Multi-slot and multi-level coding technique over amplitude-shift keying modulation for optical communication links

A new multi-slot and multi-level coding technique, which is a combination of multiplexing and coding technique, known as Multi Slot Amplitude Coding (MSAC) is presented. This technique offers better flexibility in terms of defining the symbol based on time slot and signal level in order to generate more unique symbols as a line code with better clock information since all the symbols have zero level (return-to-zero) at the beginning. In this paper, 3 tributary channels at 10Gbps per channel is simulated for optical communication link with amplitude-shift keying (ASK) modulation. The performance of 3×10Gbps MSAC is compared with 30Gbps RZ ETDM in terms of spectral width, OSNR and chromatic dispersion tolerance. The results show that 3×10Gbps MSAC occupy 47% less spectral width, thus a better chromatic dispersion tolerance compared to 30Gbps RZ ETDM with 10.5dB OSNR penalty at the BER of 10^-9. If the channel bit rate is increased to 40Gbps, the aggregate bit rate will be 120Gbps with 5.6dB OSNR penalty.