A gate electrode is formed in a trench reaching a drain region so as to leave a concave portion on the top of the trench. The logical interfaces can advantageously be used by the management system, management plane, andor control plane as one of restoration bandwidth or short-lived bandwidth-on-demand connections, such as sub-network connections or label switched paths. Further, the tunable delay line may be a voltage tunable delay line that includes a voltage tunable dielectric capacitor to facilitate the control of the tunable delay and the voltage tunable dielectric capacitor may include a layer of voltage tunable dielectric material positioned on a surface of a low loss, low dielectric substrate.