An edge detector applied to a vertical-cavity surface-emitting laser is provided. The edge detector includes an alignment circuit, a rising-edge detecting circuit and a falling-edge detecting circuit. The alignment circuit is configured to receive and align multiple sets of differential input data and output multiple sets of differential output data corresponding to the multiple sets of differential input data. The multiple sets of differential output data includes a set of delayed differential output data. The rising-edge detecting circuit is coupled to the alignment circuit. The rising-edge detecting circuit is configured to detect rising-edges of the multiple sets of differential output data and output corresponding multiple sets of differential rising data. The falling-edge detecting circuit is coupled to the alignment circuit. The falling-edge detecting circuit is configured to detect falling-edges of the multiple sets of differential output data and output corresponding multiple sets of differential falling data. |