Abstract

Frequency doubling of diode lasers has significant technological applications in imaging and optical recording. The major hurdle toward achieving efficient doubling remains to develop highly nonlinear materials with appropriate linear optical properties such as birefringence and transparency. One approach is to engineer materials by doping or grafting nonlinear organic molecules into transparent polymeric matrices. Second-order nonlinearity is obtained by the eccentric alignment of these molecules along their dipole moments under an external electric field. With this approach, several molecular properties are important including large molecular dipole moment and hyperpolarizability product (μβ) as well as very low absorption at the first and second harmonic wavelengths of diode lasers (near 800 and 400 nm). An established guideline in identifying organic molecules with large hyperpolarizabilities is by the presence of low lying strong charge— transfer (CT) electronic transitions. However, such an approach is in conflict with the requirement of transparency. Our primary objective is to investigate the extent of such a nonlinearity—transparency tradeoff and to identify suitable classes of organic molecules for the frequency doubling of diode lasers.

© 1990 Optical Society of America