Next-Generation TDM-PON Based on Multilevel Differential Modulation

In this letter, a next-generation time-division multiplexed passive optical network (TDM-PON) based on multilevel differential modulation formats is proposed. Multilevel modulation enables the efficient scaling of bit rates without resorting to very high-speed electronics and photonics, while differential detection simplifies the detection process. The 40 Gb/s downstream signal is implemented with Star 16 quadrature amplitude modulation, while two upstream channels are evaluated, a simple, asymmetrical 10 Gb/s on-off keying signal and a 30-Gb/s differential eight phase-shift keying signal. Experimental results show very good receiver sensitivities, indicating the proposed modulation format's suitability for future very high-speed TDM-PONs.