Driving optical network innovation by extensively using transparent domains

Optical transparency giving full-flexibility to the end systems with respect to transmission rate, coding, format and protocol has been an early vision in optical networking. Depending on the timing period, channel transparency such as in WDM channels or timed transparency such as in optical burst or packet switching applies. Operation of current optical networks is completely based on a small number of transmission standards of electronic transmission equipment both in the high-bit core and metro networks and the low-bit optical access networks. The use of optical switching in form of crossconnects is very limited. An increasing trend can be observed in the usage of optical add-drop units. In access networks, radio-over-fiber to increase the flexibility of the allocation of radio frequency carriers in mobile communication cells has attracted global interest. The paper presents the properties, merits, limits as well as networking and application issues.