In addition to silicon photonics process technology, interface technology is also a very important part of the process. Figure 2 shows the development of communication interfaces for data centers. The first copper cable connectors were used to route the telecom signals from the circuit boards to the switch chips. Copper cables were replaced by fiber optic cables, and then pluggable optical transceiver modules were used to convert the optical signals into telecom signals for transmission over the circuit board wiring to the switch chip. Twinax cables could be used to reduce signal degradation. In order to further reduce signal transmission loss, the development of On-Board Optics (OBO) technology, which installs optical transceiver modules on circuit boards to reduce the signal transmission distance, and the establishment of the COBO organization by Microsoft, Cisco, Broadcom, Arista, and other companies in 2015 in order to develop relevant standards. If optical signal transceiver modules can be fabricated into wafers using silicon photonics technology and integrated with the switch chip on the carrier board by means of co-packaged optical (CPO) technology, signal transmission loss can be significantly reduced, and with the increase in transmission capacity, the distance between the switch and the optical engine chip can be reduced to 50 μm as it evolves from a 2.5D package to a 3D package.