We have constructed a digital all fiber optic 1st order PMD compensator and verified its compensation performance with 10Gb/s transmission system. The proposed compensator was composed of several pieces of polarization maintaining(PM) fibers of different differential Group Delay(DGD) which were spliced together with short length of single mode fibers between them. The DGD of the Nth PM fiber segments has the value of $2^{N-1}\tau_{min}$, where N is a natural number which satisfies 1≤N≤Toatal number of PM fiber sections and $\tau_{min}$ is the minimum DGD of fiber segment. The total DGD of the compensator is determined by the alignment of fast and slow axis of the PM fiber sections. The constructed compensator was composed of 7 pieces of PM fiber segments and could compensate arbitrary value of 1st order PMD less than 63.5ps with 1ps step and switching time of 300ms. We slao suggested the reference for determining minimum compensation step in thos structure for practical application in 10Gb/s system from the result of compensation test result.
