Analysis of 80km 1550nm Gigabit SFP Single-mode Optical Module

1.What are dual-fiber and single-fiber optical modules?

Dual-fiber SFP optical modules are a commonly used type of 1G SFP optical module. They utilize a bidirectional transmission mechanism and have two independent channels or ports for sending and receiving data. One port is the transmit port, and the other is the receive port. Both transmission and reception require a single optical fiber connection. Common 1G dual-fiber optical module wavelengths include 850nm, 1310nm, and 1550nm.

Single-fiber SFP optical modules, also known as BIDI optical modules, utilize a unidirectional transmission mechanism and have only one port. This fiber port is used for both transmission and reception. The wavelength range of single-fiber SFP optical modules is between 1300nm and 1600nm.

2.What is the difference between dual-fiber and single-fiber SFP optical modules?

2.1 Transmission Distance

1G SFP optical modules use single-mode and multimode optical fibers to transmit data. Using multimode fiber, 1G SFP optical modules can transmit data up to 2 km, while single-mode SFP optical modules can reach up to 160 km.

BIDI single-fiber SFP optical modules can be used with either OS2 or multimode fiber cables. Transmission distances typically range from 2 km to 120 km.

2.2 Fiber Utilization

Dual-fiber SFP optical modules use a duplex interface (typically an LC connector), requiring at least two optical fibers for connection.

Single-fiber SFP optical modules can efficiently utilize a single optical fiber for bidirectional communication. If a 6-fiber fiber is used, all 6 fibers can be used simultaneously, rather than using 3 fibers in one direction and 3 fibers in the other. This means fewer fiber patch cords and patch panel ports are required, reducing the space needed for fiber management.

2.3 Using in pairs

Dual-fiber 1G SFP optical modules operate at 850nm, 1310nm, and 1550nm wavelengths. All SFP optical modules must be used in pairs. For common SFP optical modules, two SFP optical modules with the same wavelength should be connected together. For example, if an 850nm SFP optical module is used on one end, an 850nm SFP optical module must also be used on the other end.

For dual-fiber SFP optical modules, they must be deployed in pairs, just like common SFP optical modules. However, it is important to note that two duplex SFP optical modules with opposite wavelengths should be connected together. Common wavelengths for dual-fiber SFP optical modules include TX1310/RX1550nm, TX1550/RX1310nm, TX1490/RX1550nm, TX1550/RX1490nm, TX1310nm/Rx1490nm, and TX1490nm/Rx1310nm. If we use a TX1310/RX1550nm dual-fiber SFP optical module on one end, we must use a TX1550/RX1310nm dual-fiber SFP optical module on the other end.

3.1000BASE-ZX SFP 1550nm 80km DOM LC Transceiver SMF Module

YXFiber's YXF-GE-S55L-80D is a high performance, cost effective modules, which is supporting up to 1.25Gbps, and transmission distance up to 80km on SM fiber. The transceiver consists of two sections: The transmitter section incorporates a laser driver and a 1550nm DFB laser. The receiver section consists of a PIN photodiode integrated with a transimpedance preamplifier (TIA) and a Limitting Amplifier. The module is hot pluggable into the 20-pin connector. The high-speed electrical interface is base on low voltage logic, with nominal 100Ohms differential impedance and AC coupled in the module.

The optical output can be disabled by LVTTL logic high-level input of TX_DIS. Transmit Fault (Tx_Fault) is provided to indicate that the module transmitter has detected a fault condition related to laser operation or safety. Loss of signal (RX_LOS) output is provided to indicate the loss of an input optical signal of receiver. A serial EEPROM in the transceiver allows the user to access transceiver monitoring and configuration data via the 2-wire SFP Management Interface. This interface uses a single address, A0h, with a memory map divided into a lower and upper area. Basic digital diagnostic (DD) data is held in the lower area while specific data is held in a series of tables in the high memory area.

4.Q&A

Q1:Can we use SFP transceivers in SFP+ slots?

In many cases, SFP+ ports can accept SFP transceivers, but the speed will be reduced to 1G instead of 10G. However, SFP+ transceivers cannot be inserted into SFP ports because SFP+ does not support speeds below 1G. Additionally, almost all SFP+ ports on Cisco switches support SFP, but many SFP+ ports on Brocade switches only support SFP+ transceivers.

Q2:Can 1000Base-LX SFP transceivers be used with 1000Base-SX fiber?

Generally speaking, they are not interchangeable. 1000Base-SX and LX are two fiber standards that operate at different wavelengths. 1000Base-LX SFP transceivers typically operate at a 1310nm wavelength and use single-mode fiber connections, while 1000Base-SX typically operates at an 850nm wavelength and use multimode fiber connections.

Q3:Can multiple SFP ports be aggregated?

Absolutely. Link aggregation offers benefits such as increased bandwidth, redundancy, and load balancing. This ensures that if a link fails, another available link can be immediately switched. Therefore, SFP port aggregation is essential for enterprise networks where performance and security are paramount. However, please note that before connecting an SFP port, ensure that the switch is configured for link aggregation. Failure to do so may result in a network loop.