We experimentally demonstrated polarization-mode dispersion (PMD) compensation by distributing polarizers with only 1 degree of freedom (DOF) along the transmission line. The average power penalty was measured to be 0.4 dB by inserting four compensators, where average differential group delay was 47% of bit period.

We have developed a complete chromium oxide (Cr2O3) passivated gas tubing system by introducing ferritic stainless steel instead of conventional austenitic stainless steel (SUS316L). 100% Cr2O3 passivation film can be formed on electropolished ferritic stainless steel surface because the diffusion coefficient of Cr in ferritic stainless steel is 104 times larger than in austenitic stainless steel. In ferritic stainless steel, moreover, welded bead surface is covered by 100% Cr2O3 pas-sivated film by an introduction of advanced welding technology.