Fiber to Home (FTTH) technology provides an ideal platform for high-speed broadband access to home users, and brings huge benefits to fixed access networks and advanced wireless networks. PON (Ethernet Passive Optical Network), as a leading technology in fiber to home deployment, is now widely used in network deployment. The widespread application of PON Ethernet passive optical networks cannot be separated from PON optical modules, as they are an important component of PON systems. Gigac will introduce some practical PON optical module knowledge in this article.
What is a PON optical module? What are the functions and roles of PON optical modules?
PON optical module is a high-performance optical module used in PON systems, also known as PON module, which complies with the 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).
The development of PON technology
PON technology was proposed in 1995, and the GPON technology standard was proposed in September 2002, which was approved by ITU in March 2003. Nowadays, PON technology with speeds above 10Gbit/s is the focus of research at the Gigac Technology Center, and the Gigac Technology Center has identified TWDM PON as the future technology choice for NG-PON2. At present, the PON technologies used for broadband access mainly include EPON and GPON, which adopt different standards. The future development is towards higher bandwidth, such as the development of 10G EPON/10G GPON technology in EPON/GPON, which will result in a higher improvement in bandwidth.
Characteristics of PON optical modules
There are four transmission protocols for PON optical modules: APON (ATM PON), BPON (Broadband Passive Optical Network), EPON, and GPON. Currently, the latter two are widely used; The working temperature is 0 ° C-70 ° C or -20 ° C-70 ° C; 1310/1490 burst mode transmitter and continuous mode receiver (ONU); 1490/1310 continuous mode transmitter and burst mode receiver (OLT); The transmission distance can reach 10km or 20km; The interface type is duplex SC or SC/APC; It can avoid electromagnetic interference and lightning effects from external devices; Reducing the failure rate of lines and external equipment improves system reliability while reducing maintenance costs.
What are the types of PON optical modules?
1. SFF/SFP/SFP+and XFP optical modules
According to different packaging types, PON optical modules can be divided into several types: SFF (small-sized), SFP (small-sized pluggable), SFP+(enhanced small-sized pluggable), or XFP (small-sized pluggable).
2. OLT optical module and ONU optical module
According to the different types of plug-in devices, PON optical modules come in two types: OLT optical modules and ONU (Optical Network Unit) optical modules, both of which are SFP packaging types. However, OLT optical modules are more complex than ONU optical modules because each OLT optical module must transmit signals to 64 ONU optical modules.
3. GPON optical module and EPON optical module
According to technical standards, PON optical modules can be divided into two types: GPON (Gigabit Passive Optical Network) optical modules and EPON (Ethernet Passive Optical Network) optical modules. GPON optical module is a high-performance and cost-effective optical module used for 2.5Gpbs serial optical data communication applications. The advantage of this optical module is that it can ensure no harm to the eyes in any fault situation. The EPON optical module comes in SFP, XFP, and SFP+packaging forms, with a transmission distance of up to 20km, and the receiver part has a sealed preamplifier and a limiting amplifier with LVPECL compatible differential output.
Application of PON optical modules
The increasing demand for internet access in applications such as video conferencing and cable television has led to the widespread deployment of fiber to the home. PON, as a leading technology in the field of fiber-optic to home applications, is also widely used in access networks for PDH SONET, ATM/SDH, data communication, and telecommunications networks.
Differences between PON optical modules and traditional optical modules
1. Traditional optical modules
When using traditional optical modules, the optical signal transmission mode is point-to-point (P2P), and the modules should be used in pairs, using one or two optical fibers for transmission (duplex or simplex); Fiber optic link losses include attenuation, dispersion, fiber optic connection insertion losses, etc; Has a long transmission distance, up to 200km; Due to cost factors, it is less used for access networks and mainly applied to backbone networks.
2. PON optical module
When using PON optical modules, the transmission mode of optical signals is point-to-point (P2MP), and the modules are not used in pairs; Fiber optic link losses include attenuation, dispersion, division ratio losses, fiber optic connection insertion losses, etc; The transmission distance is shorter than traditional modules, with a distance of only 20km; Mainly used for access networks.
The challenges of PON optical modules
Although PON optical modules provide satisfactory performance in FTTH applications, there are still some challenges in the following areas:
Burst mode optical transmission technology for uplink;
High output optical power and high sensitivity OLT from CO (central office) are required to connect optical splitters and fiber optic losses in user premises;
The Optical Line Terminal (OLT) RX needs to be able to receive data packets with significant differences in optical power and phase alignment;
Rapid rise/fall time to minimize protection time during transmission.
conclusion
GPON optical modules have better performance than EPON optical modules, but EPON optical modules have more cost advantages. Both have their own advantages and disadvantages, and can coexist and complement each other. If you have high requirements for bandwidth, multi service, QoS, and security, as well as customers who use ATM technology as the backbone network, we recommend that you choose GPON optical modules. If you want to save costs and do not have high requirements for QoS and security, EPON optical modules may be more suitable for you.
