Ultra-Low Crosstalk En/Decoder Using an Amplitude-Shaping Technique for 100 Gbps/λ OCDM-PAM-4 Transmission in O-Band

Abstract

This paper proposes an optimized 16-chip multi-level phase-shifted optical code division multiplexing (OCDM) en/decoder for 4-level pulse amplitude modulation (PAM-4) format by using an amplitude-shaping (AS) technique. The optimized en/decoder can efficiently suppress the crosstalk and the primary beat noise (PBN). The code detection performance for 4-OCDM PAM-4 becomes the lowest to our knowledge. The numerical bit error rate analysis and the back-to-back simulation are shown. We also successfully demonstrate by computer simulation a 100 Gbps/λ enabling by 12.5 GBaud 4-OCDM PAM-4 transmission in O-band over 6×30 km with in-line optical amplifiers.INDEX TERMS Amplitude shaping, optical amplifier, o-band transmission, optical code division multiplexing, pulse amplitude modulation

Reach Extension of a 53.12 Gbps PAM-4 IM/DD Signals With Optimized Extinction Ratio in Amplified Multi-Span O-Band Transmission

“…An optical code-division multiplexing (OCDM) signal with optimized amplitudeshaping (AS) en/decoders could multiplex 4 users of 25 Gbps PAM-4 simultaneously, resulting in transmission rates of 100 Gbps per wavelength. This method could reduce the symbol rate whilst keeping the net bit rate high, and in addition this scheme can support longer transmission to its low baud rate [33]. Moreover, geometric constellation shaping (GCS) in which constellation points of multi-level modulation formats like PAM-N or m-QAM are adjusted to optimize a cost function such as general mutual information (GMI) and bit error rate (BER), has the potential to solve the extra power penalty governed by power-dependent noise distribution especially from optical signal amplification [34].…”