Introduction to the types of 10G EPON optical modules

EPON is a passive optical network based on Ethernet and an important part of optical access technology. PON network consists of OLT (optical line terminal), ODN (passive splitter network) and ONU (optical network terminal).

The OLT device is at the core of the network topology. It accesses multiple service networks upward and multiple users' services downward through ODN. It is an important node for service aggregation and distribution.

At the same time, OLT realizes the control, management, ranging and other network management functions of the user end equipment ONU. The OLT device is the core of PON network regardless of its network location or network functions.

PON optical module is a high-performance optical module for PON system, which conforms to ITU-T G.984.2 standard and multi-source protocol (MSA). It uses different wavelengths to send and receive signals between OLT (optical line terminal) and ONT (optical network terminal).

In order to achieve compatibility with 1G EPON, 10G EPON does not use the downlink wavelength of 1490nm used by 1G EPON system. At the same time, consider avoiding analog video wavelength (1550nm) and OTDR test wavelength (1600-1650nm). IEEE 802.3av standard selects 1577nm as the wavelength of 10Gbit/s downlink signal (wavelength range 1574-1580nm).

Therefore, in the downlink direction, 10Gbit/s signals and 1Gbit/s signals are WDM. In the upstream direction, the wavelength of the 1Gbit/s signal is 1310nm (1260~1360nm), and the IEEE 802.3av standard stipulates that the upstream wavelength of the 10Gbit/s signal is 1270nm (1260~1280nm). There is overlap between the two, so the WDM mode cannot be used, and the dual rate TDMA mode can only be used. 10G EPON OLT can find 10G/10G ONU at the same time. 10G/1G ONU and 1G/1G ONU can coexist.

At present, 10G EPON optical modules on the market can be divided into OLT (optical line terminal) optical modules and ONU (optical network unit) optical modules according to different insertion devices. In addition, 10G EPON has two packaging types: XFP and SFP+. Here are the optical modules of 10G EPON.

1. 10G EPON XFP OLT optical module (asymmetric/symmetric)

The optical module adopts pluggable XFP package, with SC optical port, downlink rate of 10.3125Gbps, uplink rate of 1.25Gbps&10.3125Gbps, working wavelength of Tx1577nm/Rx1270nm (symmetric type), and Tx1270nm/1310nm (asymmetric type).

2. 10G EPON SFP+OLT optical module (asymmetric type)

The optical module is packaged with pluggable SFP+, with SC optical port. The downlink rate is 10.3125Gbps&1.25Gbps, and the uplink rate is 1.25Gbps&10Gbps. The operating wavelength is Tx1577nm/Rx1270nm, and the maximum transmission distance is 20km.