Cushman Darby & Cushman, IP Group of Pillsbury Madison & Sutro, LLP
Optical waveguide module having waveguide substrate made of predetermined material and ferrule made of material different from that of waveguide substrate
 This invention relates to an optical waveguide module having stable temperature characteristics and moist heat characteristics even in a severe environment. This optical waveguide module includes a waveguide component having an optical waveguide on a waveguide substrate made of silicon or silica glass as the first material, and a ferrule made of a plastic material as the second material. An end face of an optical fiber is fixed by adhesion while it is inserted in a through hole of the ferrule, the through hole having a continuous inner wall. This ferrule is fixed with an adhesive having a predetermined strength so that its the end face opposes the end face of the waveguide component. The second material satisfies a relationship: EQU .vertline..DELTA.L/(E.sub.1 /E.sub.2).vertline.<3.0.times.10.sup.-6 (.degree.C..sup.-1) with respect to the first material forming the waveguide substrate, where .DELTA.L is a difference in thermal expansion coefficient between the first material and the second material, E.sub.1 is a modulus of elasticity of the first material, and E.sub.2 is a modulus of elasticity of the second material. 
Sumitomo Electric Industries, Ltd.
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Shigeru Shinji Masahide
Semura Ishikawa Saito