An interoperable access network based on CWDM-routed PONs

PON topologies for dynamic optical access networks

“…To address a WDM-PON, TL1 will switch on all 16 wavelengths, centred ±3.2 nm around coarse channel λ 2 , i.e. λ 2 1-16 , to address jointly all ONUs in WDM-PON4 [5]. The established network interoperability is a key feature since it allows a smooth migration from single to multiwavelength optical access to address increasing bandwidth requirements.…”

“…Reflective semiconductor optical amplifier (RSOA)-based ONUs are universally employed, avoiding the necessity of wavelength-specific, local optical sources. The use of multiple transceivers in a single OLT to serve all reflective PONs [5] allows for centralised control to distribute ONU capacity among upstream and downstream on demand and concurrently provide each PON with multiple wavelengths for enhanced bandwidth allocation flexibility. Finally, the network exhibits increased scalability since extra TLs can be directly applied at unused AWG ports in the OLT, e.g.…”

“…It has been previously established that PDW shift of up to 1.8 nm could potentially impose a restriction in multi-wavelength operation over wide-passband AWG channels and therefore limit the routing performance of the entire network [2,5]. Figure 2(a) displays the measured PDL versus operating wavelength at PDW shifts of 0, 1.5 and 1.8 nm using VPI physical layer simulation platform.…”

“…It can be observed that on top of the 5 dB insertion loss of the channel, the longest wavelength at λ 2 1 = 1553.33 nm can suffer up to 5.5 dB loss, compared to the central wavelength at λ 2 9 = 1550.12 nm, due to the increase of PDL and the AWG passband Gaussian response. To evaluate the bidirectional network performance, bit-error-rate (BER) responses have been recorded [5] for the least and most severely degraded ONUs of WDM-PON4. Results confirmed error-free transmission with measured 10 -9 BER achieved by 93% of ONUs when 1.8 nm PDW is employed.…”

A Full-duplex Access Network based on CWDM-routed PONs

“…A scalable access network architecture has been developed featuring interoperability among time division multiplexing (TDM) and wavelength division multiplexing (WDM) PONs by means of a coarse passband array waveguide grating (AWG)-based optical line terminal (OLT) in the presence of polarisation-dependent wavelength (PDW) shifting and phase errors [2]. This letter proposes the application of polarisation division multiplexing (PDM) [3] and colourless optical network units (ONUs), by employing reflective semiconductor optical amplifiers (RSOAs), to demonstrate full-duplex transmission over the formerly developed access network architecture [2] and subsequently increase bandwidth utilisation in both upstream and downstream. This is achieved by splitting the original continues waves (CWs) into orthogonal polarisations, one of which is modulated for downstream data transmission and the other fed to an RSOA for upstream transmission.…”