Second-harmonic generation in smectic A phase of ferroelectric liquid crystal induced by electroclinic effect

Second-harmonic generation (SHG) of ferroelectric liquid crystal (FLC) has been studied in the smectic A (Sm A) phase in 4'-(1-butoxycarbonyl-1-ethoxy)-3'-nitrophenyl 4-[4-(ω-alkenyloxy)phenyl]benzoate (1BC1ENPAPB) with large electroclinic (EC) effect and a large spontaneous polarization. Type I phase-matching has been observed in the angular dependence of SHG intensity in the Sm A phase. SHG intensity caused by the EC effect is proportional to the square of applied electric field, and it has been found that the effective optical coefficient is proportional to electric field.