Optical packet switching promises to bring the flexibility and efficiency of the Internet to transparent optical networking with bit rates extending beyond that currently available with electronic router technologies. New optical signal processing techniques have been demonstrated that enable routing at bit rates from 10 Gb/s to beyond 40 Gb/s. In this article we review these signal processing techniques and how all-optical wavelength converter technology can be used to implement packet switching functions. Specific approaches that utilize ultra-fast all-optical nonlinear fiber wavelength converters and monolithically integrated optical wavelength converters are discussed and research results presented.
Advanced transceivers generally require a multi-lane approach, which necessitates the integration of multiple subcomponents. The use of mature, generally available, and low-cost single element components such as electro-absorption modulated lasers, silica planar lightwave circuits, and direct-modulated distributed feedback lasers, integrated in a hybrid fashion and optically aligned with micro-electromechanical systems provides a practical solution. Standard bonding tools with positioning tolerances of approximately ten micrometers are used to populate a silicon microbench that incorporates micro-adjustable elements with various optical components. After diebonding, the positions of coupling microlenses are adjusted to correct for the poor diebond accuracy, and then these movable elements are fixed in place with built-in heaters and solder. The net result is highly uniform, manufacturable, and low loss coupling between the optical elements, with typically 1 to 2 dB of loss. Using this packaging technique, we demonstrate a 40 Gb/s four-channel (4 × 10 Gb/s) DML-based transceiver and a 100 Gb/s ten-channel (10 × 10 Gb/s) EML-based transceiver for 10 and 80 km reach respectively.
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