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SFP working principles and applications of optical modules

Time : 2021-11-18 Hits : 1

In the field of communication, the electrical interconnect transmission of metal wires is greatly limited by electromagnetic interference, inter-code crossingand loss, wiring cost and other factors.  


Light transmission was born.  Optical transmission has the advantages of high bandwidth, large capacity, easy integration, low loss, good electromagnetic compatibility, no crosstalk, light weight, small size, so optical output is widely used in digital signal transmission.  


Basic structure of an optical module  

Among them, optical module is the core component in optical fiber transmission, and its indicators determine the overall performance of transmission.  An optical module is used for transmission between a switch and a device. It converts electrical signals of the device into optical signals at the terminal.  The basic structure is composed of two parts: "light-emitting 

element and its driving circuit" and "light-receiving element and its receiving circuit". The optical module consists of two channels, namely sending channel and receiving channel.  


The composition and working principle of the transmitting channel  

The transmission channel of optical module consists of electrical signal input interface, laser drive circuit, impedance matching circuit and laser element TOSA.  


Its working principle is the electrical interface transport channel, complete electrical signals through electrical interface circuit of coupling, and then to modulation of laser driver circuit of transmission channel, and then through the impedance matching part of the impedance matching complete signal modulation and drive, finally send laser (TOSA) electro-optic converts light signals for optical signal transmission. 


The composition and working principle of receiving channel  

The receiving channel of the optical module consists of ROSA (composed of photoelectric detection diode (PIN) and transresistance amplifier (TIA)), impedance matching circuit, amplifying circuit and electrical signal output interface circuit.  


It works by converting the optical signals collected by PIN into electrical signals in proportion.  TIA converts this electrical signal into voltage signal, amplifies the converted voltage signal to the required amplitude, and transmits it to the limiter through the impedance matching circuit. The amplification circuit 

completes the re-amplification and shaping of the signal, improves the signal-to-noise ratio and reduces the bit error rate, and finally completes the signal output by the electrical interface circuit.  


SFP Module Application  

As the core component of photoelectric conversion in optical communication, optical module is widely used in data center.  Traditional data centers mainly use 1G/10G low-speed optical modules, while cloud data centers mainly use 40G/100G high-speed optical modules.  With the rapid growth of global 

network traffic driven by new application scenarios such as HD video, live broadcasting and VR, higher requirements are put forward for emerging applications such as cloud computing, Iaa S service and big data. Optical modules with higher transmission rates will be generated for internal data transmission in data centers in the future.  

When selecting an optical module, consider the application scenario, data transmission rate requirements, interface type, optical transmission distance (optical fiber mode, required optical power, central wavelength, and laser type).