TUNABLE OF GROUP VELOCITY OF LIGHT IN A RING-IN-RING STRUCTURE

Abstract

We theoretically study a ring-in-ring resonator which is coupled with a straight waveguide to yield coupled-resonator-induced transparency. Its absorption spectrum has a narrow transparency peak with respect to low group velocity, analogizing to that in electromagnetically induced transparency. The transparency peak, the phase difference between the split modes, dispersion, and group velocity can be controlled by changing reflection coefficients. Explicit expression of the group velocity at resonance are derived and discussed, the group velocity can be reached to 104 m/s -106 m/s orders of magnitude with proper choice of the parameters.