The optical tapped delay line (OTDL) is a parallel-to-serial converter that splits a single picosecond (ps)  pulse into N+1 pulses.  N of these pulses represent data, while one acts as a timing pulse for use in the demultiplexer.  The OTDL delays the first data bit by 9.4 ps with respect to the timing pulse, and it delays each successive data bit by an additional 6.25 ps. Solid-state multiple-quantum-well (MQW) modulators incorporated in each data path permit the dynamic encoding of the optical pulse stream. A prototype OTDL with N = 4 and a burst rate of 160 Gb/s is being developed with silica-on-silica technology.  Hybrid integration and optical mode field conversion between the active semiconductor devices and the passive silica waveguides are the primary fabrication issues.

Publications & Presentations

J. T. Simmons, B. R. Washburn, T. G. Ulmer, W. S. Astar, S. E. Ralph, R. P. Kenan, and C. M. Verber, “Femtosecond pulse performance of an integrated optical tapped delay line,” 1999 Annual Meeting of the Optical Society of America, Santa Clara, CA, Sept. 26-30, 1999

For more information, contact Dr. Stephen Ralph at stephen.ralph@ece.gatech.edu.