With increasing demand for data and video from home, business and wireless, higher and higher bandwidth for the Optical Access Network is required.

FSAN (Full Service Access Network) initiated a working group to work on NG-PON2 in 2010 in collaboration with ITU-T. TWDM (TDM/WDM: Time Division Multiplexing/Wavelength Division Multiplexing) was selected as the preferred technology for NG-PON2.The first recommendation of NG-PON2 general requirements was published by ITU-T (G.989.1) in late 2012, and the physical layer requirements (ITU G.989.2) was approved in December 2014.

The major requirements (physical layer) of NG-PON2 can be summarized as

• Downstream 40 Gb/s, upstream 10Gb/s , per OLT port
• 4 wavelengths per OLT port, both upstream and downstream (option for future upgradeable to 8 wavelengths)
• 100GHz channel spacing
• Wavelength plan, downstream: 1596 ~ 1603nm; upstream: 1532~1540nm
• Colorless ONU
• Support ≥ 64 ONUs per port (256 ONUs or more also of interest)
• Max loss >=29dB (Class N1)
• Compatible with legacy PON infrastructure (> 40 km reach)
• Smooth Migration
• Legacy PON co-existence (G-PON and/or XG-PON1)
• Smooth migration from a legacy PON on a per ONU basis
• Support for multiple applications on the same ODN (e.g. residential + business + backhaul)
• PtP WDM overlay channels were added for easier handling of mobile front-haul applications

Optoplex started to work closely with major GPON equipment suppliers (the leading companies in FSAN) to develop colorless ONU for NG-PON2 since the very beginning when FSAN initiated the working group. With proprietary technology, Optoplex developed a periodic tuning filter – cost effective and small form factor for easy integration with APD/TIA, suitable for NG-PON2 application, and then a 10Gbps Tunable ROSA (10G APD/TIA integrated with a tunable filter). This 10G tunable ROSA has been successfully verified by many major companies in past three years and then deployed in field by a couple of T-1 service providers recently. The tunable ROSA used in NG-PON2 is illustrated in Figure 3.

• 100GHz tunable filter with tuning range of 4 channels
• InGaAs APD for 10Gbps
• High gain 12kΩ transimpedance pre-amplifier
• Differential data output
• High sensitivity: < -28dBm
• Low power consumption: < 0.4W

• Digital fiber optic receiver for access networks for telecom
• High speed optical data networks
• Fiber in the loop (FTTx)
• SFP+/XFP/300pin MSA optical transceiver

Notes:

1. 1600 ~ 1625nm is the required operating wavelength for the 4 TWDM channels of NGPON2. Optoplex tunable filter can work in a much wider wavelength range from 1500 ~ 1650nm
2. The maximum working temperature of wavelength tuner is 120°C