An all-fiber, all-states of polarization linear design depolarizer is provided. It is made of two polarization combiners (PC1,PC2) with a 2.times.2 directional coupler (DC) between them. The connections between the coupler (DC) and the two polarization combiners (PC1,PC2) have optical phase delays (L1,L2) and half wave polarization rotators (PR1,PR2,PR3) to make proper adjustments.