Janet Jackel

Optical networking for quantum key distribution and quantum communications

Modern optical networking techniques have the potential to greatly extend the applicability of quantum communications by moving beyond simple point-to-point optical links and by leveraging existing fibre infrastructures. We experimentally demonstrate many of the fundamental capabilities that are required. These include optical-layer multiplexing, switching and routing of quantum signals; quantum key distribution (QKD) in a dynamically reconfigured optical network; and coexistence of quantum signals with strong conventional telecom traffic on the same fibre. We successfully operate QKD at 1310 nm over a fibre shared with four optically amplified data channels near 1550 nm. We identify the dominant impairment as spontaneous anti-Stokes Raman scattering of the strong signals, quantify its impact, and measure and model its propagation through fibre. We describe a quantum networking architecture which can provide the flexibility and scalability likely to be critical for supporting widespread deployment of quantum applications.

Spectrally efficient optical CDMA using coherent phase-frequency coding

We demonstrate feasibility of a spectrally efficient wavelength-division-multiplexing-compatible optical code-division multiple-access system using 16 phase-locked laser lines within an 80-GHz tunable window as frequency bins and an ultrahigh frequency resolution spectral phase encoder-decoder. Coding and decoding using binary [0, /spl pi/] phase chips were demonstrated for four users at 2.5 Gb/s, and a single coded signal was separated from four copropagating signals, with bit-error rate <10/sup -9/.

Fully programmable ring-resonator-based integrated photonic circuit for phase coherent applications

A novel ring-resonator-based integrated photonic chip with ultrafine frequency resolution, providing programmable, stable, and accurate optical-phase control is demonstrated. The ability to manipulate the optical phase of the individual frequency components of a signal is a powerful tool for optical communications, signal processing, and RF photonics applications. As a demonstration of the power of these components, we report their use as programmable spectral-phase encoders (SPEs) and decoders for wavelength-division-multiplexing (WDM)-compatible optical code-division multiple access (OCDMA). Most important for the application here, the high resolution of these ring-resonator circuits makes possible the independent control of the optical phase of the individual tightly spaced frequency lines of a mode-locked laser (MLL). This unique approach allows us to limit the coded signals spectral bandwidth, thereby allowing for high spectral efficiency (compared to other OCDMA systems) and compatibility with existing WDM systems with a rapidly reconfigurable set of codes. A four-user OCDMA system using polarization multiplexing is shown to operate at data rates of 2.5 Gb/s within a 40-GHz transparent optical window with a bit error rate (BER) better than 10/sup -9/ and a spectral efficiency of 25%.

A theoretical investigation of dynamic all-optical automatic gain control in multichannel EDFA's and EDFA cascades

We present a detailed theoretical analysis of the gain dynamics of erbium-doped fiber amplifiers (EDFAs) that have been gain-clamped using a ring laser structure and of gain-stabilized EDFA chains. We examine and analyze the effects of attenuator level in the optical feedback path, switching speed, number of channels dropped or added and the choice of lasing wavelength on the stabilization of the individual EDFA. In particular, we look at the transient power excursions and relaxation oscillations experienced by surviving channels when the number of channels passing through an EDFA changes. Using this analysis as a guide, we present and compare two different approaches to chain stabilization. We highlight the robustness of each approach, show some of their limitations and advantages, and comment on the impact on multiwavelength communication systems.

Evolution of the acousto-optic wavelength routing switch

Through the efforts of many research groups and consortia over the last several years, the acousto-optic tunable filter has evolved into a device capable of high-performance wavelength-selective optical switching and wavelength routing in dense WDM systems. The distinguishing feature of the AO switch is its ability to sustain many independent coexisting passbands, thus allowing in a simple integrated-optic device, the parallel processing capability of much more complex designs. The AOTF has also found a role in active gain equalization of optically amplified networks. In this paper, we review the design of both hybrid and fully integrated AO switches. The theory of operation is reviewed and recent advances in passband engineering are described which have made low-crosstalk, wavelength misalignment-tolerant switches to be possible. Advanced issues such as mechanisms of interchannel crosstalk and its reduction are also discussed. Both device and system issues are covered.

Architectures and Protocols for Capacity Efficient, Highly Dynamic and Highly Resilient Core Networks [Invited]

The Core Optical Networks (CORONET) program addresses the development of architectures, protocols, and network control and management to support the future advanced requirements of both commercial and government networks, with a focus on highly dynamic and highly resilient multi-terabit core networks. CORONET encompasses a global network supporting a combination of IP and wavelength services. Satisfying the aggressive requirements of the program required a comprehensive approach addressing connection setup, restoration, quality of service, network design, and nodal architecture. This paper addresses the major innovations developed in Phase 1 of the program by the team led by Telcordia and AT&T. The ultimate goal is to transfer the technology to commercial and government networks for deployment in the next few years.

Observation of nonlinear optical transmission and switching phenomena in polydiacetylene‐based directional couplers

Nonlinear optical transmission and switching phenomena have been observed in directional coupler devices fabricated from soluble polydiacetylenes. Effects due to both slow thermal nonlinearities and ultrafast (picosecond) electronic nonlinearities were identified. At the operating wavelength of 1.06 μm used here, the ultrafast electronic nonlinear phenomena originated from intensity‐dependent changes in the imaginary part of the refractive index due to two‐photon absorption effects.

Experimental investigation of quantum key distribution through transparent optical switch elements

Quantum key distribution (QKD) enables unconditional physical layer security for the distribution of cryptographic key material. However, most experimental demonstrations have relied on simple point-to-point optical links. In this paper we investigate the compatibility of QKD with reconfigurable optical networks. By performing the first tests of QKD transmission through optical switches, we study if there are impairment mechanisms other than switch insertion loss that impact the sifted and error corrected secret bit yield. Three types of transparent optical switch elements are investigated including lithium niobate (LiNbO/sub 3/), microelectromechanical systems (MEMS), and optomechanical. We show that QKD can be extended beyond point-to-point links to switched multinode architectures including protected ring networks to enhance quantum channel availability.

Acousto-optic tunable filters (AOTFs) for multiwavelength optical cross-connects: crosstalk considerations

Acousto-optic tunable filters (AOTF) have been investigated as a potential basis for multiwavelength cross-connects in optical networks. In this paper, we discuss crosstalk issues, some of which are common to other cross-connect technologies, and some of which are unique to the AOTF, which will determine the suitability of the AOTF technology for this application. In particular we show how the interactions between wavelength channels make the AOTF sensitive to switch architectures, we conclude that significant performance improvements will be required to diminish crosstalk if the AOTF is to be useful in any but small-size cross-connects, even when spare and wavelength dilation are used.

Fabrication of channel waveguides in polydiacetylenes: composite diffused glass/polymer structures

We report the fabrication of single‐mode channel waveguides in spun films of polydiacetylenes using an inverted rib design. These robust guides consist of a planar layer of the polydiacetylene spun on a glass substrate in which high‐index channels have been defined by ion exchange. Models of such guides show that most of the optical field of the guided wave is confined to the polymer layer, with the high‐index glass channels providing lateral confinement. End‐fire coupling of 1.06, 1.15, 1.32, and 1.55 μm light into the composite guides resulted in single‐mode guiding with the light confined to the polymer layer. This approach to waveguide formation should be applicable to a wide range of polymeric materials.