Performance Evaluation of 100 Gb/s 16-QAM Alamouti-coded Optical Coherent System.

Alamouti polarization time block coding (PTBC) coherent optical technology has been drawing attention as a technology for future optical access networks because it enables a polarization insensitive simple coherent receiver without any polarization tracking. We compare and analyze a 100 Gb/s/λ single-carrier 16-QAM Alamouti PTBC coherent system and a 100 Gb/s/λ single-carrier 16-QAM polarization division multiplexed (PDM) coherent system about their performance under the conditions of the same data rates and the same optical access channel impairments. The Alamouti PTBC coherent system has performance degradations for a few impairments that degrade the orthogonality between the transmitted symbol pairs. Nevertheless, the Alamouti PTBC coherent system has little SNR penalty compare to PDM coherent system even in the worst case of optical access channel impairments.