Flexibility evaluation of hybrid WDM/TDM PONs

A hybrid WDM/TDM passive optical network (PON) is a promising candidate for next-generation optical access (NGOA) solutions. Several hybrid WDM/TDM PON architectures can be designed, each with a different degree of flexibility, going from fully static, over partially flexible to fully flexible architectures. A flexible architecture can serve several advantages, like energy efficiency, network migration and network extensibility. The more flexible architectures, however, are either more expensive, experience a higher power loss or are less secure. A question that arises is if a fully flexible architecture really needed. An important assessment parameter is the number of wavelengths required at a certain network load. In this paper, we introduce and compare two different flavors of flexibility based on the multicasting and switching functionality of different architectures. By exhaustive simulation, we study the gains of different variants of flexibility with different traffic models

Metropolitan all-pass and inter-city quantum communication network

We have demonstrated a metropolitan all-pass quantum communication network in field fiber for four nodes. Any two nodes of them can be connected in the network to perform quantum key distribution (QKD). An optical switching module is presented that enables arbitrary 2-connectivity among output ports. Integrated QKD terminals are worked out, which can operate either as a transmitter, a receiver, or even both at the same time. Furthermore, an additional link in another city of 60 km fiber (up to 130 km) is seamless integrated into this network based on a trusted relay architecture. On all the links, we have implemented protocol of decoy state scheme. All of necessary electrical hardware, synchronization, feedback control, network software, execution of QKD protocols are made by tailored designing, which allow a completely automatical and stable running. Our system has been put into operation in Hefei in August 2009, and publicly demonstrated during an evaluation conference on quantum network organized by the Chinese Academy of Sciences on August 29, 2009. Real-time voice telephone with one-time pad encoding between any two of the five nodes (four all-pass nodes plus one additional node through relay) is successfully established in the network within 60km.Comment: 9 pages, 2 figures, 2 table

Design and development of a 5 kV isolated solid state switch

A unique microcircuit intended for use as a shorting switch for large extraterrestrial solar cell arrays is described. The packaging design for the 5 kV isolated hybrid switch is different from most hybrid microcircuits in that it utilizes a compartmentalized plastic case (a portion of which is encapsulated), is not hermetic, and is designed for high voltage operation