Improved 10-Gbps uplink transmission in WDM-PON with RSOA-based colorless ONUs and MZI-based equalizers

• We propose a WDM-PON system with RSOA-based ONU and MZI-based optical equalizers.
• MZI and cascaded MZIs are a two-tap and a three-tap optical equalizers.
• The modulation bandwidth of RSOA is increased by using optical equalizer.
• Performance of the system is improved by optimizing RSOA and optical equalizer.

Proposed and demonstrated in this paper is an improved scheme of 10 Gbps uplink transmission in wavelength-division multiplexed passive optical network (WDM-PON) with RSOA-based colorless optical network units (ONUs) and MZI-based optical equalizers. The transmission functions of MZI and cascaded MZIs are verified to be a two-tap and a three-tap optical equalizer respectively. The results of experiment and simulation show that the MZI with proper delay time and initial phase shift is able to improve the modulation bandwidth of RSOA-based colorless ONU. By using a single MZI, a received sensitivity of −16.2 dBm at bit error rate (BER) of 1.0×10−3 which is the threshold of Reed-Solomon (255, 223) can accommodate the round trip loss of 37.6 dB after 25 km standard-single-mode-fiber (SSMF) transmission. Moreover, optical equalizer with cascaded-MZIs is confirmed to be able to achieve more than two order-of-magnitude reduction in BER through 40 km transmission via simulation. The results present useful insights for the practicality of the optical equalizers used before uplink receiver in the next-generation access network.