SUBSTRATE FOR OPTICAL PART AND ITS MANUFACTURE, AND CONTROLLING METHOD FOR THERMAL EXPANSION COEFFICIENT OF THE SUBSTRATE

摘要

PROBLEM TO BE SOLVED: To provide a substrate for optical parts capable of manufacturing a polymer substrate for a polymer optical waveguide excellent in surface smoothness and having a thermal expansion coefficient of 4×10-5/ deg.C or higher and 1.2×10-4/ deg.C or lower, and to provide a manufacturing method for the substrate for optical parts, and a controlling method for the thermal expansion coefficient of the polymer substrate. SOLUTION: Thin polymer films with smooth surfaces are laminated to form a laminated body, which is applied to a substrate for optical parts. In addition, one kind of polyimide film or two or more kinds of polyimide films of different thermal expansion coefficients are used to make a laminated body in which the polyimide films are laminated in an appropriate order. This laminated body is used as a substrate, which changes the chemical structure of the polyimide and the constitution of the laminating to control the thermal expansion coefficient of the substrate for optical parts in a wide range.