GPON OLT SFP Class B+ Transceiver | 2.5G/1.25G | 28dB Budget | Tx 1490nm

Overview

The GPON OLT SFP Class B+ Transceiver is the widely adopted standard module for deploying Gigabit Passive Optical Networks (GPON). Designed to comply strictly with ITU-T G.984.2 specifications, this SFP module serves as the interface between the Service Provider’s Optical Line Terminal (OLT) and the subscriber’s passive optical distribution network (ODN).

Operating with a Class B+ optical power budget (approx. 28dB), this transceiver is engineered for standard network architectures. It delivers asymmetric data rates of 2.488 Gbps downstream and 1.244 Gbps upstream, utilizing a 1490nm DFB transmitter and a 1310nm APD receiver. It is the most cost-effective choice for networks with standard split ratios (typically 1:32) and distances up to 20km.

Key Features

• Standard Power Budget: Class B+ specification provides ~28dB optical budget, ideal for standard FTTH loops.
• Asymmetric Throughput: Supports 2.5Gbps downstream and 1.25Gbps upstream data links.
• Industry Standard: Fully compliant with ITU-T G.984.2 and Small Form-Factor Pluggable (SFP) MSA.
• Burst-Mode Receiver: Advanced 1310nm APD receiver designed to handle bursty upstream traffic from multiple ONUs.
• Digital Diagnostics: Features SFF-8472 DDM for real-time monitoring of voltage, temperature, and optical power.
• SC/UPC Interface: Simplex SC receptacle for easy connection to the ODN.

Applications

• Standard FTTH Access: Perfect for residential deployments utilizing 1:32 splitters.
• Cost-Sensitive Rollouts: The most economical option for greenfield projects where high-power Class C+ budgets are not required.
• Campus Networks: Reliable connectivity for educational or corporate campus passive optical LANs (POL).
• Maintenance Spares: Essential inventory for replacing legacy Class B+ modules in existing OLT chassis.

Specifications

Class B+ vs. Class C+

Choosing between Class B+ and Class C+ depends on your network design, specifically the loss generated by splitters and cable distance:

• Class B+ (~28dB Budget): The standard option. Typically supports 1:32 split ratios comfortably. Ideal for networks with lower insertion loss.
• Class C+ (~32dB Budget): The high-power option. Required for 1:64 split ratios or long-distance runs where extra signal strength is needed to overcome attenuation.

FAQ

1. What is the maximum split ratio for a Class B+ module?

While the theoretical limit often depends on total link loss, Class B+ modules are typically designed for 1:32 split ratios within a 20km radius. Using a 1:64 splitter with Class B+ may result in insufficient signal strength unless the distance is very short.

2. Can I replace a Class B+ module with a Class C+ module?

Yes. A Class C+ module is a direct upgrade. It provides stronger signal output and better sensitivity. If you are experiencing signal loss issues at the edge of a Class B+ network, upgrading the OLT optic to Class C+ is a common troubleshooting step.

3. Does this module work with any brand of OLT?

This is a generic standard GPON SFP. However, many OLT manufacturers (like Huawei, ZTE, Nokia, etc.) implement vendor-locking in their firmware. You must ensure the transceiver is coded specifically for your OLT brand.

4. What connector type does this use?

This module uses a Blue SC/UPC connector. Do not use Green SC/APC connectors, as the angled polish will create an air gap, causing high return loss and potential damage to the laser.

5. Is this module hot-swappable?

Yes, standard SFP modules are hot-swappable. However, in a live GPON environment, removing the OLT SFP will disconnect service for all ONUs/ONTs connected to that PON port.