Since in the previous existing optical designs, the electronic-optic-electronic conversion has not been completely eliminated. Construction of the optical circuits with nonlinear waveguides can overcome this drawback. We have developed a nonlinear directional coupler theory to describe novel all-optical parity circuits. By using three channels, appropriate adjusting of the refractive indices, and selecting the correct length for coupling event, even/odd parity circuits can be obtained. The operation of these circuits is simulated with the aid of RSoft CAD-Layout (BeamPROP) simulator. Towards the end of the work, we compared the speed of our proposed novel circuit with the existing optical designs and also electronic structure of which we have a better result.