Patent ID: 7389028

Claim:
A multiple resonator comprising: first to third resonators, each having different light path length, connected via optical coupling means, wherein all the following Expressions <1>, <2> and <3> hold: L 1 ={M 1/( M 1−1)} L 0 <1> L 2 ={M 2/( M 2−1)} L 0 <2> M 2−1=( M 1−1) 2 <3> where L 0 is a light path length of said first resonator, L 1 is a light path length of said second resonator and L 2 is a light path length of said third resonator, and M 1 and M 2 are integers of 3 or greater; a first waveguide, one end of which is connected to one of said first to third ring resonators via optical coupling means; and a second waveguide, one end of which is connected to another of said first to third ring resonators via optical coupling means, wherein said first to third resonators are first to third ring resonators made up of ring-shaped waveguides each having different light path length.