Growth and characterization of amino based organic nonlinear optical l-Lysine-l-Aspartate (LLA) single crystal for electo-optic applications

Organic nonlinear optical single crystal of l-Lysine-l-Aspartic acid (LLA) has been successfully grown from solution by slow evaporation technique at room temperature. Single crystal X-ray diffraction and fourier transform infrared spectral analyses are carried out to confirm the LLA crystal. The transparency of LLA crystal is confirmed by optical absorption spectrum and direct band gap energy is found to be 4.87 eV. Thermal stability of the crystal is found to be 212 °C. The hardness of the grown crystal is checked using Vickers’ micro hardness tester. Laser damage threshold of the grown crystal is also studied and reported. The electrical studies are performed and the activation energy is calculated from Arrhenius relation. Negative photo conducting nature of the crystal is obtained by photoconductivity measurements. The Kurtz powder second harmonic generation test indicates that the grown crystal is nearly 2 times more efficient than conventional KDP crystal, which is a prospective crystalline material for electro-optic device fabrication.