Optical transmission device

An optical transmission device comprising light guides each having light incidence/emission sections, a substrate which fixes the light guides, and optical elements arranged on the substrate to match the light incidence/emission sections of the light guides, wherein a total of differences between the substrate and the light guides in a rate of dimensional variation due to linear expansion and the rate of the dimensional variation due to water absorption is:

• not more than 0.6% where the light guide size is 50 mm or less;
• not more than 0.3% where the light guide size is 50 to 100 mm;
• not more than 0.15% where the light guide size is 100 to 200 mm;
• not more than 0.1% where the light guide size is 200 to 300 mm;
• not more than 0.08% where the light guide size is 300 to 400 mm;
• not more than 0.06% where the light guide size is 400 to 500 mm;
• not more than 0.05% where the light guide size is 500 to 600 mm;
• not more than 0.04% where the light guide size is 600 to 800 mm;
• or
• not more than 0.03% where the light guide size is 800 to 1000 mm or more.

An optical transmission device comprising light guides each having light incidence/emission sections, a substrate which fixes the light guides, and optical elements arranged on the substrate to match the light incidence/emission sections of the light guides, wherein a relationship between the substrate and the light guides is such that:

• a difference in a coefficient of linear expansion is not more than 300% and a difference in a rate of dimensional variation due to water absorption is not more than 0.6% where the light guide size is 50 mm or less;
• the difference in the coefficient of linear expansion is not more than 150% and the difference in the rate of dimensional variation due to water absorption is not more than 0.3% where the light guide size is 50 to 100 mm;
• the difference in the coefficient of linear expansion is not more than 100% and the difference in the rate of dimensional variation due to water absorption is not more than 0.15% where the light guide size is 100 to 200 mm;
• the difference in the coefficient of linear expansion is not more than 80% and the difference in the rate of dimensional variation due to water absorption is not more than 0.1% where the light guide size is 200 to 300 mm;
• the difference in the coefficient of linear expansion is not more than 50% and the difference in the rate of dimensional variation due to water absorption is not more than 0.08% where the light guide size is 300 to 400 mm;
• the difference in the coefficient of linear expansion is not more than 40% and the difference in the rate of dimensional variation due to water absorption is not more than 0.06% where the light guide size is 400 to 500 mm;
• the difference in the coefficient of linear expansion is not more than 30% and the difference in the rate of dimensional variation due to water absorption is not more than 0.05% where the light guide size is 500 to 600 mm;
• the difference in the coefficient of linear expansion is not more than 25% and the difference in the rate of dimensional variation due to water absorption is not more than 0.04% where the light guide size is 600 to 800 mm;
• or
• the difference in the coefficient of linear expansion is not more than 15% and the difference in the rate of dimensional variation due to water absorption is not more than 0.03% where the light guide size is 800 to 1000 mm or more.