Observation of the transition from inverted coupled-resonator-induced transparency to inverted Autler-Townes splitting

Inverted coupled-resonator-induced transparency eliminates amplification as a result of destructive interference between two competing excitation pathways and induces a ``nonamplifying'' transparency window in an otherwise strongly amplifying spectral region. Using coupled ring resonators as a model system, we systematically examined the transition from inverted induced transparency to Autler-Townes splitting (ATS) by controlling the coupling strength between two resonators. The inverted induced transparency spectrum transitioned into different ATS spectra depending on the parameters of the resonators. We also examined the transition that occurs when the second resonator has gain. In this case, the system showed enhanced transparency, in which the intensity of the induced window was much greater than the incident laser level.