An advanced digital communications infrastructure lies at the heart of our society, and supports every sector of the economy and our lives. Optical networks underpin this infrastructure and enable the Internet and cloud services which we all use. The promise of high-bandwidth, low-delay, secure, 5G mobile services, will not be possible without new, intelligent, adaptive optical networks. These networks must be able to dynamically provide capacity where and when it is needed, be fast, intelligent and secure.