Bidirectional Symmetrical 100 Gb/s/λ Coherent PON Using a Simplified ONU Transceiver

Abstract

In this paper, a bidirectional symmetric 100 Gb/s/λ coherent passive optical network (PON) scheme with a simplified optical network unit (ONU) transceiver is proposed and experimentally demonstrated. In the proposed scheme, the downstream signal is generated in a dual-polarization coherent transmitter with Alamouti-coding at the optical line terminal (OLT) side and then received by a single-polarization heterodyne receiver at the ONU side. The upstream signal is generated in a low-cost C-band electro-absorption modulated laser (EML) at the ONU side and then received by a standard dual-polarization integrated coherent receiver at the OLT side. The experimental results show that more than 30 dB power budget is achieved after 25 km standard single mode fibre transmission for both downstream and upstream signal at 100 Gb/s/λ. The cost at the ONU side is maintained low as the required bandwidth of the optoelectrical device is >25 GHz and the local oscillator power at the ONU side can be as low as 4 dBm.

A Minimal Coherent Receiver for 200 Gb/s/λ PON Downstream With Measured 29 dB Power Budget

“…We elaborate on the results and show that employing preemphasis to the transmitted signal for reducing transmitter linear impairments such as frequency dependent gain and IQ skew, can further improve sensitivity and thus the power budget. The results build on work presented in [10], where ad-0000-0000/00$00.00 © 2021 IEEE Fig. 2: Experimental setup for 200 Gb/s/λ downstream transmission.…”

Overview of high-speed TDM-PON beyond 50 Gbps per wavelength using digital signal processing [Invited Tutorial]

“…Note that the complexity of the coherent receiver for the upstream is usually not as much concern as the ONU receiver since the cost of OLT equipment is shared among many users. Therefore, to get better performance, a full dual-polarization coherent receiver can be considered at the OLT side while a DML or EML-based simple transmitter can be used at the cost-sensitive ONU side [92] . Still, the OLT coherent receiver should work in burst-mode, a request that opens several technical challenges, as discussed before and described in detail in [93], such as dynamic range adaptation to allow a linear handling of the received signal, and then fast and DSP-based polarization, frequency, phase and clock recovery.…”

200 Gb/s/λ Upstream PON Using Polarization Multiplexed PAM4 With Coherent Detection

“…Both MZM and EDFA have clear performance benefits with higher extinction ratio, lower noise figure and higher gain, however in the PON scenario, especially at the ONU cost is the key concern, and expensive components are hard to justify. Our current approach builds on previous presentation of 100 Gb/s/λ bi-directional transmission [12]. We demonstrate a simple transmitter architecture for 200 Gb/s/λ upstream PON achieving a power budget of 29.4 dB.…”

“…The signal has the following frame structure. Firstly, there is a preamble of 1024 NRZ symbols to achieve frame synchronisation, using autocorrelation [12]. This is followed by 9216 PAM4 symbols as part of the preamble, used to train the adaptive equalizer, followed by the payload.…”