OPTICAL 2ND-HARMONIC GENERATION OF (DIMETHYLAMINO)BENZONITRILE MOLECULES INCORPORATED IN THE MOLECULAR-SIEVE ALPO4-5

For (dimethylamino)benzonitrile (DMABN) in the straight Pores of the a luminophosphate molecular sieve AlPO4-5, two components of the second harmonic generation (SHG) have been found. One component of the freque ncy-doubled radiation is polarized parallel to the length axis (z axis , phi2 = 0-degrees) of the crystal and exhibits the maximum intensity when the excitation beam has the same polarization. The second compone nt, however, is polarized perpendicularly to the z axis (phi2 = 90-deg rees) and shows the maximum efficiency for mixed excitation (phi = 45- degrees). Obviously, different components of the hyperpolarizability t ensor contribute to the resulting SHG. The reason for the different te nsor elements are the two close-lying lowest excited states in DMABN h aving transition dipole matrix elements perpendicular to each other. I n contrast to molecular sieves loaded with p-nitroaniline which arc ab le to mix waves of the same polarization only, for the DMABN-based mat erials a mixing of waves of different polarizations is observed. This is a promising property for phase-matching as a prerequisite for a tec hnical application.