PHASE DETERMINATION OF 2ND-ORDER SURFACE SUSCEPTIBILITY TENSOR OF LIQUID-CRYSTAL MONOLAYER USING ULTRA-THIN FILM LOCAL OSCILLATOR

We demonstrated full determination of second-order nonlinear susceptib ility of a 4'-n-octyl-4-cyanobiphenyl (8CB) liquid crystal (LC) monola yer adsorbed on a second-harmonic (SH) active polyimide (PI) substrate . In order to separate the SH signal of the LC film from that of the P I film, we adopted an interferometry technique of second-harmonic gene ration (SHG) using an ultra-thin film local oscillator. We have found a variety of phases in the components of susceptibility; those of chi( zu) and chi(izi), are almost the same but the phase of chi(zzz) differ s by 80 degrees from the other two. The phases of the components of th e surface susceptibility tensor are not always identical. This fact in dicates that the surface SH response is more complicated than what we expected.