Winston I. Way

Large signal nonlinear distortion prediction for a single-mode laser diode under microwave intensity modulation

The large-signal nonlinear distortions from a directly-modulated single-mode GaAlAs laser diode are closely predicted by using a large-signal equivalent circuit model. Criteria for determining intrinsic parameter values are described. The simulations are done in the time domain and then transformed to the frequency domain by FFT. Second harmonics, two-tone third-order intermodulation, multicarrier intermodulation, and intermodulation due to two arbitrarily separated tones have all been simulated and match well with corresponding measured results.

Fiber nonlinearity limitations in ultra-dense WDM systems

Transmission performance of ultra-dense 2.5- and 10-Gb/s nonreturn-to-zero intensity-modulated direct-detection wavelength-division-multiplexing systems in various single-mode fibers is investigated. Fundamental limiting factors and their remedies by using optimum dispersion compensation for periodically amplified systems in C band are presented.

Multichannel single-sideband SCM/DWDM transmission systems

To understand the transmission limitation of multiple narrow single-sideband subcarrier-multiplexed (SSB/SCM) signals, this paper first presents a closed-form analysis to predict Mach-Zehnder intensity modulator-induced composite triple beat (CTB), and linear-fiber-dispersion-induced composite second-order (CSO) and CTB distortions. To combine SSB/SCM with dense-wavelength-division-multiplexing (DWDM) systems, analytical and numerical tools, which are not constrained by any wavelength spacing and modulation frequencies, are used to analyze cross-phase modulation-induced crosstalk. All the analytical and numerical results are verified by computer simulations. Several multichannel SSB/SCM/DWDM systems with transport capacities of 10 or 20 Gb/s per wavelength, with a wavelength spacing of 25, 50, and 100 GHz, are also studied in this paper to understand the fundamental transmission limitations.

A self-routing WDM high-capacity SONET ring network

A dynamic control mechanism, based on subcarrier-multiplexed pilot-tones and acoustooptic tunable filters, is proposed for wavelength routing in a high-capacity wavelength division multiplexed (WDM) SONET interoffice ring network. The authors experimentally verified the network concept and discussed different network applications for bursty data traffic and continuous voice/video traffic.<<ETX>>

A novel passive protected SONET bidirectional self-healing ring architecture

Among SONET ring alternatives, the four-fiber bidirectional self-healing ring architecture (BSHR/4) has the highest available capacity and can work with todays systems with minimum change. A cost-effective implementation for a BSHR/4 which uses a totally passive ring as the protection ring of the BSHR/4 is presented. The ring uses a SONET ring to carry working traffic and a passive ring to carry protection traffic in case of network component failures. The passive ring, which is composed of optical switches and optical amplifiers, is essentially an optical add-drop protection ring. The optical signal add-drop is controlled by SONET add-drop multiplexers using existing SONET self-healing protocols. A SONET control scheme for this implementation is also discussed. The proposed BSHR/4 not only has a significant cost advantage over conventional implementations, but also can easily evolve from any two-fiber ring, with a minimum capital investment and offering twice the capacity. >

Dynamic range and switching speed limitations of an N/spl times/N optical packet switch based on low-gain semiconductor optical amplifiers

Two important system performance limitations-dynamic range and switching speed-of an integrated packet switch fabric based on low-gain semiconductor optical amplifiers (SOAs) have been examined by using cascaded blocks of an SOA model, which includes transient effect, nonlinear pulse distortion effect, and amplified spontaneous emission (ASE) noise. Low-gain SOAs were used to minimize ASE noise considering that no optical filters can be integrated in an SOA-based switch fabric. The system performance with and without a narrowband optical filter at the receiver were both studied. By assuming fixed-wavelength transmitters and no optical filter can be used at the receiving end owing to the unpredictability of arriving packet wavelengths, our simulation results indicate that the dynamic ranges of 4/spl times/4 and 8/spl times/8 SOA-based packet switches at 2.5 Gb/s can only be about 3.2 and 0.8 dB, respectively. However, at 155 Mb/s, even without a receiving-end optical filter, the dynamic range of each switch size can be increased by more than 17 dB as compared to the cases of 2.5 Gb/s. Note that the dynamic ranges were estimated under the conditions of a bit error rate (BER) /spl les/10/sup -9/ and a pulse distortion ratio /spl les/30%. We have also shown that, when an optical filter with a 1 nm bandwidth was used at the receiving end to simulate (1) a circuit-switched condition where the center wavelength of the filter can be adjusted according to the established circuit, or (2) a packet-switched condition where each receiver has a wavelength demultiplexer and a detector array, the dynamic range of 4/spl times/4 and 8/spl times/8 switches can be increased to 16.3 and 14 dB, respectively, at 2.5 Gb/s.

Optical power limiting amplifier and its applications in an SONET self-healing ring network

The authors demonstrate an erbium-doped optical power limiting amplifier (OLA), study its noise characteristics, and discuss its application in the protection rings of a four-fiber, SONET self-healing interoffice ring network. System and network considerations are also presented. The feasibility of the network was tested by a system experiment using an OLA for up to 200-km conventional single-mode fiber transmission at a bit rate of 1.244 Gb/s (OC-24 line rate). >

Reduction of nonlinear distortion in MQW semiconductor optical amplifier using light injection and its application in multichannel M-QAM signal transmission systems

By using an external light-injected multiple-quantum-well (MQW) semiconductor optical amplifier (SOA), we have demonstrated a 100-km optical fiber link that transports 77 channels of 64-QAM signals. This is equivalent to a system capacity of 2.3 Gb/s, while using a laser bandwidth of only 550 MHz. Under a requirement of carrier to noise and nonlinear distortion ratio of 30 dB per channel, the 1310-nm gain-peaked SOA input dynamic range was increased from 0 to 9 dB due to an injected light with 8.8 dBm and a wavelength of 1284 nm.

Optimum architecture for M×N multicast switch-based colorless, directionless, contentionless, and flexible-grid ROADM

Targeting on flexible-grid/CDC ROADM for coherent systems, we present an M×N multicast switch-based architecture which can reduce the cost of a conventional architecture by up to 50%.

Using Superimposed ASK label in a 10-Gb/s multihop all-optical label swapping system

A novel optical-label-swapping technique is proposed, experimentally verified, and theoretically analyzed in this paper. The technique superimposes a low-speed amplitude-shift-keying (ASK) label on top of a high-speed dc-balanced-line-coded ASK payload. A multihop long-distance transmission experiment using a recirculating loop has been successfully demonstrated, and an experimental record is set when compared with other optical-label-swapping techniques.