Advances in Optical Components and Subsystems for Wavelength-Division Multiplexing Communications Abdul Ahad S. Awwal, FELLOW SPIE Lawrence Livermore National Laboratory NIF Programs/NIF Project/Systems Engineering L-495, P. O. Box 0808 Livermore, California 94551 E-mail: awwal1@llnl.gov Achyut K. Dutta, FELLOW SPIE Banpil Photonics, Inc. 1299 Parkmoor Avenue San Jose, California 95126 E-mail: akdutta@banpil.com The implementation of optical networks is considered to be the only solution to meet the future demands in the communications area. Despite the economic downturn, we received an encouraging level of submissions for this special section. Some of the papers included here were initially presented in the SPIE Information Technologies and Communications ITCOM conference on active and passive components and also in the optical computing al- gorithms and architecture conference. This special section is comprised of 14 papers in the areas of wavelength- division multiplexing WDM components, systems and optimization, and applications. Between the source and the detector of an optical net- work, there are a number of important components tech- nologies that make up the optical WDM network. The WDM components papers included in this special section are on interconnections, waveguides, fiber amplifiers, dis- persion compensators, switching, add-drop multiplexers, clock recovery circuits, and detectors. In the first paper of this series, Kawai discusses interconnections between vertical-cavity surface emitting lasers VCSEL sources and fibers. Various alignment and packaging issues for developing interconnections between VCSEL sources and fiber waveguides are addressed in this paper. Waveguides consisting of heterostructured photonic crystals are the topic of the next paper by Ohtera et al. The authors de- scribe an autocloning technology that minimizes the propagation loss to 0.1 dB/mm. To reduce the propagation loss while increasing the capacity and distance of an op- tical network, laser amplifiers are essential. In the next paper, Wang and Dutta present a model for an Er-Yb double-clad amplifier. Theoretical as well as numerical analysis of amplifier gains for various pump and signal powers are presented. One of the critical components for achieving high-bit-rate communications systems is polar- ization mode dispersion PMD compensation. In the next paper, Khosravani quantifies the effect of PMD on system performance. The author presents ways to compensate for the PMD and minimize signal distortion. Distortion may degrade the performance of optical switching devices. In the next paper, by Pe ´ rennou et al., cross talk performance of an acousto-optic switch caused by distortion induced by multiple modulation signals is analyzed. They show a degradation of signal-to-noise ratio caused by these inter- modulation effects. The next three papers address components at the re- ceiving end of the transmission system. Resonances char- acterized by maximum transmission/absorption have been used successfully for creating passive optical components. The paper by I ˙ s ¸c ¸i et al. uses a microsphere resonator to produce dips in the transmission characteristics, which can subsequently be used to construct an add/drop multi- plexer. Add/drop multiplexers and demultiplxers at the re- ceiving end need a stable clock source to operate. The next paper by Zhu et al. presents a method of clock re- covery using a phase-locked loop in a Mach-Zehnder modulator. They show that it is possible to recover a 10- GHz clock from a 40- and 80-Gb/s data signal with only 50-fs jitter. Demultiplexer design using phased arrays is the topic of the last paper in the component category by Yehia and Khalil. Cascading small multimode interfer- ence phasar devices with high uniformity, they optimize a large structure with very low nonuniformity less than 0.2 dB. Special Section Guest Editorial 1016 Optical Engineering, Vol. 43 No. 5, May 2004 Downloaded From: https://www.spiedigitallibrary.org/journals/Optical-Engineering on 05 Jun 2019 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use