Group delay manipulation in a passive microwave-photonic fiber optic Mach-Zehnder interferometer

Conventional slow and fast light (SFL) systems are based on active or nonlinear media or photonic band-gap systems. Radio-frequency (RF) interferometric systems were recently explored for sustaining fast and slow light, owing to their simple structures and passive operation. This Letter introduces a simple, effective, and efficient SFL system based on a linear and passive microwave-photonic (MWP) fiber optic Mach-Zehnder interferometer (MZI). By optically tuning the light transmission ratio of the two fiber beams of the MZI (i.e., the optical carrier), we demonstrate that both delay and advancement of a RF signal (i.e., the envelope signal) can be realized. The magnitude of the signal group delay can also be adjusted using the optical tuning method. Therefore, high-degree manipulation of signal group delay can be achieved using the proposed MWP fiber optic MZI system.