Optical network is widely regarded as the backbone of the modern internet. Future optical network applications in the cloud era will be diverse and the demands of these new applications will not be limited to bandwidth. For instance, 4K/8K video traffic and AR/VR are sensitive to network latency, financial and industrial automation networks require high security, and cloud leased lines need to provide bandwidth-on-demand. Moreover, the massive growth in bandwidth requires 10 to 100-fold decrease in cost and power consumption per bit. Accompanying these technological challenges in the cloud era are opportunities for the optical networking industry.