The output characteristics of nonlinear optical fiber-loop mirror are analyzed in detail when the pump pulses with the same wavelength are input in the both directions for recovering the clock component of the signal spectrum. It is found that the double output pulses are produced in the transmission port of the nonlinear optical fiber-loop mirror. The output pulse peaks are located in time domain at the rising and falling edges of the pump pulses. It is demonstrated that the rising and falling edges of the pump pulse can be directly extracted by this method. Through numerical simulation, the effects of the relative delay of pump pulses and the dispersion of fiber on the characteristics of output pulses are studied. By spectrum analysis, it is found that the spectrum of output pulse sequence includes the clock components of the pump pulse sequence, and a new idea is provided for all-optical clock extraction.