William S. Wong

All-Optical Network Consortium-ultrafast TDM networks

We describe recent results of the Advanced Research Projects Agency (ARPA) sponsored Consortium on Wideband All-Optical Networks which is developing architectures, technology components, and applications for ultrafast 100 Gb/s time-division multiplexing (TDM) optical networks. The shared-media ultrafast networks we envision are appropriate for providing low-access-delay bandwidth on demand to both future high-burst rate (100 Gb/s) users as well aggregates of lower-rate users (i.e., a heterogeneous user population). To realize these goals we are developing ultrafast network architectures such as HLAN, described here, that operate well in high-latency environments and require only limited processing capability at the ultrafast bit rates. We also describe results on 80-Gb/s, 90-km soliton transmission, 100-Gb/s soliton compression laser source technology, picosecond short-pulse fiber ring lasers, picosecond-accuracy optical bit-phase sensing and clock recovery, all-optical injection-locked fiber figure-eight laser clock recovery, short-pulse fiber loop storage, and all-optical pulse width and wavelength conversion.

Breaking the limit of maximum effective area for robust single-mode propagation in optical fibers

We propose and demonstrate a novel approach in optical fiber design in which the optical waveguide is formed by a ring of large air holes surrounding a solid silica core. With an appropriate choice of the geometrical configuration, robust single-transverse-mode propagation with a record effective area of 1417 microm2, verified by various methods, was demonstrated. A breakthrough was made toward the development of practical ultra-high-power fiber lasers as we observed negligible loss of the fiber at bending diameters as small as 15 cm.

Self-switching of optical pulses in dispersion-imbalanced nonlinear loop mirrors.

We report a novel nonlinear filter that transmits and shortens incident pulses while rejecting cw background as well as resonant continuum. A relative extinction of 22dB is reported for the cw background.

Gigahertz-repetition-rate mode-locked fiber laser for continuum generation

We report direct generation of <500-fs pulses at a 1-GHz rate from a self-starting passively mode-locked fiber laser by regeneratively synchronizing the pulses with a phase modulator. The pulses are amplified and passed through a dispersion-decreasing fiber and a normal-dispersion supercontinuum fiber. The resulting continuum is wider than 350 nm.

Stability and timing maintenance in soliton transmission and storage rings

Abstract Several compensation techniques, including intensity-dependent absorption/gain, filtering, and phase- and amplitude-modulation, are considered for use in high bit rate (100+ Gb/s) pulse storage rings and transmission. We propose novel memory devices utilizing intensity-dependent absorption/gain. Other compensation methods include filtering and amplitude- and phase-modulation, which provide restoring forces to suppress frequency- and timing shifts of pulses. The relative merits of these compensation techniques are evaluated perturbatively. We consider the influence of amplifier noise, Raman self-frequency shift, and third-order dispersion. In the absence of compensation, Raman timing fluctuations grow with the fifth power of distance, and may exceed Gordon-Haus jitter at approximately 40 Gb/s. The compensation techniques can eliminate the asymptotic growth of timing variance.

20-GHz optical storage loop/laser using amplitude modulation, filtering, and artificial fast saturable absorption

An optical pulse storage ring, storing 1.76 kb of 20 Gb/s pulsed, on-off keyed, noise-generated data has been demonstrated. Stable operation is achieved using amplitude modulation, filtering, and artificial fast saturable absorption. Patterns with widely varying densities of ONEs have been stored, including patterns with all ONEs (harmonic mode-locking).<<ETX>>

50-Gbit / s optical pulse storage ring using novel rational-harmonic modulation.

50-Gbit/s, 3.8-kbit packets of optical return-to-zero data have been stored in a unidirectional fiber storage ring by use of a novel modulation scheme in which the ratio of the fundamental modulation frequency to the cavity fundamental frequency is rational (nonintegral). The modulation technique should be applicable to lasers and to soliton transmission.

Additive-pulse mode-locking/limiting storage ring.

A pulse-storage ring is an optical device capable of memorizing a pulse sequence of 0s and ls. The soliton ring of Nakazawa et al. [Electron. Lett. 29, 729 (1993)] with nearly unlimited transmission distance is such a device. We propose and experimentally demonstrate a different type of pulse-storage ring that uses intensity-dependent interferometric action to create a stronger intracavity transmission differential between the 0s and the ls.

All-optical storage of a 1.25 kb packet at 10 Gb/s

An all-optical pulse storage ring storing a 1.25 kb packet at 10 Gb/s is demonstrated. Optical modulation of the transmission of a semiconductor diode amplifier via cross-gain saturation provides timing stability in the ring.<<ETX>>

Photon statistics of amplified spontaneous emission noise in a 10-Gbit/s optically preamplified direct-detection receiver.

We verify experimentally, over a dynamic range of 55 dB in the probability distribution, that the amplified spontaneous emission noise of the 0s from an optically preamplified receiver is degenerate Bose-Einstein distributed. Using the noise parameters extracted from the experiment, we are able to predict the sensitivity of a 10-Gbit/s direct-detection receiver.