Gigabit single-mode single-core fiber optic module

The general parameters and basic knowledge of Gigabit optical transceivers are difficult to master. The following will introduce the general parameters of the optical module and the basic knowledge of the optical module.

Gigabit single-mode fiber optic module

Common parameters of optical modules

1. Center wavelength

1) 850nm (MM, multi-mode, low cost, but short transmission distance, usually only 500M);

2) 1310nm (SM, single mode, large loss during transmission, small dispersion, generally used for transmission within 40KM);

3) 1550nm (SM, single mode, small loss during transmission, but large dispersion, generally used for long-distance transmission above 40KM, and can directly transmit 120KM without relay);

2. Transmission rate

Currently, there are four commonly used data transmission bits per second (unit: bps): 155Mbps, 1.25Gbps, 2.5Gbps, and 10Gbps. Transfer rates are generally backward compatible. Therefore, the 155M optical module is also called FE (100M) optical module, and the 1.25G optical module is also called GE (gigabit) optical module. This is the most widely used module in optical transmission equipment. In addition, its transmission rate in optical fiber storage system (SAN) is 2Gbps, 4Gbps and 8Gbps;

3. Transmission distance

Optical signals are transmitted directly without repeater amplification. Gigabit single-mode single-core optical fiber modules usually have the following specifications: multi-mode 550m, single-mode 15km, 40km, 80km, 120km, etc.

In addition to the above three main technical parameters, the optical module also has the following basic concepts, which only need to be briefly understood:

1) Laser category

The laser is the core component of the optical module. It injects current into the semiconductor material and emits laser light through photon oscillation and gain in the cavity.

2) Loss and dispersion

Loss is the loss of light energy due to absorption and scattering of the medium and light leakage as light propagates in the fiber. As the transmission distance increases, this part of the energy is dissipated at a certain rate.

3) Transmitting optical power and receiving sensitivity

The transmit optical power refers to the output optical power of the light source at the transmit end of the optical module. Receive sensitivity refers to the minimum received optical power of an optical module under a certain bit error rate.

4) The service life of the optical module

International unified standard, 50,000 hours of uninterrupted work, 7×24 hours of continuous work (equivalent to 5 years);

5) Optical fiber interface

SFP optical modules are all LC interfaces. All GBIC optical modules are SC interfaces. Other interfaces include FC and ST.

6) Working temperature

0°+70°C; Storage temperature: -45°+ 80°C; Working voltage: 3.3V; Working level: TTL/PECL/CML/LVDS.