Patent ID: 7194150

Claim:
An optical modulation element module comprising an optical modulation element, a case with said optical modulation element being integrated thereto, input output fibers being connected to said optical modulation element and also guided to an exterior of said case, and a terminal for introducing a modulating signal and a bias adjustment voltage that are to be applied to said optical modulation element, said case being hermetically sealed, wherein: said case is made of a material having almost the same coefficient of linear expansion as the optical modulation element; said optical modulation element is affixed to said case by using a thermoplastic and high-elastic adhesive material; a linear expansion difference between each material of said case and said fiber is less than 16×10 −6 /° C.; and a distance between a fixed point of said fiber with said case, and a fixed point of said fiber with said optical modulation element is more than 3 mm.