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 (Ip-ex), and s-polarization (perpendicular to the c-axis of AlPO4-5 crystal) SH intensity (Is-ex) of DR1-loaded AlPO4-5 single crystals can be well fitted as a function of input polarization angle (alpha): Ip-ex = 0.69 cos(4) alpha + 0.37 sin(4) alpha - 0.17, Is-ex = 0.69 cos(2) alpha sin(2) alpha + 0.06, respectively. This polarization angle dependence can be well explained by three different SHG processes of I-p (0 degrees), I-p (90 degrees), and I-s (45 degrees), originated from different combinations of two polarized photons.