PMD Tolerance of 10 Gbps Modulated Signals due to SOA-Induced Chirp in SOA Booster Amplifiers

Abstract

We investigated how the polarization-mode dispersion (PAID) tolerance was degraded by semiconductor optical amplifier (SOA)-induced chirp for the 10 Gb/s nonreturn-to-zero (NRZ), duobinary NRZ, return-to-zero (RZ), and carrier-suppressed RZ (CS-RZ) modulation formats. The power penalty was calculated as a measure of the system performance due to PAID for a given SOA-induced chirp. Considering only first-order PMD, all modulation formats have a similar PAM tolerance regardless of SOA-induced chirp. Oil the other Band; when both first- and second-order PAID are considered; the PMD tolerance of all modulation formats with the exception of the CS-RZ modulation format are degraded by SOA-induced chirp. Among all modulation formats considered here; the NRZ modulation format has the PMD tolerance with the highest sensitivity to SOA-induced Chirp. When the peak-to-peak chirp induced by SOAs is 0.28 angstrom, its PMD tolerance is degraded up to 4 dB for a differential group delay (DGD) of 50 ps. However, the PAID tolerance of the CS-RZ modulation format is largely unaffected by SOA-induced chirp.