Interferometric Noise Characterization and Suppression in Optical CDMA Networks

A solution for suppressing multiple-access interference and incoherent interferometric noise in 2-D optical code-division multiple access (CDMA) networks is demonstrated using a dispersion-imbalanced loop mirror containing a 15-m heavily GeO2-doped fiber. From the experimental study of the degradation caused by noise, bit-error-rate (BER) measurements in a two-user system having coherent, partially coherent, and incoherent interferometric noise without the dispersion-imbalanced loop mirror exhibit error floors above BER = 10-6. Including the dispersion-imbalanced loop mirror before the receiver allows error-free transmission, and reduces the power penalty from the noise by 7 dB. The solution presented increases the receiver sensitivity and accentuates the flexibility of the optical CDMA networks.