80 Gb/s to 10 Gb/s polarization-insensitive demultiplexing with circularly polarized spun fiber in a two-wavelength nonlinear optical loop mirror

We demonstrate the first polarization insensitive demultiplexing of 10-Gb/s channels from 80-Gb/s pseudorandom bit streams using a two-wavelength nonlinear optical loop mirror with circularly polarized spun fiber. The polarization sensitivity of the device is reduced to <1 dB for >90% transmission, and bit-error-rate measurements show that the remaining polarization sensitivity leads to a power penalty difference of 1.5 dB. The nonlinear transmission is 91% for a switching energy of 4 pJ/pulse, and the full-width at half-maximum timing window is 9.6 ps. The circularly polarized spun fiber has a /spl lambda//sub 0/ of 1541 nm, a length of /spl sim/1 km, and /spl sim/4.1 times higher nonlinearity than that of conventional dispersion-shifted fiber. The spin rate is 16 turns/m and the birefringence is /spl Delta/n/spl sim/1/spl times/10/sup -6/, corresponding to 25 turns/beat length.