By using an indirect method the refractive index of the guest host polymer thin film made up of DCNP and polyetherketone (PEK c) was calculated at the wavelength of 1 300 nm.On the basis of the study on polymeric slab optical waveguide,a novel single moded polymeric converse ridge waveguide was designed and fabricated.The results show that this kind of optical waveguide possesses good single mode property for practical application.