An approach is proposed to implement diffractive optical elements for the conversion of the polarization state of beams. Calcite crystal etching technology is developed and applied to manufacture a four-sector polarization converter. The fabricated four-sector polarization converter is experimentally investigated. The orthogonal polarization state of beams in opposite sectors is achieved by selecting a wavelength with a tunable laser. The experimental results of focusing the converted beams are consistent with the numerical simulation.