This is an introductory article for IC researchers and engineers to understand the main issues in current optical module and photonics integration. We will start from the bandwidth demand drivers, an analysis of the obstacles impeding bandwidth scaling, and other main issues for electrical and optical systems; then we will talk about the trend of the core IC's evolution which causes higher single channel bit rate. The way to increase the bit rate is not only dependent on the physical bandwidth of the transmitting channel, but also the order of the modulation. PAM4 will be briefly discussed here, since it has been standardized for many applications. We will introduce the configuration of current 400G/800G optical module and the coming photonics integration (Co-Package Optics). From there, we will discuss the trends in optoelectronic IC for recent optical module and photonics integration.