Abstract: A method for manufacturing a combination pattern-refraction modification type phase grating comprises the steps of (1) forming a thin film of composition which includes a photosensitive acrylic acid or methacrylic acid group polymer including double bonds between carbons and at least one of compounds selected from aromatic aldehyde and aromatic ketone which have a substituent or a no-substituent (2) irradiating the thin film in a regularly arranged pattern with ultraviolet rays and (3) removing the non-reacted compound.

Abstract: A combination pattern-refraction modification type phase grating comprises dual grating elements which are regularly arranged and each includes convex and concave portions which have respectively different thickness and are formed of material respectively different in refractive index so as to combine respective characteristics of a pattern and a refraction modification type phase grating.

Abstract: A thin film waveguide path comprises a waveguide path layer overlying a substrate but separated therefrom by at least one intermediate layer. The waveguide path layer comprises a first transparent high molecular material. The at least one intermediate layer comprises a second organic high molecular material having a solubility different from that of the first material and a lower refractive index lower than that of the first material, the substrate comprises a third high molecular material different from the first and second materials for supporting the waveguide path and intermediate layers.