Assembly of Disperse Red 1 Molecules in the Channels of AlPO4-5 Single Crystals for Second-Harmonic Generation

Disperse red 1 (DR1) molecules have been successfully incorporated into the one-dimensional channels of AlPO4-5 single crystals by means of vapor-phase diffusion. Polarizing microscope and SHG results indicate that the DR1 molecules are well aligned in a preferred direction along the crystal channels. The p-polarization (parallel to the c-axis of AlPO4-5 crystal) SH intensity (I p - ex), and s-polarization (perpendicular to the c-axis of AlPO4-5 crystal) SH intensity (I s - ex) of DR1-loaded AlPO4-5 single crystals can be well fitted as a function of input polarization angle (α): I p - ex = 0.69 cos4 α + 0.37 sin4 α − 0.17, I s - ex = 0.69 cos2 α sin2 α + 0.06, respectively. This polarization angle dependence can be well explained by three different SHG processes of I p (0°), I p (90°), and I s (45°), originated from different combinations of two polarized photons.