Pyroelectric liquid-crystal polymers were prepared by photopolymerization of binary mixtures of two monomers that exhibit a smectic phase: A2c, and A1b, acryloyloxy)undecyloxy]phenyl) benzoate. Both liquid-crystal monomers have a substituent to enhance the nonlinear optical properties, and one of the monomers, A2c, permits polymerization to a cross-linked polymer. During the polymerization an electric field of approximately 25–50 V/μm was applied over the ferroelectric liquid-crystal cells. All cases of polymers formed from the chiral smectic phase showed a second-harmonic-generated signal with no external field present, indicating that polar order became fixed. The orientation dependence of the second-harmonic-generated intensity was similar to that of the ferroelectric liquid-crystal monomer; however, some changes were observed that might be due to changes in the dielectric axes of the system. The highest and coefficients were found to be in the range 0.65–0.8 pm/V and differed depending on the detailed preparation of the sample. Experimental results of several polarization combinations of the pump and frequency-doubled light are presented and discussed.
© 1998 Optical Society of America