Graeme J. Pendock

Transmission performance of high bit rate spectrum-sliced WDM systems

We simulate transmission of a spectrum-sliced WDM channel operating at high bit rates (e.g., 622 to 2488 Mb/s). We calculate the bit error rate using the non-Gaussian statistics of thermal light sources that are commonly used in spectrum slicing and account for the effects of fiber dispersion. We evaluate the tradeoff in optical slice linewidth between signal-to-excess optical noise ratio and dispersion penalty in spectrum-sliced WDM systems, and determine the channel slicewidth that minimizes transmission penalty for a given link length and bit rate. We compare our simulations against the measured performance of a 1244 Mb/s channel over 20 km of fiber. The results in this paper provide useful information for the design of spectrum-sliced WDM networks.

Photonic code-division multiple-access communications

Abstract Photonic code-division multiple access schemes have been proposed since the 1970s. Although there are many published proposals for new coding schemes, there are many less experimental verifications of these schemes, even fewer reports of successful data transmission, and no commercial systems. We attempt to explain the key factors that have led to the current state-of-the-art. In so doing, we describe the fundamental principles of matched filtering and noise in photonic CDMA schemes. We survey important developments and show how various schemes are related. We review recent experimental advances and compare the published experimental and theoretical performance for different schemes. We discuss the current major issues and likeb future directions.

Optical performance monitoring in coherent optical OFDM systems

Optical performance monitoring is an indispensable feature for optical systems and networks. In this paper, we propose the concept of optical performance monitoring through channel estimation by receiver signal processing. We show that in coherent-optical-orthogonal-frequency-division- multiplexed (CO-OFDM) systems, critical optical system parameters including fiber chromatic dispersion, Q value, and optical signal-to-noise ratio (OSNR) can be accurately monitored without resorting to separate monitoring devices.

All-optical 1300-nm to 1550-nm wavelength conversion using cross-phase modulation in a semiconductor optical amplifier

All-optical 1300-nm to 1550-nm wavelength converters may be important components in lightwave networks which use both the 1300-nm and the 1550-nm low-loss transmission windows of silica optical fiber. We describe a new all-optical 1300-nm to 1550-nm wavelength converter, based on cross-phase modulation in a 1300-nm semiconductor optical amplifier. We demonstrate operation of the wavelength converter at 1.25 Gb/s, and present bit-error rate measurements. The wavelength converter demonstrated here potentially operates at high speed, with low input power and low polarization-sensitivity.

Capacity of coherence-multiplexed CDMA networks

Summary form only given. We have presented calculations of the capacity and number of users that can be supported by CDMA networks using coherence multiplexing with differential detection. These calculations are supported by the measured performance of our demonstration optical network.

Increasing the transmission capacity of coherence multiplexed communication systems by using differential detection

We experimentally verify the impact of optical beat noise on a coherence-multiplexed optical communication system. We then show that optical beat noise can be significantly reduced, and transmission capacity increased, by using differential detection. We demonstrate transmission at low bit error rate of four coherence multiplexed channels, each having a capacity of 1 Gb/s, over 8 km of dispersion-shifted fiber. This is the highest capacity demonstration to date for any code-division multiplexing scheme.

Hybrid coherence multiplexing/coarse wavelength-division multiplexing passive optical network for customer access

We propose a passive optical network for customer access based on a hybrid coherence multiplexing/coarse wavelength-division multiplexing (WDM) technique. Coherence multiplexing provides asynchronous multichannel transmission, and coarse WDM provides bidirectional transmission. A cost-shared superfluorescent source is used for downstream transmission, and inexpensive lightemitting diodes are employed for upstream transmission. Asynchronous two channel transmission at 40 Mb/s per channel is demonstrated for both upstream and downstream. Our experiment indicates that upstream and downstream aggregate bit rates of 640 Mb/s are feasible based on current commercially available components.

Noise in coherence-multiplexed optical fiber systems.

We present measurements, in good agreement with theory, of the noise power spectral density at the outputs of a coherence-multiplexed system employing a low-coherence source. We investigate correlations in the noise between outputs and confirm that differential detection can be used to improve the signal-to-noise ratio of sensor and communication systems based on coherence multiplexing.

Experimental Demonstration of Optical Performance Monitoring in Coherent Optical OFDM Systems

We experimentally demonstrate optical performance monitoring through optical channel estimation in coherent optical OFDM systems without the need for separate monitoring devices. The monitoring results of OSNR, Q-factor, fiber chromatic dispersion, and PMD are presented.

Improved chromatic dispersion monitoring using single RF monitoring tone.

We demonstrate an improved chromatic dispersion monitoring technique using a single RF monitoring tone. Compared to conventional techniques using a single RF monitoring tone, our proposed technique is able to monitor the sign of the residual dispersion and doubles the monitoring range. Our proposed technique utilizes the RF fading caused by chromatic dispersion and a two-detector dispersion monitor setup, where a dispersion offset is inserted before one of the detectors. The observed monitoring error is less than +/-35 ps/nm over a 1300 ps/nm monitoring range. A small power penalty less than 0.5 dB is observed due to the addition of the RF monitoring tone. Our technique is more than twice as accurate as the conventional technique.