SFPs: B+ and C+ – What’s the Difference?

GPON stands for ‘Gigabit Passive Optical Network’. GPON is one of the key technologies that are being used in fiber-based (FTTx) access networks, including fiber to the home (FTTH), fiber to the business (FTTB), fiber to the curb (FTTC), etc.

GPON systems contain two main active transmission components:

  • Optical Line Termination (OLT)
  • Optical Network Termination (ONT) or Optical Network Unit (ONU)

Modern OLTs and ONT/ONUs use compact fiber optic modules to achieve Triple-play GPON services. These modules are known as GPON SFP transceivers.

What Is a GPON SFP?

SFP stands for ‘Small Form-factor Pluggable’. A GPON SFP is one type of Gigabit Optical Transceivers that are used in GPON system, which is compliant with ITU-T G.984.2 standard. It is a bidirectional module that has SC receptacle and works over simplex single-mode fiber optic cable.

A GPON SFP module transmits and receives signals of different wavelengths between the OLT at the ‘Central Office’ side and the ONT at the end users side. GPON SFPs utilize both the upstream data and downstream data by means of Optical Wavelength Division Multiplexing (WDM).

GPON SFP: Class B+ vs. Class C+

GPON SFP transceivers are categorized into GPON OLT SFP and GPON ONT SFP or GPON ONU SFP depending on the devices they are used in. And there are Class B+ GPON SFP and Class C+ GPON SFP.

The major differences between them are the transmit power and the receive sensitivity. The table below lists the TX power and RX sensitivity of Class B+ GPON SFP and Class C+ GPON SFP:

 SFP Module B+ C+
Type One fiber, Bi-directional Optical Module
Operating Wavelength TX: 1490nm
RX: 1310nm
Port Rate TX: 2.49 Gbit/sec
RX: 1.24 Gbit/sec
Minimum Output
Optical Power		 1.50 dBm 3.00 dBm
Maximum Output
Optical Power		 5.00 dBm 7.00 dBm
Maximum Receiver
Sensitivity		 -28 dBm -32 dBm
Optical Connector Type SC/PC
Optical Fiber Type Singlemode
Distance 20 KM
Overload Optical Power -8 dBm -12 dBm
Extinction Ratio 8.2 dB

 Benefits of Using GPON SFPs

Using a GPON SFP is considered a more convenient and cost-effective solution for the end customers. And it also reduces the devices that need to be provided by the Internet Service Provider (ISP). The SFP module has simplified the implementation of GPON services. It benefits both the service providers and the end users, making using GPON a cost-effective and efficient way of delivering high quality broadband services.

Harmonic - FIN - 10Gb SFP+ Based OLT

Features:

  • Compact & Efficient - Use 10Gb XGS/EPON optics to enable 10G PON solutions at a fraction of the cost of fixed-format OLT chassis
  • Standardized & Universal - Integrates into commercially available Ethernet switches or other Ethernet-enabled networking equipment with SFP+ sockets to become apart of any 10Gb PON network
  • Flexible deployment - Leverage Ethernet switch PON extension or co-location, or outside plant PON access bridge connectivity with support for variants of 10G PON and Remote PHY (R-PHY)