Organic materials for nonlinear optics; new efficient derivatives of nitrobenzene and nitropyridine

Abstract

Donor-acceptor substituted derivatives of aromatic compounds are now known to possess large intrinsic optical nonlinearities. To utilize fully the large molecular hyperpolarizabilities inherent in these compounds in the crystalline state, special constraints on the relative orientations of the molecules must be fulfilled. Not only must the material crystallize in a noncentrosymmetric unit cell, but the individual molecular dipoles must be properly aligned to obtain a large net macroscopic crystal dipole moment and yet meet additional phase matching conditions.1 It has been found that such enhanced alignment is more likely to occur in molecules containing polar functionality (in addition to the usual donor and acceptor substituents) which interact in such a fashion so as to overcome electrostatic dipolar interactions which otherwise lead to the centrosymmetric crystal habit. © 1983 Optical Society of America