We report experimental observations of the negative-group-velocity phenomenon in an integrated-optical two-port ring-resonator circuit. We demonstrate that when the is negative, the (main) peak of output pulse appears earlier than the peak of a reference pulse, while for a positive , the situation is the other way around. We observed that a pulse splitting phenomenon occurs in the neighborhood of the critical-coupling point. This pulse splitting limits the maximum achievable delay and advancement of a single device as well as facilitating a smooth transition from highly advanced to highly delayed pulse, and vice versa, across the critical-coupling point.
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