Bing C. Wang

Experimental multiuser quantum key distribution network using a wavelength-addressed bus architecture

A six-user quantum key distribution network implemented on a bus topology is experimentally demonstrated. The network employs the BB84 protocol to transmit cryptographic keys encoded unto the phase states of highly attenuated laser light to distances of up to 31 km in a standard telecommunication-grade fiber. Each user on the network is assigned a unique wavelength for communication with the network server at a time. The measured quantum bit error rate and sifted key rate compare favorably with theoretical results

All-optical Lyot-filter-assisted flip-flop operation using a semiconductor optical amplifier

All-optical flip-flop operation using external optical control is demonstrated in a single semiconductor optical amplifier (SOA)-based fiber ring laser with an intracavity Lyot filter. Its operation is based on the principle of cross-gain saturation in the SOA. A unique feature of this flip-flop is its ability to be set and reset at multiple wavelength pairs of an auxiliary continuous wave control light that is injected into the fiber ring cavity; this, together with the wide wavelength tunability of the Lyot filter makes the flip-flop potentially useful in wavelength-division multiplexing applications. Bistable output at 1571 nm with a contrast ratio of 20 dB between the two output power states of the flip-flop using -3 dBm power of the external optical control is demonstrated

Demonstration of a six-user quantum key distribution network on a bus architecture

A six-user quantum key distribution over a bus network spanning a total distance 30km of standard telecommunication-grade fiber is demonstrated. Each user on the network has one unique address wavelength channel for establishing secure quantum cryptographic keys with a central network server. The address wavelengths are all in the C-band region of between 1553 nm and 1557 nm, making the system compatible with present fiber-optic communication network infrastructures. The quantum bit error rate measurements made on the network agree favorably with theoretically calculated values.

Comparison of three multiuser quantum key distribution networks

In this paper, we explore the performance of two network topologies: the optical ring network based on the Sagnac Interferometer and the wavelength routed optical network. The performance of all three networks for multiuser quantum key distribution are then computer simulated and compared by quantum bit error rate (QBER) analysis. To the best of our knowledge, this is the first time system level analysis have been performed on the suitability of various optical networks for quantum key distribution.

Quantum cryptography on multi-user network architectures

Quantum cryptography applies the uncertainty principle and the no-cloning theorem to allow to parties to share a secret key over an ultra-secure link. Present quantum cryptography technologies provide encryption key distribution only between two users. However, practical implementations of encryption key distribution schemes require establishing secure quantum communications amongst multiple users. This paper looks at some of the advantages and drawbacks of some common network topologies that could be used in sending cryptographic keys across a network consisting of multiple users. These topologies are the star, ring, and bus networks. Their performances are compared and analyzed using quantum bit error rate analysis. The paper also presents an experimental demonstration of a six-user quantum key distribution network implemented on a bus topology.

Fast tunable parallel optical delay line for communication and dynamic bandwidth allocation

Here we demonstrate that the fast tunable parallel optical delay line (FTDL) may be used to achieve high speed switching between optical time division multiplexing (OTDM) channels with multiple bit rates and explain how this capability can be used to implement dynamic bandwidth allocation (DBA). These capabilities can provide enhanced functionality to high speed LANs and optical interconnects. This is also useful for local area networks and metro area networks that support users that have different service demands.

Analysis of time-correlated single photon detection in a multi-wavelength quantum key distribution network

We evaluate time-correlated single photon detection as a key rate enhancement technique in a wavelength-addressed, auto-compensating quantum key distribution network by calculating the networks aggregate effective key rate.

Multi-user quantum cryptography

Quantum cryptography applies the uncertainty principle and the no-cloning theorem of quantum mechanics to provide ultra-secure encryption key distribution between two parties. Present quantum cryptography technologies provide encryption key distribution between two parties. However, practical implementations encryption key distribution schemes require establishing secure quantum communications amongst multiple users. In this talk, we survey some of the state of the art quantum encryption deployment in communication networks. We will also discuss some common topologies that are being considered for multi-user quantum encryption networks. The performance of the multi-user quantum key distribution systems is then compared for four different optical network topologies: the Sagnac-based fiber ring, the wavelength routed, the passive star and the bus network. Their performances are compared and analyzed using quantum bit error rate analysis.

All-optical packet processing and contention resolution using O-CDMA and optical bistability

The application of optical code division multiple access (O-CDMA) to the realm of all-optical packet switching is studied. O-CDMA encoded headers could be decoded by tuned delay lines and used to make routing decisions. By encoding only the header with O-CDMA codes, the bandwidth requirement on the O-CDMA encoder and decoder is lessened. Using the inherent threshold capability of bistable optical elements and wavelength routing, decoding of the packet headers and subsequent routing can be done all optically. Contention resolution is one of the challenges facing an all optical packet switching network. A scheme to reduce dropped packets due to collisions is presented by using optical bistability, four wave mixing and Mach-Zehnder interferometer (MZI) based optical switch with a loop delay line. This scheme, however, is limited to resolving contention between fix-length packets in a synchronous network.

Application of O-CDMA techniques to all optical packet header processing

This study reports the application of code division multiplexing (CDMA) in the creation of an all-optical packet switching network that would allow for high-speed, asynchronous packet switching. Such a system requires an all-optical packet header processor using fixed length packets. Possible methods for such encoding are discussed. These methods include synchronous prime codes, optical orthogonal codes (OOC), and a binary coding scheme.