Organic nonlinear optical materials

Organic materials are expected to have relatively strong nonlinear optical properties due to delocalized electrons at π − π* orbitals. This expectation explains extensive search for better NLO materials among organic crystals.

L-arginine maleate dihydrate (LAMD)

L-Arginine is one of the essential amino acids widely distributed in biological substances. It forms a number of salts with organic and inorganic acids showing non-linear optical properties. L-Arginine maleate dihydrate (LAMD, C₆H₁₄N₄O₂,C₄H₄O₄,2H₂O) is one of these L-arginine salts which is a complex of strongly basic amino acid, carboxylic acid and provides useful information in relation to molecular interaction in present day biological systems and to prebiotic self-organisms.^[1] It is also a nonlinear optical material with second harmonic generation efficiency 1.68 times that of KDP.^[2] LAMD crystals are grown from solution by solvent evaporation; they belong to the triclinic space group P1.

L-methionine L-methioninium hydrogen maleate (LMMM)

LMMM too belongs to the amino acid family. Crystals are grown by slow evaporation of an aqueous solution containing L-methionine and maleic acid, resulting in centimeter-large crystals of a non-centrosymmetric space group.^[3] They were applied for second harmonic generation of an Nd:YAG laser (wavelength 1064 nm), and SHG efficiency equal to that of KDP has been obtained.

References

1. ^ S.L. Miller, E.L. Orgel, "The Origins of Life on the Earth", Prentice- Hall, New Jersey, 1974.
2. ^ "Synthesis, crystal structure and solubility of C6H14N4O2,C4H4O4,2H2O" Sci. Technol. Adv. Mater. 6 (2005) 508 (free download)
3. ^ "Crystal growth and structure of L-methionine L-methioninium hydrogen maleate—a new NLO material" Sci. Technol. Adv. Mater. 9 (2008) 025012 (free download)