Patent ID: 7319800

Claim:
An optical waveguide device comprising: a substrate comprising an electro-optical material; an optical waveguide formed in or on the substrate and comprising at least a first branch and a second branch; a signal electrode; a first ground electrode; and a second ground electrode, wherein a voltage is applied on said first branch by means of said first ground electrode and said signal electrode, a voltage is applied on said second branch by means of said second ground electrode and said signal electrode, a first gap is formed between said first ground electrode and said signal electrode, a second gap is formed between said second ground electrode and said signal electrode, each of the first gap and the second gap is respectively divided into a voltage applying portion, a feed-through portion, and a connection portion therebetween, and the first gap and the second gap satisfy the following formula: G 12 /G 11 ≦G 22 /G 21 <G 32 /G 31 where G 11 represents a width of the first gap at the connection portion, G 12 represents a width of the second gap at the connection portion, G 21 represents a width of the first gap at an end nearer to the connection portion of the voltage applying portion, G 22 represents a width of the second gap at an end nearer to the connection portion of the voltage applying portion, G 31 represents a width of the first gap at the voltage applying portion, and G 32 represents a width of the second gap at the voltage applying portion, and wherein said first ground electrode and said second ground electrode are positioned to extend along and oppose said signal electrode along the entire length of said voltage applying portion.