Experimental verification of finesse enhancement scheme in two-ring resonator system

We propose a finesse enhancement scheme by a simple two-ring system, in which the resonance finesse is dependent on the relative intensity buildup of the second ring with respect to the first. In lossless case, it is possible to obtain finesse two orders of magnitude higher than that of the single ring system. The two-ring system is fabricated in silicon-on-insulator using deep UV (DUV) lithography and shown to exhibit the finesse of 100 to 300. The associated finesse enhancement of 20 is in a good agreement with the theory.