Abstract: Optical module is the core device in optical fiber transmission, and its index determines the overall performance of transmission. Optical module is the carrier for transmission between switch and equipment, and its main function is to convert the electrical signal of equipment into optical signal at the transmitting end. The basic structure consists of two parts: light emitting part and its driving circuit, and light receiving part and its receiving circuit. So what is the working principle of optical module and what are its applications? Let's look at the text together! What is the working principle of 1. optical module?

1, composition and principle of transmission channel

The transmitting channel of the optical module consists of an electrical signal input interface, a laser driving circuit, an impedance matching circuit and a laser component TOSA.

Its working principle is that the electrical interface input of the transmission channel completes the coupling of the electrical signal through the electrical interface circuit, then modulates it through the laser driving circuit in the transmission channel, and then performs impedance matching through the impedance matching part to complete the modulation and driving of the signal. Finally, it is sent to a laser (TOSA) for electro-optic conversion into optical signals for optical signal transmission.

2. Composition and working principle of receiving channel

The receiving channel of optical module consists of photodetector module ROSA (composed of photodiode (PIN) and transimpedance amplifier (TIA)), impedance matching circuit, limiting amplifier circuit and electrical signal output interface circuit.

Its working principle is that PIN converts the collected optical signal into a proportional electrical signal, TIA converts this electrical signal into a voltage signal, amplifies the converted voltage signal to the required amplitude, and transmits it to the amplitude limiting amplifier circuit through the impedance matching circuit to complete the re-amplification and shaping of the signal, improve the signal-to-noise ratio and reduce the bit error rate. Finally, the electrical interface circuit completes the signal output.

2. What are the applications of optical modules?

As the core device to realize photoelectric conversion in optical communication, optical module is widely used in data centers. Traditional data centers mainly use 1G/ 10G low-speed optical modules, while cloud data centers mainly use 40g/ 10g high-speed modules. With high-definition video, live broadcast, VR and other new application scenarios promoting the rapid growth of global network traffic, in order to cope with the future development trend, emerging application requirements such as cloud computing, IaaS services and big data put forward higher requirements for data transmission within data centers, which will give birth to optical modules with higher transmission rate in the future.

Generally, we mainly consider the application scenario, data transmission rate requirements, interface type, optical transmission distance (fiber mode, required optical power, center wavelength, laser type) and other factors when selecting optical modules.