The present invention regenerates optical signals in an intact optical state according to a low-speed optical clock. In one embodiment, an optical splitter applies a portion of optical pulse signals to a clock recovery circuit and the rest to an optical splitter. The optical splitter applies half of the input signal to an optical regenerator and the rest to another optical regenerator. The clock recovery circuit regenerates an electric clock signal with half the frequency of the input optical pulse and applies the clock to an optical clock pulse generator. The optical clock pulse generator generates an optical clock signal with half the frequency of the input optical pulse whose phase matches with that of the optical signal at the optical regenerator. An optical regenerator regenerates the optical signal from the optical splitter in an intact optical state. A polarization combiner combine the optical signals from the optical regenerators in mutually orthogonal polarization.