PURPOSE: To obtain the titled material free from birefringence, having high optical uniformity, excellent mechanical strength, and remarkably high Kerr effect, and composed of a dielectric polymer exhibiting birefringence in an electrical field by the secondary electro-optical effect and containing a specific side- chain terminal group.

CONSTITUTION: A dielectric polymer (e.g. of formula) having nitro group or cyano group at the terminal of the side chain and exhibiting birefringence in an electrical field by the secondary electro-optical effect, is synthesized so as to introduce a nitro group or cyano group at the terminal of the side chain interposing a resonance system of preferably benzene ring, biphenyl ring, etc. between the terminal group and the main chain. The obtained polymer is used as the objective material.

EFFECT: It facilitates the miniaturization of an optical modulation element, polarization element, etc.

USE: An electro-optical element integrated with optical wave-guide and a thin- film dye laser, etc.