Effects of substrate micropatterning on nonlinear optical properties of polar self-assembling films

Self-assembling triblock molecules were previously shown to form thin films with polar order. These films are also known to contain polar supramolecul ar aggregates that are layered in head-to-tail fashion. In this work, glass substrates were prepared using a focused-ion-beam system to generate 1 mmx 1 mm areas containing periodic arrays of squares with lateral dimensions of 7 and 17 mum. The squares were defined by 3 mum wide and 10 nm deep trough s created by Ga ion beams. Using second-harmonic-generation measurements, t he average molecular tilt angle was found to be smaller in patterned films, suggesting that micropatterning enhances overall polarization in these fil ms. (C) 2001 American Institute of Physics.