Using gain to tune the dispersion relation of coupled-resonator optical waveguides

Realistic coupled-resonator optical waveguides need gain to compensate for the absorption and scattering losses. Varying the gain and the loss are shown to be a simple way to tune the dispersion relationship. For coupled microrings, the difference between putting the gain in the coupler and putting the gain in the ring are explained. Applications include modulation of light, and tuning waveguides into and out of regions of slow light