The present invention relates to a wavelength insensitive passive polarization converter which can rotate the direction of optic axis of waveguide by employing poled electro-optic polymer waveguides and a method for controlling the optic axis direction of the poled polymer waveguides. A passive polarization converter of present invention is equipped with poling electrodes at top and bottom of a planar waveguide consisting of three layers of electro-optic polymer, and it comprises: a polarizer in which poling-induced optic axis aligned horizontally; a polarization rotator in which the azimuth angle of the optic axis is slowly changed along the propagation direction from horizontal to vertical direction; and, an analyzer in which poling-induced optic axis aligned vertically. The polarization converter of the invention which contains no periodic structures, is much less sensitive to wavelength, channel dimensions and polarizing structures in principle and may be more easily fabricated by the design of the poling electrode structure, as compared with prior art devices containing such structures.