First, the basic knowledge of the optical module

1 .Definition.

Optical module. that is, the optical transceiver module

2.Structure.The optical transceiver module is composed of an optoelectronic device, a functional circuit and an optical interface, and the optoelectronicdevice includes two parts: transmitting and receiving.

The transmiting part is: an electric sinal inputting a certain code rate s processed by an interna drving chip to drive a semiconductor laseILD)or a light emiting diode (LED) to emit a modulated ight signal of a coresponding rate, and an optical power automatic control circuitisinternally provided therein. The output optical signal power remains stableThe receiving partis an optical signal input module of a certain code rate is converted into an electrical signal by the photodetecting diodeAfter the preamolifer the electrical sional of the corresponding code rate is output, and the output signal is generally PECL level. At the sametime, an alarm signal is output after the input optical power is less than a certain value

3.the parameters and significance of the optical module

Opfical modules have many impotant optoelectronic technical parameters. However, for the two hot-swappable opfical modules. GBIC and

SFP. the following three parameters are most concerned when selecting.

(1) Center wavelength

In nanometers (nm), there are currently three main types

850nm (MM, multimode, low cost but short transmission distance, generally only 500M), 1310nm (SM, single mode, large loss duringtransmission but small dispersion, generally used for transmission within 40KM).1550nm (SM, single mode,low loss during transmission but large dispersion, generaly used for long-distance transmission above 40KM. andcan directly transmit 120KM without relay);

(2) Transmission rate

The number of bits (bits) of data transmitted per second, in bps.

There are currently four types commonly used: 155 Mbps, 1.25 Gbps, 2.5 Gbps, 10 Gbps, and the like. The transmission rate is generallyackward comoatible Therefore the 155M otcal module is als caled the EF (100 Mbps onfcal modul and the 1 25G ontcal module is

also called the GE (Gigabit) optical module.This is the most widely used module in optical transmission equipment. In addition, its transmission rate in fber storage systems (SAN) is2Gbps,4Gbps and 8Gbps.

(3) Transmission distance

The optical sional does not need to be relayed to a distance that can be directly transmitted, in kilometers also called kilometers, km). Opticamodules generally have the following specifications: mulimode 550m, single mode 15km, 40km, 80km, and 120km, and so on.