Circularly polarized fiber in a nonlinear optical loop mirror for 80 Gb/s to 10 Gb/s polarization-insensitive demultiplexing

Summary form only given. We demultiplex 10 Gb/s channels from a fully-populated 8/spl times/10 Gb/s pseudo-random bit stream by using a polarization-insensitive, two-wavelength, nonlinear optical loop mirror (NOLM) with high-nonlinearity, circularly-polarized, spun fiber (CPF). The polarization sensitivity (PS) is reduced to 90% transmission in CPF because the nonlinear phase shift induced by the control wavelength is the same for all signal input polarizations. The remaining polarization dependence gives a maximum of 1.5 dB power penalty differences for the bit-error-rates (BERs) of demultiplexed bits. In contrast to other NOLM demultiplexers, we achieve polarization insensitivity by spinning high-nonlinearity fiber preform at 10 turns/m during the drawing process so that the fiber is intrinsically circularly polarized and environmentally stable.