Quantum key distribution (QKD) systems can generate unconditionally secure common keys between remote users. Improvements of QKD performance, particularly in key generation rate, have been required to meet current network traffic. A high-speed QKD system should be equipped with low-loss receivers with high visibility, highly efficient photon detectors with small dark count probability. A solution to these issues is to employ planar lightwave circuit (PLC) interferometers, single photon detection circuits and modules, together with multi-wavelength channels transmission using wavelength division multiplexing (WDM) technique.

This paper proposes Photonic Core Node based on a 2.56-Terabit/s opto-electronic switching fabric, which can economically handle the rapidly increasing multimedia traffics, such as Internet traffic. We have successfully developed the first prototype of Photonic Core Node. The prototype consists of a single-stage full-crossbar opto-electronic switching fabric, super-packet buffers for input queuing, and a desynchronized-round-robin scheduler. The switching fabric is upgradable up to 2.56 Tb/s, and employs wavelength-division-multiplexing techniques, which dramatically reduce the total number of optical switching elements down to one-eighth the number of those used in a conventional switching fabric. The super-packet buffer assembles 16 ATM cells routed to the same output port into a single fixed-length packet. The super-packet-switching scheme drastically reduces the overhead of optical switching from 32 to 2.9%, although it tends to decrease effective throughput. The desynchronized-round-robin scheduler maintains nearly 100% effective throughput for random traffic, recursively resolving the contention of connection requests in one scheduling routine while keeping fairness in a round robin manner. The proposed Photonic Core Node can accommodate not only ATM switching but also WDM optical path grooming/multiplexing, and IP routing by using IP input buffer interfaces, because optical switches are bit-rate/format-independent.

This paper proposes Photonic Core Node based on a 2.56-Terabit/s opto-electronic switching fabric, which can economically handle the rapidly increasing multimedia traffics, such as Internet traffic. We have successfully developed the first prototype of Photonic Core Node. The prototype consists of a single-stage full-crossbar opto-electronic switching fabric, super-packet buffers for input queuing, and a desynchronized-round-robin scheduler. The switching fabric is upgradable up to 2.56 Tb/s, and employs wavelength-division-multiplexing techniques, which dramatically reduce the total number of optical switching elements down to one-eighth the number of those used in a conventional switching fabric. The super-packet buffer assembles 16 ATM cells routed to the same output port into a single fixed-length packet. The super-packet-switching scheme drastically reduces the overhead of optical switching from 32 to 2.9%, although it tends to decrease effective throughput. The desynchronized-round-robin scheduler maintains nearly 100% effective throughput for random traffic, recursively resolving the contention of connection requests in one scheduling routine while keeping fairness in a round robin manner. The proposed Photonic Core Node can accommodate not only ATM switching but also WDM optical path grooming/multiplexing, and IP routing by using IP input buffer interfaces, because optical switches are bit-rate/format-independent.

A new kind of optical local area network (LAN), using a demand assign wavelength division multiple access (DA-WDMA) scheme, has been proposed. The proposed LAN consists of two parts; an ordinary standardized LAN and an overlaid network using wavelength division (WD) channels. The proposed network can provide bit-rate independent communication channels on the ordinary LAN without limiting the capacities for the other channels. It also exhibits upgrade possibilities from present standardized networks. An access controller, which consists of software in addition to the ordinary LAN controller, a digital signal processor (DSP) etc., was developed for DA-WDMA control. The network node operation has been demonstrated using guided-wave acousto-optic (AO) mode converters as a tunable wavelength add-drop multiplexer (ADM).

This paper reviews next generation optical access network standardization activities, focusing on 10-Gbps class TDM PON, and introduces key technologies for their co-existence with deployed systems.