Amplified double-coupler double-ring optical resonators with negative optical gain

Optical resonators with a double-coupler and double-ring configuration incorporated into optical amplifiers that have negative gain are analyzed. The resonators are presented with a unique signal-flow graph together with z-transform variables for sampled optical signals. Their optical transfer functions are obtained by a graphical technique. The poles and zeroes in the z plane of the transfer functions are examined, which leads to some unique design features of the resonators for optical-filtering applications.