The influence of the extinction ratio (ER) of the input signal on the copying optical signal
are analyzed theoretically for the first time to our knowledge and the deterioration of the ER of the
output signal result from continuous - wave (CW) is noticed. The relationship between the ER of the
output and the input signals are given quantificationally. The experiment results are agree with the
theory. The recopied optical signal using fiber ring cavity is realized in experiment by reducing CW.
An Erbium-doped optical fiber amplifier (EDFA) is employed for compensating the round - trip loss
of the fiber ring cavity and a semiconductor optical amplifier (SOA) is used for the power
equalizing of the output signal, the tenth copied optical signal is implemented.