Group velocity control in reconfigurable phase-shifted superstructures

Tuneable optical delaying of short pulses is one of the key components for future all-optical telecommunication networks and information processing systems. Important applications include optical buffering, synchronisation, optical delay lines or jitter correction. One dimensional resonant structures such as Fiber Bragg gratings (FBG) provide large group index enhancements and strong dispersion far away from any material resonance. Beside their small size and compatibility to fiber optics they offer low loss narrow frequency rejection and the possibility to operate at room temperature. The main disadvantage of these systems is that once these types of gratings have been induced, possibilities to manipulate the spectral response are limited to mechanical strain or temperature tuning. In this work we present a versatile holographic approach to dynamically implement gratings into photorefractive LiNb03 crystals. Subsequently, we demonstrate control of the group velocity these gratings that are dynamically addressed and phase-engineered to obtain complex structures as e.g. multiple π phase-shifted and super-structured gratings.