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UBC Theses and Dissertations

Automatic tuning circuits for Mach-Zehnder interferometer optical switches AlTaha, Mohammed Wadah


Optical communication networks are the foreseeable solution to meet the increasing demand for high data rates. An important part of a communication network is the network switch that facilitates the routing of data from sources to destinations, from a set of input streams to a set of output streams. Silicon photonics is poised to play a significant role in optical communication networks due to its suitability to build scalable and highly integrated photonic structures and systems, in addition to the use of established fabrication methods inherited from the electronics industry. One of the applications where silicon photonics can play a critical role is in implementing network switches. A Mach-Zehnder interferometer (MZI) is an optical device that is ideally suited to build network switches, as it can be dynamically controlled to achieve high-quality switching of optical signals. However, the performance of silicon photonics devices is sensitive to fluctuations in ambient temperature, fabrication tolerances, and device aging, and MZI devices are no exception. This work describes the factors that degrade the performance of an MZI switch, and then presents an electronic feedback system that monitors and automatically tunes a 1x2 MZI switch to its optimum operating point and compensate for the aforementioned performance-degrading factors. A design for a 2x2 MZI switch monitoring technique is also presented that uses feedforward interferometry to enable more efficient use of the MZI as a switch for two simultaneous optical inputs at different wavelengths, and an electronic feedback and tuning system for such switches is also demonstrated.

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