The design and simulation of a new optical add-drop multiplexer (OADM) made of two pairs of grating-frustrated directional couplers is presented. Design theory and simulation are introduced to support its feasibility. The directional couplers are proposed to use polymeric waveguides as the cores. The inverted-ridge waveguide fabrication is proposed using lithography and etching process. The proper dimensions and parameters of each waveguides for OADM are simulated. The designed OADM is a 1550 nm wavelength with add-drop filters, bandwidth 20 nm, and 80% peak transmission showing the application for wavelength division multiplexing (WDM).