All - Optical Pulse Regeneration in a Faraday Stabilized Ultrafast Nonlinear Interferometer

Modern fiber optic communications networks multiplex data onto many different channels, each with its own carrier frequency. In order to meet rising demand for high data rates, researchers have begun to consider methods to use the bandwidth of optical fibers more efficiently. In particular, more efficient use might come from operating fewer channels with each channel at a higher data rate, or perhaps even, ultimately, from operating one ultrafast time division multiplexed channel. High data rate optical channels already surpass the limits of electronic processing, which today cannot handle rates greater than 40 Gbit/s. Researchers must design the individual hardware elements, like address recognizers, demultiplexers, and regenerators, that will be necessary for any practical system. One promising idea is to make these devices all-optical. Already all-optical logical switching has been demonstrated at 100 Gbit/s and all-optical demultiplexing at hundreds of Gbit/s. But, in any long haul system, it is also necessary to develop optical pulse regenerators to regenerate data encoded as optical pulses before those pulses become too distorted to detect. This thesis investigates an all-optical pulse regenerator that reshapes, retimes, and amplifies optical data pulses. A Faraday polarization rotator mirror is used to make it much more polarization stable than other designs. The physical principle on which it is based, the nonlinear index of refraction, is a nearly instantaneous effect and, therefore, does not suffer from the speed limitations of modern electronics. We test the design for its switching window, bit error rates, and sensitivity to timing jitter to show its usefulness as an optical pulse regenerator. Thesis Supervisor: Erich P. Ippen Title: Professor Thesis Supervisor: Scott A. Hamilton Title: MIT Lincoln Laboratory Staff Member