The 5G industry chain is very broad, including components, main equipment, operators and downstream applications. Vacuum technology, as a modern basic science closely combined with applied science, has a wide range of applications in the 5G industry chain. From the preparation process of materials and devices in 5G base stations, vacuum leak detection of optical communication devices in the acceptance network, to the preparation of core components in 5G mobile phones, VR/AR equipment, and unmanned vehicles, vacuum technology is involved and widely used.

5G industry chain

From the hardware point of view, the 5G industry chain is mainly divided into two categories: 5G network and 5G terminal. As shown in Figure 1, 5G network can be divided into three areas, namely access network (including 5G base station and supporting power supply, antenna, radio frequency device, etc.), bearer network (including optical fiber, optical cable, optical module, optical communication equipment, etc.) and core network (including server, switching equipment, etc.). 5G terminal refers to the application end of 5G technology, including 3D communication, ultra-high-definition video, online AR/VR, cloud office, cloud games, etc., as well as a series of new application scenarios suitable for mobile Internet and Internet of Things, such as the Internet of Things, autonomous vehicles, industrial automation, electronic medicine, etc.

Application of vacuum technology in 5G bearer network

3.1 Optical passive devices

Optical passive device is an important part of optical fiber communication, with low insertion loss, high reliability and other characteristics, need to consume energy in the optical path, to achieve connection, shunt or combine, signal modulation, filtering and other functions. Optical passive devices have high requirements for vacuum sealing, and if there is leakage, it will affect its performance and accuracy. The leakage rate standard in the optical communication industry is less than 5×10 Pa·m3/s, so it is necessary to carry out leak detection. Because of the high leak detection accuracy of optical passive devices, helium mass spectrometry is used to replace traditional foam leak detection and pressure difference leak detection.

3.2 Thin Film Filter (TFF)

One advantage of fiber optic communications is that dozens of wavelengths can be transmitted simultaneously in a single fiber, called wavelength division multiplexing (WDM). The basic component of WDM transmission is optical filter, which can be realized by fiber fusion tapering (FBT), thin film filter (TFF), array waveguide grating (AWG) and optical comb filter. TFF and AWG are the two most commonly used WDM technologies. Devices based on thin film filters are widely used in both forward and intermediate wavelength division multiplexing schemes. At present, thin film filters are mainly produced by plasma assisted electron beam evaporation coating (IAD) or ion beam direct sputtering coating with light control. The film filter used in the 5G undertaking network, through the coating process, the SiO2 and Ti2O5 are alternately deposited on the surface of the filter, the deposition thickness is on the order of molecular layer, and the deposition layer varies from several layers to several hundred layers according to the need. The more layers, the closer the response spectrum curve is to the rectangle, the better the filter performance.