 wt % Boric acid doped L-alanine crystals are grown using the slow evaporation technique at room temperature. Single crystal XRD reported that the crystals formed attained the orthorhombic system of noncentrosymmetric space group P2 1 2 1 2 1 . FTIR analysis established the presence of groups such as COO − , NH 3 + , CH 2 , CH and boron (B) element from shift in vibrational modes of at lower frequency region is also confirmed by EDAX measurement. The UV–Vis spectral study predicted the cut-off wavelength for pure LA and boric acid doped LA at 245 nm and 238 nm and thereby energy gap, urbach energy were also evaluated. Vicker’s microhardness study categorized the harvested crystals as soft materials following RISE effect. The dielectric characterization such as dielectric constant and dielectric loss were studied at various temperature ranges. Jonscher’s power law verifies the conductivity mechanism with s = 0.988, 0.985 for pure LA and doped LA. Laser damage threshold study using an Nd:YAG laser (1064 nm) evinces the stability of the material to withstand high intensity lasers in NLO applications. The luminescence nature of crystals was investigated in the range 250–600 nm and confirmed violet emission radiation. TGA-DTA analysis showed that the crystals possess good thermal stability. Second harmonic generation (SHG) was examined from the emission of green light from the samples by Kurtz Perry technique. The Z-scan investigations on the crystals reveal that they undergo two photon absorption, self-defocusing and hence greater third order nonlinear susceptibility χ 3 of order of 10 –8 esu encompasses the grown crystals in the development of opto-electronic devices and for the conversion of energy process.